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Review
Polysaccharide Nanocrystals-Based Chiral Nematic Structures: From Self-Assembly Mechanisms, Regulation, to ApplicationsClick to copy article linkArticle link copied!
- Huan LiuHuan LiuBiofuels Institute, School of the Environment and Safety Engineering, School of Emergency Management, Jiangsu University, Zhenjiang 212013, ChinaNational Forestry and Grassland Administration Key Laboratory of Plant Fiber Functional Materials, Fuzhou 350108, ChinaMore by Huan Liu
- Zhihao WangZhihao WangBiofuels Institute, School of the Environment and Safety Engineering, School of Emergency Management, Jiangsu University, Zhenjiang 212013, ChinaMore by Zhihao Wang
- Haowei XinHaowei XinBiofuels Institute, School of the Environment and Safety Engineering, School of Emergency Management, Jiangsu University, Zhenjiang 212013, ChinaMore by Haowei Xin
- Jun LiuJun LiuBiofuels Institute, School of the Environment and Safety Engineering, School of Emergency Management, Jiangsu University, Zhenjiang 212013, ChinaMore by Jun Liu
- Qianqian WangQianqian WangBiofuels Institute, School of the Environment and Safety Engineering, School of Emergency Management, Jiangsu University, Zhenjiang 212013, ChinaMore by Qianqian Wang
- Bo Pang*Bo Pang*E-mail: [email protected]Department of Food Science and Technology, National University of Singapore, 2 Science Drive 2, Singapore, 117542, SingaporeDepartment of Materials and Environmental Chemistry, Stockholm University, Stockholm 10691, SwedenMore by Bo Pang
- Kai Zhang*Kai Zhang*E-mail: [email protected]Sustainable Materials and Chemistry, Department of Wood Technology and Wood-Based Composites, University of Göttingen, Göttingen 37077, GermanyMore by Kai Zhang
ACS Nano
Cite this: ACS Nano 2024, 18, 34, 22675–22708
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Abstract
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Chiral architectures, one of the key structural features of natural systems ranging from the nanoscale to macroscale, are an infinite source of inspiration for functional materials. Researchers have been, and still are, strongly pursuing the goal of constructing such structures with renewable and sustainable building blocks via simple and efficient strategies. With the merits of high sustainability, renewability, and the ability to self-assemble into chiral nematic structures in aqueous suspensions that can be preserved in the solid state, polysaccharide nanocrystals (PNs) including cellulose nanocrystals (CNCs) and chitin nanocrystals (ChNCs) offer opportunities to reach the target. We herein provide a comprehensive review that focuses on the development of CNCs and ChNCs for the use in advanced functional materials. First, the introduction of CNCs and ChNCs, and cellulose- and chitin-formed chiral nematic organizations in the natural world, are given. Then, the self-assembly process of such PNs and the factors influencing this process are comprehensively discussed. After that, we showcased the emerging applications of the self-assembled chiral nematic structures of CNCs and ChNCs. Finally, this review concludes with perspectives on the challenges and opportunities in this field.
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License Summary*
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Copyright © 2024 The Authors. Published by American Chemical Society
1. Introduction
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Nature, as the ever-greatest magician, has created numerous materials with intricate structures in elegant ways. Chiral structure is one of the most fascinating architectures, well-developed in various natural systems spanning from subnanoscale to galactic scale, such as angstrom-sized neutrino and amino acids, nanosized proteins, DNA, and polysaccharides, micrometer-scale bacteria, macroscopic living systems (e.g., seashell, plants, and horns), and even our light-year scale galaxy. (1−3) Notably, such a structure is closely related to the physical, chemical, and biological properties of its chiral counterparts, especially those at the molecular and supramolecular levels. For instance, isomers of chiral small molecule drugs generally exhibit different biological activities and pharmacological functions, although they share the same chemical formula. (4) The chirality of the sugars found in a hairpin-structured RNA minihelix (l-ribose or d-ribose) is the key factor that determines whether the amino acids loaded onto the RNA are left- or right-handed. (5) Learning nature’s design principles involved in these fascinating structures offers a possibility for constructing functional materials.
Among these chiral systems, chiral architectures composed of various polysaccharides, in particular cellulose and chitin, provide excellent paradigms for disclosing their formation mechanism and developing chiral artificial materials considering their inherent merits, such as easy availability, low cost, and high abundance. (14,15) Currently, various top-down, bottom-up self-assemblies, and combinations of both approaches have been explored for the manufacture of polysaccharide-based chiral structures. Compared to top-down fabrication approaches, the bottom-up self-assembly strategy using polysaccharides nanocrystals (PNs), in particular, cellulose nanocrystals (CNCs) and chitin nanocrystals (ChNCs) as nanobuilding blocks, has established itself as the leading approach for fabricating chiral materials because of its nanoscale precision, and high time- and cost-efficiency. (16) Rapid development has been witnessed in the realm of self-assembly of PNs regarding the elucidation of their self-assembly mechanism and the exploration of their applications over the past two decades (Figure 1). (17−29) These studies greatly promote the development of chiral materials, including but certainly not limited to those derived from polysaccharides, thus requiring comprehensive analysis to identify future challenges and opportunities.
Figure 1
Figure 1. Schematic diagram showing the main contents of this review from the introduction and self-assembly of PNs to the potential applications of the self-assembled materials. Responsive photonic materials. Reprinted with permission from ref (6). Copyright 2017 Wiley-VCH. Reprinted with permission under a Creative Commons Attribution (CC BY) License from ref (7). Copyright 2019 Springer Nature. Photonic encryption. Reprinted with permission from refs (8) and (9). Copyright 2020 Wiley-VCH. Copyright 2023 Wiley-VCH. Mesoporous materials. Reprinted with permission from refs (10) and (11). Copyright 2010 Springer Nature. Copyright 2012 Wiley-VCH. Others. Reprinted with permission from ref (12). Copyright 2020 Wiley-VCH. Reprinted with permission under a Creative Commons Attribution (CC BY) License from ref (13). Copyright 2022 Springer Nature.
Several recent articles have reviewed the self-assembly of CNCs, with most of them focusing on their optical applications. (18,30−32) However, to the best of our knowledge, very few articles have summarized and systematically discussed the self-assembly of polysaccharide nanocrystals containing CNCs and ChNCs in a comprehensive scope. Thus, in this review, we began with the introduction of CNCs and ChNCs followed by the chiral nematic structures in nature. We then comprehensively discussed the mechanism of the self-assembly of CNCs and ChNCs, and the regulation methods. Next, applications of the self-assembled materials were introduced. Finally, we present our viewpoints on some challenges that need to be further addressed in the area of PNs self-assembly. The purpose of this review is to offer perspectives on the development of PNs-based self-assembled functional materials with diverse possibilities in chiral photonic crystals, sensors, and other highly adaptable multifunctional systems.
1.1. Introduction to Cellulose Nanocrystals (CNCs)
Cellulose, a highly functionalizable polymer with many existing industrial applications, occupies a prominent position in abundant organic raw materials due to its availability, biocompatibility, biological degradability, and sustainability. (37) It is a linear natural polymer composed of d-anhydro-glucose (C6H11O5) repeating units linked by 1,4-β-d-glycosidic linkages at the C1 and C4 positions (Figure 2a). There are three hydroxyl groups on each monomer, which result in the formation of a network of intra- and intermolecular bonds along the cellulose chain. (38,39) Besides, a network of van der Waals connections is established between the chain layers. The van der Waals interactions and the intermolecular hydrogen bonds between hydroxyl groups and oxygens of adjacent molecules promote the arrangement and stabilization of the cellulose molecules into a highly organized structure through crystalline packing. (33) It gives rise to structures having a width of 2–20 nm and a length of up to a few micrometers, with crystalline rods along the microfibril axis. These crystalline domains are interspersed with amorphous regions in the fibril structure, where the cellulose molecules cannot be stabilized laterally through H-bonding. Compared with the crystalline parts, the density of the amorphous domains is much lower, which facilitates the hydrogen bond formation with other molecules, for instance, water. Note that for some plant species, these amorphous regions can account for up to 50% of the structure, while in bacterial cellulose and cellulose extracted from some algae the crystalline domains, they account for almost 100% of the fibril. Moreover, these crystalline domains are almost defect-free. (40)
Figure 2
Figure 2. a) Schematic diagram showing the isolation of CNCs from plants. Reprinted with permission from ref (33). Copyright 2021 Wiley-VCH. TEM images of CNCs extracted from b) bacterial cellulose, c) wood pulp, and d) tunicate. b) Reprinted with permission from ref (34). Copyright 2023 Elsevier. c) Reprinted with permission from ref (35). Copyright 2020 American Chemical Society. d) Reprinted with permission from ref (36). Copyright 2024 Elsevier.
As a result of the hierarchically ordered structures and semicrystalline properties of cellulose, different kinds of nanocellulose including CNCs, also with other designations, e.g., cellulose nanowhiskers (CNWs) and nanocrystalline cellulose (NCC), as well as cellulose nanofibers (CNFs) can be isolated from cellulose by employing suitable strategies. (41,42) Of note, bacterial cellulose (BC), also termed bacterial nanocellulose or microbial cellulose, is generally produced by aerobic bacteria and has an inherent nanoscale dimension.
Among these cellulose nanomaterials, rod-like or needle-shaped CNCs have attracted significant interest from various research communities due to their distinctive structural characteristics and outstanding physicochemical properties, including nontoxicity, stiffness, low density, optical transparency, adaptable surface chemistry, biocompatibility, biodegradability, and sustainability, just to name a few. (43,44) Acid hydrolysis utilizing concentrated mineral acids, such as sulfuric acid, phosphoric acid, and hydrochloric acid, is currently the most commonly employed process to extract CNCs. (45−47) However, some limitations such as relatively high corrosion of equipment, excessive degradation of cellulose, and high water consumption greatly hinder the practical applications of these mineral acid hydrolysis-based processes. Recently, to address these limitations, many other techniques such as organic acid hydrolysis, enzymatic hydrolysis, ionic liquid treatment, subcritical water hydrolysis, oxidation method, mechanical refining, and combined processes have been developed to prepare CNCs. (48−52) Generally, according to the sources of cellulosic raw materials, e.g., wheat straw, cotton linters, algal cellulose, microcrystalline cellulose, bacterial cellulose, wood pulp, and tunicates, and the isolation approaches employed, CNCs with varying morphologies, dimensions, and crystalline properties could be obtained (Figure 2b–d). The dimensions of CNCs range from 100 nm to several micrometers in length and several to tens of nanometers in width, while the crystallinity of CNCs varies from 50% to 88%.
1.2. Introduction to Chitin Nanocrystals (ChNCs)
Chitin, the second most abundant natural polysaccharide following cellulose, is commonly found in the cell walls of yeast and fungi, insect cuticles, shrimp shells, and tendons and shells of lobster and crab, and has the characteristics of biodegradability, biocompatibility, nontoxicity, and antibacterial activity as well as low immunogenicity. (57−59) In 1811, chitin was extracted from mushrooms by the French botanist Henri Braconnot. (60) Chitin is a linear polymer comprising repeated N-acetyl-d-glucosamine units linked with β-1,4-glycosidic bonds (Figure 3a), and it is the most prevalent biopolymer containing nitrogen on the planet. (61,62) Chitin generally exists in nature in the form of ordered, crystalline microfibrils. The crystalline structures of chitin consist of three distinct forms, i.e., α-chitin, β-chitin, and γ-chitin. These structures exhibit variations in the arrangement and packing of chitin molecular chains. In the cuticles of arthropods and fungi, chitin is in the α-form, showing antiparallel structures. β-Chitin with parallel arrangements was mainly extracted from marine fish cartilage. However, γ-chitin is a mixture of α-chitin and β-chitin, characterized by both parallel and antiparallel chain structures. (33,63,64) Among the three types of crystals, α-chitin is the most prevalent and stable form, with the highest degree of crystallinity and the strongest intermolecular interactions.
Figure 3
Figure 3. a) Schematic illustration of the hierarchical organization of the exoskeleton of lobster. Reprinted with permission from ref (53). Copyright 2022 Wiley-VCH. b) TEM image of ChNCs extracted from the chitin of crab shell through acid hydrolysis. Reprinted with permission from ref (54). Copyright 2020 American Chemical Society. c) TEM image of ChNCs extracted from the chitin of crab shell through TEMPO-mediated oxidation. Reprinted with permission from ref (55). Copyright 2022 Elsevier. d) TEM image of ChNCs after periodate oxidation from shrimp chitin. Reprinted with permission from ref (56). Copyright 2021 Royal Society of Chemistry.
ChNCs, the crystalline components isolated from chitin sources at the nanoscale, are also rod-shaped structures with an average length of about 100–1500 nm and a diameter of about 5–80 nm. (61) Similar to the preparation of CNCs, the primary approach for preparing ChNCs is also acid hydrolysis. During the acid hydrolysis process, the hydrolysis and dissolution of chitin primarily occur in the amorphous regions, resulting in the formation of rod-like ChNCs (Figure 3a). (61,65) Figure 3b shows the ChNCs extracted from crab shell using the acid hydrolysis method. Except for acid hydrolysis, many other approaches, such as 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation (Figure 3c), (55) periodate oxidation (Figure 3d), (56) ammonium persulfate (APS) oxidation, (66) and mechanical disintegration, (67) have also been applied to isolate ChNCs. ChNCs have a high surface area and aspect ratio as well as low density while retaining the original chitin properties. Until now, ChNCs have been widely utilized in water purification, packaging products, cosmetics, food industry, biomedicine electronics, and other fields.
1.3. CNCs-Based Chiral Nematic Structures in Nature
Chiral nematic structure, also referred to as a helicoidal structure, has chirality at the molecular level and a nonsuperimposable helicoidal superstructure at the macroscale level. (68) As shown in Figure 4a, the building blocks of the chiral nematic structure exhibit spatial helical orientation along the helical axis. Since the helical direction of the director cannot be superimposed with its mirror image, this structure becomes chiral. The arrangement of helicoidal building blocks is usually characterized by two parameters, i.e., twist handedness and helical pitch (P). (74) The handedness characterizes how the direction of the molecules rotate along the helical axis, which can be clockwise (referred to as left-handed) or counterclockwise (referred to as right-handed). Helical pitch is the distance over which the director of chiral nematic liquid crystalline rotates a full 360°. (75)
Figure 4
Figure 4. a) Helicoidal arrangement of molecules in chiral nematic liquid crystals. Reprinted with permission from ref (68). Copyright 2018 Wiley-VCH. b) Photograph of Danaea nodosa. Reprinted with permission from ref (69). Copyright 2007 University of Chicago Press. c) Cross-sectional TEM image of the cell wall of a juvenile Danaea nodosa leaf. Reprinted with permission from ref (70). Copyright 1993 Wiley-VCH. d) TEM image of helicoidal cell wall of Elaphoglossum herminieri. Reprinted with permission under a Creative Commons Attribution (CC BY) License from ref (71). Copyright 2024 Oxford University Press. e) Photograph of Microsorum thailandicum. f) TEM image of the adaxial cell wall. Reprinted with permission from ref (72). Copyright 2018 Royal Society. g) Photograph of Mapania caudata. h) TEM image of the adaxial wall near the surface. i) TEM image of the central part of the adaxial wall. Reprinted with permission from ref (73). Copyright 2013 Oxford University Press.
Naturally occurring cellulosic chiral nematic architecture has been discovered in the cell walls of a variety of land plants including ferns, mosses, angiosperms, and gymnosperms. (71,76,77) The interesting helicoidal structures resulted in vivid structural colors as found in many plants and insects. A typical example is fern Danaea nodosa, which displays a strong blue iridescent color in its young leaves (Figure 4b). The strong blue iridescent color is caused by the constructive interference of the thin films composed of multilayers of cellulose microfibrils in adaxial epidermal cell walls (Figure 4c). (70) The brilliant structural color has also been observed in the leaves of many other fern species, such as Elaphoglossum herminieri and Microsorum thailandicum, which possess a similar helicoidal ordering of chiral nematic structures (Figure 4d). Iridescence in the ferns Elaphoglossum herminieri and Microsorum thailandicum is caused by the multilayered structure of their outermost cell walls, where the cellulose microfibrils of each layer are arranged in slightly different directions, resulting in helical patterns of cellulose direction by the stacked layers (Figure 4e–f). (72)
The Mapania caudata, showing a blue-green iridescent color, provides a different example of iridescent chiral nematic cellulose containing silica nanoparticles (Figure 4g). (73) Silica nanoparticles spread within the graded-pitch chiral nematic organization of microfibrils (Figure 4h, i) and contribute to the blue iridescence of the entire structure. Of note, the blue color disappears after the removal of silica from the walls.
The chiral nematic structure that forms the iridescent effect does not only exist in leaves but also in fruits. Generally, various pigments, e.g., flavonoids, carotenoids, and betalains, are responsible for the colors of fruits. However, the fruits of some plant species, such as Pollia condensata and Margaritaria nobilis, are able to show highly metallic and intense color via nanostructured multilayered cell walls. Pollia condensata (Figure 5a) is a kind of African forest understory species showing a shiny metallic blue color, which is mainly due to the chiral nematic structures present in the cell walls of the epicarp cells. In dried fruits, this structure can be preserved for many years. (78,80) Moreover, the cellulose microfibrils in each cell are arranged in a clockwise or counterclockwise helical orientation, allowing each cell to randomly produce left-handed or right-handed circularly polarized light (CPL) (Figure 5b and c). Figure 5d shows the multilayered helicoidal structure comprising numerous twisted arcs, which are responsible for fruit coloration. The fruits of Margaritaria nobilis also exhibit a metallic greenish-blue color (Figure 5e). The fresh fruits show strong circularly polarized reflections similar to those of Pollia condensata fruit. However, unlike the left- and right-handed circular polarizations detected in Pollia condensata, only left-handed polarization is reflected in Margaritaria nobilis (Figure 5f and g). Using TEM and polarization-resolved spectroscopy, Vignolini et al. found that the intense greenish-blue coloration is caused by the helical structures assembled by the cellulose in the multilayered cell walls (Figure 5h). (79) Additionally, the structural color of the Margaritaria nobilis fruit disappears when it is dry. This is mainly due to the shrinkage of the seeds, which generates an air layer between the seeds and the fruit, reducing the saturation and contrast of the structural color.
Figure 5
Figure 5. a) Picture of a Pollia condensata fruit. b,c) Microscope image in the two circular polarization channels showing the strongly pointillistic coloration originating in individually colored cells of the epicarp. d) TEM image of the epicarp showing the typical helicoidal motif (red line shows one pitch). Reprinted with permission from ref (78). Copyright 2012 National Academy of Sciences. e) Picture of Margaritaria nobilis fruits. f,g) Microscope image of a fresh fruit in different circular polarization configurations. h) TEM image of the cell wall of Margaritaria nobilis fruits. Reprinted with permission under a Creative Commons Attribution 4.0 International License from ref (79). Copyright 2016, The Royal Society.
1.4. Chitin-Based Chiral Nematic Structures in Nature
Structural color and iridescence are not limited to plants but are also commonly observed in the animal kingdom. Note that chitin macromolecules, as the basic building blocks of many arthropods, e.g., insects, crustaceans, and spiders, can also self-assemble into helicoidal structures and generate chiral nematic liquid crystal phases due to their chiral nature. As a Bragg medium, the chiral nematic phase exhibits the ability to selectively reflect light, and the helical pitch of the chiral nematic phase determines the wavelength of reflection. (82) The detailed self-assembly mechanism will be discussed in the next section.
Chrysina gloriosa shows a brilliant metallic appearance under a left circular polarizer, while the bright green reflection of the beetle will disappear under a right circular polarizer (Figure 6a and b). (81) This is mainly due to the selective reflection of the left CPL by the exocuticle of the beetle Chrysina gloriosa. As shown in Figure 6c, the green stripe exhibits an exoskeleton consisting of hexagonal cells (with an average diameter of about 10 μm), which contain bright yellow cores embedded within green cells with a yellow border. The typical chiral nematic fingerprint texture can be clearly recognized from the SEM images of the Chrysina gloriosa cuticle (Figure 6d and e). (82)
Figure 6
Figure 6. a) Photograph of the beetle Chrysina gloriosa under a left circular polarizer. b) Photograph of the beetle Chrysina gloriosa under a right circular polarizer. c) A microscopy image shows the exoskeleton of beetle Chrysina gloriosa. Reprinted with permission from ref (81). Copyright 2021 Optica Publishing Group. d) Cross-sectional SEM image of green stripes. e) Cross-sectional SEM image of silver stripes. Reprinted with permission from ref (82). Copyright 2017 Elsevier. f) Photograph of Plusiotis resplendens. Reprinted with permission from ref (83). Copyright 2005 Springer Nature. g) Electron micrograph showing a cross-section of the reflective layer of Plusiotis resplendens. Reprinted with permission from ref (84). Copyright 1971 The Royal Society.
Apart from Plusiotis resplendens, in all examined Plusiotis species, the reflected light is entirely left circularly polarized across the visible spectrum. However, Plusiotis resplendens reflects not only left CPL but also right CPL (Figure 6f), (83) which is mainly because of more complex helicoidal structures present in the cuticle of Plusiotis resplendens. As shown in Figure 6g, the cuticles exhibit a three-layered structure in which half-wave retardation plates are located in two left-handed helicoids. (84) When light passes through this three-layered structure, the left-handed CPL is reflected via the upper left-handed helicoids. However, the right-handed CPL will traverse half-wave retardation plates and be converted to left-handed, which will further interact with the left-handed helicoids at the bottom and then be reflected as a right-handed light after traversing a half-wave retardation plate. Thus, both left- and right-handed CPL can be successfully reflected with the same spectral content.
2. SELF-ASSEMBLY OF CNCs AND ChNCs
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The birefringent property of CNC suspension was reported by Marchessault and co-workers in 1959. (87) However, the chiral nematic (cholesteric) phase of CNC suspension was not identified until 1992 by Gray et al. (88) Subsequently, Gray and co-workers found that the chiral nematic structure of CNC suspensions can be preserved in thin films after water evaporation. (89,90) As shown in Figure 7a, only when the concentration of CNC is higher than a critical point does an ordered chiral nematic phase appear, forming an orientationally anisotropic phase. (18) In the dilute regime (isotropic phase) with the CNC concentration below around 6 wt %, these nanocrystals are randomly dispersed and oriented so that the suspension appears as a single isotropic phase. When the concentration of CNC exceeds the critical threshold of around 6 wt %, a second phase is observed, resulting in the coexistence of an anisotropic phase in the lower layer and an isotropic phase in the upper layer. Note that the volume of the anisotropic phase increases as the suspension concentration increases. As the concentration of CNC increases further to 14.5 wt %, the entire suspension becomes anisotropic. The liquid crystalline textures formed during the self-assembly process can be detected using a polarized light microscope (PLM). Of note, different textures are determined by the relative orientation between the helicoidal axis and the PLM. As shown in Figure 7b, the planar texture (I) and fingerprint texture (II) of the CNC suspension can be clearly observed. (85) Birefringence occurs when the helicoidal axes are perpendicular to a substrate, which is known as a planar structure. However, when the helicoidal axes are parallel to a substrate, alternating bright and dark stripes are formed, which are known as a fingerprint structure.
Figure 7
Figure 7. a) Phase diagram illustrating the transition of isotropic-to-chiral nematic phase and the corresponding equilibrium pitch with the increasing of CNC concentration. Reprinted with permission under a Creative Commons Attribution (CC BY) License from ref (18). Copyright 2017 Wiley-VCH. b) Regions show the (I) planar texture and (II) fingerprint texture. Reprinted with permission under a Creative Commons Attribution (CC BY) License from ref (85). Copyright 2015 MDPI. c) Schematic diagram showing the chiral nematic structures formed by CNCs that can selectively reflect CPL. Reprinted with permission from ref (86). Copyright 2019 Royal Society of Chemistry.
The helix orientation of CNC chiral nematic phase has been demonstrated to be left-handed (Figure 7c). (86) The reflected wavelength of chiral nematic structures (λmax) is usually expressed according to the equation below: (91)
Where P represents the helical pitch of chiral nematic structure, navg is the average refractive index of the substance, and θ refers to the angle of incident light. When half of the pitch (P/2) matches the wavelength of visible light, the material appears to be iridescent. The light reflected by the chiral nematic structure is circularly polarized, and its handedness is mainly dependent on the chirality of the structure. (86)
Similar to CNCs, ChNCs can also spontaneously self-assemble into chiral nematic phases in an aqueous suspension when the concentration is above a threshold concentration. Furthermore, the chiral nematic structures are retained upon drying the dispersion to produce solid iridescent films. (92−94) For ChNCs, the wavelength of light reflected by chiral nematic structures can also be described according to the same equation for CNCs. The iridescent colors in ChNC films with chiral nematic structures are also angle-dependent and are determined by the average reflective index and pitch of the helical structures.
3. INFLUENCE AND REGULATION OF LIQUID CRYSTAL BEHAVIORS OF CNCs
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A CNC suspension generates a film with an iridescent color at visible wavelength after complete evaporation of water. Various crucial parameters including internal factors (e.g., morphology, dimension, and surface charge density) and external factors (electrical field, magnetic field, and mechanical stress) could be tuned to realize the adjustment of the pitch of the chiral nematic structures in CNC suspensions, thus leading to the formation of CNC films with desired structural colors.
3.1. Effects of Internal Factors During the Self-Assembly Process
As reported in many previous studies, the size of CNC particles has a significant impact on the evolution of the self-assembly process and the optical properties of CNC films. Thus, controlling the size of CNCs has been actively pursued to obtain self-assembled CNC films with the desired chiral nematic structures. He and co-workers investigated the self-assembly behaviors of carboxylated tunicate CNCs (tCNCs), prepared through ammonium persulfate (APS) oxidation in combination with subsequent ultrasonication. (95) They found that tCNCs with smaller sizes require a slightly higher critical concentration to form the anisotropic phase. Two different CNCs with similar diameters, zeta potential, and sulfur group contents but different lengths were isolated from softwood by sulfuric acid hydrolysis. (96) To understand the interaction and self-assembly of CNCs with different lengths in an aqueous suspension, experimental small-angle X-ray scattering (SAXS) and the theoretical Derjaguin–Landau–Verwey–Overbeek (DLVO) theory were applied. The results showed that the balance between attractive and repulsive interactions has a significant influence on the chiral nematic self-assembly of CNCs with different morphologies. Zhao et al. fabricated CNCs with various aspect ratios through changing the temperature of hydrolysis and acid-to-pulp ratio. (97) CNCs with higher aspect ratios obtained at lower hydrolysis temperatures and acid-to-pulp ratios are more likely to form chiral nematic structures and generate films with structural colors. The obtained film reflected natural light in wavelengths ranging from 360 to 695 nm and exhibited structural colors from blue to orange. It is noteworthy that strong acid hydrolysis would disrupt the cellulose lattice planes, which is not conducive to the formation of chiral nematic structures. Generally, unlike rod-like particles, spherical particle suspensions with a concentration higher than the critical value tend to form crystalline colloids instead of liquid crystalline phases. However, Wang and co-workers reported that highly polydisperse spherical CNCs can also form a liquid crystalline phase in suspension. (98) Spherical CNCs started to show a liquid crystalline phase when the concentration of CNC exceeded 3.9 wt %. When the concentration increased to 4.5 wt %, the suspension displayed a chromatic color and had a banded texture. With a further increase in CNC concentration (7.1 wt %), a crosshatch pattern was detected. Vermal et al. extracted CNCs with varying morphologies such as sphere, flake, and needle from different sources. (99) They found that these CNCs with varying morphologies have different liquid crystalline properties and self-assembly patterns. Only the needle-shaped nanocrystals captured the characteristic fingerprint pattern. A banded pattern was observed for the spherical CNCs, which may be due to the inevitable aggregation of nanocrystals, leading to the change in the effective particle shape of nanocrystals. Nanocrystals with a flakelike morphology could not produce long-range order, thus resulting in the formation of inhomogeneously ordered patterns.
In addition to size and morphology, the surface charge density also strongly influences the self-assembly of CNCs. It was found to affect not only the colloid stability of the CNC suspension but also the chiral nematic pitch of the dry film. Various approaches, including physical adsorption of surfactants, chemical grafting with polymer chains, and changing the synthesis conditions of CNCs, have been developed to tune the surface charge of CNCs. For instance, CNCs with almost identical dimensions but different surface charges were extracted from bleached softwood kraft pulp by using the sulfuric acid hydrolysis method. (100) It was found that the critical concentration of CNC suspension required to form a chiral nematic phase increased as the surface charge increased. Moreover, there was a surface charge density threshold of around 0.3% S, below or close to which the end-to-end aggregated CNCs tended to form gelation and disturbed the formation of the ordered phase. CNCs with different sulfate contents were fabricated by Yao et al. by changing the sulfuric acid hydrolysis time. (6) With an increasing hydrolysis time, the sulfate content of the CNC increased, while the size of the CNC decreased. The electrostatic repulsion increased with increasing surface charge density, which resulted in the predominant reflectance peak of the dried CNC films increasing from 271 ± 10 to 517 ± 8 nm. Compared with H2SO4-hydrolyzed CNCs, the negatively charged carboxylated CNCs obtained by pre- (101) or post-treatment (102) with TEMPO can form a chiral nematic phase with apparent optical birefringence at a critical concentration of about 4.1 wt %, which was lower than that of CNCs prepared with H2SO4 (4.8 wt %). When the concentration increased to 9.0 wt %, the fingerprint could be clearly observed under a PLM, and the helical pitch was about 6 μm. (103) Fan et al. prepared carboxylated CNCs from bleached cotton pulp via hydrochloric acid hydrolysis in combination with subsequent TEMPO-mediated oxidation. (104) For CNCs with similar aspect ratios, a higher surface charge density resulted in enhanced dispersity of the negatively charged nanoparticles and the stability of the suspension. When the surface charge density of CNCs was 0.16, 0.56, and 1.00 e·nm–2, the CNC suspensions showed a birefringent pattern without clear fingerprint texture. However, clear fingerprint textures can be found when the surface charge density of CNCs increases to 1.25 and 1.42 e·nm–2. Lin et al. reported a facile method to prepare carboxylated CNCs from degreasing cotton using aqueous recyclable oxalic acid as the sole catalyst for esterification and hydrolysis. (105) It was found that the self-assembly behaviors of the CNC were highly determined by the aspect ratio and surface charge. The formation of chiral liquid crystal phases was observed in samples with aspect ratios greater than 5.5 and surface charges higher than 30.0 mV.
Many groups investigated the effect of polymer-graft modification on the CNC self-assembly process. Araki and co-workers produced sterically stabilized CNC suspensions via grafting polyethylene glycol (PEG) onto the surface of the nanocrystals through a carboxylation-amidation procedure. (102) Owing to the fact that the PEG used in this study was too short to produce steric barriers that shield the surface charge effects, the PEG-grafted CNCs displayed self-assembly behavior similar to the unmodified CNCs. By using the classical surface-initiated atom transfer radical polymerization (SI-ATRP) method, Risteen et al. produced thermally switchable liquid crystalline CNC by regioselective grafting of thermoresponsive polymer poly(N-isopropylacrylamide) (PNIPAM) from the reducing ends of the nanocrystals. (106) They found that the phase transition from liquid crystalline to isotropic was reversible and driven by the collapse of PNIPAM chains on top of the lower critical solution temperature (LCST), leading to a decrease in rod packing density and an increase in translational and rotational degrees of freedom. CNCs surface grafted with poly(PMMAZO) were prepared via ATRP. (107) The PMMAZO-grafted CNCs displayed smectic-to-nematic transition and nematic-to-isotropic transition at 95 and 135 °C, respectively. When the temperature exceeded 135 °C, the grafted CNC showed lyotropic liquid-crystalline phase behavior and a lyotropic nematic phase in chlorobenzene when the concentration was above 5.1 wt %. With the same method of ATRP, it is also possible to graft poly(styrene) (PSt) on the surface of CNCs. (108) The PSt-grafted CNCs showed chiral nematic structures in both the thermotropic and lyotropic states. Delepierre et al. reported that end-grafted CNCs could self-assemble into a chiral nematic liquid crystalline phase. (109) One end of the reducing end-groups of CNC-I and both ends of CNC-II were grafted with poly[2-(2-(2-methoxyethoxy)ethoxy)ethyl acrylate] (POEG3A). Compared to the unmodified CNC, the thermal properties and liquid crystalline phase behavior of the CNCs changed after modification. Both modified CNC-I and CNC-II produced chiral nematic tactoids in aqueous suspensions, but the domain sizes and pitches were different. Chiral nematic tactoids could only be formed when the concentration of modified CNC-II exceeded 14 wt %, while a concentration of CNC-I of 10% was sufficient. However, the symmetrical grafting of POEG3A onto the reducing end group of CNC-II significantly shortened the time required for the chiral nematic texture formation. CNCs with surface-grafted ionic liquids (CNC-IL) were synthesized by Qin et al. (110) It was found that positively charged CNC-IL formed a chiral nematic phase at a significantly lower concentration than nonfunctionalized CNCs. In addition, the chiral nematic pitch increased with increasing concentration of CNC-IL due to the increased particle size of the CNCs and the high viscosity of the CNC-IL suspension after surface modification with ILs.
3.2. Effects of External Factors During the Self-Assembly Process
The concentration of CNCs, as one of the most easily adjustable external factors, is greatly associated with the microstructure of the chiral nematic phase formed by CNC. Momeni et al. discovered that the chiral nematic pitch decreased with increasing the concentration of CNC. (111) This is consistent with the results of previous works, where an increase in the coexisting concentration of isotropic and anisotropic phases but a decrease in the chiral nematic pitch of the anisotropic phase was observed as the total concentration of the CNC suspension increased. Two main mechanisms have been used to explain the decrease in pitch as the CNC concentration increases. First, the strength of the total force for twisting increases with increasing CNC content in the suspension, which facilitates the formation of a chiral nematic structure. Second, the ionic strength also increases with increasing concentration of charged CNCs, which reduces the range of exponentially decaying electrostatic repulsion, resulting in a tight alignment of CNCs. (112) Klockars et al. fabricated CNC films with structural color by casting CNC suspensions with different concentrations of 3, 4, 5, and 6 wt %, and their morphology and optical properties were characterized. (113) Results showed that the drying time decreased with an increase of concentration. A more dilute CNC suspension required a longer evaporation time, resulting in a film with larger and more uniform crystalline domains, while a more concentrated CNC suspension required a shorter evaporation time, producing a film with smaller domains. This is mainly because the sample assembled from a higher concentration of the suspension reached the kinetic stagnation or gelation stage more quickly after evaporation, and there was not enough time to rearrange into long-range orders. The influence of concentration on the self-assembly behavior of carboxylated CNCs was investigated by Lin et al. (105) The study found that the suspension was optically isotropic when the concentration was lower than 1.0%. Increasing the concentration of the suspension to 1.0% produced a biphasic suspension with an upper isotropic phase and a bottom anisotropic phase. The suspension became fully anisotropic when the concentration was increased to 3.0%.
Ionic strength is also an essential external factor influencing the self-assembly of CNC into a chiral nematic phase in suspension due to the charged character of CNCs. Generally, the chiral nematic pitch can be controlled by adjusting the ionic strength of the suspension, resulting in the formation of CNC films with tunable reflected colors. Bukharina et al. investigated the effect of ionic strength on the chiral nematic phase of sulfuric acid hydrolyzed CNCs extracted from wood pulp. (114) Prior to evaporation, an appropriate amount of the NaOH solution was added to the CNC suspension. It was found that the pitch decreased with increasing NaOH concentrations. This was mainly due to the strong interaction between Na+ and the surface of CNCs shielding the surface charges and reducing the effect of Coulombic repulsion. Such a phenomenon was also revealed by Lin and coauthors. (115) Cao and coauthors studied the effect of counterions on the aggregation kinetics and surface charging properties of CNCs in aqueous suspensions containing various inorganic salts. (116) They found that for monovalent salts, the critical coagulation concentration (CCC) followed the order of Cs+ < K+ < Na+ < Li+, consistent with the Hofmeister series, suggesting specific interactions between cations and the CNCs surface. The CCC values for the divalent salts followed the order Mg2+ > Ca2+ > Ba2+, which was the opposite order of counterion ion size. The properties of the counterions also affect the stability of the suspension.
The solvent of CNC suspensions also greatly affects their self-assembly behavior. Of note, CNCs prefer to form aggregates in an apolar solvent owing to strong hydrogen bonds and weak electrostatic repulsion. Thus, so far, the dispersion and self-assembly properties of CNCs are limited to aqueous suspensions or a few organic solvents with high dielectric constants, such as N,N-dimethylformamide (DMF), ethylene glycol, and dimethyl sulfoxide (DMSO). (117−119) To understand how different solvents affect the self-assembly of CNCs, Bruckner et al. dispersed CNCs in different polar but nonaqueous solvents, such as formamide, N-methylformamide (NMF), and DMF. (120) They developed an aggregation-free method for exchanging solvents in the CNC suspensions. The desired solvent was first mixed with the aqueous suspension of CNCs, and then water was removed through distillation under reduced pressure. The solvent with a high dielectric permittivity was found to have the ability to significantly accelerate the self-assembly process and reduce the concentration dependence of the helical pitch. High-permittivity solvents increased the degree of order in CNC suspensions, resulting in a shorter pitch and lower threshold for liquid crystallinity. In contrast, low-permittivity solvents hindered the formation of helical superstructures due to kinetic arrest. The electrostatic repulsion is a key factor for CNC to form chiral nematic phases in a suspension. However, some researchers reported that the modified CNCs are also capable of forming a chiral nematic phase, suggesting that surface charge is not a prerequisite for isotropic self-assembly. (108,121) Saraiva et al. reported the production of hydrophobic CNCs through surfactant-functionalization of sulfuric acid hydrolyzed CNCs with a commercial surfactant of STEPFAC 8170-U. (122) Surfactant-functionalized CNCs suspended in toluene formed the chiral nematic phase within a few hours, which was unexpectedly fast compared with pure CNCs in water. Furthermore, the concentration of the suspensions could reach up to 50 wt %. They also found that the pitch values of the chiral nematic phase decreased with an increase in CNC concentration. In addition to surface modification, CNCs can be dispersed in toluene by adding surfactants to the suspension. In the study reported by Frka-Petesic et al., CNC toluene suspensions were obtained by adding Beycostat NA surfactant (BNA) at a surfactant/CNC ratio of 4/1 (w/w) to aqueous CNC dispersions. (123) CNCs in toluene can spontaneously form iridescent liquid crystal phases. The cholesteric orientation and the periodicity could be controlled by using electric fields to achieve uniformity of macroscopic samples and dynamic adjustment of the iridescent hues.
External physical methods can be used to tune the self-assembly of CNC during the fabrication of free-standing structurally colored CNC films. Evaporation-induced self-assembly (EISA) is the most commonly used method to produce colored CNC films. The evaporation process can be altered via simply changing the environment of the suspension. For instance, inputting external energy through heating was reported for constructing structural color films with CNC prepared by the sulfuric acid hydrolysis method. The surface charges of sulfuric-acid-treated CNCs are highly sensitive to thermal treatment as the elevated temperature causes the desulfation of sulfate ester groups on CNC surfaces. (32) These functional groups play a key role in the formation of long-range ordered chiral nematic structures. Vanderfleet et al. investigated the influence of hydrothermal treatments on the properties such as the uniformity, colloidal stability, and color of the sulfated, phosphate, and carboxylated CNC suspensions. (127) It was found that the morphology, molecular weight, and crystallinity of CNCs were almost unchanged after treatment, while the surface charge content decreased significantly, resulting in the loss of colloidal stability and aggregation of CNCs. Compared with phosphated and carboxylated CNCs, sulfated CNCs were most likely to decrease colloidal stability and form CNC aggregates. The study reported by Nyström et al. demonstrated that the pitch of the chiral nematic phase formed by carboxylated CNCs was not affected by temperature changes between 10 and 43 °C (Figure 8a). (20) Liu et al. found that a free-standing film with perfect chiral nematic liquid crystal characteristics can be obtained at a low temperature of 30 °C. (128) As the casting temperature increased, the liquid crystal structures of the CNC films underwent a process of gradually changing from chiral nematic phases to nematic phases until no chiral nematic phase remained due to the deep desulfurization of CNCs. Beck and coauthors prepared solid iridescent CNC films with predefined patterns by heating aqueous CNC suspensions differentially during film casting. (129) It was found that the thickness and chiral nematic pitches of the patterned areas were different from those of the surrounding films. The red-shifted pattern can be formed at a higher casting temperature, while the blue-shifted pattern was obtained by decreasing the casting temperature. Moreover, the red-shifted area was thicker than the blue-shifted area due to the longer chiral nematic pitch. Tran and coauthors explained the red-shift phenomenon detected in CNC film when external energy was input by heating. This may be due to the kinetic entrapment of water molecules between the layers of CNC rod resulting in the increase of helical pitch value, while also introducing obvious disorders into the produced chiral nematic structures. (16) Applying heat treatment during film preparation affects the self-assembly of CNCs, while heat treatment of the dried CNC film can also have an effect on the film. D’Acierno et al. reported the changes in the optical and structural properties of the iridescent CNC films with different monovalent cations (CNC-H, CNC-Li, CNC-Na, CNC-K, CNC-Rb, CNC-Cs) after thermal annealing at 200 and 240 °C for up to 2 days. (124) They found that the birefringent properties of the CNC-H films were destroyed within a few seconds after annealing at 200 °C, along with the rapid disappearance of the domain structure, indicating poor thermal stability (Figure 8b). For CNC-Li, CNC-Na, CNC-K, CNC-Rb, and CNC-Cs films, the chiral nematic structures were retained in these films due to the structural and chemical stability of the cellulose backbone and the large surface alkali ions. Furthermore, the stability of CNC-X films increased as the radius of the alkali ions increased. Guidetti et al. also investigated the impact of thermal treatments on the optical properties of chiral nematic CNC films. (130) The research demonstrated that the helicoidal architecture and chiral optical response of CNC films can be maintained at temperatures up to 250 °C through base treatment and cross-linking with glutaraldehyde. Additionally, exposure to a vacuum allows preservation of the helicoidal arrangement up to 900 °C, resulting in the production of aromatic chiral carbon.
Figure 8
Figure 8. a) PLM images of the bulk chiral nematic phase at 10 and 43 °C. Reprinted with permission from ref (20). Copyright 2018 American Chemical Society. b) PLM images of CNC-X films under different annealing temperatures and annealing times. The annealing times from left to right in each group of images are 0 h, 30 min, 1, 3, 6, 12, 18, 24, and 48 h. Scale bar: 100 μm. Reprinted with permission from ref (124). Copyright 2021 Elsevier. c) PLM images and cross-sectional SEM images of CNC iridescent films with different ultrasonic time. d) Schematic illustration of the mechanism of sonication-driven increase in pitch. Reprinted with permission from ref (125). Copyright 2024 Wiley-VCH. e) Schematic illustration of the evolution of particle distribution under sonication. Scale bar 200 nm. f) The relationship between relative volume fraction of each particle subpopulation and sonication dose. g) Modulation of chiral strength with relative dopant volume fraction. Reprinted with permission under a Creative Commons Attribution (CC BY) License from ref (29). Copyright 2022 Springer Nature. h) Schematic illustration of the fabrication of Mn2+ doped C–CNC iridescent films and images of the color of the prepared iridescent films as a function of ultrasound time. i) Schematic diagram of the mechanism of ultrasonic destruction of C–CNC agglomerates. Reprinted with permission from ref (126). Copyright 2022 Elsevier.
Ultrasonic treatment prevents the aggregation of CNCs by destroying the hydrogen bonding, resulting in small CNC particles and stable CNC suspensions. (131,132) Recently, ultrasonic treatment has been established as an efficient way to tune the chiral nematic pitch of CNCs in suspension by changing the applied energy. (29,125,133) Of note, it was found that short-term sonication was sufficient to disperse CNCs, whereas long-term sonication was counterproductive as it increased the critical concentration required for the liquid crystalline phase formation. (134) Moreover, the influence of sonication on the treated CNC suspension is cumulative and permanent. Chen et al. demonstrated that ultrasonic treatment of CNC suspensions before film casting increased the chiral nematic pitch and gave rise to the final iridescent CNC film with reflection bands of longer wavelengths (Figure 8c). (125) This is mainly due to the fact that some of the incompletely dialyzed counterions from acidolysis were bound to the surface layer of CNCs, partially shielding the surface negative charge of CNCs (Figure 8d). Without ultrasonic treatment, the reduced electrostatic repulsion allows the CNC to self-assemble with a shorter chiral nematic pitch. After ultrasonication, the shielding effect was diminished and the electrostatic repulsion during CNC self-assembly increased due to the gradual input of energy into the system causing some counterions in the surface layer of the CNC to leave and diffuse into the suspension, thus enlarging the pitch of the CNC chiral nematic structure. In contrast to such a model, Parton et al. proposed a chiral dopant model that composite CNCs, namely CNC bundles, functioning as chiral dopants, are the main driving force for the pitch increase upon sonication. (29) Through investigating the evolution in particle morphology upon sonication, it was found that aggregates and bundles were initially dominant, and upon sonication, aggregates were broken into smaller structures, while the bundles are more persistent and require higher doses to be broken down into individual elementary crystallites, including crystallites and distorted crystallites (Figure 8e and f). Among these four subpopulations, the bundle population was identified as the chiral dopant. Moreover, the chiral strength κ, extrapolated from the measurements of the volume fraction and the pitch, shows a clear positive trend with dopant abundance (Figure 8g). Yang et al. changed the input sonication energy to broaden the color spectrum of photonic oxidized CNC (OXCNC) films. (135) For the OXCNCs with low surface charges, no obvious color change was observed, even with a relatively high sonication energy input. By contrast, for OXCNCs with high surface charges exhibiting strong electrostatic repulsion, a stronger red color could be observed with an increase in the input sonication energy. Sui et al. reported that the color uniformity of CNC films obtained from suspensions was significantly reduced without ultrasonication due to the competition between the surface energy and nematic energy between CNCs during water evaporation. (136) The color uniformity improved after applied ultrasonication on the CNC suspension, and the fingerprint structure in the films was clearly observed by PLM. When CNCs are mixed with metal ions to prepare iridescent films, ultrasonication can also be used to improve the dispersibility of the suspension. Qin et al. reported the fabrication of Mn2+-doped carboxylated CNC iridescent films through ultrasonication pretreatment followed by the vacuum-assisted self-assembly (VASA) method. (126) The color of the composite films could be controlled by changing the ultrasonication time (Figure 8h). Ultrasonication treatment not only facilitated the uniform dispersion of CNC in the suspension but also partially destroyed the strong bonding between carboxylate and Mn2+ (Figure 8i).
External electric fields have also been verified as a facile yet efficient tool to control the self-assembly of CNCs. Bordel et al. reported that CNCs were aligned along the direction of the electric field and the birefringence of the suspension disappeared immediately when the electric field was turned off. (139) Additionally, the orientation and degree of alignment of the rod-like particles can be controlled by changing the applied field strength and frequency during film formation. This method provides dynamic modulation of the structural colors in addition to sample uniformity at the macroscopic scale and exact pitch adjustment. (123) At a lower field, the light intensity increased with increasing electric field intensity, accompanied by a red-shift in color. However, as the intensity increased further, the color became a scattering white and finally disappeared (Figure 9a). Qu et al. reported the use of an alternating current electric field to dynamically control the chiral nematic and nematic structures of CNC tactoids. (137) When a weak electric field was applied, the helical axes of the CNC tactoids were perpendicular to the electric field. This is mainly due to the positive dielectric anisotropy of CNCs and the synergistic effect of assembled CNCs. When the frequency of the applied electric field decreased or the strength increased, the pitch of CNC tactoids increased and then shifted from a chiral nematic structure to a nematic structure. At the same time, the response of CNC tactoids was significantly different at different frequencies (Figure 9b). Atifi et al. successfully fabricated photonic CNC films with long-range chiral nematic order in minutes via electrophoretic deposition (EPD)-induced self-assembly. (138) When an electric field was applied between the electrodes, CNCs moved toward the anode and generated a concentration gradient, which facilitated CNC interaction and self-assembly (Figure 9c). A relatively homogeneous and dense gel was formed near the deposition electrode after the aggregation of the CNCs. The drying time for mechanically stable gels typically did not exceed 10 min, either in situ or removed for drying. Furthermore, different grades of well-dispersed CNCs could be deposited on rigid and flexible substrates in a very short time by applying the pulsed EPD technique (Figure 9d). The SEM images clearly showed the homogeneous layered structure, which was characteristic of a left-handed helical arrangement for CNCs (Figure 9e and f). The thickness of the films was primarily affected by the nature of CNCs and the applied EPD parameters. Furthermore, the reflection intensity of the obtained films could be adjusted through changing the duration and number of electrodeposition cycles.
Figure 9
Figure 9. a) Evolution of iridescence in chiral nematic suspension with increasing electric field. Reprinted with permission from ref (123). Copyright 2017 Wiley-VCH. b) Schematic diagram of the reversible electrical response properties of CNC tactoid and PLM images of tactoid with increasing E. Reprinted with permission from ref (137). Copyright 2020, American Chemical Society. c) Schematic diagram of the self-assembly of CNC by electrophoretic deposition. d) Photographs of the electrodeposited CNC film on a flexible substrate. e–f) SEM images of CNC film illustrating the chiral nematic structures under different magnifications. Reprinted with permission from ref (138). Copyright 2022, Wiley-VCH.
Apart from an electric field, a magnetic field can also be employed to promote the alignment of the CNC nanorods. Note that the perpendicular alignment is locally induced due to the negative diamagnetic susceptibility of CNCs. Sugiyama et al. demonstrated that aqueous suspensions of CNC isolated from tunicate could be strongly oriented under a magnetic field of 7 T. (143) The orientation of the crystal axis was perpendicular to the magnetic field direction due to the intrinsic anisotropic magnetic susceptibility of the individual C–C, C–O, C–H, and O–H bonds from CNC and their relative orientation in the crystal. Recently, De France et al. utilized SAXS to investigate how weak magnetic fields and CNC suspension concentration affect the kinetics and degree of CNC alignment. (144) Results showed that partial alignment occurred with the CNCs suspension above the critical concentration under a 1.2 T magnetic field within 2 min. After that, a slower cooperative ordering was observed and finally resulted in the formation of an almost perfect alignment within 200 min. Such a near-perfect alignment also formed at a relatively low magnetic field of 0.56 T, but the ordering was 36% slower. However, for the suspensions below the critical concentration, no magnetic alignment was observed. Similarly, small commercial magnets (≈ 0.5–1.2 T) were used by Frka-Petesic et al. to tune the arrangement of the chiral nematic domains in suspension and to generate CNC films with structural colors (Figure 10a). (140) When the surface of CNCs was decorated with magnetic nanoparticles, the strength of the magnetic field used to tune CNC self-assembly could be very low. For instance, Chen et al. reported that the self-assembly of the CNCs decorated with Fe3O4 nanoparticles could be facilely tuned using a small magnetic field of 7 mT. (141) When the strength of the magnetic field increased from 7 mT to 15 mT, the pitch of the chiral nematic structure decreased from 302 to 206 nm (Figure 10b). However, an increase in pitch with increasing external magnetic force was observed in pure CNC. Zhang et al. prepared uniformly aligned flexible magnetic films with Fe3O4-nanoparticles-decorated CNCs. (145) The original helicoidal organization underwent unwinding and transformed to uniaxial alignment under a magnetic field lower than 150 mT, resulting in the formation of an almost perfect orientation over a large area. The results demonstrated that the high shear rate of circular flow triggered by the magnetic field exceeded that of classical EISA by 2 orders of magnitude. Such a high shear rate promoted the nontraditional, unidirectional orientation and untwisting helical arrangement of nanorods along the gradient magnetic field. Moreover, the obtained films showed fast actuation and shape deformation under weak magnetic fields, local humidity changes, and photothermal-induced one-side stresses. Wang et al. explored the manipulation of lyotropic liquid crystal systems through the integration of superparamagnetic nanoparticles. (142) By doping CNCs with these nanoparticles, a distinction was made between isotropic and liquid crystalline phases based on their differing magnetic susceptibilities. Utilizing gradient magnetic fields, the study demonstrated the spatial separation of these phases, with liquid crystalline tactoids migrating toward lower-field regions, while isotropic phases gravitate toward higher-field areas (Figure 10c–e). Furthermore, this technique enabled precise control over the positioning and orientation of chiral nematic liquid crystalline phases. In another study reported by MacLachlan and co-workers, tunable diffraction gratings were produced with vertically aligned uniform periodic structures by immobilizing highly oriented chiral nematic liquid crystals of CNCs in polymer networks using the synergistic effect of gravity on phase separation and magnetic field on liquid crystal orientation. (146)
Figure 10
Figure 10. a) Films produced by slow evaporation of aqueous CNC suspension in a dish placed on NdFeB magnets. Reprinted with permission under a Creative Commons Attribution (CC BY) License from ref (140). Copyright 2017 Wiley-VCH. b) SEM images of CNC films under magnetic fields with varying strength. Reprinted with permission from ref (141). Copyright 2020 American Chemical Society. c) PLM image showing the phase separation of a CNC/MNP dispersion in a vertical gradient magnetic field. d) 3D model showing the phase separation and orientation of tactoids when the magnet was placed under the vial. e) 3D model showing the phase separation and orientation of tactoids when the magnet was placed on the right side of the vial. Reprinted with permission from ref (142). Copyright 2019 Elsevier.
Although EISA has been widely used to fabricate iridescent films, there are still some limitations to this approach, such as a long fabrication time, color nonuniformity, high initial concentration, and uneven surface. Figure 11a shows the nonuniform color of the CNC film fabricated through EISA, indicating that the helical directions of CNC chiral nematic domains are randomly distributed. (147) In contrast to EISA, vacuum-assisted self-assembly (VASA) can produce CNC films with more uniform color. Wang et al. reported the preparation of chiral pearlescent films with tunable optical properties from CNCs by using vertical pressure to direct their self-assembly (Figure 11b). (94) Such vertical pressure was achieved by using a vacuum filtration cup, where CNCs and water were separated by a pressure difference created by a vacuum pump removing air from below the filtration membrane. The vertical pressure directed the CNCs to align perpendicular to the film plane, forming a densely stacked structure. Initially, the CNC suspension experienced a decreasing pressure, followed by a steady pressure on the remaining suspension, resulting in a bilayer film. The bottom layer had densely stacked microdomains with a vertical gradient pitch, while the top layer had a uniform pitch (Figure 11c). This vertical pressure filtration produced bilayer films with chiral pearlescence and a specular reflectivity. The mechanism of CNC self-assembly into chiral nematic structures during VASA was investigated by Zhang’s group. (148) The structural evolution of CNC aggregations on filter paper was clarified by “freezing” the CNC suspensions in polyacrylamide matrices at different filtration stages. It was found that the self-assembly of CNC transferred from the isotropic phase to the chiral nematic phase at the paper/suspension interface (Figure 11d). Tactoids were formed in the concentrated CNC suspension near the filter paper. The VASA promoted the helical axes of the CNC tactoids along the flow-field direction, resulting in a faster formation of long-range ordered liquid crystals through nucleation growth. VASA, in comparison to EISA, is a less time-consuming approach. Thus, the precursor suspensions do not require long-term stabilization, which facilitates the coassembly of CNCs with other functional nanoparticles, such as graphene oxide (GO) and carbon nanotubes (CNTs). Li et al. also investigated the effects of two different film-making techniques, EISA and VASA, on the structural, optical and mechanical properties of the obtained iridescent CNC films. (150) The results showed that the films obtained from VASA exhibited a smooth surface and a uniform and dense chiral nematic organization due to the strong pressure, while the films obtained from EISA exhibited a fish-scale-like surface and a more random chiral nematic structure with voids due to the multistage assembly. Consequently, VASA-CNC films exhibited a more uniform structural color and enhanced mechanical performance. CNC/PEG/GO composite films with superior UV-blocking and transparency were produced by Xia et al. through VASA (Figure 11e). (149) The filtration process reduced the helical pitch of the CNCs’ chiral nematic structure, shifting the photonic bandgap to the UV region. This structure, combined with the UV absorption of GO, enabled efficient UV-blocking while maintaining transparency. Similarly, Ren et al. fabricated conductive chiral composite films by assembling a CNC host matrix with multiwalled carbon nanotubes (MWCNTs). (151) The addition of MWCNTs had an important impact on the chiral nematic structure of the prepared nanopaper. With the increase in the content of MWCNTs, the chiral nematic structure of the composite shifted from left-handed to right-handed.
Figure 11
Figure 11. a) Photographs and PLM images of iridescent CNC films fabricated with the EISA technique (left) and the VASA technique (right). Reprinted with permission from ref (147). Copyright 2019, Elsevier. b) Schematic illustration of pressure-directed self-assembly of chiral pearlescent CNC films. c) Cross-sectional SEM image of the chiral pearlescent CNC films. Reprinted with permission from ref (94). Copyright 2023 Wiley-VCH. d) Schematic illustration of VASA of CNCs. Reprinted with permission from ref (148). Copyright 2020 Elsevier. e) Schematic illustration of the CNC/PEG/GO film fabrication process. Reprinted with permission from ref (149). Copyright 2024 Elsevier.
Shear stress applied to the CNC suspensions during the drying process also greatly affects the self-assembly behavior of these nanocrystals and the texture of the CNC films. Pignon and co-workers investigated the underlying mechanisms of structural evolution in concentrated CNC suspensions under shear and during relaxation postshear using small-angle X-ray scattering, light scattering, and rheometry. (152) They linked dynamic structural changes across nanometer to micrometer scales to the well-known three-regime rheological behavior. The first shear-thinning part, regime I at lowest shear rate, is ascribed to the progressive disruption of liquid crystalline domains into micrometer-sized tactoids aligned toward the velocity direction with an internal cholesteric organization of the CNCs and the helical axes oriented vertically (Figure 12a). In the intermediate shear rate domain, regime II, upon reaching the viscosity plateau, the micrometer-sized tactoids break down into elongated tactoids with a critical size even smaller than the pitch value, oriented along the velocity direction. Regime III at high shear rate was associated with the parallel flow of individual CNCs along the velocity direction. Feng et al. investigated the tailoring of the chiral nematic organization of CNCs via shear flow through complete polarization analysis using Mueller matrix microscopy. (153) An early in-plane unwinding followed by a later helically vertical unwinding was proposed as the main process of the self-assembled structure changes under shear flow (Figure 12b and c). Sufficient shearing is necessary for the reorientation of the helically aligned CNCs to form the nematic structures. All in all, the structure of CNC films prepared from chiral nematic CNC suspensions is sensitive to the shear stress applied during the drying process. Applying a suitable shear stress is thus crucial to produce a photonic film with desirable optical properties.
Figure 12
Figure 12. a) Schematic illustration of CNC suspensions from rest to increasing applied shear rates. Reprinted with permission from ref (152). Copyright 2021 Elsevier. Schematic illustration of the reorientation of CNCs by shear flow b) in-plane unwinding process and c) later vertical helical unwinding process. Reprinted with permission from ref (153). Copyright 2023 American Chemical Society. d) The CNC particles were reoriented from a chiral nematic state to an aligned structure via stretching. Reprinted with permission under a Creative Commons Attribution (CC BY) License from ref (7). Copyright 2019 Springer Nature. e) Schematic illustration of the hydrodynamic alignment of CNCs in dynamic hydrogels under stretching. Reprinted with permission from ref (154). Copyright 2019 American Chemical Society.
Mechanical stress induced by both stretching and compressing was also employed for tailoring the pitch and the alignment of the resulting nanostructure. Applying tensile load facilitated the alignment of CNC along the direction of the induced stretch. Such alignment was detected in both wet and dry all-cellulose nanocomposites under high strain conditions. (7,154) However, note that it is not feasible to change the alignment of CNCs by mechanical stretching within pure CNC films due to their brittle nature. Incorporating CNCs into elastomers is an effective way to produce highly stretchable composites with aligned CNCs. For instance, Kose et al. prepared a highly stretchable and homogeneous CNC/elastomer composite film with a chiral nematic structure. This structure could be easily tuned by stretching and relaxing (Figure 12d). (7) The chiral nematic structures transformed into pseudonematic structures when the composite film was stretched. The composite film displayed bright interference colors between crossed polarizers in response to stretching and relaxing. It was also found that when stretching was applied parallel to the direction of CNC alignment, the arrangement of CNCs was further enhanced and the birefringence of the film was increased. (155) On the contrary, when stretching was applied perpendicular to the direction of CNC alignment, the arrangement of CNCs became more disordered and the birefringence of the film was decreased. Such a composite can be used to fabricate reversible stimuli-responsive materials for applications in flexible optics and sensors. Dynamic hybrid hydrogels with highly variable birefringence were prepared by utilizing the hydrodynamic alignment of CNCs through the shear-thinning phenomenon in the hydrogel network (Figure 12e). (154) The hydrodynamic aligned structure could be preserved when the stretching was terminated due to the fact that the reconstruction of hydrogel networks was much faster than the dissipation of CNCs orientation. Moreover, the surface tension of hydrogels during the drying process further enhanced the orientation index of CNC, resulting in anisotropic behavior with a tunable birefringence.
Similarly, the alignment of CNCs can also be tuned by applying mechanical compression. For instance, MacLachlan et al. reported the fabrication of a shape-memory photonic crystal thermoplastic which allows reversible capture of different colored states by embedding chiral nematic CNCs into a polyacrylate matrix. (156) After equilibration at a temperature above its glass transition temperature, e.g. 100 °C, pressure was applied to the resultant thermoplastic composite. Then it was cooled down to room temperature while maintaining the applied pressure (Figure 13a). Upon removal of the pressure, the sample could retain its deformed shape. By simply increasing the pressure applied, the structural color could be tailored from red to blue due to compression of the helical pitch of the CNC chiral nematic structure. Moreover, heating the composite to 100 °C caused it to return to its original shape (Figure 13b–e). By taking a similar strategy, the CNC self-assembled chiral nematic structure was embedded into a kind of thermosensitive copolymer, i.e, poly(isopropylacrylamide-co-stearyl acrylate) to prepare a pressure/temperature dual-responsive hydrogel. (157) When the resultant hydrogel was subjected to a gradually increasing external pressure, the chiral nematic structure embedded in the composites was correspondingly compressed in the vertical direction so that the helical pitch decreased, which resulted in a blue shift of the structural color (Figure 13f). Moreover, owing to the thermoresponsive molecular structures of the polymer matrix, as the sample was heated from 25 °C, 35 °C, 45 to 55 °C, the main structural color correspondingly changed from red, orange, yellow to blue because of the decrease of the helical pitch.
Figure 13
Figure 13. a) Schematic illustration of the sequential programming and recovery of CNC-SMP. Photos of the CNC-SMP pressed at b) 0 N, c) 140 N, d) 180 N, and e) 230 N. Reprinted with permission from ref (156). Copyright 2021 Wiley-VCH. f) Pressure-responsive property of the hydrogel. Reprinted with permission from ref (157). Copyright 2023 Wiley-VCH.
Except for the above external factors, the supported substrate was also verified as an important parameter that can be employed to tune the pitch of the CNC-based chiral films. Nguyen et al. investigated the influence of different supported substrates, including aluminum, alloy steel sheet, acid-treated silicon wafer, mica, cellulose acetate, polystyrene, Teflon, paraffin, polyethylene, nitrocellulose, and a polydimethylsiloxane (PDMS)-coated glass plate, on the formation of CNC films. (158) A photonic pattern in the CNC film showing almost colorless letters of “NCC” on a blue background was successfully achieved by changing the substrate to adjust the pitch. The almost colorless region had a chiral nematic structure and reflected NIR light. It is worth noting that the substrate affects the thickness of the films due to the apparent change in the helical pitch.
The introduction of a nonvolatile solute also greatly affects the equilibrium pitch of the chiral nematic structure. Mu et al. found that the addition of d-(+)-glucose resulted in a decrease in the pitch of chiral nematic suspensions, but an increase in the pitch of the dry films and therefore a red-shift reflection band. (90) Results showed that there were two different stages of changing the pitch during the evaporation process. In the first stage, the pitch decreased with the increase of concentration due to evaporation. At this stage, the addition of glucose caused a decrease in the pitch. In the second stage, with the evaporation of the solvent, the concentration of CNCs reached where the formation of ordered gels and glasses occurred, thus preventing further major changes in pitch. At this stage, the addition of glucose lowered the CNCs concentration and led to an increase in pitch.
4. INFLUENCE AND REGULATION OF LIQUID CRYSTAL BEHAVIORS OF ChNCs
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ChNCs, like CNCs, can self-assemble into a chiral nematic phase with the critical concentration being a key factor in this process. Initially, when the CNC volume fraction exceeds a critical value (ϕ0), the chiral nematic phase coexists with the isotropic phase. As the concentration increases further, the chiral nematic phase grows until the suspension is entirely chiral nematic at a second critical volume fraction (ϕ1). Importantly, these critical concentrations (ϕ0 and ϕ1) are inversely proportional to the particle aspect ratio. Fungi-derived ChNCs have a higher aspect ratio than shrimp-derived ChNCs when prepared under similar hydrolysis conditions. (92) As expected, they exhibited lower biphasic threshold concentrations and a narrower biphasic region. Additionally, fungi-derived ChNC suspensions had significantly lower pitch values compared to shrimp chitin suspensions at similar concentrations.
Previous experiments have confirmed that the self-assembly of ChNCs is greatly influenced by many other internal and external factors. (22,54) Depending on the isolation approaches, diverse functional groups can be introduced onto the surface of ChNCs, resulting in different surface charges. Tuning electrostatic interaction by changing the pH value or ionic strength of ChNC suspensions has been extensively studied and employed as an effective way to tailor their self-assembly process. (160) For instance, Luo et al. reported an electrolyte-free ChNC suspension with a concentration of 5 wt % without exhibiting a highly ordered chiral nematic structure (Figure 14a). (159) The ordered structure can be partially retained at a concentration of 5 mM NaCl. With a further increase in the NaCl concentration, the suspension transformed from a liquid crystal phase to a colloid glass state and then to an elastic gel state. Increasing the pH value of the suspension leads to deprotonation of the surface amine groups of ChNCs, thus resulting in changes in the interactions between these nanocrystals. Results showed that no birefringence could be observed in the 5 wt % ChNCs suspension at a pH of 1.81 (Figure 14b). When the pH was 3.5, randomly distributed decentralized liquid crystal domains were observed (Figure 14b). As the pH increased further, the birefringent structure of the suspensions became increasingly apparent. This could be explained by the fact that at a low pH value, e.g., pH 1.8, all the amine groups were protonated, resulting in strong electrostatic repulsion between these nanocrystals. As the pH increased, the amino groups were deprotonated, reducing the nanocrystal–nanocrystal electrostatic repulsion. Therefore, the nanocrystals were arranged in an orderly manner with enhanced orientation. Note that ChNCs synthesized with different reactions generally have distinct surface physicochemical properties, and thus, they may exhibit different self-assembly behaviors at the same pH condition. The same group reported in another study that ChNC suspensions with pH ranging from 3 to 11 exhibited fingerprint-like liquid crystal texture. (160)
Figure 14
Figure 14. a) PLM images of 5.0 wt % ChNC aqueous suspension with different salt concentrations. b) PLM images of 5.0 wt % ChNC aqueous suspensions with different pH values. Reprinted with permission from ref (159). Copyright 2019 Elsevier. c) TEM images of ChNCs with different deacetylation time. d) PLM images of ChNC suspensions. Reprinted with permission from ref (160). Copyright 2023 American Chemical Society. e) Photograph and optical microscopy image of the ChNC film before (A, B) and after alkaline treatment (C, D). f) Reflection spectra under crossed polarizers of (B) and (D). Reprinted with permission under a Creative Commons Attribution (CC BY) License from ref (92). Copyright 2022 Wiley-VCH.
Deacetylation of ChNCs, generally achieved via NaOH treatment, causes the elimination of acetyl groups and the exposure of amine groups, thus influencing their self-assembly behavior and liquid crystalline features. ChNCs can maintain the crystalline structure well after NaOH treatment for a certain period. However, with the increase of the deacetylation time, the aspect ratio of the nanocrystals decreased (Figure 14c), the zeta potential increased, and the fingerprint-like texture progressively vanished. (160) Compared with the pristine ChNC suspension, only sparse liquid crystalline domains were observed for the ChNC suspensions deacetylated for 2 h, indicating the disruption of the well-ordered Bougliand structure (Figure 14d). In-situ deacetylation was employed to increase the birefringence of the ChNCs photonic film, which was fabricated by slow-evaporation of suspensions of ChNCs isolated from mushrooms. (92) Although the pitch of the photonic films was in the range to reflect visible color, unlike CNC photonic films prepared by using the same methods, the resultant films appeared macroscopically transparent, and only weak coloration was observed using polarized microscopy (Figure 14e). To enhance the birefringence of the photonic films, an in situ deacetylation treatment was applied to the photonic film. The deacetylated photonic film showed an obvious blueshift in the reflected color and a surprising 50-fold enhancement in the reflected intensity (Figure 14f), which was ascribed to the decrease in the pith due to the elimination and solubilization of the acetyl groups.
Tip sonication has been widely employed as a posthydrolysis treatment to disaggregate large bundles of ChNCs, leading to well-dispersed ChNC suspensions. Silvia investigated the effect of sonication energy input on the final properties of the ChNC suspensions and their liquid crystal phase behavior. (22) As expected, tip sonication reduced the dimensions and polydispersity of ChNCs, but it did not significantly affect their surface charges. The ChNC suspensions treated with various sonication energy inputs exhibited comparable threshold concentrations at which they separated into two liquid crystalline phases and then into a fully chiral nematic phase. However, the chiral nematic pitches of the samples varied considerably. The ChNC suspension treated with higher energy input possessed a larger pitch at low nanocrystal concentrations and showed a steeper decrease in the pitch with increasing ChNC concentration. This could be explained by the fact that the ChNC bundles, characterized by a strong chiral shape and twisting power in the anisotropic suspensions, were broken into smaller rod-like units, leading to a smaller induced twist between ChNCs and, consequently, a larger pitch.
Li et al. investigated the effect of the surface charge of ChNCs on the formation of the chiral nematic phase. (161) By N-sulfonation of the amino groups, the surface charge of ChNCs was changed from positive to negative without affecting the axial ratio of the crystallites. When the N-sulfonation reached S/N > 3, the N-sulfonated ChNCs formed a chiral nematic phase. As the N-sulfonation increased to S/N = 5, tactoids with a chiral nematic pitch of about 40 μm were found (5 wt %, pH 7). The surface charge of ChNCs can also be changed from positive to negative after hydrolyzation with H2O2, allowing the resultant nanocrystals to disperse well in alkaline or neutral aqueous media. (162) It was found that with the increase in the ChNC concentration, the dispersion showed a typical lyotropic phase transition from anisotropic monophase to birefringent mesogence and then gelation. Furthermore, the sol–gel transition of ChNCs was influenced by the surface charge density, concentration, temperature, and aging time.
Similar to what has been reported for CNC-based self-assembly materials, adding additives and applying external energy fields are efficient strategies for regulating the optical properties of ChNC films. Nge et al. studied the liquid crystal phase behavior of ChNC/acrylic acid (AA) liquid mixture. (163) The concentration required to form a complete chiral nematic phase in the ChNC/AA mixture was higher than that in pure ChNCs in water. The high concentration of AA increased the viscosity, thus hindering the phase separation of the mesophase. The fingerprint-like patterns, characteristic of chiral nematic textures, were observed only at low AA concentrations (Figure 15a). After the addition of AA, a stable flow-birefringence glassy phase was observed within a narrow ChNC concentration range of approximately 6.22–6.41%. This phase yielded a clear boundary between the isotropic phase and anisotropic phase. The composite film of ChNC/poly(acrylic acid) (PAA), which was magnetically aligned and optically anisotropic, was achieved by applying a high magnetic field of 5 T. (164) It was found that the orientation of the optical texture preferred to be perpendicular to the direction of the applied magnetic field (Figure 15b). From the results of PLM and XRD, the composite with a higher ChNC concentration (10.70 wt %) exhibited a high degree of crystallite orientation of 0.70. However, at a certain concentration of AA, the degree of orientation decreased with decreasing ChNC concentration.
Figure 15
5. APPLICATIONS OF SELF-ASSEMBLED PNs FUNCTIONAL MATERIALS
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The self-assembly behavior of PNs is attractive for various potential advanced applications. In this section, we mainly introduce recent advances in self-assembled PN functional materials and their promising applications.
5.1. Stimuli-Responsive Photonic Materials
Recently, stimuli-responsive photonic materials have received widespread attention owing to their giant potential in information storage materials, sensors, intelligent devices, etc. A variety of spectral features of CNCs- and ChNCs-based structural color materials offer great opportunities for designing and fabricating stimuli-responsive photonic materials via diverse approaches. For instance, rich surface hydroxyl groups on CNCs and ChNCs allow easy functionalization with various functional groups that can respond to external stimuli such as humidity, pH, temperature, or specific gases. (32) Additionally, stimuli-responsive photonic materials could be fabricated by directly adding stimuli-responsive components into the chiral nematic structures formed by CNCs or ChNCs. (31)
It has been found that the iridescent color of self-assembled CNC films can be adjusted by controlling the humidity. The sorption–desorption of water leads to changes in the chiral nematic pitch, thereby altering the reflectivity of the CNC film. Lu et al. fabricated a high-performance photonic humidity-responsive sensor consisting of CNCs, polyacrylamide, and glutaraldehyde (Figure 16a). (165) When the relative humidity increased from 11% to 97%, the pitch of the chiral nematic structure enlarged due to the water-induced swelling of the polyacrylamide matrix. As a result, the color of the composite changed from green to red. In a similar way, Yao et al. reported the fabrication of flexible CNC/PEG composite films with homogeneous structural color. The regulation of the structural color could be realized by adjusting the composition of CNCs and PEG or by changing the relative humidity of the external environment. (6) Due to the reversible swelling and dehydration of the chiral nematic structure, the composite film of CNC/PEG (80/20) displayed a reversible structural color change from green to transparent at varying relative humidity from 50% to 100%. Additionally, the composite also exhibited superior thermal and mechanical properties, endowing it with attractive versatility. Zhao et al. developed a scalable printing method to produce arrays of structurally colored CNC microfilms from spatially defined nanoliter sessile droplets (Figure 16b and c). (166) Arrays can be transferred to a wide range of substrates using adhesive tape to separate them (Figure 16d). The resulting films exhibited remarkably homogeneous and intense color, resulting in an extremely consistent optical appearance across the array and a significant response to variations in humidity (Figure 16e). The printed CNC microfilm arrays have wide application prospects in interactive pigments, cosmetics, and anticounterfeiting applications.
Figure 16
Figure 16. a) Schematic diagram showing the structure of iridescent films changed with humidity. Reprinted with permission from ref (165). Copyright 2017, American Chemical Society. b) Dot matrix image of a “Christmas tree” observed by circular polarizer. c) CNC microfilm obtained on a flexible PDMS substrate. d) CNC photonic array transferred to adhesive tape. e) Response of CNC microfilms to humidity changes. Reprinted with permission under a Creative Commons Attribution (CC BY) License from ref (166). Copyright 2019, Wiley-VCH.
Multistimuli-responsive CNC-based chiral materials have been fabricated to broaden the scope of applications of CNC-based chiral nematic materials. For instance, light- and humidity-responsive chiral nematic photonic crystal films were fabricated by the coassembly of CNCs and poly(3,3′-benzophenone-4,4′-dicarboxylic acid dicarboxylate polyethylene glycol) ester (PBD–PEGE) with the addition of PEG (Figure 17a). (167) After light irradiation under different relative humidities (RHs), the composite films preserved the chiral nematic and helical lamellar structures (Figure 17b). This dual-stimuli response of the composite films was related to the synergistic effects of the photoactive benzophenone groups of PBD–PEGE and the water-induced swelling of the hydrophilic polymer. A bioinspired bilayer actuator with reversible color- and shape-changing capabilities was fabricated by taking advantage of the CNCs-based self-assembled chiral nematic structures and their water or temperature response behaviors (Figure 17c). (168) In the bilayer film, the soft polyurethane elastomer layer served as a self-assembly platform for CNCs to increase the flexibility of the material. Additionally, to achieve the ideal photothermal effect of the elastomer layer, AgNPs were added due to their high photothermal conversion efficiency. The actuator obtained with a synergistic iridescent appearance exhibited superfast actuation responses to humidity and near-infrared light (Figure 17d). Sun et al. successfully constructed humidity and heat dual response composite films by simply mixing hydrazone-groups-modified poly(N-isopropylacrylamide) (PNIPAM) copolymers and CNCs. (169) The structural color of the films could be easily tuned by humidity, heat, or the content of the modified PNIPAM copolymers. More importantly, the change in color can be easily discriminated by the naked eye. Under high humidity conditions, water adsorption caused the resin to expand in volume, leading to a redshift. However, at a temperature higher than the lowest critical solution temperature of PNIPAM, the resin shrank, resulting in a blueshift. As shown in Figure 17e, the films displayed clear words under steam stimulation. Furthermore, the films demonstrated outstanding stability and cyclability to steam or liquid water owing to the strong chemical bonding between the resins and CNCs. Fan et al. fabricated visible multiresponse electrochemical sensors by simply mixing polyaniline (PANI) and CNC suspensions. (170) The introduction of PANI not only offered a dark background to make the structural color of CNC more visible but also improved the conductivity of the composite film. The resulting films displayed potential applications in the field of visible electrochemical multisensing due to their responsiveness to pH, humidity, and organic solvents as well as changes in reflection wavelength, visible structural color, and conductivity. Meng et al. developed photonic films with multistimuli response behaviors to humidity, pH, and ethanol concentration by the coassembly of CNCs, sorbitol, and anthocyanin. (171) The obtained photonic films showed significant color changes in response to a relative humidity change in the range of 50% to 100% or a pH change in the range of 2 to 12. Additionally, under different ethanol concentrations, these films displayed a fast response and good reversibility.
Figure 17
Figure 17. a) Schematic diagram of the coassembly process of the CNC-based composite films. b) Response of composite films to light at different relative humidities. Reprinted with permission from ref (167). Copyright 2020 American Chemical Society. c) Schematic diagram of the production of bioinspired composite films. d) A smart “mimosa” responded to moisture and NIR light. Reprinted with permission under a Creative Commons Attribution (CC BY) License from ref (168). Copyright 2021 Wiley-VCH. e) CNC composite film was used as humidity-responsive color-changing paper. Reprinted with permission from ref (169). Copyright 2019 American Chemical Society.
Dai et al. designed a simple, inexpensive, and highly sensitive colorimetric sensor for detecting ammonia gas by doping copper salt into chiral nematic CNC film (Figure 18a). (172) Since copper ions have a strong chelating affinity to ammonia gas, the composite film with a copper ion loading of 125 mmol/g showed remarkable sensitivity to ammonia gas. The composite film displayed a maximum redshift of 75 nm when the copper ion loading increased to 225 mmol g–1. Of note, excessive copper ions also have several negative effects on the chiral nematic CNC film, including salt microparticle deposition, which destroys the internal chiral nematic structure. Subsequently, Song et al. developed a CNC-based colorimetric sensor that changes color upon exposure to aldehyde gases, for example, propanal and formaldehyde. (173) A layer of close-packed CNC was first deposited onto a silicon substrate by a dip-and-pull process with the aid of (1-butyl-3-methylimidazolium) molecules that can shield the electrostatic repulsion between CNCs. The thickness of the CNC layer could be easily adjusted by changing the pulling speed, thus giving rise to films with various colors in the visible range. The obtained CNC films were then chemically functionalized with amine groups. The films underwent obvious physical and chemical changes such as swelling as they were exposed to aldehyde gases. The color change could be readily observed with the naked eye at high concentrations of aldehyde gas or detected by a digital camera at parts per million levels (Figure 18b and c). Zhao et al. fabricated a dual-stimuli-responsive chiral nematic iridescent CNC film that exhibited a reversible response to environmental humidity and formaldehyde gas (Figure 18d and e). (174) The dual response of the iridescent CNC films was related to the synergistic effect of cooperation and competition between water and the formaldehyde molecules. The humidity sensitivity of iridescent CNC films could be modulated by exposing the films to formaldehyde gas. Similarly, the formaldehyde sensitivity of the iridescent CNC film was also greatly affected by the humidity.
Figure 18
Figure 18. a) Schematic diagram of the structure and color-tuning mechanism of CNC or CNC-Cu(II) films. Reprinted with permission from ref (172). Copyright 2017 Elsevier. b) Schematic diagram of the production of the CNC-based films. c) Images of a CNC colorimetric sensor before (left) and after (right) exposure to formaldehyde at a concentration of 100 ppm. Reprinted with permission from ref (173). Copyright 2018 American Chemical Society. d) Optical images of a CNC film at different RHs. e) Optical images of a CNC film at different concentrations of formaldehyde gas. Reprinted with permission from ref (174). Copyright 2020 American Chemical Society.
Although there are a large number of reports on the use of CNC to construct stimuli-responsive materials, little work has been done on combining stimuli-responsive materials with chiral nematic ChNCs. In 2022, Lee et al. designed a kind of anisotropic stimuli-responsive microgels depending on the chiral nematic phase of ChNCs and NIPAM. (27) The microgels with controlled dimensions were prepared by emulsifying the mixture of ChNC suspension, NIPAM, the cross-linking agent, and initiator in a microfluidic device. After polymerization, the chiral nematic structures formed by ChNCs were embedded in the hydrogel matrix. The resultant microgel showed an asymmetric response to temperature, resulting in an obvious change in shape and optical properties. Additionally, the obtained chiral nematic structures possess the ability to deform in a constricted space. This study provides design guidance for biopolymer composites with programmable motion.
5.2. Photonic Encryption
As mentioned above, structural colors generated by the periodic variance of the refractive index have many merits such as nonfade character, high color saturation, and angle-dependent reflection. By taking advantage of the structural color features, complicated information can be encoded into the chiral nematic CNC- or ChNC-based functional materials for anticounterfeiting and/or encryption applications. For instance, inspired by the skin of chameleons, Wang et al., fabricated highly flexible and free-standing PEG/CNC composite structural color films. (175) A reversible structural color change of the resulting films upon stretching could be observed by the naked eye. Moreover, the composite films showed compressive and water-responsive properties, allowing them to be used as photonic paper. At an RH of 56%, the characters written on the film by ink-free writing were yellow and showed clear outlines. As the RH increased to 100%, the whole film exhibited a slightly reddish translucence appearance and the characters were visible. The marks could be viewed again when the RH decreased to 56% and 16%.
Yang et al. developed an optical encryption system based on polyacrylamide (PAM)/CNC composite films. (8) The composite films containing highly ordered CNCs were fabricated via mechanical stretching, followed by air drying of the dynamic-bond cross-linked PAM hydrogel (Figure 19a). Of note, CNCs within the hydrogel were prealigned via mechanical stretching. After that, the surface tension during the air-drying process further improved the orientation of the nanocrystals, resulting in the formation of the nematic CNC composite films. Owing to the light retardation resulting from the oriented CNCs, vivid interference colors presented by the composite films could be observed. The composite films were employed as modular components and piled together in certain thicknesses and rotation angles to realize the appearance of desirable interference colors. An optical ternary-coded decimal system was developed based on the as-prepared piled composite films. In this system, each decimal numeral of 0–9 was represented by the four colorful squares (Figure 19b). As shown in Figure 19c, 3D QR codes containing desirable digital information were successfully constructed with the CNC film piles. Xu et al. reported that chiral nematic CNC films fabricated by the EISA approach enabled left-handed and right-handed passive CPL (passive L-CPL and R-CPL), and right-handed CPL emission because of its left-handed helical structure and photonic bandgap (PBG). (21) Moreover, the passive CPL was possible in the region ranging from near-UV to near-IR. By coassembling with achiral luminophores, the resulting photonic composite films with desirable R-CPL emission could be obtained. Notably, the R-CPL emission could be tuned by selecting the types of luminophores and tailoring the PBG. Given the intrinsic CPL ability of the photonic CNC-based films, they showcased the potential of neat CNC films and CNC/luminophores composite films in encryption. As shown in Figure 19d, the designed pattern consisted of JLU-shaped photonic neat CNC film and butterfly shaped CNC/luminophores composite film. Of note, the CNC composite film contained two types of organic luminophores, i.e., M1 emission at 512 nm and M3 emission at 585 nm, which were inside and outside the PBG, respectively. M1 contributed to the modulation of the R-CPL emission, while M3 was responsible for the tuning of the film color under irradiation. When observed under natural light against a black background, the iridescent color of the JLU-butterfly pattern was easily discernible to the naked eye. Moreover, the colors appeared more vibrant and subdued when viewed through left- and right-polarizing filters, respectively. Under 365 nm irradiation, “JLU” was nonemitting, while the combination of the right-circularly polarized (R-CPL) emission from M1 within the photonic bandgap (PBG) and the spontaneous emission from M3 resulted in the reddish beige color of the “butterfly”. Thus, the “JLU-butterfly” pattern was observed as “butterfly”. By observation of the “butterfly” pattern through left-polarizing and right-polarizing filters, distinct color variations were observed. When viewed through a left-polarizing filter, the “butterfly” took on an orange hue, predominantly due to the left-circularly polarized (L-CPL) emission from M3. Conversely, when observed through a right-polarizing filter, the “butterfly” exhibited a beige color, primarily attributed to the combined R-CPL emissions from both M1 and M3. Given that such a simple design utilizing neat photonic CNC film and CNC composite film can lead to diverse optical patterns, it is believed that a powerful system with multiple channels based on structural-color CNC or ChNC materials is possible for encryption/anticounterfeiting applications.
Figure 19
Figure 19. a) Schematic diagram showing the fabrication of CNC composite films with uniform and tunable colors. b) Ten fundamental elements, representing 0–9 decimal, were formed by stacking patterned composite films between the crossed polarizers. c) A 3D code for information storage and encryption through the combination of fundamental elements. Reprinted with permission from ref (8). Copyright 2020 Wiley-VCH. d) The potential of chiral photonic CNC films for polarization-based encryption. Reprinted with permission from ref (21). Copyright 2018 Wiley-VCH. e) Integrated five-channel encryption of CNC/bioAuNCs biolabels. Reprinted with permission from ref (9). Copyright 2023 Wiley-VCH.
Chiroptical biolabels with multiple channels were constructed by the host–guest self-assembly of chiral CNCs and photoluminescent bovine serum albumin (BSA) stabilized-gold nanoclusters (AuNCs) (Figure 19e). (9) The chiral nematic CNCs and the well-organized AuNCs immobilized on their surfaces were responsible for the structural color and photoluminescent color with strong circularly polarized luminescence (CPL) activity, respectively. The resulting CNC/AuNC composite films enabled anticounterfeiting and complex information encryption through multidimensional control of the polarization and lighting environment. Considering the fact that Cu2+ can competitively coordinate with BSA, while l-ascorbic acid (VC) exhibits stronger coordination and redox reaction with Cu2+ than BSA, the reversible PL was achieved by the addition of BSA and VC, which enabled encoding/erasing rewriting capability in the photoluminescent channel. Meanwhile, Ca2+-induced cross-linking of CNC templates allowed the humidity-responsive patterning in structural color channels. Moreover, customized micro/nano physical patterns that are only visible in microscopy were integrated onto the surface of the biolabels via self-assembling CNC/AuNC at the predesigned topographical patterned templates, which greatly extended information encryption capability. Although different types of CNC-based photonic encryption/anticounterfeiting systems have been developed, considerable efforts are still required to promote the practical application of such promising materials.
5.3. Templates for Chiral Mesoporous Materials
Functional materials that combine photonic structures and porosity have been actively pursued, owing to their significant potential in chiral sensing/recognition, chiral separation, and stereospecific catalysis. The chiral nematic self-assembling behaviors of CNCs and ChNCs, as well as their nanosized dimensions and high surface area, make such nanocrystals promising templates for constructing various types of chiral nematic mesoporous materials.
The idea of synthesizing mesoporous silica films by sol–gel mineralization using CNC as a template was reported in 2003. Dujardin et al. found that aqueous CNC suspensions could be mixed with prehydrolyzed tetramethoxysilane (TMOS) solutions. Birefringent silica replicas exhibiting patterned mesoporosity were obtained after the removal of CNC templates by calcining at 400 °C for 2 h. (179) However, long-range chiral nematic structures were not found in this material. Until 2010, free-standing chiral nematic mesoporous silica films with long-range chiral nematic structures imparted by CNCs were fabricated by MacLachlan et al. (Figure 20a–c). (10) The high surface area and chiral nematic structure of CNCs were precisely replicated in an inorganic solid. The reflected wavelengths of the films can be varied in the visible and near-infrared spectral ranges by changing the silica precursor-to-CNC ratio. Note that owing to their mesoporosity and chiral nematic structures, such chiral nematic mesoporous materials, inherited from self-assembled CNC, have emerged as promising chiral mesoporous hosts to combine achiral luminescent materials for the synthesis of circularly polarized luminescence (CPL)-active materials. For instance, chiral mesoporous silica was successfully utilized as a host to allow the in situ growth of various achiral halide perovskite nanocrystals (PNCs) (Figure 20d). (176) The resulting composite displayed stable CPL emissions with full-color tunability and remarkable luminescent dissymmetric factors reaching up to −0.17.
Figure 20
Figure 20. a) Photograph of mesoporous silica films with different colors. b–c) Photograph of a mesoporous silica film taken at different incidences. Reprinted with permission from ref (10). Copyright 2010 Springer Nature. d) Schematic diagram of in situ confined growth of PNCs within CNC film. Reprinted with permission from ref (176). Copyright 2024 Wiley-VCH. e) Photo of TiC film. f) PLM image of the TiC film. Reprinted with permission from ref (177). Copyright 2019 American Chemical Society. g) Schematic illustration of the production of templated ZIF. h) Typical I–V curve of templated ZIF to l-Ala and d-Ala at 400 μM. i) Current change (ΔI/I0) plot of templated ZIF at different l- and d-Ala concentrations from 50 to 400 μM. Reprinted with permission from ref (178). Copyright 2023 Wiley-VCH.
More recently, besides chiral nematic mesoporous silica, considerable efforts have been devoted to synthesizing many other types of materials with chiral nematic mesoporous structures, including metal, metal oxides, and polymers, just to name a few, by taking advantage of the nanoscale and the chiral nematic order of the CNC templates. For instance, by using a similar sol–gel process, mesoporous TiO2 films containing replicas of the chiral nematic structures were synthesized and utilized as photocatalysts for phenol degradation and H2 production. (180) Controlling the amount of d-glucose added into the CNC suspension resulted in the formation of chiral nematic structures with different helical pitches, thus finally leading to the photonic TiO2 films with the desired stopband. Compared to mesoporous TiO2 without chiral nematic structures, the obtained mesoporous TiO2 films containing replicas of the chiral nematic structures showed improved kinetics of H2 production and phenol photocatalytic degradation, as well as enhanced TiO2 photoconductivity. To further enhance the photoefficiency, various types of metal oxides including copper oxide, vanadium oxide, nickel oxide, and bismuth oxide, could be easily coupled the lamellar mesostructured TiO2 via a straightforward self-assembly method, resulting in higher H2 generation. Peroxotitanates (PTs), a kind of anionic, water-soluble complexes, were reported to coassemble with CNCs to fabricate peroxotitanate/CNC composites with tunable colors. (177) After hydrothermal treatment followed by calcination in air, the obtained peroxotitanate/CNC composites could be transformed into robust, semitransparent TiO2 films with layered mesoporous structures. Additionally, freestanding mesoporous TiC films with chiral nematic order were successfully obtained by the magnesiothermic reduction of carbonized peroxotitanate/CNC assemblies (Figure 20e and f). The mesoporous TiC films showed excellent capacity retention performance, which may serve to develop freestanding anode materials for rechargeable lithium-ion batteries with long-term stability.
Chiral metal–organic frameworks (MOFs), as ordered porous materials with great potential for chiral catalysis, sensing, and enantiomers, have attracted considerable attention. The conventional approach to synthesizing chiral MOFs involves utilizing chiral organic molecules as primary linkers or auxiliary ligands. However, this method presents a significant limitation, as it often necessitates the use of costly and specialized chiral building blocks, which are available from a restricted selection of sources. Recently, Tsukruk et al. reported a scalable and effective method for achieving chiral zeolitic imidazolate framework (ZIF) MOF, unc-[Zn(2-MeIm)2,2-MeIm = 2-methylimidazole], from achiral precursors by utilizing chiral nematic organization of CNCs as hierarchical biotemplates (Figure 20g). (178) CNCs were selected as biotemplates due to their three levels of chirality: (i) asymmetric carbon atoms in d-glucose units at the molecular level; (ii) spindle-shaped nanocrystals at the nanoscale; and (iii) left-handed chiral nematic liquid crystal organization at the macroscale. The templated chiral ZIF demonstrates chiral sensing and enantioselective recognition abilities with a low detection limit of 39 μM and a chiral detection limit of 300 μM for the chiral amino acids d- and l-alanine (Figure 20h and i). The chiral nematic CNC suspension, beyond serving as templates, can be transformed into free-standing cellulosic aerogels through supercritical CO2 drying. (181) Subsequent carbonization under an Ar atmosphere resulted in the formation of free-standing activated carbon aerogels with a hierarchical order derived from the chiral nematic organization of CNCs. These activated carbon aerogels exhibited interconnected meso/micropores and boasted specific surface areas of up to 820 m2 g–1. Notably, they also displayed superparamagnetic behavior with a maximum magnetization value of 17.8 ± 0.1 emu g–1. Depending on the composition, such aerogels possessed compressive modulus values ranging from 179 to 400 kPa. When utilized as symmetric supercapacitor electrodes, the activated carbon chiral nematic aerogels showcased an impressive specific capacitance of 294 F g–1, maintaining 92.8% capacitance retention after 2500 cycles at a scan rate of 50 mV s–1.
The CNC templating strategy was additionally employed to create chiral nematic mesoporous polymers. It is important to note that, compared to extensive research on inorganic mesoporous materials synthesized through chiral nematic CNC templates, there has been significantly less investigation into the fabrication and application of organic mesoporous materials using chiral nematic CNC organizations. Khan et al. reported a chiral mesoporous phenol-formaldehyde (PF) resins by using CNCs as templates (Figure 21a). (182) The color of the composite films can be tuned by varying the ratio of the PF precursor to CNC or the ionic strength of the mixture. Flexible mesoporous polymer films with photonic properties were obtained after the CNC template was removed by NaOH treatment. These films appeared bright red under a left-handed circular polarizer while turning to dull brown under a right-handed circular polarizer (Figure 21b). Moreover, the films showed only a slight color change after immersing in anhydrous ethanol. In contrast, polymer films immersed in ethanol/water mixtures and pure water displayed obvious, tunable color changes. Furthermore, the systematic changes in color can be easily observed by the naked eye when swelling in ethanol/water mixtures with different proportions (Figure 21c). These mesoporous films have potential applications in sensing and optics due to their flexibility, photonic properties, and responsive swelling behavior. Then, the same group reported a bilayer chiral nematic resin film with tunable optical properties and rapid mechanical response. (186) The bilayer film was fabricated by using two mesoporous phenol formaldehyde (PF) resin layers containing CNCs-based chiral nematic structures with different helical pitches. Such a mesoporous PF resin bilayer film with chiral nematic structures can selectively reflect light of two different wavelengths. Moreover, the differential swelling behaviors of the two layers caused the thin films to curl after exposure to different solvents. The stimulation of reactive actuation combined with the changes in photonic properties makes these materials attractive in the field of optics and soft-body robotics.
Figure 21
Figure 21. a) Schematic diagram showing the synthesis of mesoporous chiral nematic phenol-formaldehyde resins. b) Photographs of a sample under left-handed circular polarizer (left) and right-handed polarizer (right). c) Schematic illustration (top) and photographs (bottom) of the samples in water and ethanol mixtures. Reprinted with permission from ref (182). Copyright 2013, Wiley-VCH. d) Schematic illustration of the fabrication of latex-GO composite film. e) Photographs of the film strips immersed in the mixtures of H2O/n-PrOH with different VH2O. Reprinted with permission from ref (183). Copyright 2019 Royal Society of Chemistry. f) Illustration and photographs of the film strips with predetermined shapes treated by FoA and their responses to the wetting-drying circle. Reprinted with permission from ref (184). Copyright 2019 Royal Society of Chemistry. g) Photographs of mesoporous polymer resin films in a mixture of water and ethanol with different proportions. h) Complicated image patterned on a mesoporous film, and the pattern can be revealed by swelling in water. i) Complicated image patterned on a mesoporous film, and the pattern can be revealed by swelling in 20/80 (v/v) water/ethanol mixture. Reprinted with permission from ref (185). Copyright 2015, Wiley-VCH.
Actuators with a bilayer structure often suffer from weak interlayer connections, leading to detachment after repeated use. Yuan et al. recently reported the fabrication of flexible mesoporous latex/GO composite films with a single-layer structure, templated by CNCs through EISA of an aqueous dispersion containing latex, GO, and CNCs (Figure 21d). (183) Driven by gravitational differences and entropy increases, GO distributed unevenly, predominantly gathering at the top of the film. This asymmetrical organization imparts different wettabilities to the top and bottom surfaces of the film. Furthermore, the chiral nematic order was retained within the film after the removal of CNC via NaOH treatment. As a result, the film exhibited synchronous color and actuation responses (Figure 21e).
The aforementioned mesoporous films generally exhibit simple bending and curling movements due to their undesigned shapes. To achieve more sophisticated motions, mesoporous PF resin/GO-based actuators with predesigned shapes were fabricated via the standard EISA approach. (184) Similar to latex/GO composite films, the obtained mesoporous resin film exhibited a GO-depleted top surface and a GO-rich bottom surface and displayed structural colors derived from the internal chiral nematic architecture. By selectively treating the films with aldehydes followed by thermopolymerization, objects formed from fully wetted film bars can achieve various permanent shapes and exhibit robust shape recovery behavior over multiple wetting-drying cycles (Figure 21f).
Dynamic photonic patterns were fabricated with mesoporous phenol-formaldehyde resins. (185) After swelling in polar solvent, the mesoporous PF resins showed red-shift which can be tuned by postsynthetic treatment with acid or formaldehyde (Figure 21g). With acidification, the cross-linking of the films increased, leading to a decrease in the concentration of methylol groups on the surface of the films and a decrease in hydrophilicity. Conversely, formaldehyde treatment increased the density of methylol groups, thereby increasing the hydrophilicity. After treatment, the resin exhibited different swelling behaviors, leading to changes in chiral nematic pitch and reflected color. Thus, acid and formaldehyde could be used as inks to write on the films, generating latent images that appear only when the film swells (Figure 21h and i).
Inorganic optical mesoporous materials have also been successfully prepared by ChNC-induced ordering self-assembly of inorganic particles. Kato and co-workers fabricated anisotropic ChNC-templated calcium carbonate (CaCO3) composite materials. (187) First, free-standing ChNC gel films were obtained by soaking the concentrated liquid crystalline solution (15 wt %) in methanol. Then, the gels were manually stretched to further align the nanocrystals. The obtained ChNC films were used as templates for the growth of CaCO3. It was found that rod-shaped CaCO3 crystals grew along the long axis of the ChNC backbone within the stretched films. However, no rod-shaped crystals were obtained when unstretched ChNCs films were used as the matrix. ChNCs/CaCO3 composite films with helical structures were prepared by a biomineralization-inspired crystallization process. (188) Helical chitin/PAA templates were synthesized from a chiral nematic liquid crystalline ChNC suspension, which were then immersed in the colloidal CaCO3 suspension at room temperature. Transparent films were obtained after complete drying, in which the weight fraction of CaCO3 increased from 12 wt % after 1 day of deposition time to 23 wt % after 7 d.
Mesoporous silica materials were obtained after calcination of nanocomposites, and the porosity was strongly correlated to the initial concentration of ChNC. When using ChNCs as templates to prepare mesoporous silica materials, the porosity and chiral nematic structure of films were determined by the initial concentration of ChNC. (189) Though layered nematic structures in the films were confirmed by TEM, no chiral nematic structure was found. Nguyen et al. reported the preparation of mesoporous silica and organosilica films with layered structures and high surface areas using ChNCs as templates. (190) ChNC templates were removed by calcination or sulfuric-acid-catalyzed hydrolysis to yield large, crack-free mesoporous silica and ethylene-bridged organosilica films. Mesoporous nitrogen-doped carbon materials with layered structures were fabricated using ChNC as a soft template by a three-step method. (191) ChNCs were first encapsulated within sol–gel silica; then, the resulting silica/ChNC composite was carbonized, and the silica was etched. The resultant mesoporous nitrogen-doped carbon films can be used as electrode materials for supercapacitors.
5.4. Self-Assembly in Confined Geometry
Recently, the self-assembly of CNCs and ChNCs in confined spaces such as tubular and spherical geometries has established itself as an efficient way to construct chiral nematic materials that possess properties distinct from those fabricated in planar unconfined geometry. Of note, in comparison to self-assembly in unconfined space that has been widely explored, the self-assembly of CNCs/ChNCs under confinement is still in its infancy.
Xiong et al. explored the combination of optical structures and 3D chiral arrangement in CNC films by patterning the surface of CNC films with different templates. (192) The surface-patterned CNC films displayed ordered chiral nematic structures inside the film and highly oriented CNC gratings on the topmost embossed grooves (Figure 22a). Compared with traditional uniform CNC films, the patterned films exhibited narrower selective reflection width, high CPL, and a view-angle-dependent color appearance (Figure 22b). Utilizing the same method, Chu et al. developed a hierarchically structured paper with dual photonic structures, including the interior chiral nematic organizations and the periodic grating lines on its surface. (195) The patterned photonic films were fabricated by confining CNC suspensions in highly aligned microgrooves via soft nanoimprinting lithography and EISA processes. After drying, the films with highly ordered grating lines on their underside were peeled off of the template. Liu et al. developed a simple microfluidic strategy to produce hierarchical liquid metacrystal (LMC) fibers with core–sheath structures through the confined self-assembly of CNC within a hydrogel sheath formed by the fast gelation of sodium alginate (Na-Alg) and Ca2+ ions (Figure 22c). (12) 3D topological architectures consisting of long-range chiral nematic liquid crystalline configurations were formed within the LCM fibers, including radial topological structures and axial awl-shaped topological structures. The sheath layer played an important role in preventing shape deformation and providing a continuous and stable self-assembly environment (Figure 22d). During the drying process, the shape of LMC fibers could be reconfigured by applying external stress, resulting in a highly controlled color distribution (Figure 22e). The obtained LMC fibers not only displayed vivid, tunable interference colors and inverse optical activity but also had the ability to precisely tune linearly and CPL in a half-sync/half a sync form (Figure 22f). The obtained fibers showed potential applications in the field of advanced textiles with different colors for identification (Figure 22g).
Figure 22
Figure 22. a) Schematic illustration of the self-assembly of chiral CNC photonic structures with surface gratings. b) Photographs of CNC film patterned with the grating periodicity of 1.6 μm under no polarizers (left), left-hand circular polarizer (middle), and right-hand circular polarizer (right). Reprinted with permission from ref (192). Copyright 2019 Wiley-VCH. c) Fabrication of scalable LMC fibers. d) Schematic illustration showing the formation of the chiral nematic liquid crystalline phase within the LMC fibers and the mechanism of the self-organization of LMCs in a dynamically confined, cylindrical geometry. e) PLM-λ images of the LMC fibers with different optical appearances by applying external stress. f) PLM-λ images of two crossed LMC fibers showing different combinations of optical appearances at the position of right-rotated 45°. g) Schematic illustration of the advanced fabrics showing different colors for identification. Reprinted with permission from ref (12). Copyright 2020 Wiley-VCH. h) Photographs of four curved films with a radius R = 2 mm (top) and the corresponding polarized optical microscopy images of these films (down). Reprinted with permission from ref (193). Copyright 2018 Wiley-VCH. i) PLM images of pure and composite CNC films drying in the rectangular capillaries. Reprinted with permission from ref (194). Copyright 2021 American Chemical Society. j) Photographs of cellulosic photonic pigments. Reprinted with permission under a Creative Commons Attribution (CC BY) License from ref (13). Copyright 2022 Springer Nature.
Rofouie et al. reported the production of semispherical photonic chiral nematic films through the confined self-assembly of CNC in semispherical cavities (Figure 22h). (193) The optical properties and structure of the resulting films can be tuned by changing the cavity curvature, the composition of the precursor CNC suspension, and its liquid crystalline or isotropic state. The spherical shape of the films facilitated polydomain structure formation and helix axis inclination, thereby producing a broadband reflection spectrum. Crack-free, uniform, and monolithic thin photonic films were produced through confined self-assembly of CNC in rectangular capillaries (Figure 22i). (194) CNC, PEG, and 3,4,5-trihydroxyphenethylamine hydrochloride (TOPA) were used as the liquid crystalline phase material, polymer plasticizer, and adhesion promoter, respectively. It was found that no cracks formed for CNC/TOPA/PEG composite film, while numerous cracks formed for pure CNC film and few cracks formed for CNC/PEG composite film. The improved hydrogen bonding achieved by the addition of TOPA and the relaxation of the internal stress with the assistance of PEG jointly suppressed the formation of cracks for the CNC/TOPA/PEG composite film. Moreover, the chiral nematic structure propagated through the entire thickness and across centimeter-sized surface areas, enabling the obtained uniform, crack-free films with vivid interference colors and improved toughness as well as the ultimate tensile strength. Photonic pigments that reflect colors across the entire visible spectrum were produced by confined self-assembly of chiral nematic CNC suspension within emulsified microdroplets (Figure 22j). (13) During the drying process, the droplets underwent numerous buckling events, which made the shrinkage of the nanostructure greater than that predicted for spherical geometries. The interfacial buckling distorted the chiral nematic structure of CNCs, resulting in both LCP and RCP light reflections. Furthermore, the cellulose photonic pigments integrated into a matrix displayed an angle-independent structural color. Liu et al. reported the confined self-assembly of ChNCs in the capillaries. (28) In the confined environment, the air–liquid interface at the end of the capillary served as both the evaporation interface and the initial deposition site of ChNCs, which was different from the moving evaporation interface in the previous EISA modalities. The formation of tactoids was suppressed during the whole self-assembly process, while birefringent ChNC multilayers with nested multiple paraboloid structures and a density gradient were gradually generated, finally resulting in the formation of cylindrical ChNCs-based photonics.
5.5. Potential Strategies for Large-Scale Production of PNs-Based Chiral Nematic Materials
The traditional methods for fabricating chiral nematic CNC films, such as EISA, often require several hours or even days and are limited to small-scale production, hindering their industrial application. Thus, there is a significant demand for simple and efficient methods to enable the continuous production of large-scale chiral nematic films. As introduced above, Atifi and colleagues reported a rapid and scalable technique using electrodeposition to create chiral nematic CNC films with long-range order in just a few minutes. (138) Although this approach demonstrated the ability to prepare chiral nematic CNC films within a short time, the possibility of fabricating large-scale photonic films via this method was not verified. Vignolini et al. presented an industrially relevant method to scale up the production of structurally colored films by casting a commercially available CNC suspension on a commercial roll-to-roll (R2R) coating unit (Figure 23). (196) The formulation of the CNC suspension and the deposition and drying conditions were extensively studied to enable the production of flexible structural CNC films. Notably, to demonstrate the continuous production of photonic CNC films, the R2R process was modified to include an in-line hot-air dryer to accelerate evaporation and stepwise translation to reduce the effective deposition speed of the web. After heating at 180 °C for 30 min, the prepared films could be ground into particles suitable for use as effect glitter and pigments, providing an eco-friendly alternative to nonbiodegradable microplastics and unsustainable inorganic pigments. Not only that, despite the growing demand for chiral nematic films derived from PNs, progress in developing suitable approaches for their large-scale production has been limited. Concerted efforts should be devoted to advancing technologies for the large-scale production of chiral nematic films in the near future.
Figure 23
Figure 23. a) Flowchart describing the key steps in the fabrication of photonic CNC particles. b) Photograph of the corona etching step. c) Photograph of the slot-die coating of CNC suspension onto the web. d) Photograph of static drying at 20 °C. e) Photograph of continuous progressive drying at 60 °C. f) In-line peeling of a CNC film from the web. g) CNC films deposited onto a black PET web. h) Photograph of a free-standing R2R-cast CNC film. i) Untreated (left) and heat-treated (right) photonic CNC particles embedded in transparent varnish before size sorting. j) Heat-treated photonic CNC particles (pigments) immersed in ethanol and 50% aqueous ethanol (from left to right). Reprinted with permission from ref (196). Copyright 2022 Springer Nature.
6. CONCLUSIONS AND OUTLOOK
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Chiral nematic architectures featuring special functionalities have been found in various living systems on different scales. Replicating such structures and exploring their fascinating properties and broad applications have been and continue to be highly pursued. With merits of abundance, intrinsic high biocompatibility and biodegradability, and ease of modification, PNs, in particular, CNCs and ChNCs, are capable of self-organizing into chiral nematic structures, making them ideal nanobuilding blocks for constructing various functional biomimetic chiral nematic materials.
This review intends to summarize the latest advances and current knowledge regarding the self-assembly of CNCs/ChNCs into chiral nematic structures, highlighting the introduction of cellulose- and chitin-based chiral nematic structures in living organisms, various crucial factors affecting the chiral nematic structures formed via self-assembly of CNCs and ChNCs as well as the optical properties of the self-assembled materials. The application of the CNCs- and ChNCs-based materials containing chiral nematic structures in stimuli-responsive photonic sensors, photonic encryption, and templating for chiral mesoporous materials have also been described. Moreover, a largely underexplored area, that is, self-assembly of these nanocrystals under confinement, has also been summarized.
While significant progress has been achieved during the past decades in the aspects of unveiling self-assembly mechanisms, easing fabrication procedures, and broadening applications, there are still some grand challenges for large-scale construction and application of CNC- and ChNC-based chiral nematic materials. First, the realization of uniform structural colors within large-scale CNC- and/or ChNC-based functional materials is of paramount significance but extremely challenging owing to the difficulty of precisely controlling the alignment of chiral nematic domains and the helical pitch during the self-assembly process. Some recent research findings, for instance, the visualization of the structural evolution of CNC tactoids to chiral nematic films, may contribute to the preparation of high-quality photonic materials with uniform structural color. Second, time-saving, effective, and feasible approaches that can accommodate large-scale and continuous production of chiral nematic materials are highly required. For most self-assembly approaches, for instance, EISA, the long time required for film formation is a major hurdle to the large-scale production of CNC/ChNCs-based chiral nematic materials. Notably, the self-assembled materials prepared by EISA showed poor repeatability. Third, the precise mechanism lying behind the self-assembly process or, in other words, the driving force in the self-organization of CNCs/ChNCs into chiral nematic structures is not yet clear. Multiple advanced characterization techniques, e.g., in situ synchrotron X-ray scattering and cryogenic electron microscopy, combined with theoretical and rational modeling, could offer rich possibilities for a deeper understanding of the self-assembly mechanism.
Overall, despite the great strides that have been fulfilled in the area of self-assembly of CNCs and ChNCs into chiral nematic architectures, this research realm is still in its infancy. We believe that interdisciplinary communication and collaboration are key to future research and the acceleration of the development of chiral nematic PNs-based products and technologies.
Author Information
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- Kai Zhang - Sustainable Materials and Chemistry, Department of Wood Technology and Wood-Based Composites, University of Göttingen, Göttingen 37077, Germany;
https://orcid.org/0000-0002-5783-946X;
- Huan Liu - Biofuels Institute, School of the Environment and Safety Engineering, School of Emergency Management, Jiangsu University, Zhenjiang 212013, China; National Forestry and Grassland Administration Key Laboratory of Plant Fiber Functional Materials, Fuzhou 350108, China;https://orcid.org/0000-0001-5725-750X
- Jun Liu - Biofuels Institute, School of the Environment and Safety Engineering, School of Emergency Management, Jiangsu University, Zhenjiang 212013, China;https://orcid.org/0000-0001-5393-3187
- Qianqian Wang - Biofuels Institute, School of the Environment and Safety Engineering, School of Emergency Management, Jiangsu University, Zhenjiang 212013, China;https://orcid.org/0000-0003-3514-455X
The manuscript was written through contributions of all authors. All authors have approved the final version of the manuscript.
Acknowledgments
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The authors are grateful for the support of the National Natural Science Foundation of China (22208131), the Natural Science Foundation of Jiangsu Province (BK20220547), the University Natural Science Research Project in Jiangsu Province (21KJB610009), the National Natural Science Foundation of China (22278195), the Start-up Fund for Introduced Scholar of Jiangsu University (5501370016), and the National Forestry and Grassland Administration Key Laboratory of Plant Fiber Functional Materials (2022KFJJ03).
| Polysaccharide nanocrystals | crystalline regions derived from polysaccharides such as cellulose nanocrystals and chitin nanocrystals, which are large carbohydrate molecules composed of repeating sugar units. |
| Cellulose nanocrystals | the crystalline components isolated from cellulose at the nanoscale. |
| Chitin nanocrystals | the crystalline components isolated from chitin sources at the nanoscale. |
| Self-assembly | a process in which molecules or nanoscale building blocks spontaneously organize into well-defined, stable structures without human intervention or guidance. This process is driven by various noncovalent interactions such as hydrogen bonding, van der Waals forces, electrostatic interactions, and hydrophobic effects. |
| Chiral nematic structure | a type of liquid crystal phase that exhibits a helical arrangement of molecules. This structure combines the properties of nematic liquid crystals, where molecules are aligned parallel to each other, with a chiral order, resulting in a helical pattern. |
References
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- 6Yao, K.; Meng, Q.; Bulone, V.; Zhou, Q. Flexible and Responsive Chiral Nematic Cellulose Nanocrystal/Poly(ethylene glycol) Composite Films with Uniform and Tunable Structural Color. Adv. Mater. 2017, 29, 1701323 DOI: 10.1002/adma.201701323Google ScholarThere is no corresponding record for this reference.
- 7Kose, O.; Tran, A.; Lewis, L.; Hamad, W. Y.; MacLachlan, M. J. Unwinding a Spiral of Cellulose Nanocrystals for Stimuli-Responsive Stretchable Optics. Nat. Commun. 2019, 10, 510, DOI: 10.1038/s41467-019-08351-6Google Scholar7Unwinding a spiral of cellulose nanocrystals for stimuli-responsive stretchable opticsKose, Osamu; Tran, Andy; Lewis, Lev; Hamad, Wadood Y.; MacLachlan, Mark J.Nature Communications (2019), 10 (1), 510CODEN: NCAOBW; ISSN:2041-1723. (Nature Research)Cellulose nanocrystals (CNCs) derived from biomass spontaneously organize into a helical arrangement, termed a chiral nematic structure. This structure mimics the organization of chitin found in the exoskeletons of arthropods, where it contributes to their remarkable mech. strength. Here, we demonstrate a photonic sensory mechanism based on the reversible unwinding of chiral nematic CNCs embedded in an elastomer, leading the materials to display stimuli-responsive stretchable optics. Vivid interference colors appear as the film is stretched and disappear when the elastomer returns to its original shape. This reversible optical effect is caused by a mech.-induced transition of the CNCs between a chiral nematic and pseudo-nematic arrangement.
- 8Yang, Y.; Wang, X.; Huang, H.; Cui, S.; Chen, Y.; Wang, X.; Zhang, K. Modular Nanocomposite Films with Tunable Physical Organization of Cellulose Nanocrystals for Photonic Encryption. Adv. Opt. Mater. 2020, 8, 2000547 DOI: 10.1002/adom.202000547Google Scholar8Modular Nanocomposite Films with Tunable Physical Organization of Cellulose Nanocrystals for Photonic EncryptionYang, Yang; Wang, Xiaojie; Huang, Heqin; Cui, Shiqiang; Chen, Ye; Wang, Xiaohui; Zhang, KaiAdvanced Optical Materials (2020), 8 (12), 2000547CODEN: AOMDAX; ISSN:2195-1071. (Wiley-VCH Verlag GmbH & Co. KGaA)Reported herein is the novel achievement of uniform and tunable interference colors of nanocomposite films contg. organized cellulose nanocrystals (CNCs) from dynamic hydrogel precursors. Homogeneous and amendable interference colors with broad range are obtained either by stacking the nanocomposite films to adjust the amt. of CNCs in the propagation pathway of light or by regulating the rotation angles between the individual films to alter the relative organization of CNCs within the system. Moreover, the precise and controllable patterned CNC composite films with multicolors in one film are facilely fabricated for the first time from the patterned hydrogel precursors. Based on this stacking/rotation-method, these patterned nanocomposite films with tunable interference colors can be further applied as fundamental elements for optical encryption by establishing a ternary-coded decimal system with encoded decimal numerals, paving the way for the development of photonic functional materials based on CNCs.
- 9Zhou, Y.; Lu, C.; Lu, Z.; Guo, Z.; Ye, C.; Tsukruk, V. V.; Xiong, R. Chiroptical Nanocellulose Bio-Labels for Independent Multi-Channel Optical Encryption. Small 2023, 19, 2303064 DOI: 10.1002/smll.202303064Google Scholar9Chiroptical Nanocellulose Bio-Labels for Independent Multi-Channel Optical EncryptionZhou, Yi; Lu, Canhui; Lu, Zhixing; Guo, Zhen; Ye, Chunhong; Tsukruk, Vladimir V.; Xiong, RuiSmall (2023), 19 (32), 2303064CODEN: SMALBC; ISSN:1613-6810. (Wiley-VCH Verlag GmbH & Co. KGaA)Advanced multiplexing optical labels with multiple information channels provide a powerful strategy for large-capacity and high-security information encryption. However, current optical labels face challenges of difficulty to realize independent multi-channel encryption, cumbersome design, and environmental pollution. Herein, multiplexing chiroptical bio-labels integrating with multiple optical elements, including structural color, photoluminescence (PL), circular polarized light activity, humidity-responsible color, and micro/nano phys. patterns, are constructed in complex design based on host-guest self-assembly of cellulose nanocrystals and bio-gold nanoclusters. The thin nanocellulose labels exhibit tunable circular polarized structural color crossover the entire visible wavelength and circularly polarized PL with the highest-recorded dissymmetry factor up to 1.05 due to the well-ordered chiral organization of templated gold nanoclusters. Most importantly, these elements can independently encode customized anti-counterfeiting information to achieve five independent channels of high-level anti-counterfeiting, which are rarely achieved in traditional materials and design counterparts. Considering the exceptional seamless integration of five independent encryption channels and the recyclable features of labels, the bio-labels have great potential for the next generation anti-counterfeiting materials technol.
- 10Shopsowitz, K. E.; Qi, H.; Hamad, W. Y.; MacLachlan, M. J. Free-Standing Mesoporous Silica Films with Tunable Chiral Nematic Structures. Nature 2010, 468, 422– 425, DOI: 10.1038/nature09540Google Scholar10Free-standing mesoporous silica films with tunable chiral nematic structuresShopsowitz, Kevin E.; Qi, Hao; Hamad, Wadood Y.; MacLachlan, Mark J.Nature (London, United Kingdom) (2010), 468 (7322), 422-425CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)Chirality at the mol. level is found in diverse biol. structures, such as polysaccharides, proteins and DNA, and is responsible for many of their unique properties. Introducing chirality into porous inorg. solids may produce new types of materials that could be useful for chiral sepn., stereospecific catalysis, chiral recognition (sensing) and photonic materials. Template synthesis of inorg. solids using the self-assembly of lyotropic liq. crystals offers access to materials with well-defined porous structures, but only recently has chirality been introduced into hexagonal mesostructures through the use of a chiral surfactant. Efforts to impart chirality at a larger length scale using self-assembly are almost unknown. Here we describe the development of a photonic mesoporous inorg. solid that is a cast of a chiral nematic liq. crystal formed from nanocryst. cellulose. These materials may be obtained as free-standing films with high surface area. The peak reflected wavelength of the films can be varied across the entire visible spectrum and into the near-IR through simple changes in the synthetic conditions. To the best of our knowledge these are the first materials to combine mesoporosity with long-range chiral ordering that produces photonic properties. Our findings could lead to the development of new materials for applications in, for example, tuneable reflective filters and sensors. In addn., this type of material could be used as a hard template to generate other new materials with chiral nematic structures.
- 11Shopsowitz, K. E.; Stahl, A.; Hamad, W. Y.; MacLachlan, M. J. Hard Templating of Nanocrystalline Titanium Dioxide with Chiral Nematic Ordering. Angew. Chem., Int. Ed. 2012, 51, 6886– 6890, DOI: 10.1002/anie.201201113Google Scholar11Hard Templating of Nanocrystalline Titanium Dioxide with Chiral Nematic OrderingShopsowitz, Kevin E.; Stahl, Alexander; Hamad, Wadood Y.; MacLachlan, Mark J.Angewandte Chemie, International Edition (2012), 51 (28), 6886-6890, S6886/1-S6886/9CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)Chiral nematic mesoporous silica can be used as a template to synthesize titania. In this hard-templating method, structural features are replicated at several length scales: (1) the titania is mesoporous with a surface area and pore size that is detd. by the porosity of the starting silica template; (2) the material obtained selectively reflects left-handed circularly polarized light, which indicates a chiral nematic organization of the titania crystallites; and (3) the titania is obtained as films with similar dimensions as the original silica films.
- 12Liu, Y.; Wu, P. Bioinspired Hierarchical Liquid-Metacrystal Fibers for Chiral Optics and Advanced Textiles. Adv. Funct. Mater. 2020, 30 (27), 2002193 DOI: 10.1002/adfm.202002193Google Scholar12Bioinspired Hierarchical Liquid-Metacrystal Fibers for Chiral Optics and Advanced TextilesLiu, Yanjun; Wu, PeiyiAdvanced Functional Materials (2020), 30 (27), 2002193CODEN: AFMDC6; ISSN:1616-301X. (Wiley-VCH Verlag GmbH & Co. KGaA)The organization of nanoparticles in constrained geometries has attracted increasing attention due to their promising structures and topologies. However, the control of hierarchical structures with tailored periodicity at different length scales and topol. stabilization in a dynamic environment are very limited and challenging. Herein, through self-assembly of cellulose nanocrystals (CNCs) within an in situ formed hydrogel sheath using a simple microfluidic strategy, a new breed of liq. crystal (LC) fibers with hierarchical core-sheath architectures, metaperiodic cholesteric alignments, and 3D topol. defects, termed as liq. metacrystal (LMC) fibers, is created. The resulting LMC fibers not only exhibit vivid, tunable interference colors, and even inverse optical activity but also have a unique ability to precisely regulate linearly and circularly polarized light in a half-sync/half-async form. Furthermore, robust hydrogel sheath enables the LMCs with alignment stability and configuration programmability during drying, which endows the unprecedented freedom to tailor different optical appearances for polarization-based encryption and recognition. This work opens an avenue toward the fabrication of length-scale colloidal LCs with continuous and stable topologies and expands the application regimes of LC materials in chiral optics and smart textiles.
- 13Parker, R. M.; Zhao, T. H.; Frka-Petesic, B.; Vignolini, S. Cellulose Photonic Pigments. Nat. Commun. 2022, 13, 3378, DOI: 10.1038/s41467-022-31079-9Google Scholar13Cellulose photonic pigmentsParker, Richard M.; Zhao, Tianheng H.; Frka-Petesic, Bruno; Vignolini, SilviaNature Communications (2022), 13 (1), 3378CODEN: NCAOBW; ISSN:2041-1723. (Nature Portfolio)When pursuing sustainable approaches to fabricate photonic structures, nature can be used as a source of inspiration for both the nanoarchitecture and the constituent materials. Although several biomaterials have been promised as suitable candidates for photonic materials and pigments, their fabrication processes have been limited to the small to medium-scale prodn. of films. Here, by employing a substrate-free process, structurally colored microparticles are produced via the confined self-assembly of a cholesteric cellulose nanocrystal (CNC) suspension within emulsified microdroplets. Upon drying, the droplets undergo multiple buckling events, which allow for greater contraction of the nanostructure than predicted for a spherical geometry. This buckling, combined with a solvent or thermal post-treatment, enables the prodn. of dispersions of vibrant red, green, and blue cellulose photonic pigments. The hierarchical structure of these pigments enables the deposition of coatings with angular independent color, offering a consistent visual appearance across a wide range of viewing angles.
- 14Habibi, Y.; Lucia, L. A.; Rojas, O. J. Cellulose Nanocrystals: Chemistry, Self-Assembly, and Applications. Chem. Rev. 2010, 110, 3479– 3500, DOI: 10.1021/cr900339wGoogle Scholar14Cellulose Nanocrystals: Chemistry, Self-Assembly, and ApplicationsHabibi, Youssef; Lucia, Lucian A.; Rojas, Orlando J.Chemical Reviews (Washington, DC, United States) (2010), 110 (6), 3479-3500CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)A review discussing chem. and phys. features of the most dominant fundamental building block in the biosphere, cellulose nanocrystals. A brief introduction to cellulose was followed by the discussion of morphol., chem., including prepn. and chem. routes for functionalization, and self-assembly in various media under various conditions, and applications in the nanocomposites.
- 15Bai, L.; Liu, L.; Esquivel, M.; Tardy, B. L.; Huan, S.; Niu, X.; Liu, S.; Yang, G.; Fan, Y.; Rojas, O. J. Nanochitin: Chemistry, Structure, Assembly, and Applications. Chem. Rev. 2022, 122, 11604– 11674, DOI: 10.1021/acs.chemrev.2c00125Google Scholar15Nanochitin: Chemistry, Structure, Assembly, and ApplicationsBai, Long; Liu, Liang; Esquivel, Marianelly; Tardy, Blaise L.; Huan, Siqi; Niu, Xun; Liu, Shouxin; Yang, Guihua; Fan, Yimin; Rojas, Orlando J.Chemical Reviews (Washington, DC, United States) (2022), 122 (13), 11604-11674CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)A review. Chitin, a fascinating biopolymer found in living organisms, fulfills current demands of availability, sustainability, biocompatibility, biodegradability, functionality, and renewability. A feature of chitin is its ability to structure into hierarchical assemblies, spanning the nano- and macroscales, imparting toughness and resistance (chem., biol., among others) to multicomponent materials as well as adding adaptability, tunability, and versatility. Retaining the inherent structural characteristics of chitin and its colloidal features in dispersed media has been central to its use, considering it as a building block for the construction of emerging materials. Top-down chitin designs have been reported and differentiate from the traditional mol.-level, bottom-up synthesis and assembly for material development. Such topics are the focus of this Review, which also covers the origins and biol. characteristics of chitin and their influence on the morphol. and phys.-chem. properties. We discuss recent achievements in the isolation, deconstruction, and fractionation of chitin nanostructures of varying axial aspects (nanofibrils and nanorods) along with methods for their modification and assembly into functional materials. We highlight the role of nanochitin in its native architecture and as a component of materials subjected to multiscale interactions, leading to highly dynamic and functional structures. We introduce the most recent advances in the applications of nanochitin-derived materials and industrialization efforts, following green manufg. principles. Finally, we offer a crit. perspective about the adoption of nanochitin in the context of advanced, sustainable materials.
- 16Tran, A.; Boott, C. E.; MacLachlan, M. J. Understanding the Self-Assembly of Cellulose Nanocrystals-Toward Chiral Photonic Materials. Adv. Mater. 2020, 32, 1905876 DOI: 10.1002/adma.201905876Google Scholar16Understanding the Self-Assembly of Cellulose Nanocrystals-Toward Chiral Photonic MaterialsTran, Andy; Boott, Charlotte E.; MacLachlan, Mark J.Advanced Materials (Weinheim, Germany) (2020), 32 (41), 1905876CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)Review. Over millions of years, animals and plants have evolved complex mols. and structures that endow them with vibrant colors. Among the sources of natural coloration, structural color is prominent in insects, bird feathers, snake skin, plants, and other organisms, where the color arises from the interaction of light with nanoscale features rather than absorption from a pigment. Cellulose nanocrystals (CNCs) are a biorenewable resource that spontaneously organize into chiral nematic liq. crystals having a hierarchical structure that resembles the Bouligand structure of arthropod shells. The periodic, chiral nematic organization of CNC films leads them to diffract light, making them appear iridescent. Over the past two decades, there have been many advances to develop the photonic properties of CNCs for applications ranging from cosmetics to sensors. Here, the origin of color in CNCs, the control of photonic properties of CNC films, the development of new composite materials of CNCs that can yield flexible photonic structures, and the future challenges in this field are discussed. In particular, recent efforts to make flexible photonic materials using CNCs are highlighted.
- 17Wang, P.-X.; Hamad, W. Y.; MacLachlan, M. J. Structure and Transformation of Tactoids in Cellulose Nanocrystal Suspensions. Nat. Commun. 2016, 7, 11515, DOI: 10.1038/ncomms11515Google Scholar17Structure and transformation of tactoids in cellulose nanocrystal suspensionsWang, Pei-Xi; Hamad, Wadood Y.; MacLachlan, Mark J.Nature Communications (2016), 7 (), 11515pp.CODEN: NCAOBW; ISSN:2041-1723. (Nature Publishing Group)Cellulose nanocrystals obtained from natural sources are of great interest for many applications. In water, cellulose nanocrystals form a liq. cryst. phase whose hierarchical structure is retained in solid films after drying. Although tactoids, one of the most primitive components of liq. crystals, are thought to have a significant role in the evolution of this phase, they have evaded structural study of their internal organization. Here we report the capture of cellulose nanocrystal tactoids in a polymer matrix. This method allows us to visualize, for the first time, the arrangement of cellulose nanocrystals within individual tactoids by electron microscopy. Furthermore, we can follow the structural evolution of the liq. cryst. phase from tactoids to iridescent-layered films. Our insights into the early nucleation events of cellulose nanocrystals give important information about the growth of cholesteric liq. cryst. phases, esp. for cellulose nanocrystals, and are crucial for prepg. photonics-quality films.
- 18Parker, R. M.; Guidetti, G.; Williams, C. A.; Zhao, T.; Narkevicius, A.; Vignolini, S.; Frka-Petesic, B. The Self-Assembly of Cellulose Nanocrystals: Hierarchical Design of Visual Appearance. Adv. Mater. 2018, 30, e1704477 DOI: 10.1002/adma.201704477Google ScholarThere is no corresponding record for this reference.
- 19Tardy, B. L.; Ago, M.; Guo, J.; Borghei, M.; Kämäräinen, T.; Rojas, O. J. Optical Properties of Self-Assembled Cellulose Nanocrystals Films Suspended at Planar-Symmetrical Interfaces. Small 2017, 13, 1702084 DOI: 10.1002/smll.201702084Google ScholarThere is no corresponding record for this reference.
- 20Nyström, G.; Arcari, M.; Adamcik, J.; Usov, I.; Mezzenga, R. Nanocellulose Fragmentation Mechanisms and Inversion of Chirality from the Single Particle to the Cholesteric Phase. ACS Nano 2018, 12, 5141– 5148, DOI: 10.1021/acsnano.8b00512Google Scholar20Nanocellulose fragmentation mechanisms and inversion of chirality from single particle to cholesteric phaseNystrom, Gustav; Arcari, Mario; Adamcik, Jozef; Usov, Ivan; Mezzenga, RaffaeleACS Nano (2018), 12 (6), 5141-5148CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)Understanding how nanostructure and nanomechanics influence phys. material properties on the micro- and macroscale is an essential goal in soft condensed matter research. Mechanisms governing fragmentation and chirality inversion of filamentous colloids are of specific interest because of their crit. role in load-bearing and self-organizing functionalities of soft nanomaterials. Here we provide a fundamental insight into the self-organization across several length scales of nanocellulose, an important biocolloid system with wide-ranging applications as structural, insulating, and functional material. Through a combined microscopic and statistical anal. of nanocellulose fibrils at the single particle level, we show how mech. and chem. induced fragmentations proceed in this system. Moreover, by studying the bottom-up self-assembly of fragmented carboxylated cellulose nanofibrils into cholesteric liq. crystals, we show via direct microscopic observations that the chirality is inverted from right-handed at the nanofibril level to left-handed at the level of the liq. crystal phase. These results improve our fundamental understanding of nanocellulose and provide an important rationale for its application in colloidal systems, liq. crystals, and nanomaterials.
- 21Zheng, H.; Li, W.; Li, W.; Wang, X.; Tang, Z.; Zhang, S. X.-A.; Xu, Y. Uncovering the Circular Polarization Potential of Chiral Photonic Cellulose Films for Photonic Applications. Adv. Mater. 2018, 30, 1705948 DOI: 10.1002/adma.201705948Google ScholarThere is no corresponding record for this reference.
- 22Narkevicius, A.; Steiner, L. M.; Parker, R. M.; Ogawa, Y.; Frka-Petesic, B.; Vignolini, S. Controlling the Self-Assembly Behavior of Aqueous Chitin Nanocrystal Suspensions. Biomacromolecules 2019, 20, 2830– 2838, DOI: 10.1021/acs.biomac.9b00589Google Scholar22Controlling the Self-Assembly Behavior of Aqueous Chitin Nanocrystal SuspensionsNarkevicius, Aurimas; Steiner, Lisa M.; Parker, Richard M.; Ogawa, Yu; Frka-Petesic, Bruno; Vignolini, SilviaBiomacromolecules (2019), 20 (7), 2830-2838CODEN: BOMAF6; ISSN:1525-7797. (American Chemical Society)As with many other biosourced colloids, chitin nanocrystals (ChNCs) can form liq. cryst. phases with chiral nematic ordering. In this work, we demonstrate that it is possible to finely tune the liq. cryst. behavior of aq. ChNC suspensions finely. Such control was made possible by carefully studying how the hydrolysis conditions and suspension treatments affect the colloidal and self-assembly properties of ChNCs. Specifically, we systematically investigated the effects of duration and acidity of chitin hydrolysis required to ext. ChNCs, as well as the effects of the tip sonication energy input, degree of acetylation, pH and ionic strength. Finally, we show that by controlled water evapn., it is possible to retain and control the helicoidal ordering in dry films, leading to a hierarchical architecture analogous to that found in nature, e.g. in crab shells. We believe that this work serves as a comprehensive insight into ChNC prepn. and handling which is required to unlock the full potential of this material in both a scientific and industrial context.
- 23Rofouie, P.; Galati, E.; Sun, L.; Helmy, A. S.; Kumacheva, E. Hybrid Cholesteric Films with Tailored Polarization Rotation. Adv. Funct. Mater. 2019, 29, 1905552 DOI: 10.1002/adfm.201905552Google Scholar23Hybrid Cholesteric Films with Tailored Polarization RotationRofouie, Pardis; Galati, Elizabeth; Sun, Lu; Helmy, Amr S.; Kumacheva, EugeniaAdvanced Functional Materials (2019), 29 (43), 1905552CODEN: AFMDC6; ISSN:1616-301X. (Wiley-VCH Verlag GmbH & Co. KGaA)Incorporation of metal nanoparticles in chiral (Ch) films of cellulose nanocrystals (CNCs) enhances nanoparticle plasmon resonances, due to the coupling of the intrinsic properties of the plasmonic guest and the photonic properties of the Ch-CNC host. In contrast with previous reports, the properties of the Ch-CNC host are focused and an effective strategy is developed for tuning the optical polarization rotation of the composite films formed by the CNCs and gold nanoparticles. A twofold enhancement in the polarization rotation power of the composite Ch-CNC films, with an insignificant change in the incurred optical losses, is achieved by varying the d. and dimensions of gold nanoparticles embedded in the Ch-CNC films. For such films, a new approach is developed to obtain broadband CD by fabricating films from mixts. of CNC suspensions ultrasonicated for different time intervals. These new findings enable fine-tuning of the power and spectral range of the polarization rotation and offer a novel strategy for the fabrication of broadband reflectors and polarizers, smart solar windows, and detectors for circularly polarized light.
- 24Xiong, R.; Yu, S.; Smith, M. J.; Zhou, J.; Krecker, M.; Zhang, L.; Nepal, D.; Bunning, T. J.; Tsukruk, V. V. Self-Assembly of Emissive Nanocellulose/Quantum Dot Nanostructures for Chiral Fluorescent Materials. ACS Nano 2019, 13, 9074– 9081, DOI: 10.1021/acsnano.9b03305Google Scholar24Self-Assembly of Emissive Nanocellulose/Quantum Dot Nanostructures for Chiral Fluorescent MaterialsXiong, Rui; Yu, Shengtao; Smith, Marcus J.; Zhou, Jing; Krecker, Michelle; Zhang, Lijuan; Nepal, Dhriti; Bunning, Timothy J.; Tsukruk, Vladimir V.ACS Nano (2019), 13 (8), 9074-9081CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)Chiral fluorescent materials with fluorescent nanoparticles assembled into a chiral structure represent a grand challenge. Here, we report self-assembled emissive needle-like nanostructures through decorating cellulose nanocrystals (CNCs) with carbon quantum dots (CQDs). This assembly is facilitated by the heterogeneous amphiphilic interactions between natural and synthetic components. These emissive nanostructures can self-organize into chiral nematic solid-state materials with enhanced mech. performance. The chiral CQD/CNC films demonstrate an intense iridescent appearance superimposed with enhanced luminescence that is significantly higher than that for CQD films and other reported CQD/CNC films. A characteristic fluorescent fingerprint signature is obsd. in the CQD/CNC film, proving the well-defined chiral organization of fluorescent nanostructures. The chiral organization of CQDs enables the solid CQD/CNC film to form a right-hand chiral fluorescence with an asym. factor of -0.2. Addnl., we developed chem. 2D printing and soft lithog. patterning techniques to fabricate the freestanding chiral fluorescent patterns that combines mech. integrity and chiral nematic structure with light diffraction and emission.
- 25Guo, J.; Haehnle, B.; Hoenders, D.; Creusen, G.; Jiao, D.; Kuehne, A. J. C.; Walther, A. Biodegradable Laser Arrays Self-Assembled from Plant Resources. Adv. Mater. 2020, 32, 2002332 DOI: 10.1002/adma.202002332Google Scholar25Biodegradable Laser Arrays Self-Assembled from Plant ResourcesGuo, Jiaqi; Haehnle, Bastian; Hoenders, Daniel; Creusen, Guido; Jiao, Dejin; Kuehne, Alexander J. C.; Walther, AndreasAdvanced Materials (Weinheim, Germany) (2020), 32 (29), 2002332CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)The transition toward future sustainable societies largely depends on disruptive innovations in biobased materials to substitute nonsustainable advanced functional materials. In the field of optics, advanced devices (e.g., lasers or metamaterial devices) are typically manufd. using top-down engineering and synthetic materials. This work breaks with such concepts and switchable lasers self-assembled from plant-based cellulose nanocrystals and fluorescent polymers at room temp. and from water are shown. Controlled structure formation allows laser-grade cholesteric photonic bandgap materials, in which the photonic bandgap is matched to the fluorescence emission to function as an efficient resonator for low threshold multimode lasing. The lasers can be switched on and off using humidity, and can be printed into pixelated arrays. Addnl., the materials exhibit stiffness above typical thermoplastic polymers and biodegradability in soil. The concept showcases that highly advanced functions can be encoded into biobased materials, and opens the design space for future sustainable optical devices of unprecedented function.
- 26Lizundia, E.; Nguyen, T.-D.; Winnick, R. J.; MacLachlan, M. J. Biomimetic Photonic Materials Derived from Chitin and Chitosan. J. Mater. Chem. C 2021, 9, 796– 817, DOI: 10.1039/D0TC05381CGoogle Scholar26Biomimetic photonic materials derived from chitin and chitosanLizundia, Erlantz; Nguyen, Thanh-Dinh; Winnick, Rebecca J.; MacLachlan, Mark J.Journal of Materials Chemistry C: Materials for Optical and Electronic Devices (2021), 9 (3), 796-817CODEN: JMCCCX; ISSN:2050-7534. (Royal Society of Chemistry)A review. Insight into the hierarchical structures of carbohydrate nanofibrils such as chitin and cellulose is important in order to exploit their unique geometrical features for materials innovation and emerging applications. Chitin nanofibrils are responsible for the outstanding mech. strength in exoskeletons of some animals, and for the iridescence of some insects. The appearance of structural colors in chitin-constituted insect shells inspires scientists to mimic their photonic properties in artificial analogs, paving the path towards new optical technologies. Although the intricate organization of chitin nanofibrils in these structures was recognized several decades ago, the use of chitin nanofibrils in biomimetic templating, to transfer their sophisticated structures into solid-state materials, has only recently been exploited. Cellulose nanocrystals (CNCs) are high aspect ratio nanomaterials prepd. by acid hydrolysis of the most abundant carbohydrate in plants. Similar to chitin nanofibrils, CNCs are readily dispersible in water and present an intriguing self-assembly behavior that can be exploited as a lyotropic liq.-cryst. template to fabricate photonic materials. Extended efforts of this research strategy are necessary to seek new organized structures of carbohydrate nanofibrils and to develop synthetic methods that offer access to novel biomimetic materials that combine chirality, coloration, and mesoporosity through colloidal templating and self-assembly. This Review summarizes recent progress to create functional optical materials templated by nanochitin and compares it with developments using nanocellulose.
- 27Lee, S. R.; Reichmanis, E.; Srinivasarao, M. Anisotropic Responsive Microgels Based on the Cholesteric Phase of Chitin Nanocrystals. ACS Macro Lett. 2022, 11, 96– 102, DOI: 10.1021/acsmacrolett.1c00675Google ScholarThere is no corresponding record for this reference.
- 28Liu, P.; Wang, J.; Qi, H.; Koddenberg, T.; Xu, D.; Liu, S.; Zhang, K. Biomimetic Confined Self-Assembly of Chitin Nanocrystals. Nano Today 2022, 43, 101420 DOI: 10.1016/j.nantod.2022.101420Google Scholar28Biomimetic confined self-assembly of chitin nanocrystalsLiu, Peiwen; Wang, Jiaxiu; Qi, Houjuan; Koddenberg, Tim; Xu, Dan; Liu, Siyuan; Zhang, KaiNano Today (2022), 43 (), 101420CODEN: NTAOCG; ISSN:1748-0132. (Elsevier Ltd.)It is a longstanding challenge to aptly describe the natural assembly process of chitin Bouligand organization as well as biomimetic construct these position-dependent structures with the isolated chitin nanodomains. Here, we report a fixed-boundary evapn.-induced self-assembly (FB-EISA) modality using chitin nanocrystals (ChNCs) in the capillaries, where the generation of continuous and ordered anisotropic phase relies on the growth of phase boundary towards the opposite direction of water evapn. Distinct from the previous EISA modalities with the moving evapn. interface, the pinned air-liq. interface at the end of capillaries in a confined environment acts as the evapn. interface and initial deposition site of ChNCs simultaneously. During the whole self-assembly process via successive evapn., the generation of droplets-like ChNCs clusters known as tactoids is suppressed. Therefore, continuous birefringent multi-layers as nested multiple paraboloid structures of ChNCs with a d. gradient are gradually generated, before cylindrical tubes are formed finally. The FB-EISA process can be accelerated by heat and maintains stable regardless of vibration or different capillary opening directions relative to gravity direction. This FB-EISA modality in confined geometry allows rapid formation of ChNCs-based photonics-quality structure of larger length scales and enables us to deepen our understanding of the natural self-assembly process in diverse biol. species.
- 29Parton, T. G.; Parker, R. M.; van de Kerkhof, G. T.; Narkevicius, A.; Haataja, J. S.; Frka-Petesic, B.; Vignolini, S. Chiral Self-Assembly of Cellulose Nanocrystals Is Driven by Crystallite Bundles. Nat. Commun. 2022, 13, 2657, DOI: 10.1038/s41467-022-30226-6Google Scholar29Chiral self-assembly of cellulose nanocrystals is driven by crystallite bundlesParton, Thomas G.; Parker, Richard M.; van de Kerkhof, Gea T.; Narkevicius, Aurimas; Haataja, Johannes S.; Frka-Petesic, Bruno; Vignolini, SilviaNature Communications (2022), 13 (1), 2657CODEN: NCAOBW; ISSN:2041-1723. (Nature Portfolio)The transfer of chirality across length-scales is an intriguing and universal natural phenomenon. However, connecting the properties of individual building blocks to the emergent features of their resulting large-scale structure remains a challenge. In this work, we investigate the origins of mesophase chirality in cellulose nanocrystal suspensions, whose self-assembly into chiral photonic films has attracted significant interest. By correlating the ensemble behavior in suspensions and films with a quant. morphol. anal. of the individual nanoparticles, we reveal an inverse relationship between the cholesteric pitch and the abundance of laterally-bound composite particles. These 'bundles' thus act as colloidal chiral dopants, analogous to those used in mol. liq. crystals, providing the missing link in the hierarchical transfer of chirality from the mol. to the colloidal scale.
- 30Peng, Z.; Lin, Q.; Tai, Y.-A. A.; Wang, Y. Applications of Cellulose Nanomaterials in Stimuli-Responsive Optics. J. Agric. Food Chem. 2020, 68, 12940– 12955, DOI: 10.1021/acs.jafc.0c04742Google Scholar30Applications of Cellulose Nanomaterials in Stimuli-Responsive OpticsPeng, Zhiwei; Lin, Qinglin; Tai, Yu-An Angela; Wang, YuHuangJournal of Agricultural and Food Chemistry (2020), 68 (46), 12940-12955CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)A Review. As one of the most abundant biopolymers, cellulose has been a basic but essential building block of human society, with its use dating back thousands of years. With recent developments in nanotechnol. and increasing environmental concerns, cellulose-based nanomaterials are now gaining attention as promising green material candidates for many high-value applications as a result of their biocompatibility and advantageous phys. and chem. properties. In particular, cellulose nanocrystals are notable for their optical properties that can respond to various environmental stimuli as a result of the unique chiral nematic structure of the material. Compositing cellulosic materials with functional polymers, small mols., and other nanomaterials can further stabilize and amplify these responsive optical signals and introduce multiple new functionalities. On the basis of these capabilities, many advanced applications of cellulose nanomaterials have been proposed, including chem. sensors, photonic papers, decorative coatings, data security, and smart textiles. In this review, we discuss and summarize recent advances in this emerging field of stimuli-responsive optics based on cellulose nanomaterials.
- 31Duan, C.; Cheng, Z.; Wang, B.; Zeng, J.; Xu, J.; Li, J.; Gao, W.; Chen, K. Chiral Photonic Liquid Crystal Films Derived from Cellulose Nanocrystals. Small 2021, 17, 2007306 DOI: 10.1002/smll.202007306Google Scholar31Chiral Photonic Liquid Crystal Films Derived from Cellulose NanocrystalsDuan, Chengliang; Cheng, Zheng; Wang, Bin; Zeng, Jinsong; Xu, Jun; Li, Jinpeng; Gao, Wenhua; Chen, KefuSmall (2021), 17 (30), 2007306CODEN: SMALBC; ISSN:1613-6810. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. As a nanoscale renewable resource derived from lignocellulosic materials, cellulose nanocrystals (CNCs) have the features of high purity, high crystallinity, high aspect ratio, high Young's modulus, and large sp. surface area. The most interesting trait is that they can form the entire films with bright structural colors through the evapn.-induced self-assembly (EISA) process under certain conditions. Structural color originates from micro-nano structure of CNCs matrixes via the interaction of nanoparticles with light, rather than the absorption and reflection of light from the pigment. CNCs are the new generation of photonic liq. crystal materials of choice due to their simple and convenient prepn. processes, environmentally friendly fabrication approaches, and intrinsic chiral nematic structure. Therefore, understanding the forming mechanism of CNCs in nanoarchitectonics is crucial to multiple fields of physics, chem., materials science, and engineering application. Herein, a timely summary of the chiral photonic liq. crystal films derived from CNCs is systematically presented. The relationship of CNC, structural color, chiral nematic structure, film performance, and applications of chiral photonic liq. crystal films is discussed. The review article also summarizes the most recent achievements in the field of CNCs-based photonic functional materials along with the faced challenges.
- 32Xu, C.; Huang, C.; Huang, H. Recent Advances in Structural Color Display of Cellulose Nanocrystal Materials. Appl. Mater. Today 2021, 22, 100912 DOI: 10.1016/j.apmt.2020.100912Google ScholarThere is no corresponding record for this reference.
- 33Pei, Y.; Wang, L.; Tang, K.; Kaplan, D. L. Biopolymer Nanoscale Assemblies as Building Blocks for New Materials: A Review. Adv. Funct. Mater. 2021, 31, 2008552 DOI: 10.1002/adfm.202008552Google Scholar33Biopolymer Nanoscale Assemblies as Building Blocks for New Materials: A ReviewPei, Ying; Wang, Lu; Tang, Keyong; Kaplan, David L.Advanced Functional Materials (2021), 31 (15), 2008552CODEN: AFMDC6; ISSN:1616-301X. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. Biopolymers, a class of fascinating polymers from biomass provide sustainability, biodegradability, availability, biocompatibility, and unique properties. A ubiquitous feature of biopolymers is their hierarchical structure, with the presence of well-organized structures from the nanoscale to macroscopic dimensions. This structural organization endows biopolymers with toughness, defect resistance, and bucking adaptability. To retain these inherent structural features, nano-structural assemblies isolated from biomass have been applied as building blocks to construct new biopolymer-based materials. This top-down processing strategy is distinct from the more traditional mol.-level bottom-up design and assembly approach for new materials. In this review, the hierarchical structures of several representative biopolymers (cellulose, chitin, silk, collagen) are introduced with a focus on these nanoscale building blocks, as well as highlighting the similarities and differences in the resp. chemistries and structures. Recent progress in prodn. strategies of these natural building blocks are summarized, covering methods and treatments used for isolations. Finally, approaches and emerging applications of biopolymer-based materials using these natural nano- and meso-scale building blocks are demonstrated in areas of biomedicine, electronics, environmental, packaging, sensing, foods, and cosmetics.
- 34Xia, J.; Sun, X.; Jia, P.; Li, L.; Xu, K.; Cao, Y.; Lü, X.; Wang, L. Multifunctional Sustainable Films of Bacterial Cellulose Nanocrystal-Based, Three-Phase Pickering Nanoemulsions: A Promising Active Food Packaging for Cheese. Chem. Eng. J. 2023, 466, 143295 DOI: 10.1016/j.cej.2023.143295Google ScholarThere is no corresponding record for this reference.
- 35Jiang, J.; Carrillo-Enríquez, N. C.; Oguzlu, H.; Han, X.; Bi, R.; Song, M.; Saddler, J. N.; Sun, R.-C.; Jiang, F. High Production Yield and More Thermally Stable Lignin-Containing Cellulose Nanocrystals Isolated Using a Ternary Acidic Deep Eutectic Solvent. ACS Sustainable Chem. Eng. 2020, 8, 7182– 7191, DOI: 10.1021/acssuschemeng.0c01724Google Scholar35High Production Yield and More Thermally Stable Lignin-Containing Cellulose Nanocrystals Isolated Using a Ternary Acidic Deep Eutectic SolventJiang, Jungang; Carrillo-Enriquez, Nancy C.; Oguzlu, Hale; Han, Xushen; Bi, Ran; Song, Mingyao; Saddler, Jack N.; Sun, Run-Cang; Jiang, FengACS Sustainable Chemistry & Engineering (2020), 8 (18), 7182-7191CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)From the aspects of green chem. and sustainability, the using of green and sustainable materials and reagents for nanocellulose prodn. is highly desirable. In this study, an acidic deep eutectic solvent (DES) pretreatment process was developed to fabricate lignin contg. cellulose nanocrystals (LCNCs) from undervalued thermo-mech. pulp (TMP). LCNCs were successfully obtained by using both binary DES (choline chloride - oxalic acid, 1:1 molar ratio), and ternary DES (choline chloride - oxalic acid - p-toluenesulfonic acid, 2:1:1 molar ratio) followed by a mild mech. disintegration process. The LCNCs with width around 6 nm, thickness of 3.3 nm, retained cellulose I crystallinity of 57.4%, high lignin content of 47.8%, and high yield of 66% were obtained under the optimum conditions using ternary DES at 80°C for 3 h pretreatment. Meanwhile, the LCNCs obtained from this process showed a high thermal stability (Tmax of 358°C), which exhibited a promising potential for further applications. The results demonstrate that the environmentally friendly DES is a promising solvent, which can provide a prospective future for both lignocellulosic material utilization and LCNCs isolation. Undervalued thermo-mech. pulp can be facially converted to thermally stable lignin contg. cellulose nanocrystals at 66% yield using a ternary deep eutectic solvent.
- 36Lv, X.; Yu, H.; Han, J.; Hou, Y.; Sun, Y.; Liu, K.; Zhou, W.; Chen, J. Tunicate Cellulose Nanocrystals Reinforced Modified Calcium Sulfate Bone Cement with Enhanced Mechanical Properties for Bone Repair. Carbohydr. Polym. 2024, 323, 121380 DOI: 10.1016/j.carbpol.2023.121380Google ScholarThere is no corresponding record for this reference.
- 37Li, T.; Chen, C.; Brozena, A. H.; Zhu, J. Y.; Xu, L.; Driemeier, C.; Dai, J.; Rojas, O. J.; Isogai, A.; Wågberg, L.; Hu, L. Developing Fibrillated Cellulose As a Sustainable Technological Material. Nature 2021, 590, 47– 56, DOI: 10.1038/s41586-020-03167-7Google Scholar37Developing fibrillated cellulose as a sustainable technological materialLi, Tian; Chen, Chaoji; Brozena, Alexandra H.; Zhu, J. Y.; Xu, Lixian; Driemeier, Carlos; Dai, Jiaqi; Rojas, Orlando J.; Isogai, Akira; Wagberg, Lars; Hu, LiangbingNature (London, United Kingdom) (2021), 590 (7844), 47-56CODEN: NATUAS; ISSN:0028-0836. (Nature Research)A review. Cellulose is the most abundant biopolymer on Earth, found in trees, waste from agricultural crops and other biomass. The fibers that comprise cellulose can be broken down into building blocks, known as fibrillated cellulose, of varying, controllable dimensions that extend to the nanoscale. Fibrillated cellulose is harvested from renewable resources, so its sustainability potential combined with its other functional properties (mech., optical, thermal and fluidic, for example) gives this nanomaterial unique technol. appeal. Here we explore the use of fibrillated cellulose in the fabrication of materials ranging from composites and macrofibres, to thin films, porous membranes and gels. We discuss research directions for the practical exploitation of these structures and the remaining challenges to overcome before fibrillated cellulose materials can reach their full potential. Finally, we highlight some key issues towards successful manufg. scale-up of this family of materials.
- 38Bethke, K.; Palantöken, S.; Andrei, V.; Roß, M.; Raghuwanshi, V. S.; Kettemann, F.; Greis, K.; Ingber, T. T. K.; Stückrath, J. B.; Valiyaveettil, S.; Rademann, K. Functionalized Cellulose for Water Purification, Antimicrobial Applications, and Sensors. Adv. Funct. Mater. 2018, 28, 1800409 DOI: 10.1002/adfm.201800409Google ScholarThere is no corresponding record for this reference.
- 39Zhang, L.; Liao, Y.; Wang, Y.-C.; Zhang, S.; Yang, W.; Pan, X.; Wang, Z. L. Cellulose II Aerogel-Based Triboelectric Nanogenerator. Adv. Funct. Mater. 2020, 30 (28), 2001763 DOI: 10.1002/adfm.202001763Google Scholar39Cellulose II Aerogel-Based Triboelectric NanogeneratorZhang, Lei; Liao, Yang; Wang, Yi-Cheng; Zhang, Steven; Yang, Weiqing; Pan, Xuejun; Wang, Zhong LinAdvanced Functional Materials (2020), 30 (28), 2001763CODEN: AFMDC6; ISSN:1616-301X. (Wiley-VCH Verlag GmbH & Co. KGaA)Cellulose-based triboelec. nanogenerators (TENGs) have gained increasing attention. In this study, a novel method is demonstrated to synthesize cellulose-based aerogels and such aerogels are used to fabricate TENGs that can serve as mech. energy harvesters and self-powered sensors. The cellulose II aerogel is fabricated via a dissoln.-regeneration process in a green inorg. molten salt hydrate solvent (lithium bromide trihydrate). The as-fabricated cellulose II aerogel exhibits an interconnected open-pore 3D network structure, higher degree of flexibility, high porosity, and a high surface area of 221.3 m2 g-1. Given its architectural merits, the cellulose II aerogel-based TENG presents an excellent mech. response sensitivity and high elec. output performance. By blending with other natural polysaccharides, i.e., chitosan and alginic acid, electron-donating and electron-withdrawing groups are introduced into the composite cellulose II aerogels, which significantly improves the triboelec. performance of the TENG. The cellulose II aerogel-based TENG is demonstrated to light up light-emitting diodes, charge com. capacitors, power a calculator, and monitor human motions. This study demonstrates the facile fabrication of cellulose II aerogel and its application in TENG, which leads to a high-performance and eco-friendly energy harvesting and self-powered system.
- 40Ong, X.-R.; Chen, A. X.; Li, N.; Yang, Y. Y.; Luo, H.-K. Nanocellulose: Recent Advances Toward Biomedical Applications. Small Sci. 2023, 3, 2200076 DOI: 10.1002/smsc.202200076Google Scholar40Review on nanocellulose: recent advances toward biomedical applicationsOng, Xuan-Ran; Chen, Adrielle Xianwen; Li, Ning; Yang, Yi Yan; Luo, He-KuanSmall Science (2023), 3 (2), 2200076CODEN: SSMCBJ; ISSN:2688-4046. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. Sustainable materials are key to the continual improvement of living stds. on this planet with minimal environmental impacts. Nanocellulose combines the fascinating features of nanomaterials with favorable properties of the abundantly available cellulose biopolymer, which in recent years has gained much attention toward biomedical applications by virtue of its unique surface chem., remarkable phys. features, and inherent biol. attributes. Herein, the recent advances in nanocellulose-based biomedical materials, with foci on biomol. immobilization, drug delivery, cell culture and tissue engineering (TE), antimicrobial strategy, wound healing, and biomedical implants are summarized. Each topic is elaborated with representative examples to present the significance of nanocelluloses in their resp. material design principles utilizing different sub-types, including cellulose nanofibers (CNFs), cellulose nanocrystals (CNCs), and bacterial nanocellulose (BNC). The current state of large-scale prodn. of nanocellulose and accelerated development by artificial intelligence and machine learning are also briefly discussed, before ending with its future prospects and potential challenges.
- 41Thomas, B.; Raj, M. C.; B, A. K.; H, R. M.; Joy, J.; Moores, A.; Drisko, G. L.; Sanchez, C. Nanocellulose, a Versatile Green Platform: From Biosources to Materials and Their Applications. Chem. Rev. 2018, 118, 11575– 11625, DOI: 10.1021/acs.chemrev.7b00627Google Scholar41Nanocellulose, a Versatile Green Platform: From Biosources to Materials and Their ApplicationsThomas, Bejoy; Raj, Midhun C.; B, Athira K.; H, Rubiyah M.; Joy, Jithin; Moores, Audrey; Drisko, Glenna L.; Sanchez, ClementChemical Reviews (Washington, DC, United States) (2018), 118 (24), 11575-11625CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)A review. With increasing environmental and ecol. concerns due to the use of petroleum-based chems. and products, the synthesis of fine chems. and functional materials from natural resources is of great public value. Nanocellulose may prove to be one of the most promising green materials of modern times due to its intrinsic properties, renewability, and abundance. In this review, we present nanocellulose-based materials from sourcing, synthesis, and surface modification of nanocellulose, to materials formation and applications. Nanocellulose can be sourced from biomass, plants, or bacteria, relying on fairly simple, scalable, and efficient isolation techniques. Mech., chem., and enzymic treatments, or a combination of these, can be used to ext. nanocellulose from natural sources. The properties of nanocellulose are dependent on the source, the isolation technique, and potential subsequent surface transformations. Nanocellulose surface modification techniques are typically used to introduce either charged or hydrophobic moieties, and include amidation, esterification, etherification, silylation, polymn., urethanization, sulfonation, and phosphorylation. Nanocellulose has excellent strength, high Young's modulus, biocompatibility, and tunable self-assembly, thixotropic, and photonic properties, which are essential for the applications of this material. Nanocellulose participates in the fabrication of a large range of nanomaterials and nanocomposites, including those based on polymers, metals, metal oxides, and carbon. In particular, nanocellulose complements org.-based materials, where it imparts its mech. properties to the composite. Nanocellulose is a promising material whenever material strength, flexibility, and/or specific nanostructuration are required. Applications include functional paper, optoelectronics, and antibacterial coatings, packaging, mech. reinforced polymer composites, tissue scaffolds, drug delivery, biosensors, energy storage, catalysis, environmental remediation, and electrochem. controlled sepn. Phosphorylated nanocellulose is a particularly interesting material, spanning a surprising set of applications in various dimensions including bone scaffolds, adsorbents, and flame retardants and as a support for the heterogenization of homogeneous catalysts.
- 42Lv, P.; Lu, X.; Wang, L.; Feng, W. Nanocellulose-Based Functional Materials: From Chiral Photonics to Soft Actuator and Energy Storage. Adv. Funct. Mater. 2021, 31, 2104991 DOI: 10.1002/adfm.202104991Google Scholar42Nanocellulose-Based Functional Materials: From Chiral Photonics to Soft Actuator and Energy StorageLv, Pengfei; Lu, Xiaomin; Wang, Ling; Feng, WeiAdvanced Functional Materials (2021), 31 (45), 2104991CODEN: AFMDC6; ISSN:1616-301X. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. Nanocellulose is currently in the limelight of extensive research from fundamental science to technol. applications owing to its renewable and carbon-neutral nature, superior biocompatibility, tailorable surface chem., and unprecedented optical and mech. properties. Herein, an up-to-date account of the recent advancements in nanocellulose-derived functional materials and their emerging applications in areas of chiral photonics, soft actuators, energy storage, and biomedical science is provided. The fundamental design and synthesis strategies for nanocellulose-based functional materials are discussed. Their unique properties, underlying mechanisms, and potential applications are highlighted. Finally, this review provides a brief conclusion and elucidates both the challenges and opportunities of the intriguing nanocellulose-based technologies rooted in materials and chem. science. This review is expected to provide new insights for nanocellulose-based chiral photonics, soft robotics, advanced energy, and novel biomedical technologies, and promote the rapid development of these highly interdisciplinary fields, including nanotechnol., nanoscience, biol., physics, synthetic chem., materials science, and device engineering.
- 43Nasseri, R.; Deutschman, C. P.; Han, L.; Pope, M. A.; Tam, K. C. Cellulose Nanocrystals in Smart and Stimuli-Responsive Materials: A Review. Mater. Today Adv. 2020, 5, 100055 DOI: 10.1016/j.mtadv.2020.100055Google ScholarThere is no corresponding record for this reference.
- 44Mali, P.; Sherje, A. P. Cellulose Nanocrystals: Fundamentals and Biomedical Applications. Carbohydr. Polym. 2022, 275, 118668 DOI: 10.1016/j.carbpol.2021.118668Google Scholar44Cellulose nanocrystals: Fundamentals and biomedical applicationsMali, Prajakta; Sherje, Atul P.Carbohydrate Polymers (2022), 275 (), 118668CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)A review. The present review explores the recent developments of cellulose nanocrystals, a class of captivating nanomaterials in variety of applications. CNCs are made by acid hydrolyzing cellulosic materials like wood, cotton, tunicate, flax fibers by sonochem. It has many desirable properties, including a high tensile strength, wide surface area, stiffness, exceptional colloidal stability, and the ability to be modified. CNCs are colloidally stable, hydrophilic, and rigid rod-shaped bio-based nanomaterials in the form of rigid rods with high strength and surface area that has a diverse set of applications and properties. The intriguing features emerging from numerous fibers studies, such as renewable character and biodegradability, piqued the curiosity of many researchers who worked on lowering the size of these fibers. Physicochem. properties such as rheol., mech., thermal, lipid cryst., swelling capacity, microstructural properties result in affecting surface-area to vol. ratio and crystallinity of cellulose nanocrystals. The present article highlights the fundamentals of cellulose nanocrystals such as sources, isolation, fabrication, properties and surface modification with an emphasis on plethora of biomedical applications. Selected nanocellulose studies with significant findings on cellular labeling and bioimaging, tissue engineering, biosensors, gene delivery, anti-viral property, anti-bacterial property, ocular delivery, modified drug release, anti-cancer activity and enzyme immobilization are emphasized.
- 45Mahmud, M. M.; Perveen, A.; Jahan, R. A.; Matin, M. A.; Wong, S. Y.; Li, X.; Arafat, M. T. Preparation of Different Polymorphs of Cellulose from Different Acid Hydrolysis Medium. Int. J. Biol. Macromol. 2019, 130, 969– 976, DOI: 10.1016/j.ijbiomac.2019.03.027Google Scholar45Preparation of different polymorphs of cellulose from different acid hydrolysis mediumMahmud, Md Musavvir; Perveen, Asma; Jahan, Rumana A.; Matin, Md Abdul; Wong, Siew Yee; Li, Xu; Arafat, M. TarikInternational Journal of Biological Macromolecules (2019), 130 (), 969-976CODEN: IJBMDR; ISSN:0141-8130. (Elsevier B.V.)In this study, medical cotton was subjected to acid hydrolysis in sulfuric, hydrochloric and phosphoric acid medium to prep. cellulose nanocrystals (CNC) with different morphologies and polymorphism. Morphol. of the prepd. CNC samples revealed fiber shaped morphol. for sulfuric and hydrochloric acid hydrolyzed samples, whereas, spherical shaped for phosphoric acid hydrolyzed samples. The size of the spherical shaped CNC decreased with the increase of hydrolysis time, from 853 nm for 12 h to 187 nm for 48 h. X-ray Diffraction anal. showed that hydrochloric acid hydrolyzed CNC is cellulose I (CI), phosphoric acid hydrolyzed CNC is cellulose II (CII) and sulfuric acid hydrolyzed CNC contain both CI and CII. The crystallinity of sulfuric and hydrochloric acid hydrolysis samples was 91%, whereas, the crystallinity of phosphoric acid hydrolysis samples was between 43 and 60% depending on hydrolysis time. Thermal properties were also affected by the hydrolysis medium. Thus cellulose nanocrystals were prepd. with different morphologies and phys. characteristics through a facile method.
- 46Zhang, H.; Chen, Y.; Wang, S.; Ma, L.; Yu, Y.; Dai, H.; Zhang, Y. Extraction and Comparison of Cellulose Nanocrystals from Lemon (Citrus Limon) Seeds Using Sulfuric Acid Hydrolysis and Oxidation Methods. Carbohydr. Polym. 2020, 238, 116180 DOI: 10.1016/j.carbpol.2020.116180Google Scholar46Extraction and comparison of cellulose nanocrystals from lemon (Citrus limon) seeds using sulfuric acid hydrolysis and oxidation methodsZhang, Huan; Chen, Yuan; Wang, Shanshan; Ma, Liang; Yu, Yong; Dai, Hongjie; Zhang, YuhaoCarbohydrate Polymers (2020), 238 (), 116180CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)In this study, the lemon (Citrus limon) seeds as typical agricultural processing wastes were utilized to ext. cellulose nanocrystals (CNCs) by sulfuric acid hydrolysis (S-LSCNC), ammonium persulfate oxidn. (A-LSCNC) and TEMPO oxidn. (T-LSCNC). The properties of CNCs were comparatively investigated by Fourier transform IR spectroscopy (FTIR), XPS, X-ray diffraction (XRD), thermogravimetric anal. (TG), and at. force microscope (AFM), and the application in Pickering emulsions was also preliminarily studied. The results showed that all CNCs maintained cellulose Iβ structure and had a good dispersion regardless of extn. methods. Differently, T-LSCNC had a higher yield, larger size and lower CrI than A-LSCNC and S-LSCNC. Comparatively, A-LSCNC showed the highest CrI and S-LSCNC showed the lowest size. For the application of Pickering emulsions, S-LSCNC and A-LSCNC showed a better ability as Pickering stabilizers than T-LSCNC. This study is beneficial for developing the potential utilization of CNCs from lemon byproducts.
- 47Tang, Y.; Yang, H.; Vignolini, S. Recent Progress in Production Methods for Cellulose Nanocrystals: Leading to More Sustainable Processes. Adv. Sustainable Syst. 2022, 6, 2100100 DOI: 10.1002/adsu.202100100Google Scholar47Recent Progress in Production Methods for Cellulose Nanocrystals: Leading to More Sustainable ProcessesTang, Yimian; Yang, Han; Vignolini, SilviaAdvanced Sustainable Systems (2022), 6 (3), 2100100CODEN: ASSDAN; ISSN:2366-7486. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. Cellulose nanocrystals (CNCs) are a new class of biodegradable nanomaterial derived from the most abundant and renewable biomass on the planet: cellulose. Due to their potential as a low carbon footprint nanomaterial, CNCs have received significant interest in the community for a wide variety of applications. In this review, the most recent strategies exploited to produce CNCs are therefore summarized, focusing on the "greener" isolation methods aiming at minimizing the environmental impact of their prodn. The environmental impact of each CNCs prodn. method is qual. evaluated and the properties of the CNCs obtained are discussed. Finally, the necessary steps to address the development of the field in the industrial context are discussed, focusing on the type of applications where the CNCs can be exploited.
- 48Vanderfleet, O. M.; Cranston, E. D. Production Routes to Tailor the Performance of Cellulose Nanocrystals. Nat. Rev. Mater. 2021, 6, 124– 144, DOI: 10.1038/s41578-020-00239-yGoogle Scholar48Production routes to tailor the performance of cellulose nanocrystalsVanderfleet, Oriana M.; Cranston, Emily D.Nature Reviews Materials (2021), 6 (2), 124-144CODEN: NRMADL; ISSN:2058-8437. (Nature Research)A review. Cellulose nanocrystals (CNCs) are bio-based, high aspect ratio nanoparticles that are industrially produced in tonne-per-day quantities across the globe. CNCs can be used to improve the performance of a large range of materials such as emulsions and foams, biomedical devices, electronics and sensors, high-viscosity fluids and polymer composites. Their ability to do so, however, is highly dependent on the way they are produced. In this Review, we assess the properties of CNCs from more than 30 prodn. routes and 40 biomass sources to help CNC users select the right material for their desired application. CNCs produced by various methods are evaluated against three target properties: colloidal stability, size and crystallinity index. Alternative prodn. routes and/or starting materials are suggested to overcome challenges assocd. with CNC use, including increasing compatibility with hydrophobic materials, resistance to thermal degrdn. and colloidal stability in high ionic strength environments. Addnl., we discuss industrial prodn. of CNCs, as well as considerations for increasing the yield and reducing the environmental impact of these processes. Overall, this Review guides researchers and CNC users towards a deeper understanding of how prodn. processes can be modified to control CNC properties and subsequently tailor their performance.
- 49Lv, D.; Du, H.; Che, X.; Wu, M.; Zhang, Y.; Liu, C.; Nie, S.; Zhang, X.; Li, B. Tailored and Integrated Production of Functional Cellulose Nanocrystals and Cellulose Nanofibrils via Sustainable Formic Acid Hydrolysis: Kinetic Study and Characterization. ACS Sustainable Chem. Eng. 2019, 7, 9449– 9463, DOI: 10.1021/acssuschemeng.9b00714Google Scholar49Tailored and Integrated Production of Functional Cellulose Nanocrystals and Cellulose Nanofibrils via Sustainable Formic Acid Hydrolysis: Kinetic Study and CharacterizationLv, Dong; Du, Haishun; Che, Xinpeng; Wu, Meiyan; Zhang, Yuedong; Liu, Chao; Nie, Shuangxi; Zhang, Xinyu; Li, BinACS Sustainable Chemistry & Engineering (2019), 7 (10), 9449-9463CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)Cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) are of great interest to researchers due to their outstanding properties and wide application potentials. However, green and sustainable prodn. of CNCs and CNFs is still challenging. In this work, the integrated and sustainable prodn. of functional CNCs and CNFs was achieved by formic acids (FA) hydrolysis. Kinetic study for FA hydrolysis of cellulosic pulp was performed to investigate the hydrolysis mechanism. FA concn. of 80-98 wt %, reaction temp. of 70-100°, and reaction duration up to 24 h were employed to capture the feature of the coexistence of a diversity of reaction products, i.e., CNCs, cellulose solid residue (CSR), cellulose formate (CF), xylose, glucose, and furfural. The sepd. CSR was further fibrillated to CNFs by homogenization. It was found that the yield, morphol., crystallinity, thermal stability, and degree of esterification of CNCs and CNFs were significantly affected by hydrolysis conditions (particularly for acid concn.). Detailed characterization indicated that the as-prepd. CNCs exhibited high thermal stability (maximal wt. loss temp. of 375°) and high crystallinity index of 79%. Both the resultant CNCs and CNFs showed good dispersibility in dimethylacetamide due to the introduction of ester groups on cellulose surface during FA hydrolysis. More interestingly, the regenerated CF was also a kind of functional CNFs with more ester groups. These ester groups would enable the CNCs/CNFs to be potentially used in polymeric materials due to the hydrophobic surface. Therefore, this study provided fundamental knowledge for the sustainable and integrated prodn. of thermally stable and functional CNCs and CNFs with tailored characteristics.
- 50Pereira, B.; Arantes, V. Production of Cellulose Nanocrystals Integrated into a Biochemical Sugar Platform Process via Enzymatic Hydrolysis at High Solid Loading. Ind. Crops Prod. 2020, 152, 112377 DOI: 10.1016/j.indcrop.2020.112377Google Scholar50Production of cellulose nanocrystals integrated into a biochemical sugar platform process via enzymatic hydrolysis at high solid loadingPereira, Barbara; Arantes, ValdeirIndustrial Crops and Products (2020), 152 (), 112377CODEN: ICRDEW; ISSN:0926-6690. (Elsevier B.V.)This work evaluated the viability of integrating the isolation of cellulose nanocrystals (CNCs) via enzymic hydrolysis at a high solid loading into the biochem. platform process for the prodn. of sugars from sugarcane bagasse (SCB). SCB was first processed at a biochem. conversion pilot plant and bleached to yield a cellulose-rich pulp, which was enzymically hydrolyzed at high solid and low enzyme loadings. The resulting hydrolyzate had high sugar concn. (>120 g/L glucose) and the CNCs (20 nm in diam.) isolated directly from the hydrolysis residue showed superior properties (higher thermal stability, higher crystallinity index, and higher particle diam. uniformity) than the CNCs prepd. from com. bleached eucalyptus Kraft pulp. These findings demonstrate the tech. viability of the proposed integrated process that combined with the high CNCs yield (approx.50%) and the no need for the costly ultrasonic dispersion treatment step to obtain nanoparticles can further contribute for improving the economic and environmental viability of the proposed enzyme-mediated isolation process.
- 51Ferreira, P. F. O.; Pereira, A. L. S.; Rosa, M. F.; de Santiago-Aguiar, R. S. Lignin-Rich Cellulose Nanocrystals from Coir Fiber Treated with Ionic Liquids: Preparation and Evaluation as Pickering Emulsifier. Ind. Crops Prod. 2022, 186, 115119 DOI: 10.1016/j.indcrop.2022.115119Google Scholar51Lignin-rich cellulose nanocrystals from coir fiber treated with ionic liquids: Preparation and evaluation as pickering emulsifierFerreira, Priscilla F. O.; Pereira, Andre L. S.; Rosa, Morsyleide F.; de Santiago-Aguiar, Rilvia S.Industrial Crops and Products (2022), 186 (), 115119CODEN: ICRDEW; ISSN:0926-6690. (Elsevier B.V.)Lignocellulosic materials are promising sources of energy and biomaterials. In this context, the biomass from the mesocarp of the green coconut can be used to produce nanocellulose. For this purpose, this work proposed approaches for pretreatment of coconut biomass using protic ionic liqs. (PILs), which are solvents that have specific characteristics and less environmental impact, followed by acid hydrolysis to obtain lignin-contg. nanocellulose. Thus, three PILs were produced, and two pretreatment methodologies were evaluated. The results showed that, when using the ionic liq. 2-HEAA and Methodol. B, there was a delignification of 17.4%, a redn. of 14% of hemicelluloses and a gain of 50.8% of cellulose. Furthermore, acid hydrolysis provided a stable suspension of lignin-contg. cellulose nanocrystals (zeta potential of -34.6 mV) with particles in the nanometer scale and more thermally resistant. When testing these lignin-contg. cellulose nanocrystals as a stabilizer for oil-in-water emulsions, satisfactory results were obtained at a concn. of 0.50%, which generated a stable emulsion for 14 days (-47.5 mV of zeta potential and mean diam. of 6.23μm).
- 52Gao, M.; Shang, Y.; Li, B.; Du, H. Sustainable Preparation of Cellulose Nanocrystals: State of the Art and Perspectives. Green Chem. 2022, 24, 9346– 9372, DOI: 10.1039/D2GC03003AGoogle Scholar52Sustainable preparation of cellulose nanocrystals: state of the art and perspectivesGao, Mengge; Shang, Yazhuo; Li, Bin; Du, HaishunGreen Chemistry (2022), 24 (24), 9346-9372CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)A review. As sustainable and advanced nanomaterials, cellulose nanocrystals (CNCs) attract extensive attention from both academia and industry due to their superior phys. and chem. properties. Strong inorg. acid (e.g., H2SO4) hydrolysis is the most common method for the prepn. of CNCs because of its high efficiency. However, inorg. acid hydrolysis faces several limitations such as severe equipment corrosion, over-degrdn. of cellulose, pollution of the environment, and the use of a large amt. of water. This review comprehensively summarizes sustainable strategies invented in recent years for the prepn. of CNCs, including the oxidn. method, ionic liq. treatment, deep eutectic solvent treatment, enzymic hydrolysis, inorg. solid acid hydrolysis, org. acid hydrolysis, supercrit. water hydrolysis, HCl vapor/gas hydrolysis, and the electron beam radiation method. It is believed that CNCs, as green and renewable nanomaterials, have broad application prospects in the future, and the realization of the green, low-cost, and sustainable prepn. of CNCs will be the prerequisite guarantee for the large-scale application of CNCs.
- 53Lee, S.; Hao, L. T.; Park, J.; Oh, D. X.; Hwang, D. S. Nanochitin and Nanochitosan: Chitin Nanostructure Engineering with Multiscale Properties for Biomedical and Environmental Applications. Adv. Mater. 2023, 35, 2203325 DOI: 10.1002/adma.202203325Google Scholar53Review on nanochitin and nanochitosan and chitin nanostructure engineering with multiscale properties for biomedical and environmental applicationsLee, Suyoung; Hao, Lam Tan; Park, Jeyoung; Oh, Dongyeop X.; Hwang, Dong SooAdvanced Materials (Weinheim, Germany) (2023), 35 (4), 2203325CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. Nanochitin and nanochitosan (with random-copolymer-based multiscale architectures of glucosamine and N-acetylglucosamine units) have recently attracted immense attention for the development of green, sustainable, and advanced functional materials. Nanochitin and nanochitosan are multiscale materials from small oligomers, rod-shaped nanocrystals, longer nanofibers, to hierarchical assemblies of nanofibers. Various phys. properties of chitin and chitosan depend on their mol.- and nanostructures; translational research has utilized them for a wide range of applications (biomedical, industrial, environmental, and so on). Instead of reviewing the entire extensive literature on chitin and chitosan, here, recent developments in multiscale-dependent material properties and their applications are highlighted; immune, medical, reinforcing, adhesive, green electrochem. materials, biol. scaffolds, and sustainable food packaging are discussed considering the size, shape, and assembly of chitin nanostructures. In summary, new perspectives for the development of sustainable advanced functional materials based on nanochitin and nanochitosan by understanding and engineering their multiscale properties are described.
- 54Bai, L.; Kämäräinen, T.; Xiang, W.; Majoinen, J.; Seitsonen, J.; Grande, R.; Huan, S.; Liu, L.; Fan, Y.; Rojas, O. J. Chirality from Cryo-Electron Tomograms of Nanocrystals Obtained by Lateral Disassembly and Surface Etching of Never-Dried Chitin. ACS Nano 2020, 14, 6921– 6930, DOI: 10.1021/acsnano.0c01327Google Scholar54Chirality from Cryo-Electron Tomograms of Nanocrystals Obtained by Lateral Disassembly and Surface Etching of Never-Dried ChitinBai, Long; Kamarainen, Tero; Xiang, Wenchao; Majoinen, Johanna; Seitsonen, Jani; Grande, Rafael; Huan, Siqi; Liu, Liang; Fan, Yimin; Rojas, Orlando J.ACS Nano (2020), 14 (6), 6921-6930CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)The complex nature of typical colloids and corresponding interparticle interactions pose a challenge in understanding their self-assembly. This specifically applies to biol. nanoparticles, such as those obtained from chitin, which typically are hierarchical and multidimensional. In this study, we obtain chitin nanocrystals by one-step heterogeneous acid hydrolysis of never-dried crab residues. Partial deacetylation facilitates control over the balance of electrostatic charges (ζ-potential in the range between +58 and +75 mV) and therefore affords chitin nanocrystals (DE-ChNC) with axial aspect (170-350 nm in length), as detd. by cryogenic transmission electron microscopy and at. force microscopy. We find that the surface amines generated by deacetylation, prior to hydrolysis, play a crit. role in the formation of individual chitin nanocrystals by the action of a dual mechanism. We directly access the twisting feature of chitin nanocrystals using electron tomog. (ET) and uncover the distinctive morphol. differences between chitin nanocrystals extd. from nondeacetylated chitin, ChNC, which are bundled and irregular, and DE-ChNC (single, straight nanocrystals). Whereas chitin nanocrystals obtained from dried chitin precursors are known to be twisted and form chiral nematic liq. crystals, our ET measurements indicate no dominant twisting or handedness for the nanocrystals obtained from the never-dried source. Moreover, no sepn. into typical isotropic and anisotropic phases occurs after 2 mo at rest. Altogether, we highlight the crit. role of drying the precursors or the nanopolysaccharides to develop chirality.
- 55Liu, L.; Chen, H.; Zou, Y.; Chen, F.; Fan, Y.; Yong, Q. Zwitterionic Chitin Nanocrystals Mediated Composite and Self-Assembly with Cellulose Nanofibrils. Int. J. Biol. Macromol. 2022, 223, 108– 119, DOI: 10.1016/j.ijbiomac.2022.10.235Google Scholar55Zwitterionic chitin nanocrystals mediated composite and self-assembly with cellulose nanofibrilsLiu, Liang; Chen, Huangjingyi; Zou, Yujun; Chen, Feier; Fan, Yimin; Yong, QiangInternational Journal of Biological Macromolecules (2022), 223 (Part_A), 108-119CODEN: IJBMDR; ISSN:0141-8130. (Elsevier B.V.)Zwitterionic dispersed chitin nanocrystals and TEMPO oxidized cellulose nanofibrils can be well mixed and self-assembled to be hydrogels/membranes. Active carboxyl groups ensure the well mixing of zwitterionic chitin nanocrystals and cellulose nanofibrils under neutral and alk. condition. Electrostatic attraction between amino groups in chitin nanocrystals and carboxyl groups in chitin nanocrystals and cellulose nanofibrils further endows self-assemble property of composite suspensions. Simple standing for 12 h at room temp. is found enough for prepg. self-assembled composite hydrogels. By 1-(3-dimethy-laminopropyl)-3-ethylcarbodiimide hydrochloride/N-hydroxy succinimide (EDC/NHS) mediated chem. crosslinking, the storage modulus of composite hydrogel can achieve almost 8 times higher than self-assembled hydrogel. Well dispersed composite suspensions also can be transformed to be membranes via filtration treatment. The strain increases almost 2.3 times higher with similar tensile strength for cellulose nanofibril rich samples, and chitin nanocrystals mainly contributes to the enhancement in strain of composite membranes.
- 56Liu, P.; Liu, H.; Schäfer, T.; Gutmann, T.; Gibhardt, H.; Qi, H.; Tian, L.; Zhang, X. C.; Buntkowsky, G.; Zhang, K. Unexpected Selective Alkaline Periodate Oxidation of Chitin for the Isolation of Chitin Nanocrystals. Green Chem. 2021, 23, 745– 751, DOI: 10.1039/D0GC04054AGoogle Scholar56Unexpected selective alkaline periodate oxidation of chitin for the isolation of chitin nanocrystalsLiu, Peiwen; Liu, Huan; Schaefer, Timmy; Gutmann, Torsten; Gibhardt, Holger; Qi, Houjuan; Tian, Lin; Zhang, Xizhou Cecily; Buntkowsky, Gerd; Zhang, KaiGreen Chemistry (2021), 23 (2), 745-751CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)Periodate oxidn. reaction occurring directly on chitin has been neglected in polysaccharide chem. so far. Herein, we present the first direct alk. periodate oxidn. of chitin, which demonstrates at the same time a novel approach for the prepn. of chitin nanocrystals (ChNCs). This oxidn. is based on an unprecedented selective reaction of non-ordered domains of chitin by the dimeric orthoperiodate ions (H2I2O104-) as the major species in alk. surroundings. Nearly 50 wt% of non-ordered regions are dissolved after sequential accelerated partial deacetylation, periodate oxidn. and β-alkoxy fragmentation, which allows the isolation of up to 50 wt% of uniform anisotropic zwitterionic ChNCs.
- 57El Knidri, H.; Belaabed, R.; Addaou, A.; Laajeb, A.; Lahsini, A. Extraction, Chemical Modification and Characterization of Chitin and Chitosan. Int. J. Biol. Macromol. 2018, 120, 1181– 1189, DOI: 10.1016/j.ijbiomac.2018.08.139Google Scholar57Extraction, chemical modification and characterization of chitin and chitosanEl Knidri, Hakima; Belaabed, Raja; Addaou, Abdellah; Laajeb, Ali; Lahsini, AhmedInternational Journal of Biological Macromolecules (2018), 120 (Part_A), 1181-1189CODEN: IJBMDR; ISSN:0141-8130. (Elsevier B.V.)Chitin is the second most common polymer after cellulose in earth, existing in the shells of crustaceans like crab and shrimp. Chitosan is a natural amino-polysaccharide derived from chitin, known as one of the most abundant org. materials in nature, it has been widely used in several applications due to its natural origin and exceptional properties such as biocompatibility, biodegradability, non-toxicity, and chelating of metal ions. Chitin and chitosan are characterized by deacetylation degree, one of the most important chem. characteristics that can influence the performance of chitosan in many applications. Chitosan is usually prepd. by a thermochem. method, consuming time, energy and reagents. In this review, various methods of chitosan extn. will be approached and compared; the importance of a new method of ecol. extn. will be emphasized. Moreover, in order to improve the chitosan functionality, and better control these physicochem. properties, several chem. modifications have been reported. These chem. modifications lead to a broad range of derivs. with a wide range of applications in many fields. Recent examples of the distinct applications, with particular emphasis on environmental applications, have been presented.
- 58Mohan, K.; Ganesan, A. R.; Ezhilarasi, P. N.; Kondamareddy, K. K.; Rajan, D. K.; Sathishkumar, P.; Rajarajeswaran, J.; Conterno, L. Green and Eco-Friendly Approaches for the Extraction of Chitin and Chitosan: A review. Carbohydr. Polym. 2022, 287, 119349 DOI: 10.1016/j.carbpol.2022.119349Google Scholar58Green and eco-friendly approaches for the extraction of chitin and chitosan: A reviewMohan, Kannan; Ganesan, Abirami Ramu; Ezhilarasi, P. N.; Kondamareddy, Kiran Kumar; Rajan, Durairaj Karthick; Sathishkumar, Palanivel; Rajarajeswaran, Jayakumar; Conterno, LorenzaCarbohydrate Polymers (2022), 287 (), 119349CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)A review. Chitin is one of the most diverse and naturally occurring biopolymers, and it is mainly present in crustaceans, insects, and fungi. Chitosan is derived from chitin by deacetylation process. It is important to note that the conventional chem. method of extg. chitin includes disadvantages and it poses various environmental issues. Recently, the green extn. techniques have perceived substantial development in the field of polymer chem. A variety of methods have been successfully developed using green extn. techniques for extg. chitin and chitosan from various resources. It includes the use of ionic liqs. (ILs), deep eutectic solvents (DES), microbial fermn., enzyme-assisted extn. (EAE), microwave-assisted extn. (MAE), ultrasonic-assisted extn. (UAE), subcrit. water extn. (SWE), and electrochem. extn. (ECE). In this review, the extn. of chitin and chitosan using greener approaches were summarized. In addn., challenges, opportunities and future perspectives of green extn. methods have also been narrated.
- 59Zhou, R.; Zhao, L.; Wang, Y.; Hameed, S.; Ping, J.; Xie, L.; Ying, Y. Recent Advances in Food-Derived Nanomaterials Applied to Biosensing. TrAC Trends Anal. Chem. 2020, 127, 115884 DOI: 10.1016/j.trac.2020.115884Google ScholarThere is no corresponding record for this reference.
- 60Shahidi, F.; Arachchi, J. K. V.; Jeon, Y.-J. Food Applications of Chitin and Chitosans. Trends Food Sci. Technol. 1999, 10, 37– 51, DOI: 10.1016/S0924-2244(99)00017-5Google Scholar60Food applications of chitin and chitosansShahidi, Fereidoon; Arachchi, Janak Kamil Vidana; Jeon, You-JinTrends in Food Science & Technology (1999), 10 (2), 37-51CODEN: TFTEEH; ISSN:0924-2244. (Elsevier Science Ltd.)A review with 143 refs. Chitin is the second most abundant natural biopolymer after cellulose. The chem. structure of chitin is similar to that of cellulose with 2-acetamido-2-deoxy-β-D-glucose (NAG) monomers attached via β(1→4) linkages. Chitosan is the deacetylated (to varying degrees) form of chitin, which, unlike chitin, is sol. in acidic solns. Application of chitinous products in foods and pharmaceuticals as well as processing aids has received considerable attention in recent years as exotic synthetic compds. are losing their appeal. This review summarizes some of the important developments related to food applications of chitin, chitosan and their derivs.
- 61Kumar, S.; Foroozesh, J. Chitin Nanocrystals Based Complex Fluids: A Green Nanotechnology. Carbohydr. Polym. 2021, 257, 117619 DOI: 10.1016/j.carbpol.2021.117619Google Scholar61Chitin nanocrystals based complex fluids: A green nanotechnologyKumar, Sunil; Foroozesh, JalalCarbohydrate Polymers (2021), 257 (), 117619CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)A review. Chitin biopolymer has received significant attention recently by many industries as a green technol. Nanotechnol. has been used to make chitin nanocrystals (ChiNCs) that are rod-shaped natural nanomaterials with nanoscale size. Owing to the unique features such as biodegradability, biocompatibility, renewability, rod-shape, and excellent surface and interfacial, physiochem., and thermo-mech. properties; ChiNCs have been green and attractive products with wide applications specifically in medical and pharmaceutical, food and packaging, cosmetic, elec., and electronic, and also in the oil and gas industry. This review aims to give a comprehensive and applied insight into ChiNCs technol. It starts with reviewing different sources of chitin and their extn. methods followed by the characterization of ChiNCs. Furthermore, a detailed investigation into various complex fluids (dispersions, emulsions, foams, and gels) stabilized by ChiNCs and their characterization have been thoroughly deliberated. Finally, the current status including ground-breaking applications, untapped investigations, and future prospective have been presented.
- 62Claverie, M.; McReynolds, C.; Petitpas, A.; Thomas, M.; Fernandes, S. C. M. Marine-Derived Polymeric Materials and Biomimetics: An Overview. Polymers 2020, 12, 1002, DOI: 10.3390/polym12051002Google ScholarThere is no corresponding record for this reference.
- 63Kaya, M.; Mujtaba, M.; Ehrlich, H.; Salaberria, A. M.; Baran, T.; Amemiya, C. T.; Galli, R.; Akyuz, L.; Sargin, I.; Labidi, J. On Chemistry of γ-Chitin. Carbohydr. Polym. 2017, 176, 177– 186, DOI: 10.1016/j.carbpol.2017.08.076Google Scholar63On chemistry of γ-chitinKaya, Murat; Mujtaba, Muhammad; Ehrlich, Hermann; Salaberria, Asier M.; Baran, Talat; Amemiya, Chris T.; Galli, Roberta; Akyuz, Lalehan; Sargin, Idris; Labidi, JalelCarbohydrate Polymers (2017), 176 (), 177-186CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)The biol. material, chitin, is present in nature in three allomorphic forms: α, β and γ. Whereas most studies have dealt with α- and β-chitin, only few investigations have focused on γ-chitin, whose structural and physicochem. properties have not been well delineated. In this study, chitin obtained for the first time from the cocoon of the moth (Orgyia dubia) was subjected to extensive physicochem. analyses and examd., in parallel, with α-chitin from exoskeleton of a freshwater crab and β-chitin from cuttlebone of the common cuttlefish. Our results, which are supported by 13C CP-MAS NMR, XRD, FT-IR, Raman spectroscopy, TGA, DSC, SEM, AFM, chitinase digestive test and elemental anal., verify the authenticity of γ-chitin. Further, quantum chem. calcns. were conducted on all three allomorphic forms, and, together with our physicochem. analyses, demonstrate that γ-chitin is distinct, yet closer in structure to α-chitin than β-chitin.
- 64Huang, W.; Restrepo, D.; Jung, J.-Y.; Su, F. Y.; Liu, Z.; Ritchie, R. O.; McKittrick, J.; Zavattieri, P.; Kisailus, D. Multiscale Toughening Mechanisms in Biological Materials and Bioinspired Designs. Adv. Mater. 2019, 31, 1901561 DOI: 10.1002/adma.201901561Google Scholar64Multiscale toughening mechanisms in biological materials and bioinspired designsHuang, Wei; Restrepo, David; Jung, Jae-Young; Su, Frances Y.; Liu, Zengqian; Ritchie, Robert O.; McKittrick, Joanna; Zavattieri, Pablo; Kisailus, DavidAdvanced Materials (Weinheim, Germany) (2019), 31 (43), 1901561CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. Biol. materials found in Nature such as nacre and bone are well recognized as light-wt., strong, and tough structural materials. The remarkable toughness and damage tolerance of such biol. materials are conferred through hierarchical assembly of their multiscale (i.e., at.- to macroscale) architectures and components. Herein, the toughening mechanisms of different organisms at multilength scales are identified and summarized: macromol. deformation, chem. bond breakage, and biomineral crystal imperfections at the at. scale; biopolymer fibril reconfiguration/deformation and biomineral nanoparticle/nanoplatelet/nanorod translation, and crack reorientation at the nanoscale; crack deflection and twisting by characteristic features such as tubules and lamellae at the microscale; and structure and morphol. optimization at the macroscale. In addn., the actual loading conditions of the natural organisms are different, leading to energy dissipation occurring at different time scales. These toughening mechanisms are further illustrated by comparing the exptl. results with computational modeling. Modeling methods at different length and time scales are reviewed. Examples of biomimetic designs that realize the multiscale toughening mechanisms in engineering materials are introduced. Indeed, there is still plenty of room mimicking the strong and tough biol. designs at the multilength and time scale in Nature.
- 65Yang, T.; Qi, H.; Liu, P.; Zhang, K. Selective Isolation Methods for Cellulose and Chitin Nanocrystals. ChemPlusChem. 2020, 85, 1081– 1088, DOI: 10.1002/cplu.202000250Google Scholar65Selective Isolation Methods for Cellulose and Chitin NanocrystalsYang, Ting; Qi, Houjuan; Liu, Peiwen; Zhang, KaiChemPlusChem (2020), 85 (5), 1081-1088CODEN: CHEMM5; ISSN:2192-6506. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. This Minireview focuses on the selective isolation methods for the prepn. of cellulose nanocrystals (CNCs) and chitin nanocrystals (ChNCs). Various selective prepn. strategies with specific prepn. conditions and reaction mechanisms are summarized. In particular, these selective reaction routes include controlled acid hydrolysis and selective oxidns. at specific positions of cellulose or chitin fibers as well as particular reaction sites of the repeating monosaccharide building blocks of their main chains. These lead to selective cleavage of the ordered and non-ordered regions of cellulose and chitin and result in efficient prodn. of CNCs and ChNCs.
- 66Oun, A. A.; Rhim, J.-W. Effect of Isolation Methods of Chitin Nanocrystals on the Properties of Chitin-Silver Hybrid Nanoparticles. Carbohydr. Polym. 2018, 197, 349– 358, DOI: 10.1016/j.carbpol.2018.06.033Google Scholar66Effect of isolation methods of chitin nanocrystals on the properties of chitin-silver hybrid nanoparticlesOun, Ahmed A.; Rhim, Jong-WhanCarbohydrate Polymers (2018), 197 (), 349-358CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)Chitin nanocrystal (ChNC) was isolated using sulfuric acid hydrolysis (ChNCH2SO4), TEMPO-oxidn. (ChNCTEMPO), and ammonium persulfate (ChNCAPS) methods, and used for the prepn. of hybrid nanoparticles of ChNC/silver nanoparticles (AgNP). The ChNC exhibited a needle-shaped structure with a sulfate group content of 135 μmol/g for ChNCH2SO4 and carboxyl content of 0.71 and 1.42 mmol/g for ChNCTEMPO and ChNCAPS, resp. ChNC worked as a reducing and stabilizing agent for the prodn. of AgNP and reduced the size of AgNP from 23.9 nm to 6.3 nm in the ChNC/AgNP hybrid. The carboxyl content of ChNC played a significant role for the nucleation, size distribution, and antibacterial activity of ChNC/AgNP. ChNC/AgNP hybrid, esp. ChNCAPS/AgNP, exhibited strong antibacterial activity against food-borne pathogenic Gram-neg. (E. coli) and Gram-pos. (L. monocytogenes) bacteria. The prepd. ChNC/AgNP hybrid nanomaterials have a high potential for the application to be used as a nanofiller to improve the properties of food packaging materials to extend the shelf-life of packaged food.
- 67Nguyen, H. V. D.; de Vries, R.; Stoyanov, S. D. Chitin Nanowhiskers with Improved Properties Obtained Using Natural Deep Eutectic Solvent and Mild Mechanical Processing. Green Chem. 2022, 24, 3834– 3844, DOI: 10.1039/D2GC00305HGoogle ScholarThere is no corresponding record for this reference.
- 68Wang, L.; Urbas, A. M.; Li, Q. Nature-Inspired Emerging Chiral Liquid Crystal Nanostructures: From Molecular Self-Assembly to DNA Mesophase and Nanocolloids. Adv. Mater. 2020, 32, 1801335 DOI: 10.1002/adma.201801335Google Scholar68Nature-Inspired Emerging Chiral Liquid Crystal Nanostructures: From Molecular Self-Assembly to DNA Mesophase and NanocolloidsWang, Ling; Urbas, Augustine M.; Li, QuanAdvanced Materials (Weinheim, Germany) (2020), 32 (41), 1801335CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. Liq. crystals (LCs) are omnipresent in living matter, whose chirality is an elegant and distinct feature in certain plant tissues, the cuticles of crabs, beetles, arthropods, and beyond. Taking inspiration from nature, researchers have recently devoted extensive efforts toward developing chiral liq. cryst. materials with self-organized nanostructures and exploring their potential applications in diverse fields ranging from dynamic photonics to energy and safety issues. In this review, an account on the state of the art of emerging chiral liq. cryst. nanostructured materials and their technol. applications is provided. First, an overview on the significance of chiral liq. cryst. architectures in various living systems is given. Then, the recent significant progress in different chiral liq. cryst. systems including thermotropic LCs (cholesteric LCs, cubic blue phases, achiral bent-core LCs, etc.) and lyotropic LCs (DNA LCs, nanocellulose LCs, and graphene oxide LCs) is showcased. The review concludes with a perspective on the future scope, opportunities, and challenges in these truly advanced functional soft materials and their promising applications.
- 69Lee, D. W. Nature’s Palette: The Science of Plant Color; The University of Chicago Press: Chicago, Illinois, USA, 2007.Google ScholarThere is no corresponding record for this reference.
- 70Graham, R. M.; Lee, D. W.; Norstog, K. Physical and Ultrastructural Basis of Blue Leaf Iridescence in Two Neotropical Ferns. Am. J. Bot. 1993, 80, 198– 203, DOI: 10.1002/j.1537-2197.1993.tb13789.xGoogle ScholarThere is no corresponding record for this reference.
- 71Lundquist, C. R.; Rudall, P. J.; Sukri, R. S.; Conejero, M.; Smith, A.; Lopez-Garcia, M.; Vignolini, S.; Metali, F.; Whitney, H. M. Living Jewels: Iterative Evolution of Iridescent Blue Leaves from Helicoidal Cell Walls. Ann. Bot. 2024, 134, 131– 150, DOI: 10.1093/aob/mcae045Google ScholarThere is no corresponding record for this reference.
- 72Steiner, L. M.; Ogawa, Y.; Johansen, V. E.; Lundquist, C. R.; Whitney, H.; Vignolini, S. Structural Colours in the Frond of Microsorum thailandicum. Interface Focus 2019, 9, 20180055 DOI: 10.1098/rsfs.2018.0055Google ScholarThere is no corresponding record for this reference.
- 73Strout, G.; Russell, S. D.; Pulsifer, D. P.; Erten, S.; Lakhtakia, A.; Lee, D. W. Silica Nanoparticles Aid in Structural Leaf Coloration in the Malaysian Tropical Rainforest Understorey Herb Mapania Caudata. Ann. Bot. 2013, 112, 1141– 1148, DOI: 10.1093/aob/mct172Google Scholar73Silica nanoparticles aid in structural leaf coloration in the Malaysian tropical rainforest understory herb Mapania caudataStrout, Greg; Russell, Scott D.; Pulsifer, Drew P.; Erten, Sema; Lakhtakia, Akhlesh; Lee, David W.Annals of Botany (Oxford, United Kingdom) (2013), 112 (6), 1141-1148CODEN: ANBOA4; ISSN:0305-7364. (Oxford University Press)Background and Aims Blue-green iridescence in the tropical rainforest understory sedge Mapania caudata creates structural coloration in its leaves through a novel photonic mechanism. Known structures in plants producing iridescent blues consist of altered cellulose layering within cell walls and in special bodies, and thylakoid membranes in specialized plastids. This study was undertaken in order to det. the origin of leaf iridescence in this plant, with particular attention to nano-scale components contributing to this coloration. Methods Adaxial walls of leaf epidermal cells were characterized using high-pressure-frozen freeze-substituted specimens, which retain their native dimensions during observations using transmission and scanning microscopy, accompanied by energy-dispersive X-ray spectroscopy to identify the role of biogenic silica in wall-based iridescence. Biogenic silica was exptl. removed using aq. Na2CO3 and optical properties were compared using spectral reflectance. Key Results and Conclusions Blue iridescence is produced in the adaxial epidermal cell wall, which contains helicoid lamellae. The blue iridescence from cell surfaces is left-circularly polarized. The position of the silica granules is entrained by the helicoid microfibrillar layers, and granules accumulate at a uniform position within the helicoids, contributing to the structure that produces the blue iridescence, as part of the unit cell responsible for 2 ° Bragg scatter. Removal of silica from the walls eliminated the blue color. Addn. of silica nanoparticles on existing cellulosic lamellae is a novel mechanism for adding structural color in organisms.
- 74He, Y.; Lin, S.; Guo, J.; Li, Q. Circularly Polarized Luminescent Self-Organized Helical Auperstructures: From Materials and Stimulus-Responsiveness to Applications. Aggregate 2021, 2, e141 DOI: 10.1002/agt2.141Google ScholarThere is no corresponding record for this reference.
- 75Echeverría-Alar, S.; Clerc, M. G.; Bordeu, I. Emergence of Disordered Branching Patterns in Confined Chiral Nematic Liquid Crystals. Proc. Natl. Acad. Sci. U. S. A. 2023, 120, e2221000120 DOI: 10.1073/pnas.2221000120Google ScholarThere is no corresponding record for this reference.
- 76Mitov, M. Cholesteric Liquid Crystals in Living Matter. Soft Matter 2017, 13, 4176– 4209, DOI: 10.1039/C7SM00384FGoogle Scholar76Cholesteric liquid crystals in living matterMitov, MichelSoft Matter (2017), 13 (23), 4176-4209CODEN: SMOABF; ISSN:1744-6848. (Royal Society of Chemistry)Liq. crystals play an important role in biol. because the combination of order and mobility is a basic requirement for self-organization and structure formation in living systems. Cholesteric liq. crystals are omnipresent in living matter under both in vivo and in vitro conditions and address the major types of mols. essential to life. In the animal and plant kingdoms, the cholesteric structure is a recurring design, suggesting a convergent evolution to an optimized left-handed helix. Herein, we review the recent advances in the cholesteric organization of DNA, chromatin, chitin, cellulose, collagen, viruses, silk and cholesterol ester deposition in atherosclerosis. Cholesteric structures can be found in bacteriophages, archaea, eukaryotes, bacterial nucleoids, chromosomes of unicellular algae, sperm nuclei of many vertebrates, cuticles of crustaceans and insects, bone, tendon, cornea, fish scales and scutes, cuttlebone and squid pens, plant cell walls, virus suspensions, silk produced by spiders and silkworms, and arterial wall lesions. This article specifically aims at describing the consequences of the cholesteric geometry in living matter, which are far from being fully defined and understood, and discusses various perspectives. The roles and functions of biol. cholesteric liq. crystals include maximisation of packing efficiency, morphogenesis, mech. stability, optical information, radiation protection and evolution pressure.
- 77Almeida, A. P. C.; Canejo, J. P.; Almeida, P. L.; Godinho, M. H. Cholesteric-Type Cellulosic Structures: From Plants to Applications. Liq. Cryst. 2019, 46, 1937– 1949, DOI: 10.1080/02678292.2019.1640904Google Scholar77Cholesteric-type cellulosic structures: from plants to applicationsAlmeida, Ana P. C.; Canejo, Joao P.; Almeida, Pedro L.; Godinho, Maria HelenaLiquid Crystals (2019), 46 (13-14), 1937-1949CODEN: LICRE6; ISSN:0267-8292. (Taylor & Francis Ltd.)A review. The structural support of plant cells is provided by the cell wall, which major load-bearing component is an array of hierarchical orientedhierarchical-oriented cellulose nano-, micro- and meso-structures of cellulose microfibrils. Cellulosic structures can respond to humidity changes by expanding or shrinking and this allows, for example, the dispersion of seeds. Previous studies have shown that nanorods, extd. from cell walls, can generate lyotropic liq. crystals that are at the origin of solid cholesteric-like arrangements. Not only photonic films, but also right and left helical filaments, anisotropic films with the ability to bend back and forth under the action of a moisture gradient at room temp., are some of the materials that were produced from cellulose liq. crystal systems. This work is a review that focus on liq. cryst.-based structures obtained from cellulosic materials and how small perturbations on their structures affect significantly the response to external stimulus and interactions with the environment. Special emphasis is given to cholesteric-like organization of cellulose structures existing in plants, which are an inspiration for the prodn. of the next generation of soft interactive materials.
- 78Vignolini, S.; Rudall, P. J.; Rowland, A. V.; Reed, A.; Moyroud, E.; Faden, R. B.; Baumberg, J. J.; Glover, B. J.; Steiner, U. Pointillist Structural Color in Pollia Fruit. Proc. Natl. Acad. Sci. U. S. A. 2012, 109, 15712– 15715, DOI: 10.1073/pnas.1210105109Google Scholar78Pointillist structural color in Pollia fruitVignolini, Silvia; Rudall, Paula J.; Rowland, Alice V.; Reed, Alison; Moyroud, Edwige; Faden, Robert B.; Baumberg, Jeremy J.; Glover, Beverley J.; Steiner, UllrichProceedings of the National Academy of Sciences of the United States of America (2012), 109 (39), 15712-15715, S15712/1-S15712/2CODEN: PNASA6; ISSN:0027-8424. (National Academy of Sciences)Biol. communication by means of structural color has existed for at least 500 million years. Structural color is commonly obsd. in the animal kingdom, but has been little studied in plants. We present a striking example of multilayer-based strong iridescent coloration in plants, in the fruit of Pollia condensatea. The color is caused by Bragg reflection of helicoidally stacked cellulose micro- fibrils that form multilayers in the cell walls of the epicarp. We demonstrate that animals and plants have convergently evolved multilayer-based photonic structures to generate colors using en- tirely distinct materials. The bright blue coloration of this fruit is more intense than that of any previously described biol. material. Uniquely in nature, the reflected color differs from cell to cell, as the layer thicknesses in the multilayer stack vary, giving the fruit a striking pixelated or pointillist appearance. Because the multilayers form with both helicoidicities, optical characterization reveals that the reflected light from every epidermal cell is polarized circularly either to the left or to the right, a feature that has never previously been obsd. in a single tissue.
- 79Vignolini, S.; Gregory, T.; Kolle, M.; Lethbridge, A.; Moyroud, E.; Steiner, U.; Glover, B. J.; Vukusic, P.; Rudall, P. J. Structural Colour from Helicoidal Cell-Wall Architecture in Fruits of Margaritaria Nobilis. J. R. Soc. Interface 2016, 13, 20160645 DOI: 10.1098/rsif.2016.0645Google ScholarThere is no corresponding record for this reference.
- 80Airoldi, C. A.; Ferria, J.; Glover, B. J. The Cellular and Genetic Basis of Structural Colour in Plants. Curr. Opin. Plant Biol. 2019, 47, 81– 87, DOI: 10.1016/j.pbi.2018.10.002Google ScholarThere is no corresponding record for this reference.
- 81Lee, S.; Kim, H.; Jeong, Y. Angular Distribution of Luminescence Dissymmetry Observed from a Random Laser Built upon the Exocuticle of the Scarab Beetle Chrysina Gloriosa. Opt. Express 2021, 29, 37712– 37721, DOI: 10.1364/OE.438697Google Scholar81Angular distribution of luminescence dissymmetry observed from a random laser built upon the exocuticle of the scarab beetle Chrysina gloriosaLee, Seungsu; Kim, Hansol; Jeong, YoonchanOptics Express (2021), 29 (23), 37712-37721CODEN: OPEXFF; ISSN:1094-4087. (Optica Publishing Group)We investigate the angular distribution of luminescence dissymmetry of random lasing in the mixt. of rhodamine 6G and titanium dioxide nanoparticles upon a biocompatible natural material substrate, i.e., the elytron of the scarab beetle Chrysina gloriosa. We look into both green and gold-colored areas of the elytron that exhibit distinctly different CD properties. The fabricated sample asym. emits both left- and right-handed circularly polarized light at 570 nm when pumped at 532 nm, depending on the direction of emission and the angle of the pump incidence. We characterize the light via measuring the angular distribution of its luminescence dissymmetry factor (glum), which reaches an unusually high maximal value of 0.90 or -0.50 at some specific angle depending on the handedness of its polarization. This random laser source can be used in numerous potential optoelectronic applications which require light emission of distributed luminescence dissymmetry or of high luminescence dissymmetry.
- 82Agez, G.; Bayon, C.; Mitov, M. Multiwavelength Micromirrors in the Cuticle of Scarab Beetle Chrysina Gloriosa. Acta Biomater. 2017, 48, 357– 367, DOI: 10.1016/j.actbio.2016.11.033Google Scholar82Multiwavelength micromirrors in the cuticle of scarab beetle Chrysina gloriosaAgez, Gonzague; Bayon, Chloe; Mitov, MichelActa Biomaterialia (2017), 48 (), 357-367CODEN: ABCICB; ISSN:1742-7061. (Elsevier Ltd.)Beetles from the genus Chrysina show vivid reflections from bright green to metallic silver-gold as a consequence of the cholesteric liq. crystal organization of chitin mols. Particularly, the cuticle of Chrysina gloriosa exhibits green and silver stripes. By combining confocal microscopy and spectrophotometry, SEM and numerical simulations, the relationship between the reflectance and the structural parameters for both stripes at the micro- and nanoscales are established. Over the visible and near IR spectra, polygonal cells in tessellated green stripes behave as multiwavelength selective micro-mirrors and the silver stripes as specular broadband mirrors. Thermoregulation, conspecifics or intra-species communication, or camouflage against predators are discussed as possible functions. As a prerequisite to bio-inspired artificial replicas, the phys. characteristics of the polygonal texture in Chrysina gloriosa cuticle are compared to their equiv. in synthetic cholesteric oligomers and their fundamental differences are ascertained. It is shown that the cuticle has concave cells whereas the artificial films have convex cells, contrary to expectation and assumption in the literature. The present results may provide inspiration for fabricating multiwavelength selective micromirrors or spatial wavelength-specific light modulators. Many insects own a tessellated carapace with bumps, pits or indentations. Little is known on the phys. properties of these geometric variations and biol. functions are unknown or still debated. We show that the polygonal cells in scarab beetle Chrysina gloriosa behave as multiwavelength selective micromirrors over the visible and IR spectra, with a variety of spatial patterns. In the context of biomimetic materials, we demonstrate that the carapace has concave cells whereas the artificial films have convex cells, contrary to expectation in the literature. Thermoregulation, communication or camouflage are discussed as advanced functions. Results may provide inspiration for fabricating spatial wavelength-specific light modulators and optical packet switching in routing technologies.
- 83Hwang, J.; Song, M. H.; Park, B.; Nishimura, S.; Toyooka, T.; Wu, J. W.; Takanishi, Y.; Ishikawa, K.; Takezoe, H. Electro-Tunable Optical Diode Based on Photonic Bandgap Liquid-Crystal Heterojunctions. Nat. Mater. 2005, 4, 383– 387, DOI: 10.1038/nmat1377Google Scholar83Electro-tunable optical diode based on photonic bandgap liquid-crystal heterojunctionsHwang, Jisoo; Song, Myoung Hoon; Park, Byoungchoo; Nishimura, Suzushi; Toyooka, Takehiro; Wu, J. W.; Takanishi, Yoichi; Ishikawa, Ken; Takezoe, HideoNature Materials (2005), 4 (5), 383-387CODEN: NMAACR; ISSN:1476-1122. (Nature Publishing Group)Manipulation of light is in strong demand in information technologies. Among the wide range of linear and nonlinear optical devices that have been used, growing attention has been paid to photonic crystals that possess a periodic modulation of dielec. function. Among many photonic bandgap (PBG) structures, liq. crystals with periodic structures are very attractive as self-assembled photonic crystals, leading to optical devices such as dye lasers. Here we report a new hetero-PBG structure consisting of an anisotropic nematic layer sandwiched between two cholesteric liq.-crystal layers with different helical pitches. We optically visualized the dispersion relation of this structure, displaying the optical diode performance: i.e., the non-reciprocal transmission of circular polarized light at the photonic-bandgap regions. Transmittance spectra with circularly polarized light also reveal the diode performance, which is well simulated in calcns. that include an electro-tunable diode effect. Lasing action was also confirmed to show the diode effect with a particular directionality.
- 84Caveney, S. Cuticle Reflectivity and Optical Activity in Scarab Beetles: the Role of Uric Acid. Proc. R. Soc. London, Ser. B 1971, 178, 205– 25, DOI: 10.1098/rspb.1971.0062Google Scholar84Cuticle reflectivity and optical activity in scarab beetles: role of uric acidCaveney, S.Proceedings of the Royal Society of London, Series B: Biological Sciences (1971), 178 (1051), 205-25CODEN: PRLBA4; ISSN:0962-8452.The iridescent cuticle of certain rutelian scarab beetles, which is optically active and selectively reflects circularly polarized light, contained an NH4OH-extractable component identified as uric acid (I). All species of Plusiotis examd. had I in their reflecting layers, as did several species of Anoplognathus. P. respendens had a reflecting layer with a I vol. fraction of 0.7, and P. optima a vol. fraction of 0.6. The reflecting layer of the former had a counter-clockwise helicoidal architecture, the optical thickness of the helicoidal pitch being such that it constructively interfered with visible light wavelengths. A counter-clockwise helicoid constructively interferes with only the left circularly polarized component of incident light, right circularly polarized light being transmitted without attenuation. P. respendens had a 1.8 μ thick unidirectional layer embedded within the helicoid which functioned as a perfect halfwave retardation plate for wavelength 590 nm, enabling the helicoidal reflector to reflect both left and right circularly polarized components of incident light. After passing through the halfwave plate, transmitted right circularly polarized light became left circularly polarized; this light was reflected and emerged from the cuticle right circularly polarized, after passing back through the halfwave plate. Consequently the total reflectivity of circularly polarized incident light was greater in P. resplendens than in any other species examd.; the plate also reduced multiple internal reflections. Interferometric anal. of the refractive properties of the helicoidal reflectors in species of Plusiotis showed that the ordered incorporation of I increased the birefringence of the system 5-fold. As the coeff. of reflection of a helicoidal reflector is directly proportional to the birefringence of the individual planes comprising the helicoid, beetles incorporating I into their reflecting surfaces reflected circularly polarized light far more efficiently than beetles lacking I. Although I is a common cytoplasmic reflecting material in arthropods, this is the first record of its presence in an extracellular (cuticular) reflector.
- 85Gray, D. G.; Mu, X. Chiral Nematic Structure of Cellulose Nanocrystal Suspensions and Films; Polarized Light and Atomic Force Microscopy. Materials 2015, 8, 7873– 7888, DOI: 10.3390/ma8115427Google Scholar85Chiral nematic structure of cellulose nanocrystal suspensions and films; polarized light and atomic force microscopyGray, Derek G.; Mu, XiaoyueMaterials (2015), 8 (11), 7873-7888CODEN: MATEG9; ISSN:1996-1944. (MDPI AG)Cellulosic liq. cryst. solns. and suspensions form chiral nematic phases that show a rich variety of optical textures in the liq. cryst. state. These ordered structures may be preserved in solid films prepd. by evapn. of solvent or suspending medium. Film formation from aq. suspensions of cellulose nanocrystals (CNC) was investigated by polarized light microscopy, optical profilometry and at. force microscopy (AFM). An attempt is made to interpret qual. the obsd. textures in terms of the orientation of the cellulose nanocrystals in the suspensions and films, and the changes in orientation caused by the evaporative process. Mass transfer within the evapg. droplet resulted in the formation of raised rings whose magnitude depended on the degree of pinning of the receding contact line. AFM of dry films at short length scales showed a radial orientation of the CNC at the free surface of the film, along with a radial height variation with a period of approx. P/2, ascribed to the anisotropic shrinkage of the chiral nematic structure.
- 86Giese, M.; Spengler, M. Cellulose Nanocrystals in Nanoarchitectonics-towards Photonic Functional Materials. Mol. Syst. Des. Eng. 2019, 4, 29– 48, DOI: 10.1039/C8ME00065DGoogle ScholarThere is no corresponding record for this reference.
- 87Marchessault, R.; Morehead, F.; Walter, N. Liquid Crystal Systems from Fibrillar Polysaccharides. Nature 1959, 184, 632– 633, DOI: 10.1038/184632a0Google Scholar87Liquid crystal systems from fibrillar polysaccharidesMarchessault, R. H.; Morehead, F. F.; Walter, N. M.Nature (London, United Kingdom) (1959), 184 (Suppl. No. 9), 632-3CODEN: NATUAS; ISSN:0028-0836.A suspension of crystallite particles of chitin was prepd. by treating purified chitin from crab shells with HCl under reflux. Electron micrographs showed the presence of rodlike particles. The methods used for the prepn. of liquid crystals from such a suspension and from a suspension of cellulose are described, and micrographs are given.
- 88Revol, J. F.; Bradford, H.; Giasson, J.; Marchessault, R. H.; Gray, D. G. Helicoidal Self-Ordering of Cellulose Microfibrils in Aqueous Suspension. Int. J. Biol. Macromol. 1992, 14, 170– 172, DOI: 10.1016/S0141-8130(05)80008-XGoogle Scholar88Helicoidal self-ordering of cellulose microfibrils in aqueous suspensionRevol, J.-F.; Bradford, H.; Giasson, J.; Marchessault, R. H.; Gray, D. G.International Journal of Biological Macromolecules (1992), 14 (3), 170-2CODEN: IJBMDR; ISSN:0141-8130.In many skeletal support systems of plants and animals, cellulose, chitin, and collagen occur in the form of microfibrils ordered in a chiral nematic fashion (helicoids). However, these structures remain poorly understood due to the many constituents present in biol. tissues. Here an in vitro system is reported that is attractive for its simplicity. Only one chem. component, cellulose, is present in the form of fibrillar fragments dispersed in water. Above a crit. concn. the colloidal dispersion separates spontaneously into a chiral nematic liq. cryst. phase. On drying, this phase solidifies into regularly twisted fibrillar layers that mimic the structural organization of helicoids in nature.
- 89Edgar, C. D.; Gray, D. G. Induced Circular Dichroism of Chiral Nematic Cellulose Films. Cellulose 2001, 8, 5– 12, DOI: 10.1023/A:1016624330458Google Scholar89Induced circular dichroism of chiral nematic cellulose filmsEdgar, Catherine D.; Gray, Derek G.Cellulose (Dordrecht, Netherlands) (2001), 8 (1), 5-12CODEN: CELLE8; ISSN:0969-0239. (Kluwer Academic Publishers)Colloidal chiral nematic suspensions of cellulose (I) were prepd. from dissolving grade wood pulp. Upon evapn. of the water, the suspension dries down to give iridescent I films. The optical properties of the films may be characterized by incorporating dyes in the films, and following the ordering of the dye mols. by measurement of induced CD (ICD). Structural changes to the films, e.g. decreasing the chiral nematic pitch by increasing the salt content and increasing the chiral nematic order through magnetic alignment, can be monitored by measuring the changes in ICD.
- 90Mu, X.; Gray, D. G. Formation of Chiral Nematic Films from Cellulose Nanocrystal Suspensions Is a Two-Stage Process. Langmuir 2014, 30, 9256– 9260, DOI: 10.1021/la501741rGoogle Scholar90Formation of Chiral Nematic Films from Cellulose Nanocrystal Suspensions Is a Two-Stage ProcessMu, Xiaoyue; Gray, Derek G.Langmuir (2014), 30 (31), 9256-9260CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)The evapn. of aq. suspensions of cellulose nanocrystals (CNCs) gives iridescent chiral nematic films with reflection colors at visible wavelengths. A key problem is controlling the chiral nematic pitch, P, and hence the reflection colors of CNC films. By adding D-(+)-glucose to the suspension, the change in P during evapn. occurs in 2 distinct stages. The 1st stage is the decrease in P as the concn. of CNC in the chiral nematic suspension increases due to evapn.; the addn. of glucose causes a decrease in P at this stage. In a 2nd stage, a concn. of CNC is reached where the formation of ordered gels and glasses prevents further major changes in P. The addn. of glucose lowers the CNC concn. at which this occurs, increasing P and hence an overall shift to the red end of the spectrum in the final film.
- 91Coles, H. in Handbook of Liquid Crystals, Demus, D.; Goodby, J.; Gray, G.W.; Spiess, H.-W.; Vill, V., Eds.; Wiley-VCH: Weinheim, Germany, 1998.Google ScholarThere is no corresponding record for this reference.
- 92Narkevicius, A.; Parker, R. M.; Ferrer-Orri, J.; Parton, T. G.; Lu, Z.; van de Kerkhof, G. T.; Frka-Petesic, B.; Vignolini, S. Revealing the Structural Coloration of Self-Assembled Chitin Nanocrystal Films. Adv. Mater. 2022, 34, 2203300 DOI: 10.1002/adma.202203300Google Scholar92Revealing the Structural Coloration of Self-Assembled Chitin Nanocrystal FilmsNarkevicius, Aurimas; Parker, Richard M.; Ferrer-Orri, Jordi; Parton, Thomas G.; Lu, Zihao; van de Kerkhof, Gea T.; Frka-Petesic, Bruno; Vignolini, SilviaAdvanced Materials (Weinheim, Germany) (2022), 34 (31), 2203300CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)The structural coloration of arthropods often arises from helicoidal structures made primarily of chitin. Although it is possible to achieve analogous helicoidal architectures by exploiting the self-assembly of chitin nanocrystals (ChNCs), to date no evidence of structural coloration has been reported from such structures. Previous studies are identified to have been constrained by both the exptl. inability to access sub-micrometer helicoidal pitches and the intrinsically low birefringence of cryst. chitin. To expand the range of accessible pitches, here, ChNCs are isolated from two phylogenetically distinct sources of alpha-chitin, namely fungi and shrimp, while to increase the birefringence, an in situ alk. treatment is performed, increasing the intensity of the reflected color by nearly two orders of magnitude. By combining this treatment with precise control over ChNC suspension formulation, structurally colored chitin-based films are demonstrated with reflection tunable from blue to near IR.
- 93Andrew, L. J.; Walters, C. M.; Hamad, W. Y.; MacLachlan, M. J. Coassembly of Cellulose Nanocrystals and Neutral Polymers in Iridescent Chiral Nematic Films. Biomacromolecules 2023, 24, 896– 908, DOI: 10.1021/acs.biomac.2c01325Google Scholar93Coassembly of Cellulose Nanocrystals and Neutral Polymers in Iridescent Chiral Nematic FilmsAndrew, Lucas J.; Walters, Christopher M.; Hamad, Wadood Y.; MacLachlan, Mark J.Biomacromolecules (2023), 24 (2), 896-908CODEN: BOMAF6; ISSN:1525-7797. (American Chemical Society)Photonic materials based on composite films of cellulose nanocrystals (CNCs) and polymers are promising as they can be renewable and show tunable optical and mech. properties. However, the influence of polymers on CNC self-assembly is not always well understood, and conflicting results are present in the literature. In this study, we incorporate three neutral, water-sol. polymers-poly(ethylene glycol) (PEG), poly(vinyl pyrrolidone) (PVP), and poly(acrylic acid) (PAA)-with different mol. wts. into CNC suspensions at various concns. prior to obtaining iridescent composite thin films by solvent evapn. Through spectroscopic, potentiometric, and rheol. analyses, we find that PVP phys. adsorbs to the surface of CNCs resulting in a bathochromic shift in film color with both increasing concn. and polymer mol. wt. In contrast, PEG induces depletion interactions that result in a decrease in the size of chiral nematic CNC domains, with a negligible change in film color. Finally, PAA hydrogen bonds to the hydroxyl groups of CNCs, resulting in a bathochromic color shift along with interesting rheol. and liq.-state properties. This work demonstrates a deeper understanding of CNC-polymer interactions during coassembly and formation of iridescent chiral nematic films, allowing for greater control over optical properties of future CNC-based materials.
- 94Wang, Z.; Chu, J.; Shi, L.; Xing, T.; Gao, X.; Xu, Y. Chiral Pearlescent Cellulose Nanocrystals Films with Broad-Range Tunable Optical Properties for Anti-Counterfeiting Applications. Small 2024, 20, 2306810 DOI: 10.1002/smll.202306810Google ScholarThere is no corresponding record for this reference.
- 95He, J.; Bian, K.; Piao, G. Self-Assembly Properties of Carboxylated Tunicate Cellulose Nanocrystals Prepared by Ammonium Persulfate Oxidation and Subsequent Ultrasonication. Carbohydr. Polym. 2020, 249, 116835 DOI: 10.1016/j.carbpol.2020.116835Google Scholar95Self-assembly properties of carboxylated tunicate cellulose nanocrystals prepared by ammonium persulfate oxidation and subsequent ultrasonicationHe, Jintao; Bian, Kaiqiang; Piao, GuangzheCarbohydrate Polymers (2020), 249 (), 116835CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)Tunicate cellulose, extd. from the marine animal, has drawn increasing attention as the high crystallinity and aspect ratio. However, it is hard to prep. tunicate cellulose nanocrystals (tCNCs) with narrow size distribution in the traditional way, esp. for the carboxylated samples, which also affects their lyotropic liq. crystal behavior to a certain extent. Herein, carboxylated tCNCs with uniform nanoscale dimensions and high surface charges d. were prepd. through ammonium persulfate (APS) oxidn. and ultrasonic post-processing. Of particular interest, the formation of carboxylated tCNCs lyotropic chiral nematic liq. crystals was obsd. for the first time, which displayed obvious birefringence and fingerprint texture. Meanwhile, it was found that the crit. concn. of phase sepn. for tCNCs suspension was around 3.5 wt% from the phase diagram. This study provides an efficient way to fabricate carboxylated tCNCs, and the self-assembly properties may lead to great potential applications in constructing advanced functional materials.
- 96Raghuwanshi, V. S.; Browne, C.; Batchelor, W.; Garnier, G. Self-Assembly of Cellulose Nanocrystals of Different Lengths. J. Colloid Interface Sci. 2023, 630, 249– 259, DOI: 10.1016/j.jcis.2022.10.100Google Scholar96Self-assembly of cellulose nanocrystals of different lengthsRaghuwanshi, Vikram Singh; Browne, Christine; Batchelor, Warren; Garnier, GilJournal of Colloid and Interface Science (2023), 630 (Part_B), 249-259CODEN: JCISA5; ISSN:0021-9797. (Elsevier B.V.)The self-assembly (SA) of cellulose nanocrystals (CNC) in suspensions is important both from the fundamental and advanced technol. development perspective. CNC of different lengths self-assemble differently in suspensions by balancing attractive and repulsive interactions which depends strongly on morphol., surface chem. and concns. Two different com. CNC samples (CNC-M and CNC-C) of different lengths were dispersed in Milli-Q water at different concns. (0.5-10 wt%). CNC-M is provided as a gel at a solid concn. of 10.3 wt% which was dild. in Milli-Q water. CNC-C is sold as a powder which was dispersed in Milli-Q water with a mixer to achieve the desired concns. TEM was used to det. morphol. of CNC. Polarised optical microscopy is performed to get microscale visualisation of the chiral nematic self-assembly. High flux synchrotron SAXS is applied to evaluate and compare the nanoscale self-assembly mechanisms of CNC of different lengths. The SA of two different types of CNC rods of similar diam. but different lengths is investigated. SAXS anal. shows the short rods in suspension form an isotropic phase (randomly oriented) at lower concn. (0-4 wt%); as concn. is increased, the rods become systematically aligned in a nematic phase. The interrod distance d varies as c-0.33 at the lower concn., which changes to c-0.5 and even c-1 at the higher concns. In contrast, the long rods in suspension remain in the isotropic phase throughout the measured concn. range from 0.5 to 10 wt%. The interrod distance also follows the isotropic power law slope of c-0.33. Suspensions made of the short CNC rods show long range order and large interrod distance compared to those formed by the long rods. POM agrees with the SAXS results. A specific equil. between attractive and repulsive forces is required to maintain SA and ordering of the rods. DLVO calcns. reveal that the long rods maintain van der Waal attractive force dominating over the electrostatic repulsion, which hinders rods alignment in an ordered manner. However, for the short rods, the weaker attractive interactions are well compensated by the repulsive force which aligns rods in an ordered assembly. This fundamental understanding of the SA of rods in suspensions facilitates the engineering of novel CNC composites of unique optical properties which enables novel applications such as in sensors and bio-diagnostics.
- 97Zhao, G.; Zhang, S.; Zhai, S.; Pan, M. Fabrication and Characterization of Photonic Cellulose Nanocrystal Films with Structural Colors Covering Full Visible Light. J. Mater. Sci. 2020, 55, 8756– 8767, DOI: 10.1007/s10853-020-04616-4Google ScholarThere is no corresponding record for this reference.
- 98Wang, N.; Ding, E.; Cheng, R. Preparation and Liquid Crystalline Properties of Spherical Cellulose Nanocrystals. Langmuir 2008, 24, 5– 8, DOI: 10.1021/la702923wGoogle Scholar98Preparation and Liquid Crystalline Properties of Spherical Cellulose NanocrystalsWang, Neng; Ding, Enyong; Cheng, RongshiLangmuir (2008), 24 (1), 5-8CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)A novel kind of spherical cellulose nanocrystal (SCNC) suspension was prepd. by hydrolysis of microcryst. cellulose with a mixt. of sulfuric acid and hydrochloric acid under ultrasonic treatment. The mechanism of SCNC formation and the liq. cryst. properties of their suspensions were investigated. A suspension of spherical particles was usually inclined to form crystn. colloids rather than liq. crystals at high concn. However, a SCNC suspension with high polydispersity (49%) was obsd. to form the liq. cryst. phase, and the liq. cryst. textures changed with increasing concn. This observation offers an approach to the liq. crystal formation of highly polydisperse spherical nanoparticles.
- 99Verma, C.; Chhajed, M.; Gupta, P.; Roy, S.; Maji, P. K. Isolation of cellulose nanocrystals from different waste bio-mass collating their liquid crystal ordering with morphological exploration. Int. J. Biol. Macromol. 2021, 175, 242– 253, DOI: 10.1016/j.ijbiomac.2021.02.038Google Scholar99Isolation of cellulose nanocrystals from different waste bio-mass collating their liquid crystal ordering with morphological explorationVerma, Chhavi; Chhajed, Monika; Gupta, Pragya; Roy, Sunanda; Maji, Pradip K.International Journal of Biological Macromolecules (2021), 175 (), 242-253CODEN: IJBMDR; ISSN:0141-8130. (Elsevier B.V.)Cellulose nanocrystals (CNCs) have been recognized as one of the most promising nanofillers in modern science and technol. owing to their outstanding characteristics of renewability, biodegradability, excellent mech. strength, and liq. cryst. behavior. Interestingly, these properties are dependent on their genetic and also on the isolation process. Therefore, this research aimed to unveil how the biol. variations of cellulose can influence on the phys. properties of the extd. CNCs. A std. optimized extn. process was adopted to isolate the CNCs from different sources. Extd. CNCs were compared through characterization tools, including Fourier transformation IR spectroscopy (FTIR), X-ray Diffraction (XRD), thermogravimetry anal. (TGA), dynamic light scattering (DLS), field emission SEM (FE-SEM), at. force microscopy (AFM), and polarized optical microscopy (POM). Different self-assembly patterns were obsd. for different CNCs, owing to their biol. variations. The resultant nanocrystals displayed variable morphologies such as spherical, rod, and needle shape. The hydrodynamic diam., crystallinity index, decompn. temp., liq. crystallinity, and storage modulus were varied. Nanocrystals isolated from non-wood feedstock have shown a higher d.p. of 108.2 and a high crystllinity Index (C.I.) of 55.1%. The rod-like morphol. with the liq. cryst. pattern was obtained at 3 wt% concn. for SCNC.
- 100Abitbol, T.; Kam, D.; Levi-Kalisman, Y.; Gray, D. G.; Shoseyov, O. Surface Charge Influence on the Phase Separation and Viscosity of Cellulose Nanocrystals. Langmuir 2018, 34, 3925– 3933, DOI: 10.1021/acs.langmuir.7b04127Google Scholar100Surface Charge Influence on the Phase Separation and Viscosity of Cellulose NanocrystalsAbitbol, Tiffany; Kam, Doron; Levi-Kalisman, Yael; Gray, Derek G.; Shoseyov, OdedLangmuir (2018), 34 (13), 3925-3933CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)A series of four cellulose nanocrystal (CNC) suspensions were prepd. from bleached softwood kraft pulp using different conditions of sulfuric acid hydrolysis. The CNCs were identical in size (95 nm in length × 5 nm in width) but had different surface charges corresponding to the harshness of the hydrolysis conditions. Consequently, it was possible to isolate the effects of surface charge on the self-assembly and viscosity of the CNC suspensions across surface charges ranging from 0.27%S to 0.89%S. The four suspensions (never-dried, free of added electrolyte) all underwent liq. cryst. phase sepn., but the concn. onset for the emergence of the chiral nematic phase shifted to higher values with increasing surface charge. Similarly, suspension viscosity was also influenced by surface charge, with suspensions of lower surface charge CNCs more viscous and tending to gel at lower concns. The properties of the suspensions were interpreted in terms of the increase in effective diam. of the nanocrystals due to the surface electrostatic repulsion of the neg. sulfate half-esters, as modified by the screening effects of the H+ counterions in the suspensions. The results suggest that there is a threshold surface charge d. (∼0.3%S) above which effective vol. considerations are dominant across the concn. range relevant to liq. cryst. phase formation. Above this threshold value, phase sepn. occurs at the same effective vol. fraction of CNCs (∼10 vol. %), with a corresponding increase in crit. concn. due to the decrease in effective diam. that occurs with increasing surface charge. Below or near this threshold value, the formation of end-to-end aggregates may favor gelation and interfere with ordered phase formation.
- 101Salajkova, M.; Berglund, L. A.; Zhou, Q. Hydrophobic Cellulose Nanocrystals Modified with Quaternary Ammonium Salts. J. Mater. Chem. 2012, 22, 19798– 19805, DOI: 10.1039/c2jm34355jGoogle Scholar101Hydrophobic cellulose nanocrystals modified with quaternary ammonium saltsSalajkova, Michaela; Berglund, Lars A.; Zhou, QiJournal of Materials Chemistry (2012), 22 (37), 19798-19805CODEN: JMACEP; ISSN:0959-9428. (Royal Society of Chemistry)An environmentally friendly procedure in aq. soln. for the surface modification of cellulose nanocrystals (CNCs) using quaternary ammonium salts via adsorption was developed as inspired by organomodified layered silicates. CNCs with a high carboxylate content of 1.5 mmol g-1 were prepd. by a new route, direct hydrochloric acid hydrolysis of 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-oxidized nanofibrillated cellulose from a softwood pulp, and characterized by at. force microscopy (AFM) and X-ray diffraction (XRD). Four quaternary ammonium cation surfactants bearing long alkyl, Ph, glycidyl, and diallyl groups were successfully used to modify CNCs carrying carboxylic acid groups as characterized by Fourier transform IR spectroscopy (FTIR). The modified CNCs can be redispersed and individualized in an org. solvent such as toluene as obsd. by scanning transmission electron microscopy (STEM). One may envision removing excess surfactant to obtain CNC with a monolayer of surfactant. The toluene suspension of the modified CNCs showed strong birefringence under crossed polars but no further chiral-nematic ordering was obsd. The model surface prepd. by the CNCs modified with quaternary ammonium salts bearing C18 alkyl chains showed a significant increase in water contact angle (71°) compared to that of unmodified CNCs (12°). This new series of modified CNCs can be dried from solvent and have the potential to form well-dispersed nanocomposites with non-polar polymers.
- 102Araki, J.; Wada, M.; Kuga, S. Steric Stabilization of a Cellulose Microcrystal Suspension by Poly(ethylene glycol) Grafting. Langmuir 2001, 17, 21– 27, DOI: 10.1021/la001070mGoogle Scholar102Steric Stabilization of a Cellulose Microcrystal Suspension by Poly(ethylene glycol) GraftingAraki, Jun; Wada, Masahisa; Kuga, ShigenoriLangmuir (2001), 17 (1), 21-27CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)A sterically stabilized aq. suspension of rodlike cellulose microcrystals was prepd. by the combination of acid hydrolysis of native cellulose, oxidative carboxylation of microcrystals, and grafting of poly(ethylene glycol) having a terminal amino group on one end (PEG-NH2, MW = 1000) using water-sol. carbodiimide. Chem. binding of PEG to the microcrystals was confirmed by wt. increase, diminishment of carboxyl groups, thermogravimetry, and IR spectroscopy, resulting in consumption of 20-30% of the initially introduced carboxyl groups. The amt. of bound PEG was 0.2-0.3 g/g of cellulose. The PEG-grafted cellulose microcrystals showed drastically enhanced dispersion stability, i.e., resistance to addn. of 2 M sodium chloride, and ability to redisperse into either water or chloroform from the freeze-dried state. The concd. aq. suspension of PEG-grafted microcrystals formed a chiral nematic mesophase through a phase sepn. similar to that of the ungrafted sample, but with a reduced spacing of the fingerprint pattern.
- 103He, J.; Liu, S.; Li, L.; Piao, G. Lyotropic Liquid Crystal Behavior of Carboxylated Cellulose Nanocrystals. Carbohydr. Polym. 2017, 164, 364– 369, DOI: 10.1016/j.carbpol.2017.01.080Google ScholarThere is no corresponding record for this reference.
- 104Fan, W.; Li, J.; Wei, L.; Xu, Y. Carboxylated Cellulose Nanocrystal Films with Tunable Chiroptical Properties. Carbohydr. Polym. 2022, 289, 119442 DOI: 10.1016/j.carbpol.2022.119442Google Scholar104Carboxylated cellulose nanocrystal films with tunable chiroptical propertiesFan, Wei; Li, Jiaqi; Wei, Lihong; Xu, YanCarbohydrate Polymers (2022), 289 (), 119442CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)Carboxylated cellulose nanocrystals prepd. by TEMPO-mediated oxidn. exhibit a distinct ability to form nematic order, however, their ability to form chiral nematic films remains relatively unexplored. In this study, bleached cotton pulp hydrolyzed with hydrochloric acid and oxidized by TEMPO-mediated oxidn. produce carboxylated cellulose nanocrystals with different aspect ratios 33.1, 32.8, 30.9, 29.0 and 28.9, and surface charge densities 0.16, 0.56, 1.00, 1.25, and 1.42 e.nm2. By tuning the aspect ratio and surface charge d., the optimal carboxylated cellulose nanocrystals producing left-handed chiral nematic films by evapn.-induced self-assembly are obtained. The left-handed chiral nematic films enable selective reflection of left-handed circularly polarized light with the peak wavelength tunable from the visible to the near-IR regime by modifying the characteristics of nanorods and suspensions. Such carboxylated cellulose nanocrystal films transform spontaneous luminescence to right-handed circularly polarized luminescence with the peak luminescence dissymmetry factor of -0.51.
- 105Lin, C.; Wang, P.; Liu, Y.; Lv, Y.; Ye, X.; Liu, M.; Zhu, J. Y. Chiral Self-Assembly Behavior of Carboxylated Cellulose Nanocrystals Isolated by Recyclable Oxalic Acid from Degreasing Cotton. ACS Sustainable Chem. Eng. 2023, 11, 8035– 8043, DOI: 10.1021/acssuschemeng.3c00118Google ScholarThere is no corresponding record for this reference.
- 106Risteen, B.; Delepierre, G.; Srinivasarao, M.; Weder, C.; Russo, P.; Reichmanis, E.; Zoppe, J. Thermally Switchable Liquid Crystals Based on Cellulose Nanocrystals with Patchy Polymer Grafts. Small 2018, 14, 1802060 DOI: 10.1002/smll.201802060Google ScholarThere is no corresponding record for this reference.
- 107Xu, Q.; Yi, J.; Zhang, X.; Zhang, H. A Novel Amphotropic Polymer Based on Cellulose Nanocrystals Grafted with Azo Polymers. Eur. Polym. J. 2008, 44, 2830– 2837, DOI: 10.1016/j.eurpolymj.2008.06.010Google Scholar107A novel amphotropic polymer based on cellulose nanocrystals grafted with azo polymersXu, Qunxing; Yi, Jie; Zhang, Xuefei; Zhang, HailiangEuropean Polymer Journal (2008), 44 (9), 2830-2837CODEN: EUPJAG; ISSN:0014-3057. (Elsevier Ltd.)A novel amphotropic polymer which could exhibit liq.-cryst. behavior both in the solvent and in the heating process was synthesized through azo polymers grafting from cellulose nanocrystals (CNCs). The CNCs, prepd. by acid hydrolysis of filter paper, were characterized by At. Force Microscopy (AFM). Poly{6-[4-(4-methoxyphenylazo)phenoxy] hexyl methacrylate} (PMMAZO), which was a liq.-cryst. polymers (LCP), was successfully to graft from CNC via Atom transfer radical polymn. (ATRP). The structure and thermal properties of the PMMAZO-grafted CNC were investigated using FT-IR and thermogravimetric analyses (TGA). Its phase structures and transitions were studied by DSC and polarized optical microscopy (POM). The exptl. results showed that the PMMAZO-grafted CNC exhibited both types of liq. crystal formation, thermotropic and lyotropic.
- 108Yi, J.; Xu, Q.; Zhang, X.; Zhang, H. Chiral-Nematic Self-Ordering of Rodlike Cellulose Nanocrystals Grafted with Poly(styrene) in Both Thermotropic and Lyotropic States. Polymer 2008, 49, 4406– 4412, DOI: 10.1016/j.polymer.2008.08.008Google Scholar108Chiral-nematic self-ordering of rodlike cellulose nanocrystals grafted with poly(styrene) in both thermotropic and lyotropic statesYi, Jie; Xu, Qunxing; Zhang, Xuefei; Zhang, HailiangPolymer (2008), 49 (20), 4406-4412CODEN: POLMAG; ISSN:0032-3861. (Elsevier Ltd.)Graft copolymers of rodlike cellulose nanocrystals (CNC) with poly(styrene) (PSt) were synthesized through atom transfer radical polymn. (ATRP). The hydroxyl groups on CNC were esterified with 2-bromoisobutyrylbromide to yield 2-bromoisobutyryloxy groups, which were used to initiate the polymn. of poly(styrene). The graft copolymers were characterized by thermogravimetric anal. (TGA), fourier transform IR spectroscopy (FT-IR) and gel permeation chromatog. (GPC). The size of the original CNC is 10-40 nm in width and 100-400 nm in length, which was characterized by at. force microscopy (AFM). The thermal and liq. cryst. properties of the graft copolymers were investigated by differential scanning calorimeter (DSC) and polarizing optical microscope (POM). The graft copolymers exhibit fingerprint texture in both thermotropic and lyotropic states. In thermotropic state, the PSt-grafted CNC orient spontaneously in isotropic melt (PSt side chains acting as a solvent). The thermotropic liq. crystal phase behavior is similar to the lyotropic phase behavior.
- 109Delepierre, G.; Traeger, H.; Adamcik, J.; Cranston, E. D.; Weder, C.; Zoppe, J. O. Liquid Crystalline Properties of Symmetric and Asymmetric End-Grafted Cellulose Nanocrystals. Biomacromolecules 2021, 22, 3552– 3564, DOI: 10.1021/acs.biomac.1c00644Google Scholar109Liquid Crystalline Properties of Symmetric and Asymmetric End-Grafted Cellulose NanocrystalsDelepierre, Gwendoline; Traeger, Hanna; Adamcik, Jozef; Cranston, Emily D.; Weder, Christoph; Zoppe, Justin O.Biomacromolecules (2021), 22 (8), 3552-3564CODEN: BOMAF6; ISSN:1525-7797. (American Chemical Society)The hydrophilic polymer poly[2-(2-(2-methoxy ethoxy)ethoxy)ethylacrylate] (POEG3A) was grafted onto the reducing end-groups (REGs) of cellulose nanocrystal (CNC) allomorphs, and their liq. cryst. properties were investigated. The REGs on CNCs extd. from cellulose I (CNC-I) are exclusively located at one end of the crystallite, whereas CNCs extd. from cellulose II (CNC-II) feature REGs at both ends of the crystallite, so that grafting from the REGs affords asym. and sym. decorated CNCs, resp. To confirm the REG modification, several complementary anal. techniques were applied. The grafting of POEG3A onto the CNC REGs was evidenced by Fourier transform IR spectroscopy, at. force microscopy, and the coil-globule conformational transition of this polymer above 60°C, i.e., its lower crit. soln. temp. Furthermore, we investigated the self-assembly of end-tethered CNC-hybrids into chiral nematic liq. cryst. phases. Above a crit. concn., both end-grafted CNC allomorphs form chiral nematic tactoids. The introduction of POEG3A to CNC-I does not disturb the surface of the CNCs along the rods, allowing the modified CNCs to approach each other and form helicoidal textures. End-grafted CNC-II formed chiral nematic tactoids with a pitch observable by polarized optical microscopy. This is likely due to their increase in hydrodynamic radius or the introduced steric stabilization of the end-grafted polymer.
- 110Qin, J.; Wang, Z.; Hu, J.; Yuan, Y.; Liu, P.; Cheng, L.; Kong, Z.; Liu, K.; Yan, S.; Zhang, J. Distinct Liquid Crystal Self-Assembly Behavior of Cellulose Nanocrystals Functionalized with Ionic Liquids. Colloids Surf., A 2022, 632, 127790 DOI: 10.1016/j.colsurfa.2021.127790Google Scholar110Distinct liquid crystal self-assembly behavior of cellulose nanocrystals functionalized with ionic liquidsQin, Jinli; Wang, Zhaolu; Hu, Jie; Yuan, Yuan; Liu, Ping; Cheng, Li; Kong, Zhengqing; Liu, Ke; Yan, Shouke; Zhang, JianmingColloids and Surfaces, A: Physicochemical and Engineering Aspects (2022), 632 (), 127790CODEN: CPEAEH; ISSN:0927-7757. (Elsevier B.V.)Rod-like cellulose nanocrystals (CNCs) show the intriguing liq. crystal self-assembly ability. The understanding of the self-assembly behavior of CNCs is of fundamental importance for constructing cellulose-based functional materials. The presented work explores how the liq. crystal self-assembly behavior of CNCs is affected by the grafted ionic liqs. (IL) [VBIm][BF4]. The results demonstrate that the IL modified CNC (CNC-IL) with pos. charged form chiral nematic structure in suspensions, which was normally obsd. in neg. charged ones. Significantly, such liq.-cryst. organization can be obtained under much lower concn. (as low as 1.0 wt%) than that of the non-functionalized CNCs prepd. from paper pulp (∼ 3.0 wt%). Moreover, for CNC-IL concns. varying from 1.0 to 4.0 wt%, the tactoids (showing obvious fingerprint texture) coexist with the disordered CNC phase, rather than sepg. into two phases. Unlike original CNCs, the pitch of chiral nematic tactoids increases with increasing concn. of CNC-IL. Our study suggests that the distinct liq. crystal self-assembly behavior of CNC-IL is related to the restricted mobility of CNCs rods due to the increase in CNCs particle size and the high viscosity of CNC-IL suspension as the result of IL surface modification. The study of the liq. crystal assembly behavior of IL modified CNCs provides some new insight to understand the intriguing chiral nematic self-assembly of CNCs and for construction of CNC-IL reinforced nanocomposites.
- 111Momeni, A.; Walters, C. M.; Xu, Y.-T.; Hamad, W. Y.; MacLachlan, M. J. Concentric Chiral Nematic Polymeric Fibers from Cellulose Nanocrystals. Nanoscale Adv. 2021, 3, 5111– 5121, DOI: 10.1039/D1NA00425EGoogle Scholar111Concentric chiral nematic polymeric fibers from cellulose nanocrystalsMomeni, Arash; Walters, Christopher M.; Xu, Yi-Tao; Hamad, Wadood Y.; MacLachlan, Mark J.Nanoscale Advances (2021), 3 (17), 5111-5121CODEN: NAADAI; ISSN:2516-0230. (Royal Society of Chemistry)Hierarchical biol. materials, such as osteons and plant cell walls, are complex structures that are difficult to mimic. Here, we combine liq. crystal systems and polymn. techniques within confined systems to develop complex structures. A single-domain concentric chiral nematic polymeric fiber was obtained by confining cellulose nanocrystals (CNCs) and hydroxyethyl acrylate inside a capillary tube followed by UV-initiated polymn. The concentric chiral nematic structure continues uniformly throughout the length of the fiber. The pitch of the chiral nematic structure could be controlled by changing the CNC concn. We tracked the formation of the concentric structure over time and under different conditions with variation of the tube orientation, CNC concn., CNC type, and capillary tube size. We show that the inner radius of the capillary tube is important and a single-domain structure was only obtained inside small-diam. tubes. At low CNC concn., the concentric chiral nematic structure did not completely cover the cross-section of the fiber. The highly ordered structure was studied using imaging techniques and X-ray diffraction, and the mech. properties and structure of the chiral nematic fiber were compared to a pseudo-nematic fiber. CNC polymeric fibers could become a platform for many applications from photonics to complex hierarchical materials.
- 112Lagerwall, J. P. F.; Schütz, C.; Salajkova, M.; Noh, J.; Hyun Park, J.; Scalia, G.; Bergström, L. Cellulose Nanocrystal-Based Materials: From Liquid Crystal Self-Assembly and Glass Formation to Multifunctional Thin Films. NPG Asia Mater. 2014, 6, e80 DOI: 10.1038/am.2013.69Google Scholar112Cellulose nanocrystal-based materials: from liquid crystal self-assembly and glass formation to multifunctional thin filmsLagerwall, Jan P. F.; Schutz, Christina; Salajkova, Michaela; Noh, Jung Hyun; Park, Ji Hyun; Scalia, Giusy; Bergstrom, LennartNPG Asia Materials (2014), 6 (1), e80CODEN: NAMPCE; ISSN:1884-4057. (Nature Publishing Group)A review. Cellulose nanocrystals (CNCs), produced by the acid hydrolysis of wood, cotton or other cellulose-rich sources, constitute a renewable nanosized raw material with a broad range of envisaged uses: for example, in composites, cosmetics and medical devices. The intriguing ability of CNCs to self-organize into a chiral nematic (cholesteric) liq. crystal phase with a helical arrangement has attracted significant interest, resulting in much research effort, as this arrangement gives dried CNC films a photonic band gap. The films thus acquire attractive optical properties, creating possibilities for use in applications such as security papers and mirrorless lasing. In this crit. review, we discuss the sensitive balance between glass formation and liq. crystal self-assembly that governs the formation of the desired helical structure. We show that several as yet unclarified observations-some constituting severe obstacles for applications of CNCs-may result from competition between the two phenomena. Moreover, by comparison with the corresponding self-assembly processes of other rod-like nanoparticles, for example, carbon nanotubes and fd virus particles, we outline how further liq. crystal ordering phenomena may be expected from CNCs if the suspension parameters can be better controlled. Alternative interpretations of some unexpected phenomena are provided, and topics for future research are identified, as are new potential application strategies.
- 113Klockars, K. W.; Tardy, B. L.; Borghei, M.; Tripathi, A.; Greca, L. G.; Rojas, O. J. Effect of Anisotropy of Cellulose Nanocrystal Suspensions on Stratification, Domain Structure Formation, and Structural Colors. Biomacromolecules 2018, 19, 2931– 2943, DOI: 10.1021/acs.biomac.8b00497Google Scholar113Effect of Anisotropy of Cellulose Nanocrystal Suspensions on Stratification, Domain Structure Formation, and Structural ColorsKlockars, Konrad W.; Tardy, Blaise L.; Borghei, Maryam; Tripathi, Anurodh; Greca, Luiz G.; Rojas, Orlando J.Biomacromolecules (2018), 19 (7), 2931-2943CODEN: BOMAF6; ISSN:1525-7797. (American Chemical Society)Outstanding optical and mech. properties can be obtained from hierarchical assemblies of nanoparticles. Herein, the formation of helically ordered, chiral nematic films obtained from aq. suspensions of cellulose nanocrystals (CNCs) were studied as a function of the initial suspension state. Specifically, nanoparticle organization and the structural colors displayed by the resultant dry films were investigated as a function of the anisotropic vol. fraction (AVF), which depended on the initial CNC concn. and equilibration time. The development of structural color and the extent of macroscopic stratification were studied by optical and SEM as well as UV-vis spectroscopy. Overall, suspensions above the crit. threshold required for formation of liq. crystals resulted in CNC films assembled with longer ranged order, more homogeneous pitches along the cross sections, and narrower specific absorption bands. This effect was more pronounced for the suspensions that were closer to equil. prior to drying. Thus, we show that high AVF and more extensive phase sepn. in CNC suspensions resulted in large, long-range ordered chiral nematic domains in dried films. Addnl., the av. CNC aspect ratio and size distribution in the two sepd. phases were measured and correlated to the formation of structured domains in the dried assemblies.
- 114Bukharina, D.; Kim, M.; Han, M. J.; Tsukruk, V. V. Cellulose Nanocrystals’ Assembly under Ionic Strength Variation: From High Orientation Ordering to a Random Orientation. Langmuir 2022, 38, 6363– 6375, DOI: 10.1021/acs.langmuir.2c00293Google Scholar114Cellulose Nanocrystals' Assembly under Ionic Strength Variation: From High Orientation Ordering to a Random OrientationBukharina, Daria; Kim, Minkyu; Han, Moon Jong; Tsukruk, Vladimir V.Langmuir (2022), 38 (20), 6363-6375CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)We discuss the effect of the ionic strength and effective charge d. on the final structural organization of cellulose nanocrystals (CNCs) after drying suspensions with different ionic strengths in terms of quant. characteristics of the orientation order, rarely considered to date. We obsd. that increasing the ionic strength in the initial suspension results in continuous shrinking of the helical pitch length that shifts the photonic band gap to a far UV region from the visible range (from 400 to 250 nm) because of the increase in the helical twisting power from 4 to 6μm-1 and doubling of the twisting angle between neighboring monolayers from 5.5 to 9°. As our estn. of the Coulombic interactions demonstrates, the redn. of the Debye charge screening length below a crit. value of 3 nm results in the loss of the long-range helicoidal order and the transition to a disordered morphol. with random packing of nanocrystals. Subsequently, very high orientation ordering with the 2D orientation factor, S, within the range 0.8-0.9, close to the theor. limit of 1, gradually decreased to a very low value of S = 0.1-0.2, a characteristic of random organization at high ionic strength. We suggest that the loss of the chiral ordering is a result of the redn. of repulsive forces, promoting direct phys. contact with the reduced contact area during Brownian motion, combined with increased repulsive Coulombic interactions of nanocrystals at nonparallel local packing. Notably, electrolyte addn. enhances chiral interactions to the point where the helical twisting power is too large and the resulting nanocrystal bundles can no longer compactly pack without creating unfavorably large free vol. We propose that the Debye charge screening length in suspensions can be used as a universal parameter for CNCs under different conditions and can be used to assess expected ordering characteristics in the solid films.
- 115Lin, M.; Singh Raghuwanshi, V.; Browne, C.; Simon, G. P.; Garnier, G. Modulating the Chiral Nanoarchitecture of Cellulose Nanocrystals Through Interaction with Salts and Polymer. J. Colloid Interface Sci. 2022, 613, 207– 217, DOI: 10.1016/j.jcis.2021.12.182Google Scholar115Modulating the chiral nanoarchitecture of cellulose nanocrystals through interaction with salts and polymerLin, Maoqi; Singh Raghuwanshi, Vikram; Browne, Christine; Simon, George P.; Garnier, GilJournal of Colloid and Interface Science (2022), 613 (), 207-217CODEN: JCISA5; ISSN:0021-9797. (Elsevier B.V.)The conditions to allow self-assembly of cellulose nanocrystal (CNC) suspensions into chiral nematic structures are based on aspect ratio, surface charge d. and a balance between repulsive and attractive forces between CNC particles. Three types of systems were characterized in suspensions and subsequently in their solid dried films: 1. neat water dialyzed CNC, 2. CNC combined with polyethylene glycol(PEG) (CNC/PEG), and 3. CNC with added salt (CNC/Salt). All suspensions were characterized by polarized optical microscope (POM) and small angle X-ray scattering (SAXS), while the resultant dried films were analyzed by reflectance spectrometer, scanning electron microscope (SEM) and SAXS. The presence of chiral nematic (CN*) structures was not obsd. in dialyzed aq. suspensions of CNC during water evapn. By introducing salts or a non-adsorbing polymer, chirality was apparent in both suspensions and films. The interaxial angle between CNC rods increased when the suspensions of CNC/PEG and CNC/salt were dried to solid films. The angle was found to be dependent on both species of ions and ionic strength, while the inter-particle distance was only related to the salt concn., as explained in terms of interaction energies. The CNC suspensions/film chirality can be modulated by controlling the colloidal forces.
- 116Cao, T.; Elimelech, M. Colloidal Stability of Cellulose Nanocrystals in Aqueous Solutions Containing Monovalent, Divalent, and Trivalent Inorganic Salts. J. Colloid Interface Sci. 2021, 584, 456– 463, DOI: 10.1016/j.jcis.2020.09.117Google Scholar116Colloidal stability of cellulose nanocrystals in aqueous solutions containing monovalent, divalent, and trivalent inorganic saltsCao, Tianchi; Elimelech, MenachemJournal of Colloid and Interface Science (2021), 584 (), 456-463CODEN: JCISA5; ISSN:0021-9797. (Elsevier B.V.)Aggregation kinetics and surface charging properties of rod-like sulfated cellulose nanocrystals (CNCs) have been investigated in aq. suspensions contg. monovalent, divalent, or trivalent inorg. salts. Electrophoresis and time-resolved dynamic light scattering (DLS) were used to characterize the surface charge and colloidal stability of the CNCs, resp. The surface charge and aggregation kinetics of the sulfated CNCs were found to be independent of soln. pH (pH range 2-10). For the monovalent salts (CsCl, KCl, NaCl, and LiCl), the crit. coagulation concn. (CCC) followed the order of Cs+ < K+ < Na+ < Li+, which follows the direct Hofmeister series, indicating specific interaction of the cations with the CNCs surface. The exptl. aggregation kinetics of CNCs were in very good agreement with predictions based on the classic Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. A Hamaker const. of 3.6 x 10-20 J for the CNCs in aq. medium was derived, for the first time, from the colloidal stability curves with monovalent salts. This value is consistent with a previous value detd. by direct force measurements for cellulose surfaces in aq. solns. For the divalent salts (MgCl2, CaCl2, and BaCl2), the CCC values followed the order Mg2+ > Ca2+ > Ba2+, which is in the reverse order of the counterion ionic size. For the trivalent salts (LaCl3, AlCl3, and FeCl3), the CNCs suspension was destabilized much more effectively. The obsd. complex stability curves with AlCl3 and FeCl3 are attributed to charge neutralization and charge reversal imparted by the adsorption of aluminum and ferric hydrolysis species on the CNC surface. The significant charge reversal induced by the ferric hydrolysis species led to the restabilization of suspensions. Our results on the colloidal stability of CNCs are of central importance to the nanotechnol. and materials science communities working on various applications of CNCs.
- 117Chu, G.; Vasilyev, G.; Qu, D.; Deng, S.; Bai, L.; Rojas, O. J.; Zussman, E. Structural Arrest and Phase Transition in Glassy Nanocellulose Colloids. Langmuir 2020, 36, 979– 985, DOI: 10.1021/acs.langmuir.9b03570Google Scholar117Structural Arrest and Phase Transition in Glassy Nanocellulose ColloidsChu, Guang; Vasilyev, Gleb; Qu, Dan; Deng, Shengwei; Bai, Long; Rojas, Orlando J.; Zussman, EyalLangmuir (2020), 36 (4), 979-985CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)From drying blood to oil paint, the developing of a glassy phase from colloids is obsd. on a daily basis. Colloidal glass is solid soft matter that consists of two intertwined phases: a random packed particle network and a fluid solvent. By dispersing charged rod-like cellulose nanoparticles into a water-ethylene glycol cosolvent, here we demonstrate a new kind of colloidal glass with a high liq. cryst. order, namely, two general superstructures with nematic and cholesteric packing states are preserved and jammed inside the glass matrix. During the glass formation process, structural arrest and phase transition occur simultaneously at high particle concns., yielding solid-like behavior as well as a frozen liq. crystal texture that is because of caging of the charged colloids through neighboring long-ranged repulsive interactions.
- 118Bruel, C.; Davies, T. S.; Carreau, P. J.; Tavares, J. R.; Heuzey, M.-C. Self-Assembly Behaviors of Colloidal Cellulose Nanocrystals: A Tale of Stabilization Mechanisms. J. Colloid Interface Sci. 2020, 574, 399– 409, DOI: 10.1016/j.jcis.2020.04.049Google Scholar118Self-assembly behaviors of colloidal cellulose nanocrystals: A tale of stabilization mechanismsBruel, Charles; Davies, Tom S.; Carreau, Pierre J.; Tavares, Jason R.; Heuzey, Marie-ClaudeJournal of Colloid and Interface Science (2020), 574 (), 399-409CODEN: JCISA5; ISSN:0021-9797. (Elsevier B.V.)In solvent casting, colloidal nanocrystal self-assembly patterns are controlled by a mix of cohesive and repulsive interactions that promote destabilization-induced self-assembly (DISA) or evapn.-induced self-assembly (EISA). Tuning the strength and nature of the stabilization mechanisms may allow repulsive interactions to govern self-assembly during the casting of colloidal cellulose nanocrystal (CNC) suspensions. We propose a tool to classify the level of electrostatic and solvation-induced stabilizations based on two solvent parameters only: dielec. const., ε, and chem. affinity for CNCs, in terms of Hansen Soly. Parameters, Ra. These criteria are applied to study CNC self-assembly in solvent casting expts. in various media and binary mixts. In solvent casting of suspensions stabilized through a combination of electrostatic and solvation effects, the primarily governing mechanism is EISA, which leads to the formation of chiral nematic domains and optically active thin films. In electrostatically-stabilized suspensions, EISA and DISA are in competition and casting may yield anything from a continuous film to a powder. In other suspensions, DISA prevails and evapn. yields a powder of CNC agglomerates. By classifying media according to their stabilization mechanisms, this work establishes that the behavior of CNC suspensions in solvent casting may be predicted from solvent parameters only.
- 119Attia, D.; Cohen, N.; Ochbaum, G.; Levi-Kalisman, Y.; Bitton, R.; Yerushalmi-Rozen, R. Nano-to-Meso Structure of Cellulose Nanocrystal Phases in Ethylene-Glycol-Water Mixtures. Soft Matter 2020, 16, 8444– 8452, DOI: 10.1039/D0SM01025AGoogle ScholarThere is no corresponding record for this reference.
- 120Bruckner, J. R.; Kuhnhold, A.; Honorato-Rios, C.; Schilling, T.; Lagerwall, J. P. F. Enhancing Self-Assembly in Cellulose Nanocrystal Suspensions Using High-Permittivity Solvents. Langmuir 2016, 32, 9854– 9862, DOI: 10.1021/acs.langmuir.6b02647Google Scholar120Enhancing Self-Assembly in Cellulose Nanocrystal Suspensions Using High-Permittivity SolventsBruckner, Johanna R.; Kuhnhold, Anja; Honorato-Rios, Camila; Schilling, Tanja; Lagerwall, Jan P. F.Langmuir (2016), 32 (38), 9854-9862CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)Protic solvents with a high dielec. permittivity εr significantly speed up self-assembly (from days to hours) at high cellulose nanocrystals (CNCs) mass fraction and reduce the concn. dependence of the helix period (variation reducing from more than 30 μm to less than 1 μm). Computer simulations indicate that the degree of order at const. CNC content increases with increasing εr, leading to a shorter pitch and a reduced threshold for liq. crystallinity. In low-εr solvents, the onset of long-range orientational order is coupled to kinetic arrest, preventing the formation of a helical superstructure.
- 121Elazzouzi-Hafraoui, S.; Putaux, J.-L.; Heux, L. Self-Assembling and Chiral Nematic Properties of Organophilic Cellulose Nanocrystals. J. Phys. Chem. B 2009, 113, 11069– 11075, DOI: 10.1021/jp900122tGoogle Scholar121Self-assembling and Chiral Nematic Properties of Organophilic Cellulose NanocrystalsElazzouzi-Hafraoui, Samira; Putaux, Jean-Luc; Heux, LaurentJournal of Physical Chemistry B (2009), 113 (32), 11069-11075CODEN: JPCBFK; ISSN:1520-6106. (American Chemical Society)Cotton cellulose nanocrystals with different aspect ratios were dispersed in cyclohexane as a model apolar solvent, using surfactants. Above a crit. concn., which was higher than that in water, the suspensions spontaneously phase sepd. into a chiral nematic mesophase. According to Onsager's theory, the phase sepn. is controlled by the aspect ratio, while being influenced by the polydispersity. The sample with the highest aspect ratio did not show any phase sepn. but instead shows an anisotropic gel phase at high concn. Exptl. crit. concns. are much lower than the predicted ones, revealing an attractive interaction between the rods. Chiral nematic pitches ≥2 μm are much lower than those measured in water, due to stronger chiral interactions in the apolar medium.
- 122Saraiva, D. V.; Remiëns, S. N.; Jull, E. I. L.; Vermaire, I. R.; Tran, L. Flexible, Photonic Films of Surfactant-Functionalized Cellulose Nanocrystals for Pressure and Humidity Sensing. Small Struct. 2024, 5, 2400104 DOI: 10.1002/sstr.202400104Google ScholarThere is no corresponding record for this reference.
- 123Frka-Petesic, B.; Radavidson, H.; Jean, B.; Heux, L. Dynamically Controlled Iridescence of Cholesteric Cellulose Nanocrystal Suspensions Using Electric Fields. Adv. Mater. 2017, 29, 1606208 DOI: 10.1002/adma.201606208Google ScholarThere is no corresponding record for this reference.
- 124D’Acierno, F.; Ohashi, R.; Hamad, W. Y.; Michal, C. A.; MacLachlan, M. J. Thermal Annealing of Iridescent Cellulose Nanocrystal Films. Carbohydr. Polym. 2021, 272, 118468 DOI: 10.1016/j.carbpol.2021.118468Google Scholar124Thermal annealing of iridescent cellulose nanocrystal filmsD'Acierno, Francesco; Ohashi, Ryutaro; Hamad, Wadood Y.; Michal, Carl A.; MacLachlan, Mark J.Carbohydrate Polymers (2021), 272 (), 118468CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)The properties of chiral nematic and iridescent cellulose nanocrystal films with different monovalent cations (CNC-X) obtained through evapn.-induced self-assembly (EISA) can be modified by a variety of external stimuli. Here, we study the transformations of their optical and structural properties when the films are thermally annealed at 200°C and 240°C for up to 2 days. The chiral nematic structure of the most thermally stable films is not destroyed even after extensive heating due to the thermochem. stability of the cellulose backbone and the presence of surface alkali counterions, which suppress catalysis of early stage degrdn. Despite the resilience of the cholesteric structure and the overall integrity of heated CNC-X films, thermal annealing is often accompanied by redn. of iridescence, birefringence, and transparency, as well as formation of degrdn. products. The versatility, sustainability, and stability of CNC-X films highlight their potential as temp. indicators and photonic devices.
- 125Chen, H.; Zhang, X.; Zhou, T.; Hou, A.; Liang, J.; Ma, T.; Xie, K.; Gao, A. A Tunable Hydrophilic-Hydrophobic, Stimulus Responsive, and Robust Iridescent Structural Color Bionic Film with Chiral Photonic Crystal Nanointerface. Small 2024, 2311283 DOI: 10.1002/smll.202311283Google ScholarThere is no corresponding record for this reference.
- 126Qin, J.; Li, N.; Jiang, M.; Zong, L.; Yang, H.; Yuan, Y.; Zhang, J. Ultrasonication Pretreatment Assisted Rapid Co-Assembly of Cellulose Nanocrystal and Metal Ion for Multifunctional Application. Carbohydr. Polym. 2022, 277, 118829 DOI: 10.1016/j.carbpol.2021.118829Google Scholar126Ultrasonication pretreatment assisted rapid co-assembly of cellulose nanocrystal and metal ion for multifunctional applicationQin, Jinli; Li, Na; Jiang, Min; Zong, Lu; Yang, Hongsheng; Yuan, Yuan; Zhang, JianmingCarbohydrate Polymers (2022), 277 (), 118829CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)Co-assembly of metal ion and cellulose nanocrystals (CNC) is a promising strategy to fabricate novel iridescent CNC materials with advanced applications. By combining ultrasonication pretreatment and vacuum-assisted self-assembly (VASA) technique, a facile and rapid strategy is proposed to prep. the Mn2+-doped carboxylated CNC (C-CNC) iridescent films with multifunctional application. The ultrasonication pretreatment temporarily disassembles the aggregates of C-CNC nanorods caused by the electrostatic interaction between neg. charged C-CNC and Mn2+. The subsequent VASA process accelerates the self-assembly of chiral liq. crystals prior to the re-agglomeration of C-CNC by the bridge effect of Mn2+. Furthermore, the as-prepd. Mn2+/CNC film exhibits a rapid and visible color change in ammonia atm. along with the formation of MnO2. The reversible change can be realized by the stimulation of reducing agent. The derived MnO2/C-CNC composite film displays efficient removal of methylene blue dye in aq. soln. by both of adsorption and degrdn. procedure.
- 127Vanderfleet, O. M.; Winitsky, J.; Bras, J.; Godoy-Vargas, J.; Lafitte, V.; Cranston, E. D. Hydrothermal Treatments of Aqueous Cellulose Nanocrystal Suspensions: Effects on Structure and Surface Charge Content. Cellulose 2021, 28, 10239– 10257, DOI: 10.1007/s10570-021-04187-wGoogle Scholar127Hydrothermal treatments of aqueous cellulose nanocrystal suspensions: effects on structure and surface charge contentVanderfleet, Oriana M.; Winitsky, Jaclyn; Bras, Julien; Godoy-Vargas, Jazmin; Lafitte, Valerie; Cranston, Emily D.Cellulose (Dordrecht, Netherlands) (2021), 28 (16), 10239-10257CODEN: CELLE8; ISSN:0969-0239. (Springer)Cellulose nanocrystals (CNCs) are ideal rheol. modifiers for aq. oil and gas extn. fluids. CNCs are typically produced with sulfuric acid and their aq. suspensions have uniform and predictable properties under ambient conditions; however, drastic changes occur at elevated temps. Herein, the effects of high temp. treatments (ranging from 80 to 180°C for 1 h to 7 days) on the properties (including uniformity, colloidal stability, and color) of sulfated, phosphated, and carboxylated CNC suspensions were studied. Addnl., cellulose mol. wt., and CNC surface charge content and crystallinity index were quantified before and after heating. CNCs underwent few morphol. changes; their mol. wt. and crystallinity index were largely unchanged under the conditions tested. Their surface charge content, however, was significantly decreased after heat treatment which resulted in loss of colloidal stability and aggregation of CNCs. The largest change in suspension properties was obsd. for sulfated CNCs whereas CNCs with a combination of sulfate and phosphate esters, or carboxylate groups, were less affected and maintained colloidal stability at higher temps. In fact, desulfation was found to occur rapidly at 80°C, while many carboxylate groups persisted at temps. up to 180°C; calcd. rate consts. (based on second order kinetics) suggested that desulfation is 20 times faster than decarboxylation but with a similar activation energy.
- 128Liu, D.; Wang, S.; Ma, Z.; Tian, D.; Gu, M.; Lin, F. Structure-Color Mechanism of Iridescent Cellulose Nanocrystal Films. RSC Adv. 2014, 4, 39322– 39331, DOI: 10.1039/C4RA06268JGoogle Scholar128Structure-color mechanism of iridescent cellulose nanocrystal filmsLiu, Dagang; Wang, Shuo; Ma, Zhongshi; Tian, Donglin; Gu, Mingyue; Lin, FengyingRSC Advances (2014), 4 (74), 39322-39331CODEN: RSCACL; ISSN:2046-2069. (Royal Society of Chemistry)Chirality and repulsion interactions among sulfate cellulose nanocrystals (CNCs) have vital impact on the formation of a cholesteric liq. crystal (CLC) phase in a suspension or solidified film. In this work, a facile sonication treatment was applied to change the structure and repulsion interactions of CNCs and consequently tune the chiroptical properties of the resultant films. The results show that increasing the sonication energy either by improving the input power or prolonging the aging time resulted in the redn. of particle size and surface charge d., thereby increasing the cholesteric pitch and red-shifting the reflective wavelength of the iridescent films. The optical properties of the film followed the regulation of Bragg reflection and thin-film interference. However, an over-energy input would result in the multi-dispersion of the CNCs according to the level of the surface charge d., thus leading to the formation of polydomain CLC instead of planar CLC because of multi-distributed intra-axial drive forces. Hence, a schematic model was built up to describe the structure transition, as well as the color variation and to correlate the mesoscopic behavior of CNCs and the microscopic interactions of electrostatic repulsions, hydrogen bonding affinity and chirality. Hence, we provide some meaningful information on building up a hierarchical organization assembled from charged rigid biol. rods, and help to recognize the structure-color mechanism of solidified films of polysaccharide nanocrystals.
- 129Beck, S.; Bouchard, J.; Chauve, G.; Berry, R. Controlled Production of Patterns in Iridescent Solid Films of Cellulose Nanocrystals. Cellulose 2013, 20, 1401– 1411, DOI: 10.1007/s10570-013-9888-4Google Scholar129Controlled production of patterns in iridescent solid films of cellulose nanocrystalsBeck, Stephanie; Bouchard, Jean; Chauve, Greg; Berry, RichardCellulose (Dordrecht, Netherlands) (2013), 20 (3), 1401-1411CODEN: CELLE8; ISSN:0969-0239. (Springer)A method to produce predefined patterns in solid iridescent films of cellulose nanocrystals (CNCs) by differential heating of aq. CNC suspensions during film casting has been discovered. Placing materials of different temps. beneath an evapg. CNC suspension results in watermark-like patterns of different reflection wavelength incorporated within the final film structure. The patterned areas are of different thickness and different chiral nematic pitch than the surrounding film; heating results in thicker areas of longer pitch. Thermal pattern creation in CNC films is proposed to be caused by differences in evapn. rates and thermal motion in the areas of the CNC suspension corresponding to the pattern-producing object and the surrounding, unperturbed suspension. Pattern formation was found to occur during the final stages of drying during film casting, once the chiral nematic structure is kinetically trapped in the gel state. It is thus possible to control the reflection wavelength of CNC films by an external process in the absence of additives.
- 130Guidetti, G.; Frka-Petesic, B.; Dumanli, A. G.; Hamad, W. Y.; Vignolini, S. Effect of Thermal Treatments on Chiral Nematic Cellulose Nanocrystal Films. Carbohydr. Polym. 2021, 272, 118404 DOI: 10.1016/j.carbpol.2021.118404Google Scholar130Effect of thermal treatments on chiral nematic cellulose nanocrystal filmsGuidetti, Giulia; Frka-Petesic, Bruno; Dumanli, Ahu G.; Hamad, Wadood Y.; Vignolini, SilviaCarbohydrate Polymers (2021), 272 (), 118404CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)The ability to manipulate the optical appearance of materials is essential in virtually all products and areas of technol. Structurally colored chiral nematic cellulose nanocrystal (CNC) films proved to be an excellent platform to design optical appearance, as their response can be molded by organizing them in hierarchical architectures. Here, we study how thermal treatments influence the optical appearance of structurally colored CNC films. We demonstrate that the CNCs helicoidal architecture and the chiral optical response can be maintained up to 250°C after base treatment and crosslinking with glutaraldehyde, while, alternatively, an exposure to vacuum allows for the helicoidal arrangement to be further preserved up to 900°C, thus producing arom. chiral carbon. The ability to retain the helicoidal arrangement, and thus the visual appearance, in CNC films up to 250°C is highly desirable for high temp. color-based industrial applications and for passive colorimetric heat sensors. Similarly, the prodn. of chiral carbon provides a new type of conductive carbon for electrochem. applications.
- 131Ji, H.; Xiang, Z.; Qi, H.; Han, T.; Pranovich, A.; Song, T. Strategy Towards One-Step Preparation of Carboxylic Cellulose Nanocrystals and Nanofibrils with High Yield, Carboxylation and Highly Stable Dispersibility Using Innocuous Citric Acid. Green Chem. 2019, 21, 1956– 1964, DOI: 10.1039/C8GC03493AGoogle Scholar131Strategy towards one-step preparation of carboxylic cellulose nanocrystals and nanofibrils with high yield, carboxylation and highly stable dispersibility using innocuous citric acidJi, Hui; Xiang, Zhouyang; Qi, Haisong; Han, Tingting; Pranovich, Andrey; Song, TaoGreen Chemistry (2019), 21 (8), 1956-1964CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)Acid hydrolysis using concd. mineral acids is currently the most applied method to prep. nanocellulose, specifically cellulose nanocrystals (CNCs). However, the method exhibits several crit. defects, namely it is hazardous to the environment and human body, causes corrosion to the process equipment and the overdegrdn. of raw cellulose material, is high cost, and so on. Moreover, chem. modification to the functional groups of the CNC products is usually needed for further applications, also leading to extra costs. In this work, an innocuous weak acid (citric acid) was applied to prep. cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) from bleached bagasse pulp accompanied by simultaneous modifications of the functional groups on their mol. interface. It was discovered that with the small aid of ultrasonication at the appropriate prepn. stage, citric acid could overcome the difficulties of hydrolyzing cellulose caused by its weak acidity, and CNCs were successfully produced with good nanoscales and high yield. CNCs with a diam. of 20-30 nm and length of 250-450 nm and CNFs with a diam. of 30-60 nm and length of 500-1000 nm were achieved. Up to 32.2% of the original bagasse pulp was converted to CNCs via citric acid hydrolysis with the assistance of ultrasonication, compared to only about 10.6% of the CNC yield without ultrasonication under the same hydrolysis conditions. At least one carboxylic group of the citric acid was simultaneously introduced to the cellulose via esterification during acid hydrolysis to form carboxylic CNCs and CNFs, which is important for further functionalization. Contents of carboxylic acid groups up to 0.65 mmol g-1 for CNCs and 0.30 mmol g-1 for CNFs were obtained, which endowed the CNCs and CNFs with highly stable dispersibility. Over 90% of the citric acid could be easily recovered through a rotary evaporator. The carboxylic CNCs and CNFs presented in this work offer com. success and lower toxic risks, which means they have the potential to find applications as environmentally friendly, sustainable, and new bio-based nanomaterials in high-tech fields, such as biomaterials.
- 132Zhu, S.; Sun, H.; Mu, T.; Li, Q.; Richel, A. Preparation of Cellulose Nanocrystals from Purple Sweet Potato Peels by Ultrasound-Assisted Maleic Acid Hydrolysis. Food Chem. 2023, 403, 134496 DOI: 10.1016/j.foodchem.2022.134496Google ScholarThere is no corresponding record for this reference.
- 133Duan, R.; Lu, M.; Tang, R.; Guo, Y.; Zhao, D. Structural Color Controllable Humidity Response Chiral Nematic Cellulose Nanocrystalline Film. Biosensors 2022, 12, 707, DOI: 10.3390/bios12090707Google Scholar133Structural Color Controllable Humidity Response Chiral Nematic Cellulose Nanocrystalline FilmDuan, Ran; Lu, Mengli; Tang, Ruiqi; Guo, Yuanyuan; Zhao, DongyuBiosensors (2022), 12 (9), 707CODEN: BIOSHU; ISSN:2079-6374. (MDPI AG)Through self-assembly, environmentally friendly cellulose nanocrystals (CNCs) can form films with a photonic crystal structure whose pitch size can be adjusted in a variety of ways at the fabrication stage. Moreover, the films exhibit response performance to multiple stimuli, which offers extensive applications. Poly(ethylene glycol) (PEG) and CNCs combine to form a smaller chiral nematic domain that develops a solid film with a uniform spiral structure when slowly dried. By changing the compn. of CNCs and PEG, flexible and flat photonic composite films with uniform structural colors from blue to red are prepd. Benefiting from the change in pitch size by insertion and detachment of water mols. into the chiral nematic structure, CNCs films and CNC-PEG composite films exhibit a reversible structural color change in response to different humidity. In addn., the chiral nematic films formed by the combination of glycerol and CNCs have a reversible stimulation response to hydrochloric acid gas. Similarly, adjusting the ratio of glycerol can control the pitch size of the films and, thus, the reflective color. In summary, the pitch size of the photonic crystal structure of the films can be precisely tuned by regulating the additive ratio, and the two prepd. films have reversible responses to humidity and hydrochloric acid gas, resp. The CNC-based films show promise in the application of colorimetric biosensors.
- 134Dong, X. M.; Revol, J.-F.; Gray, D. G. Effect of Microcrystallite Preparation Conditions on the Formation of Colloid Crystals of Cellulose. Cellulose 1998, 5, 19– 32, DOI: 10.1023/A:1009260511939Google Scholar134Effect of microcrystallite preparation conditions on the formation of colloid crystals of celluloseDong, Xue Min; Revol, Jean-Francois; Gray, Derek G.Cellulose (London) (1998), 5 (1), 19-32CODEN: CELLE8; ISSN:0969-0239. (Blackie Academic & Professional)Stable colloidal suspensions of cellulose (I) microcrystallites were prepd. from filter paper by H2SO4 hydrolysis. Above a crit. concn., the suspensions formed a chiral nematic ordered phase, or "colloid crystal". The prepn. conditions governed the properties of the individual I microcrystallites, and hence,the liq. cryst. phase sepn. of the I suspensions. The particle properties and the phase sepn. of the suspensions were strongly dependent on the hydrolysis temp. and time, and on the intensity of the ultrasound irradn. used to disperse the particles. The particle size of the microcrystallites was characterized with transmission electron microscopy and photon correlation spectroscopy. The surface charge was detd. by conductometric titrn. It was possible to fractionate the microcrystallites by size using the partitioning between isotropic and liq. cryst. phases; the longer microcrystallites migrated to the liq. cryst. phase.
- 135Yang, H.; Choi, S.-E.; Kim, D.; Park, D.; Lee, D.; Choi, S.; Nam, Y. S.; Kim, J. W. Color-Spectrum-Broadened Ductile Cellulose Films for Vapor-pH-Responsive Colorimetric Sensors. J. Ind. Eng. Chem. 2019, 80, 590– 596, DOI: 10.1016/j.jiec.2019.08.039Google Scholar135Color-spectrum-broadened ductile cellulose films for vapor-pH-responsive colorimetric sensorsYang, Hakyeong; Choi, Song-Ee; Kim, Doyeon; Park, Daehwan; Lee, Duho; Choi, Sunyoung; Nam, Yoon Sung; Kim, Jin WoongJournal of Industrial and Engineering Chemistry (Amsterdam, Netherlands) (2019), 80 (), 590-596CODEN: JIECFI; ISSN:1226-086X. (Elsevier B.V.)We introduce a smart colorimetric sensor platform, in which iridescent chiral nematic films composed of oxidized cellulose nanocrystals (OxCNCs) exhibit pH-responsive color changes. To provide dried OxCNC films with the controlled reflection of circularly polarized lights at specific wavelengths, we manipulated the half-pitch distance from 145 to 270 nm by adjusting the surface charges of OxCNCs during 2,2,6,6-tetramethylpiperidine-1-oxyl-radical-mediated oxidn. Utilizing the controlled electrostatic repulsion generated by the difference in the surface charge of OxCNCs, the reflection wavelengths of the films could be tuned across a broad color spectrum. In addn., we improved flexibility or ductility of OxCNC composite films by coassembly with a hygroscopic polymer, polyethylene glycol, while maintaining their iridescent colors. We finally demonstrated that the OxCNC composite films could show reversible color changes in response to vapors of aq. solns. with different pH values, thus enabling the development of a vapor-pH-responsive colorimetric sensor technol.
- 136Sui, Y.; Li, X.; Chang, W.; Wan, H.; Li, W.; Yang, F.; Yu, Z.-Z. Multi-Responsive Nanocomposite Membranes of Cellulose Nanocrystals and Poly(N-isopropyl acrylamide) with Tunable Chiral Nematic Structures. Carbohydr. Polym. 2020, 232, 115778 DOI: 10.1016/j.carbpol.2019.115778Google Scholar136Multi-responsive nanocomposite membranes of cellulose nanocrystals and poly(N-isopropyl acrylamide) with tunable chiral nematic structuresSui, Yanqiu; Li, Xiaofeng; Chang, Wei; Wan, Hao; Li, Wei; Yang, Fan; Yu, Zhong-ZhenCarbohydrate Polymers (2020), 232 (), 115778CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)By imitating the unique structure of nature creatures, photonic membranes with periodic chiral helical structure can be assembled by cellulose nanocrystals (CNCs). It is still an issue to fabricate CNC photonic structures tunable in the entire visible spectrum with multiple stimuli-response capacities. Herein, a multi-responsive nanocomposite photonic membrane is fabricated by co-assembly of poly(N-iso-Pr acrylamide) (PNIPAM) grafted CNCs with waterborne polyurethane (WPU) latex on the basis of the chiral nematic structure of CNCs, the thermo-responsibility of PNIPAM, and the flexibility of WPU. The flexible photonic membranes with uniform structural colors from blue to red are obtained by tuning the PNIPAM content. The membrane exhibits reversible responses to solvents, and iridescence changes in response to relative humidity with excellent repeatability. Interestingly, the membrane can be transparent or opaque depending on the ambient temp. The photonic membranes are appealing in applications as humidity sensor, camouflage materials, and even smart windows.
- 137Qu, D.; Zussman, E. Electro-Responsive Liquid Crystalline Nanocelluloses with Reversible Switching. J. Phys. Chem. Lett. 2020, 11, 6697– 6703, DOI: 10.1021/acs.jpclett.0c01924Google Scholar137Electro-responsive Liquid Crystalline Nanocelluloses with Reversible SwitchingQu, Dan; Zussman, EyalJournal of Physical Chemistry Letters (2020), 11 (16), 6697-6703CODEN: JPCLCD; ISSN:1948-7185. (American Chemical Society)Liq. cryst. cellulose nanocrystals (CNCs) which can change their structural and optical properties in an elec. field could be a new choice for advanced optoelectronic devices. Unfortunately, the exploration of its performance in an elec. field is underdeveloped. Hence, we reveal some interesting dielec. coupling activities of liq. cryst. CNC in an elec. field. The CNC tactoid is shown to orient its helix axis normal to the elec. field direction. Then, as a function of the elec. field strength and frequency, the tactoid can be stretched along with a pitch increase, with a deformation mechanism significantly differing at varied frequencies, and finally untwists the helix axis to form a nematic structure upon increasing the elec. field strength. Moreover, a straightforward method to visualize the elec. field is demonstrated, by combining the CNC uniform lying helix textures with polarized optical microscopy. We envision these understandings could facilitate the development of liq. cryst. CNC in the design of electro-optical devices.
- 138Atifi, S.; Mirvakili, M.-N.; Williams, C. A.; Bay, M. M.; Vignolini, S.; Hamad, W. Y. Fast Self-Assembly of Scalable Photonic Cellulose Nanocrystals and Hybrid Films via Electrophoresis. Adv. Mater. 2022, 34, 2109170 DOI: 10.1002/adma.202109170Google Scholar138Fast Self-Assembly of Scalable Photonic Cellulose Nanocrystals and Hybrid Films via ElectrophoresisAtifi, Siham; Mirvakili, Mehr-Negar; Williams, Cyan A.; Bay, Melanie M.; Vignolini, Silvia; Hamad, Wadood Y.Advanced Materials (Weinheim, Germany) (2022), 34 (12), 2109170CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)Nano-enabled, bio-based, functional materials are key for the transition to a sustainable society as they can be used, owing to both their performance and nontoxicity, to gradually replace existing nonrenewable engineering materials. Cellulose nanocrystals (CNCs), produced by acid hydrolysis of cellulosic biomass, have been shown to possess distinct self-assembly, optical, and electromech. properties, and are anticipated to play an important role in the fabrication of photonic, optoelectronic, and functional hybrid materials. To facilitate CNCs' technol. viability, a method suitable for industrial exploitation is developed to produce photonic films possessing long-range chirality on conductive, rigid, or flexible, substrates within a few minutes. The approach is based on electrophoretic deposition (EPD)-induced self-assembly of CNCs, where photonic films of any size can be produced by controlling CNC surface properties and EPD parameters. CNC film coloration can be detd. by the CNC aq. suspension characteristics, while their reflected intensity can be tuned by changing the duration and no. of electrodeposition cycles. EPD-induced self-assembly of CNCs is compatible with in situ redn. of gold precursors without the need to use addnl. reducing agents (some of which are considered toxic), thereby allowing the prepn. of hybrid photonic films with tunable plasmonic response in a one-pot process.
- 139Bordel, D.; Putaux, J.-L.; Heux, L. Orientation of Native Cellulose in an Electric Field. Langmuir 2006, 22, 4899– 4901, DOI: 10.1021/la0600402Google Scholar139Orientation of Native Cellulose in an Electric FieldBordel, Damien; Putaux, Jean-Luc; Heux, LaurentLangmuir (2006), 22 (11), 4899-4901CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)Native cellulose has been oriented in an ac elec. field at both the macroscopic and colloidal level. Ramie fiber fragments suspended in chloroform have been shown to point along the field. Cellulose microcrystal suspensions in cyclohexane have also been allowed to evap. in an elec. field and have exhibited a high degree of orientation when further examd. by TEM and electron diffraction. Similarly, cellulose whisker suspensions showed increasing birefringence with increasing field strength and displayed interference Newton colors that satd. at around 2000 V cm-1. A high degree of order of this suspension was also obtained by evaluating the induced birefringence with color charts.
- 140Frka-Petesic, B.; Guidetti, G.; Kamita, G.; Vignolini, S. Controlling the Photonic Properties of Cholesteric Cellulose Nanocrystal Films with Magnets. Adv. Mater. 2017, 29, 1701469 DOI: 10.1002/adma.201701469Google ScholarThere is no corresponding record for this reference.
- 141Chen, T.; Zhao, Q.; Meng, X.; Li, Y.; Peng, H.; Whittaker, A. K.; Zhu, S. Ultrasensitive Magnetic Tuning of Optical Properties of Films of Cholesteric Cellulose Nanocrystals. ACS Nano 2020, 14, 9440– 9448, DOI: 10.1021/acsnano.0c00506Google Scholar141Ultrasensitive Magnetic Tuning of Optical Properties of Films of Cholesteric Cellulose NanocrystalsChen, Tianxing; Zhao, Qinglan; Meng, Xin; Li, Yao; Peng, Hui; Whittaker, Andrew K.; Zhu, ShenminACS Nano (2020), 14 (8), 9440-9448CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)Chiral photonic crystals derived from the self-assembly of cellulose nanocrystals (CNCs) have found important applications in optical devices due to the capacity to adjust the chiral nematic phase under external stimulus, in particular an applied magnetic field. To date, strong magnetic fields have been required to induce an optical response in CNC films. In this work, the self-assembly of films of CNCs can be tuned by applying an ultrasmall magnetic field. The CNCs, decorated with Fe3O4 nanoparticles (Fe3O4/CNCs), were dispersed in suspensions of neat CNCs so as to alter the magnetic response of the CNCs. A subsequent process of dispersion not only prevents the clumping of the magnetic nanoparticles but also enhances the sensitivity to an applied magnetic field. A small magnetic field of 7 mT can tune the self-assembly and the microstructure of the CNCs. The pitch of the chiral structure decreased with an increase in applied magnetic field, from 302 to 206 nm, for fields from 7 to 15 mT. This phenomenon is opposite that obsd. for neat CNCs, in which the pitch is obsd. to increase with an increase in the external magnetic strength. The optical response under application of an ultrasmall magnetic field could help with theor. research and enable more applications, such as sensors or nanotemplating agents.
- 142Wang, P.-X.; Hamad, W. Y.; MacLachlan, M. J. Liquid Crystalline Tactoidal Microphases in Ferrofluids: Spatial Positioning and Orientation by Magnetic Field Gradients. Chem. 2019, 5, 681– 692, DOI: 10.1016/j.chempr.2018.12.010Google Scholar142Liquid Crystalline Tactoidal Microphases in Ferrofluids: Spatial Positioning and Orientation by Magnetic Field GradientsWang, Pei-Xi; Hamad, Wadood Y.; MacLachlan, Mark J.Chem (2019), 5 (3), 681-692CODEN: CHEMVE; ISSN:2451-9294. (Cell Press)Macroscopic manipulation of self-assembly in lyotropic systems, such as chiral nematic liq. crystals formed by cellulose nanocrystals, is kinetically hindered by the similarity between isotropic and anisotropic phases in compn. and phys. properties. By creating a significant difference in volumetric magnetic susceptibility between discrete liq. cryst. tactoids and continuous isotropic phases (based on the exclusion effects of tactoids on superparamagnetic doping nanoparticles), we achieved position and orientation control of liq. cryst. tactoids by magnetic field gradients as weak as several hundred gauss per cm, where the movement of tactoids is detd. by competition between magnetic and gravitational acceleration fields. We also undertook a preliminary examn. of the trapping of a liq. cryst. phase in the potential well of a quadrupole magnetic field. This method enabled us to control the phase sepn. rate and configuration, as well as the orientation of director fields in both tactoids and macroscopic ordered phases.
- 143Sugiyama, J.; Chanzy, H.; Maret, G. Orientation of Cellulose Microcrystals by Strong Magnetic Fields. Macromolecules 1992, 25, 4232– 4234, DOI: 10.1021/ma00042a032Google Scholar143Orientation of cellulose microcrystals by strong magnetic fieldsSugiyama, J.; Chanzy, H.; Maret, G.Macromolecules (1992), 25 (16), 4232-4CODEN: MAMOBX; ISSN:0024-9297.Orientation of cellulose (I) microcrystals in aq. suspension was achieved using homogeneous magnetic fields ≤7 T. Under these conditions, the crystals became strongly oriented with their long axis, as well as with the mean plane of their anhydro (1→4) β-D linked glucose moieties, perpendicular to the field. By drying the suspensions in the field, uniplanar-axial I films were obtained. They were analyzed by electron microscopy and electron and x-ray diffraction.
- 144De France, K. J.; Yager, K. G.; Hoare, T.; Cranston, E. D. Cooperative Ordering and Kinetics of Cellulose Nanocrystal Alignment in a Magnetic Field. Langmuir 2016, 32, 7564– 7571, DOI: 10.1021/acs.langmuir.6b01827Google Scholar144Cooperative Ordering and Kinetics of Cellulose Nanocrystal Alignment in a Magnetic FieldDe France, Kevin J.; Yager, Kevin G.; Hoare, Todd; Cranston, Emily D.Langmuir (2016), 32 (30), 7564-7571CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)Cellulose nanocrystals (CNCs) are emerging nanomaterials that form chiral nematic liq. crystals above a crit. concn. (C*) and addnl. orient within electromagnetic fields. The control over CNC alignment is significant for materials processing and end use; to date, magnetic alignment was demonstrated using only strong fields over extended or arbitrary time scales. This work studies the effects of comparatively weak magnetic fields (0-1.2 T) and CNC concn. (1.65-8.25%) on the kinetics and degree of CNC ordering using small-angle x-ray scattering. Interparticle spacing, correlation length, and orientation order parameters (η and S) increased with time and field strength following a sigmoidal profile. In a 1.2 T magnetic field for CNC suspensions above C*, partial alignment occurred in under 2 min followed by slower cooperative ordering to achieve nearly perfect alignment in under 200 min (S = -0.499 where S = -0.5 indicates perfect antialignment). At 0.56 T, nearly perfect alignment was also achieved, yet the ordering was 36% slower. Outside of a magnetic field, the order parameter plateaued at 52% alignment (S = -0.26) after 5 h, showcasing the drastic effects of relatively weak magnetic fields on CNC alignment. For suspensions below C*, no magnetic alignment was detected.
- 145Zhang, X.; Kang, S.; Adstedt, K.; Kim, M.; Xiong, R.; Yu, J.; Chen, X.; Zhao, X.; Ye, C.; Tsukruk, V. V. Uniformly Aligned Flexible Magnetic Films from Bacterial Nanocelluloses for Fast Actuating Optical Materials. Nat. Commun. 2022, 13, 5804, DOI: 10.1038/s41467-022-33615-zGoogle Scholar145Uniformly aligned flexible magnetic films from bacterial nanocelluloses for fast actuating optical materialsZhang, Xiaofang; Kang, Saewon; Adstedt, Katarina; Kim, Minkyu; Xiong, Rui; Yu, Juan; Chen, Xinran; Zhao, Xulin; Ye, Chunhong; Tsukruk, Vladimir V.Nature Communications (2022), 13 (1), 5804CODEN: NCAOBW; ISSN:2041-1723. (Nature Portfolio)Naturally derived biopolymers have attracted great interest to construct photonic materials with multi-scale ordering, adaptive birefringence, chiral organization, actuation and robustness. Nevertheless, traditional processing commonly results in non-uniform organization across large-scale areas. Here, we report magnetically steerable uniform biophotonic organization of cellulose nanocrystals decorated with superparamagnetic nanoparticles with strong magnetic susceptibility, enabling transformation from helicoidal cholesteric (chiral nematic) to uniaxial nematic phase with near-perfect orientation order parameter of 0.98 across large areas. We demonstrate that magnetically triggered high shearing rate of circular flow exceeds those for conventional evapn.-based assembly by two orders of magnitude. This high rate shearing facilitates unconventional unidirectional orientation of nanocrystals along gradient magnetic field and untwisting helical organization. These translucent magnetic films are flexible, robust, and possess anisotropic birefringence and light scattering combined with relatively high optical transparency reaching 75%. Enhanced mech. robustness and uniform organization facilitate fast, multimodal, and repeatable actuation in response to magnetic field, humidity variation, and light illumination.
- 146Cao, Y.; Wang, P.-X.; D’Acierno, F.; Hamad, W. Y.; Michal, C. A.; MacLachlan, M. J. Tunable Diffraction Gratings from Biosourced Lyotropic Liquid Crystals. Adv. Mater. 2020, 32, 1907376 DOI: 10.1002/adma.201907376Google Scholar146Tunable Diffraction Gratings from Biosourced Lyotropic Liquid CrystalsCao, Yuanyuan; Wang, Pei-Xi; D'Acierno, Francesco; Hamad, Wadood Y.; Michal, Carl A.; MacLachlan, Mark J.Advanced Materials (Weinheim, Germany) (2020), 32 (19), 1907376CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)Diffraction gratings are important for modern optical components, such as optical multiplexers and signal processors. Although liq. crystal (LC) gratings based on thermotropic LCs have been extensively explored, they often require expensive mols. and complicated manufg. processes. Lyotropic LCs, which can be broadly obtained from both synthetic and natural sources, have not yet been applied in optical gratings. Herein, a facile grating fabrication method using a biosourced lyotropic LC formed by cellulose nanocrystals (CNCs), a material extd. from plants, is reported. Hydrogel sheets with vertically aligned uniform periodic structures are obtained by fixing the highly oriented chiral nematic LC of CNCs in polymer networks under the cooperative effects of gravity on phase sepn. and a magnetic field on LC orientation. The hydrogel generates up to sixth-order diffraction spots and shows linear polarization selectivity, with tunable grating periodicity controlled through LC concn. regulation. This synthesis strategy can be broadly applied to various grating materials and opens up a new area of optical materials from lyotropic LCs.
- 147Wang, Z.; Li, N.; Zong, L.; Zhang, J. Recent Advances in Vacuum Assisted Self-Assembly of Cellulose Nanocrystals. Curr. Opin. Solid State Mater. Sci. 2019, 23, 142– 148, DOI: 10.1016/j.cossms.2019.03.001Google Scholar147Recent advances in vacuum assisted self-assembly of cellulose nanocrystalsWang, Zhaolu; Li, Na; Zong, Lu; Zhang, JianmingCurrent Opinion in Solid State & Materials Science (2019), 23 (3), 142-148CODEN: COSSFX; ISSN:1359-0286. (Elsevier Ltd.)Cellulose nanocrystals (CNC) iridescent films composed of the chiral nematic liq. crystal phase have attracted much attention owing to their fascinating optical properties. Herein, we summarized and discussed the recent advances in prepg. iridescent CNC film via vacuum-assisted self-assembly (VASA) method, which has the advantage to fabricate large area, highly oriented and structurally homogeneous CNC liq. crystal film. The discussed aspects include (i) Factors that influence the self-assembly behavior of CNC nanorods during VASA. (ii) The strategy for modifying the optical, thermal as well as the mech. properties of VASA assisted CNC iridescent film. (iii) Co-assembling of CNC liq. crystal phase and other functional nanoparticles by VASA technique. In all cases, key issues are highlighted and future developments that we consider as the most relevant are identified. Furthermore, future research activities are suggested in the conclusion.
- 148Wang, Z.; Yuan, Y.; Hu, J.; Yang, J.; Feng, F.; Yu, Y.; Liu, P.; Men, Y.; Zhang, J. Origin of Vacuum-Assisted Chiral Self-Assembly of Cellulose Nanocrystals. Carbohydr. Polym. 2020, 245, 116459 DOI: 10.1016/j.carbpol.2020.116459Google Scholar148Origin of vacuum-assisted chiral self-assembly of cellulose nanocrystalsWang, Zhaolu; Yuan, Yuan; Hu, Jian; Yang, Jiying; Feng, Fan; Yu, Yao; Liu, Ping; Men, Yongfeng; Zhang, JianmingCarbohydrate Polymers (2020), 245 (), 116459CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)To produce functional cellulose nanocrystal (CNC) films with desirable optical and mech. properties, it is crit. to understand and control the chiral self-assembly of CNCs during solvent removal. Here, the formation mechanism of CNC chiral nematic liq. crystal phase during vacuum-assisted self-assembly (VASA) was investigated. To elucidate the structural evolution of CNC aggregations on filter paper, CNC suspensions were "frozen" at various filtration stages in a polyacrylamide matrix. In addn., the flow rate of CNC suspension was monitored in situ. We found that disordered-to-ordered CNC self-assembly occurs at the interface between the filter paper and suspension over four stages. Tactoids develop in the concd. CNC suspension close to the filter paper, which is also obsd. in evapn.-induced self-assembly (EISA) of CNC films. However, compared to EISA, VASA promotes helical axes of CNC tactoids along the flow-field direction, leading to faster liq. crystal formation with long-range order via the nucleation growth.
- 149Xia, B.; Zeng, X.; Lan, W.; Zhang, M.; Huang, W.; Wang, H.; Liu, C. Cellulose Nanocrystal/Graphene Oxide One-Dimensional Photonic Crystal Film with Excellent UV-Blocking and Transparency. Carbohydr. Polym. 2024, 327, 121646 DOI: 10.1016/j.carbpol.2023.121646Google ScholarThere is no corresponding record for this reference.
- 150Li, J.; Lu, C.; Ye, C.; Xiong, R. Structural, Optical, and Mechanical Insights into Cellulose Nanocrystal Chiral Nematic Film Engineering by Two Assembly Techniques. Biomacromolecules 2024, 25, 3507– 3518, DOI: 10.1021/acs.biomac.4c00169Google ScholarThere is no corresponding record for this reference.
- 151Ren, Y.; Wang, T.; Chen, Z.; Li, J.; Tian, Q.; Yang, H.; Xu, Q. Liquid Crystal Behavior Induced Assembling Fabrication of Conductive Chiral MWCNTs@NCC Nanopaper. Appl. Surf. Sci. 2016, 385, 521– 528, DOI: 10.1016/j.apsusc.2016.05.146Google ScholarThere is no corresponding record for this reference.
- 152Pignon, F.; Challamel, M.; De Geyer, A.; Elchamaa, M.; Semeraro, E. F.; Hengl, N.; Jean, B.; Putaux, J.-L.; Gicquel, E.; Bras, J.; Prevost, S.; Sztucki, M.; Narayanan, T.; Djeridi, H. Breakdown and Buildup Mechanisms of Cellulose Nanocrystal Suspensions under Shear and upon Relaxation Probed by SAXS and SALS. Carbohydr. Polym. 2021, 260, 117751 DOI: 10.1016/j.carbpol.2021.117751Google Scholar152Breakdown and buildup mechanisms of cellulose nanocrystal suspensions under shear and upon relaxation probed by SAXS and SALSPignon, Frederic; Challamel, Mathilde; De Geyer, Antoine; Elchamaa, Mohamad; Semeraro, Enrico F.; Hengl, Nicolas; Jean, Bruno; Putaux, Jean-Luc; Gicquel, Erwan; Bras, Julien; Prevost, Sylvain; Sztucki, Michael; Narayanan, Theyencheri; Djeridi, HendaCarbohydrate Polymers (2021), 260 (), 117751CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)The breakdown and buildup mechanisms in concd. cellulose nanocrystal (CNC) suspensions under shear and during relaxation upon cessation of shear were accessed by small-angle X-ray and light scattering combined with rheometry. The dynamic structural changes over nanometer to micrometer lengthscales were related to the well-known three-regime rheol. behavior. In the shear-thinning regime I, the large liq. cryst. domains were progressively fragmented into micrometer-sized tactoids, with their cholesteric axis aligned perpendicular to the flow direction. The viscosity plateau of regime II was assocd. to a further disruption into submicrometer-sized elongated tactoids oriented along the velocity direction. At high shear rate, regime III corresponded to the parallel flow of individual CNCs along the velocity direction. Upon cessation of flow, the relaxation process occurred through a three-step buildup mechanisms: (1) a fast reassembling of the individual CNCs into a nematic-like organization established up to micrometer lengthscales, (2) a slower formation of oriented large cholesteric domains, and (3) their isotropic redistribution.
- 153Feng, X.; Chen, B.; Kong, D.; Wang, T.; Cui, X.; Tian, Y. Visualizing the Shear Flow-Modulated Alignments in Cellulose Nanocrystal Films by the Mueller Matrix. J. Phys. Chem. C 2023, 127, 6974– 6980, DOI: 10.1021/acs.jpcc.3c00577Google Scholar153Visualizing the Shear Flow-Modulated Alignments in Cellulose Nanocrystal Films by the Mueller MatrixFeng, Xiaowei; Chen, Bo; Kong, Demei; Wang, Ting; Cui, Xiaoyan; Tian, YangJournal of Physical Chemistry C (2023), 127 (14), 6974-6980CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)The microstructures of cellulose nanocrystal (CNC) films grown from their aq. suspensions are tuned by a shear flow during the formation of the films. The modulation of the chiral nematic organization of CNCs is visualized by the complete polarization anal. using Mueller matrix microscopy. Further optical simulation has ensured the comprehensive 3D structural anal. for the complex chiral structures of CNC films. As suggested by the optical investigation, regulating the helical structure under the shear flow involves two transition processes, an early in-plane unwinding, followed by a later helically vertical unwinding. We have also confirmed that sufficient shearing is required to reorient the helically aligned CNCs to form the nematic structure.
- 154Huang, H.; Wang, X.; Yu, J.; Chen, Y.; Ji, H.; Zhang, Y.; Rehfeldt, F.; Wang, Y.; Zhang, K. Liquid-Behaviors-Assisted Fabrication of Multidimensional Birefringent Materials from Dynamic Hybrid Hydrogels. ACS Nano 2019, 13, 3867– 3874, DOI: 10.1021/acsnano.9b00551Google Scholar154Liquid-Behaviors-Assisted Fabrication of Multidimensional Birefringent Materials from Dynamic Hybrid HydrogelsHuang, Heqin; Wang, Xiaojie; Yu, Jinchao; Chen, Ye; Ji, Hong; Zhang, Yumei; Rehfeldt, Florian; Wang, Yong; Zhang, KaiACS Nano (2019), 13 (4), 3867-3874CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)Liq.-solid transition is a widely used strategy to shape polymeric materials and encode their microstructures. However, it is still challenging to fully exploit liq. behaviors of material precursors. In particular, the dynamic and static liq. behaviors naturally conflict with each other, which makes it difficult to integrate their advantages in the same materials. Here, by utilizing a shear-thinning phenomenon in the dynamic hybrid hydrogels, we achieve a hydrodynamic alignment of cellulose nanocrystals (CNC) and preserve it in the relaxed hydrogel networks due to the much faster relaxation of polymer networks (within 500 s) than CNC after the unloading of external force. During the following drying process, the surface tension of hydrogels further enhances the orientation index of CNC up to 0.872 in confined geometry, and these anisotropic microstructures demonstrate highly tunable birefringence (up to 0.004 14). Due to the presence of the boundaries of dynamic hydrogels, diverse xerogels including fibers, films, and even complex three-dimensional structures with variable anisotropic microstructures can be fabricated without any external molds.
- 155Kose, O.; Boott, C. E.; Hamad, W. Y.; MacLachlan, M. J. Stimuli-Responsive Anisotropic Materials Based on Unidirectional Organization of Cellulose Nanocrystals in an Elastomer. Macromolecules 2019, 52, 5317– 5324, DOI: 10.1021/acs.macromol.9b00863Google Scholar155Stimuli-Responsive Anisotropic Materials Based on Unidirectional Organization of Cellulose Nanocrystals in an ElastomerKose, Osamu; Boott, Charlotte E.; Hamad, Wadood Y.; MacLachlan, Mark J.Macromolecules (Washington, DC, United States) (2019), 52 (14), 5317-5324CODEN: MAMOBX; ISSN:0024-9297. (American Chemical Society)Cellulose nanocrystals (CNCs) derived from biomass have unique properties, which have inspired their incorporation into a wide variety of materials. However, the no. of highly stretchable elastomers that have been prepd. with CNCs has been limited. Here, we report shear-aligned pseudonematic CNCs embedded in a poly(Et acrylate) elastomer, a homogeneous composite that exhibits reversible optical properties in response to mech. stimuli. Due to the long-range anisotropy of CNCs, the relaxed composite shows vivid interference color as it is viewed between crossed or parallel polarizers. When the pseudonematic CNC elastomer is stretched parallel to the CNC alignment direction, the CNCs become further aligned and the birefringence of the materials increases. In contrast, when the composite is stretched perpendicular to the CNC alignment direction, the CNCs become more disordered and the birefringence decreases. The extent of the CNC reorientation when the composite was stretched was detd. by calcn. of the birefringence of the material and two-dimensional X-ray diffraction anal. Furthermore, the aligned CNCs act as nanoreinforcement in the elastomer, which resulted in the pseudonematic CNC-poly(Et acrylate) elastomer having a tensile modulus up to 120 times higher than that of pure poly(Et acrylate).
- 156Boott, C. E.; Soto, M. A.; Hamad, W. Y.; MacLachlan, M. J. Shape-Memory Photonic Thermoplastics from Cellulose Nanocrystals. Adv. Funct. Mater. 2021, 31, 2103268 DOI: 10.1002/adfm.202103268Google Scholar156Shape-Memory Photonic Thermoplastics from Cellulose NanocrystalsBoott, Charlotte E.; Soto, Miguel A.; Hamad, Wadood Y.; MacLachlan, Mark J.Advanced Functional Materials (2021), 31 (43), 2103268CODEN: AFMDC6; ISSN:1616-301X. (Wiley-VCH Verlag GmbH & Co. KGaA)Responsive materials prepd. using shape-memory photonic crystals have potential applications in rewritable photonic devices, security features, and optical coatings. By embedding chiral nematic cellulose nanocrystals (CNCs) in a polyacrylate matrix, a shape-memory photonic crystal thermoplastic (CNC-SMP) allows reversible capture of different colored states is reported. In this system, the temp. is used to program the shape-memory response, while pressure is used to compress the helical pitch of the CNC chiral nematic organization. By increasing the force applied (≈140-230 N), the structural color can be tuned from red to blue. Then, on-demand, the CNC-SMP can recover to its original state by heating it above the glass transition temp. This cycle can be performed over 15 times without any loss of the shape-memory behavior or mech. degrdn. of the sample. In addn., multicolor readouts can be programmed into the chiral nematic CNC-SMP by using a patterned substrate to press the sample, while the glass transition temp. of the CNC-SMP can be tuned over a 90°C range by altering the monomer compn. used to prep. the polyacrylate matrix.
- 157Li, X.; Liu, J.; Zhang, X. Pressure/Temperature Dual-Responsive Cellulose Nanocrystal Hydrogels for On-Demand Schemochrome Patterning. Adv. Funct. Mater. 2023, 33, 2306208 DOI: 10.1002/adfm.202306208Google Scholar157Pressure/Temperature Dual-Responsive Cellulose Nanocrystal Hydrogels for On-Demand Schemochrome PatterningLi, Xinkai; Liu, Jize; Zhang, XinxingAdvanced Functional Materials (2023), 33 (47), 2306208CODEN: AFMDC6; ISSN:1616-301X. (Wiley-VCH Verlag GmbH & Co. KGaA)Cellulose nanocrystal (CNC) based optical devices with adjustable schemochrome have attracted immense interest. However, most of the previously reported structural colored CNC-based materials can only achieve simple stress-induced color change, which have difficulty achieving multimode control of complex patterning that can be accurately identified. Here, inspired by the nanostructure-based color-changing mechanism of neon tetra, this study presents a pressure/temp. dual-responsive CNC-based schemochrome hydrogel with adjustable dynamic chiral nematic structure. By incorporating abundant interfacial noncovalent interactions, dynamic correlations between adjustable helical pitch of the vertically stacked cholesteric liq. cryst. (LC) phase and responsiveness of flexible thermosensitive substrate are established, which further enable wide-range optical characteristic (12°-213° in HSV color model and 421-734 nm in the UV-Vis spectra) and identifiable visualized patterning. The resultant hydrogels are applied in proof-of-concept demonstrations of on-demand schemochrome patterning, including customizable patterned dual-encryption label, smart digital display, temp. monitor, and intelligent recognition/control system. This study envisages that the bioinspired construction of structural colored nanomaterials will have promising applications in smart responsive photonic equipment including smart display, anticounterfeiting, and intelligent control systems.
- 158Nguyen, T.-D.; Hamad, W. Y.; MacLachlan, M. J. Tuning the Iridescence of Chiral Nematic Cellulose Nanocrystals and Mesoporous Silica Films by Substrate Variation. Chem. Commun. 2013, 49, 11296– 11298, DOI: 10.1039/c3cc47337fGoogle Scholar158Tuning the iridescence of chiral nematic cellulose nanocrystals and mesoporous silica films by substrate variationNguyen, Thanh-Dinh; Hamad, Wadood Y.; MacLachlan, Mark J.Chemical Communications (Cambridge, United Kingdom) (2013), 49 (96), 11296-11298CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)The self-assembly of cellulose nanocrystals (CNCs) into chiral nematic phases varies significantly with the substrate and evapn. rate. These variables allow the reflectance peak of iridescent chiral nematic films of CNCs and mesoporous SiO2 templated from CNCs to be tuned over a wide range of wavelengths.
- 159Li, W.; Liu, W.; Wen, W.; Liu, H.; Liu, M.; Zhou, C.; Luo, B. The Liquid Crystalline Order, Rheology and Their Correlation in Chitin Whiskers Suspensions. Carbohydr. Polym. 2019, 209, 92– 100, DOI: 10.1016/j.carbpol.2019.01.006Google Scholar159The liquid crystalline order, rheology and their correlation in chitin whiskers suspensionsLi, Wenling; Liu, Wenjun; Wen, Wei; Liu, Hua; Liu, Mingxian; Zhou, Changren; Luo, BinghongCarbohydrate Polymers (2019), 209 (), 92-100CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)To explore the concn. range of chitin whiskers (CHWs) aq. suspensions with the liq. cryst. state, and the correlation between liq. cryst. characteristic and rheol. of CHWs suspensions, the CHWs aq. suspensions with different CHWs concn., pH value, ionic strength and temp. were prepd. The liq. cryst. characteristic and rheol. properties of the obtained suspensions were investigated by polarizing microscope and rotational rheometer. The results showed that the liq. cryst. state of the suspensions appeared at the CHWs concn. of 3.5 wt% and disappeared at 22.5 wt%. Increasing the CHWs concn., pH value and ionic strength, the values of elastic modulus (G') and viscous modulus (G") increased, and the liq. crystal texture basically became more and more regular and obvious. Moreover, the value of G"/G' was always less than 1, suggesting the elastic behavior of CHWs aq. suspension. Besides, the effect caused by heating on the elastic modulus was irreversible.
- 160Luo, Y.; Li, Y.; Liu, K.; Li, L.; Wen, W.; Ding, S.; Huang, Y.; Liu, M.; Zhou, C.; Luo, B. Modulating of Bouligand Structure and Chirality Constructed Bionically Based on the Self-Assembly of Chitin Whiskers. Biomacromolecules 2023, 24, 2942– 2954, DOI: 10.1021/acs.biomac.3c00419Google ScholarThere is no corresponding record for this reference.
- 161Li, J.; Revol, J.; Marchessault, R. H. Effect of N-Sulfonation on the Colloidal and Liquid Crystal Behavior of Chitin Crystallites. J. Colloid Interface Sci. 1997, 192, 447– 457, DOI: 10.1006/jcis.1997.5003Google Scholar161Effect of N-Sulfonation on the Colloidal and Liquid Crystal Behavior of Chitin CrystallitesLi; Revol; MarchessaultJournal of colloid and interface science (1997), 192 (2), 447-57 ISSN:.Chitin crystallites were heterogeneously N-sulfonated in an aqueous medium using triethylamine/sulfur trioxide (TEA/SO3) or pyridine/sulfur trioxide. The extent of N-sulfonation of the crystallites has been controlled by the amount of TEA/SO3 added in the reaction. The concentration of sulfur in the crystallites after N-sulfonation was quantified using conductimetric titration and elemental analysis. The ratio of N-sulfonated amino groups to amino groups (S/N) was calculated based on the titration data. The presence of N-S bonds assumed to be at crystallite surfaces was demonstrated by X-ray photoelectron spectroscopy (XPS). After N-sulfonation, the crystallites have two ionizable groups at their surface: -NH3+ and -NHSO3H(Na). The former is pH dependent. The colloidal properties of the N-sulfonated crystallites having different S/N were investigated by plotting the zeta potential as a function of the pH of the suspension. The isoelectric point was found to change with the level of N-sulfonation. Transmission electron microscopy shows that the aggregation of crystallites depends strongly on the extent of N-sulfonation. Above a certain concentration, the original chitin crystallites form tactoids (chiral nematic domains) in an aqueous medium. This phenomenon was not observed for the crystallites with a low extent of surface N-sulfonation (below 70%). At about 80% N-sulfonation, the formation of tactoids was once again observed. Copyright 1997Academic Press
- 162Liu, D.; Chang, Y.; Tian, D.; Wu, W.; Lu, A.; Prempeh, N.; Tan, M.; Huang, Y. Lyotropic Liquid Crystal Self-Assembly of H2O2-Hydrolyzed Chitin Nanocrystals. Carbohydr. Polym. 2018, 196, 66– 72, DOI: 10.1016/j.carbpol.2018.04.098Google Scholar162Lyotropic liquid crystal self-assembly of H2O2-hydrolyzed chitin nanocrystalsLiu, Dagang; Chang, Yu; Tian, Donglin; Wu, Wenqi; Lu, Ang; Prempeh, Nana; Tan, Meijuan; Huang, YifengCarbohydrate Polymers (2018), 196 (), 66-72CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)H2O2 hydrolysis of mech.-defibrillated chitin nanofibrils was explored as a green way of fabricating rod-like chitin nanocrystals (H2O2-hydrolyzed CHNs) that have an av. length of 350 nm and width of 40 nm. We investigated the structure and morphol. of CHNs as well as the rheol. and lyotropic self-assembly behavior of its colloidal dispersions. The results show that although H2O2-hydrolyzed CHNs maintained the cryst. structure of α-chitin, surface charge of the nanorods was switched from pos. to neg. As a consequence, the colloidal nanocrystals were well-dispersed in neutral or alk. aq. media, and behaved as a lyotropic liq. crystal between two crit. concns. It is interesting that lyotropic liq. crystal transition was a spontaneously self-assembly from well-aligned nanofibers, to nanobelts, and to multi-layered lamellae. At high crit. concn., H2O2-hydrolyzed CHN colloids exhibited a sol-gel transition, which was discovered to be highly dependent on the storage time, concn., temp., and surface charge d. It is also suggested that nematic mesophases rather than gel could be effectively maintained by improving the surface charge d. or lowering the aging temp. and colloidal concn. of CHNs.
- 163Nge, T. T.; Hori, N.; Takemura, A.; Ono, H.; Kimura, T. Phase Behavior of Liquid Crystalline Chitin/Acrylic Acid Liquid Mixture. Langmuir 2003, 19, 1390– 1395, DOI: 10.1021/la020764nGoogle Scholar163Phase Behavior of Liquid Crystalline Chitin/Acrylic Acid Liquid MixtureNge, Thi T.; Hori, Naruhito; Takemura, Akio; Ono, Hirokuni; Kimura, TsunehisaLangmuir (2003), 19 (4), 1390-1395CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)Phase behavior of a liq. cryst. chitin/acrylic acid liq. mixt. was studied to fabricate a chitin-based composite with unique optical property. From phase sepn. studies, the authors can evaluate the ternary phase diagram of a chitin microfibril, H2O, and acrylic acid monomer system. A suitable starting liq. cryst. chitin concn. to obtain anisotropic monophase over a range of acrylic acid concn. (up to 33 (wt./wt.) %) was 14.62% (14-15%) by wt. At lower acrylic acid concn. range, cryst. microfibrillar fragments of chitin self-assembled to form upper isotropic phase and lower anisotropic liq. crystal phase at high enough concn. of chitin crystallites. The latter showed a characteristic chiral nematic order, a fingerprint-like texture. Above this chitin concn. and at higher acrylic acid concn. range, the system formed a monophasic stable flow-birefringence glassy phase, which displayed a nematic order. This phase occurred within a very limited range of chitin crystallites concn. of ∼6.22-6.41%, which provides a clear-cut boundary between isotropic phase and anisotropic phase as well as a metastable frozen-in state between chiral nematic order and nematic order.
- 164Nge, T. T.; Hori, N.; Takemura, A.; Ono, H.; Kimura, T. Synthesis and Orientation Study of a Magnetically Aligned Liquid-Crystalline Chitin/Poly(acrylic acid) Composite. J. Polym. Sci. B: Polym. Phys. 2003, 41, 711– 714, DOI: 10.1002/polb.10428Google Scholar164Synthesis and orientation study of a magnetically aligned liquid-crystalline chitin/poly(acrylic acid) compositeNge, Thi Thi; Hori, Naruhito; Takemura, Akio; Ono, Hirokuni; Kimura, TsunehisaJournal of Polymer Science, Part B: Polymer Physics (2003), 41 (7), 711-714CODEN: JPBPEM; ISSN:0887-6266. (John Wiley & Sons, Inc.)A high magnetic field of 5 T was used to fabricate a magnetically aligned, optically anisotropic, liq.-cryst. chitin/poly(acrylic acid) composite. The aligned mesophase was fixed by photoinitiated free-radical polymn. From an examn. of polarized optical micrographs and an x-ray diffraction study, a high degree of orientation of 0.70 was obsd. for the composite with a higher liq.-cryst. chitin concn. (10.70 wt. %); the orientation was reduced with a decreased chitin concn. at a given acrylic acid concn. The x-ray data for the developed composite showed a uniplanar orientation for the chitin crystallites, with its mol. long axes perpendicular to the direction of the magnetic field.
- 165Lu, T.; Pan, H.; Ma, J.; Li, Y.; Bokhari, S. W.; Jiang, X.; Zhu, S.; Zhang, D. Cellulose Nanocrystals/Polyacrylamide Composites of High Sensitivity and Cycling Performance to Gauge Humidity. ACS Appl. Mater. Interfaces 2017, 9, 18231– 18237, DOI: 10.1021/acsami.7b04590Google Scholar165Cellulose Nanocrystals/Polyacrylamide Composites of High Sensitivity and Cycling Performance To Gauge HumidityLu, Tao; Pan, Hui; Ma, Jun; Li, Yao; Bokhari, Syeda Wishal; Jiang, Xueliang; Zhu, Shenmin; Zhang, DiACS Applied Materials & Interfaces (2017), 9 (21), 18231-18237CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)Cellulose nanocrystals (CNCs) have attracted much interest due to their unique optical property, rich resource, environment friendliness, and templating potentials. CNCs have been reported as novel photonic humidity sensors, which are unfortunately limited by the dissoln. and unideal moisture absorption of CNCs. We, in this study, developed a high-performance photonic humidity composite sensor that consisted of CNCs and polyacrylamide; chem. bonding was induced between the two components by using glutaraldehyde as a bridging agent. The composites inherited the chiral nematic structure of CNCs and maintained it well through a cycling test. A distinct color change was obsd. for these composites used as a humidity indicator; the change was caused by polyacrylamide swelling with water and thus enlarging the helical pitch of the chiral nematic structure. The composites showed no degrdn. of the sensing performance through cycling. The excellent cycling stability was attributed to the bonding between polyacrylamide and CNCs. This composite strategy can extend to the development of other photonic indicators.
- 166Zhao, T. H.; Parker, R. M.; Williams, C. A.; Lim, K. T. P.; Frka-Petesic, B.; Vignolini, S. Printing of Responsive Photonic Cellulose Nanocrystal Microfilm Arrays. Adv. Funct. Mater. 2019, 29, 1804531 DOI: 10.1002/adfm.201804531Google ScholarThere is no corresponding record for this reference.
- 167Chen, H.; Hou, A.; Zheng, C.; Tang, J.; Xie, K.; Gao, A. Light- and Humidity-Responsive Chiral Nematic Photonic Crystal Films Based on Cellulose Nanocrystals. ACS Appl. Mater. Interfaces 2020, 12, 24505– 24511, DOI: 10.1021/acsami.0c05139Google Scholar167Light- and humidity-responsive chiral nematic photonic crystal films based on cellulose nanocrystalsChen, Huanghuang; Hou, Aiqin; Zheng, Changwu; Tang, Jing; Xie, Kongliang; Gao, AiqinACS Applied Materials & Interfaces (2020), 12 (21), 24505-24511CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)Light- and humidity-responsive chiral nematic photonic crystal (PC) films contg. cellulose nanocrystals (CNCs) were fabricated. A photoactive polymer with hydrophilic groups, poly-(3,3'-benzophenone-4,4'-dicarboxylic acid dicarboxylate polyethylene glycol) ester, was coassembled with CNCs to form flexible iridescent films with a tunable chiral nematic order. In the coassembly process, the intermol. hydrogen bonds of CNCs were weakened, which facilitated the fine regulation of the chiral PC nanostructure. The PC films displayed sensitive responses to both light and humidity. With increasing humidity from 30 to 100%, the chiral nematic helix pitch increased from 328 to 422 nm. The color of the PC films changed from blue to green, yellow, orange, and dark red with increasing relative humidity. Over 15 min of light irradn., the absorption intensity of the films increased gradually. The light and humidity responses of the films were reversible. The films maintained their variable cholesteric liq. crystal texture and helical lamellar structure after light irradn. at different humidities. These PC films are expected to be useful in intelligent coatings and 3D printing.
- 168Li, X.; Liu, J.; Li, D.; Huang, S.; Huang, K.; Zhang, X. Bioinspired Multi-Stimuli Responsive Actuators with Synergistic Color- and Morphing-Change Abilities. Adv. Sci. 2021, 8, 2101295 DOI: 10.1002/advs.202101295Google ScholarThere is no corresponding record for this reference.
- 169Sun, C.; Zhu, D.; Jia, H.; Lei, K.; Zheng, Z.; Wang, X. Humidity and Heat Dual Response Cellulose Nanocrystals/Poly(N-Isopropylacrylamide) Composite Films with Cyclic Performance. ACS Appl. Mater. Interfaces 2019, 11, 39192– 39200, DOI: 10.1021/acsami.9b14201Google Scholar169Humidity and Heat Dual Response Cellulose Nanocrystals/Poly(N-Isopropylacrylamide) Composite Films with Cyclic PerformanceSun, Chengyuan; Zhu, Dandan; Jia, Haiyan; Lei, Kun; Zheng, Zhen; Wang, XinlingACS Applied Materials & Interfaces (2019), 11 (42), 39192-39200CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)It has been widely reported that cellulose nanocrystals (CNCs) demonstrate a special structural color, which stems from chiral nematic domains. Herein, the humidity and heat dual response nanocomposite films with multilayered helical structure were prepd. by self-assembling of CNCs and hydrazone groups modified poly(N-isopropylacrylamide) (PNIPAM) copolymers. Furthermore, glutaraldehyde was involved to act as a chem. linker to improve cyclic stability by forming acylhydrazone bonds. The structural color of the films could be easily regulated by humidity, heat, or the content of modified PNIPAM copolymers. The absorption of water in higher humidity led to vol. expansion of the resin, resulting in a red shift for up to 145 nm. In contrast, the resin shrank under the temp. above the lower crit. soln. temp. of PNIPAM, leading to a blue shift for up to 87 nm. It was notable that the change of color can be easily captured by the naked eyes. Moreover, the films exhibited excellent stability and cyclicity in response to either vapor or liq. water due to the chem. linking between CNCs and resins. The as-prepd. CNCs/PNIPAM nanocomposite films with humidity or heat responsibilities are promising in stimuli-responsive sensors, printing industry, surface decorations, and so forth.
- 170Fan, J.; Xu, M.; Xu, Y.-T.; Hamad, W. Y.; Meng, Z.; MacLachlan, M. J. A Visible Multi-Response Electrochemical Sensor Based on Cellulose Nanocrystals. Chem. Eng. J. 2023, 457, 141175 DOI: 10.1016/j.cej.2022.141175Google ScholarThere is no corresponding record for this reference.
- 171Meng, Y.; He, Z.; Dong, C.; Long, Z. Multi-Stimuli-Responsive Photonics Films Based on Chiral Nematic Cellulose Nanocrystals. Carbohydr. Polym. 2022, 277, 118756 DOI: 10.1016/j.carbpol.2021.118756Google Scholar171Multi-stimuli-responsive photonics films based on chiral nematic cellulose nanocrystalsMeng, Yahui; He, Zhibin; Dong, Cuihua; Long, ZhuCarbohydrate Polymers (2022), 277 (), 118756CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)Multiple-stimuli-responsive bio-based materials have received considerable attention for intelligent packaging and anti-counterfeiting applications. Herein, we present a unique biobased photonics film with multi-stimuli responsive behavior based on cellulose nanocrystals (CNCs), sorbitol (S) and anthocyanin (Anth). The resulting photonics film exhibits multi-stimuli responsive behavior to humidity, solvent and pH stimuli. Notably, the photonics film showed dramatic invertible color from blue to fuchsia and high sensitivity at a relative humidity from 50% to 100%. Moreover, the photonics film exhibited fast response and good reversibility under different ethanol concns. Significant color changes of the photonics film were also obsd. in response to pH change in the range of 2 to 12. Particularly, the humidity, solvent and pH responsiveness of the photonics film did not interfere with each other.
- 172Dai, S.; Prempeh, N.; Liu, D.; Fan, Y.; Gu, M.; Chang, Y. Cholesteric Film of Cu(II)-Doped Cellulose Nanocrystals for Colorimetric Sensing of Ammonia Gas. Carbohydr. Polym. 2017, 174, 531– 539, DOI: 10.1016/j.carbpol.2017.06.098Google Scholar172Cholesteric film of Cu(II)-doped cellulose nanocrystals for colorimetric sensing of ammonia gasDai, Shidong; Prempeh, Nana; Liu, Dagang; Fan, Yimin; Gu, Mingyue; Chang, YuCarbohydrate Polymers (2017), 174 (), 531-539CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)With the increasing demand of environmental monitoring for toxic and odorous ammonia gas it is desired to develop specific green, cost-effective and in situ passive colorimetric alternatives to current complex instrumentations. The authors designed an ammonia gas sensor based on cholesteric liq. crystal films of copper(II)-doped cellulose nanocrystals (CNC-Cu(II)) whose structure, optical and sensing properties were studied. The hybrid films using the low doping Cu(II) as a color-tuning agent inherited the chiral nematic signature and optical activity of CNCs, suggesting a strong chelation between copper ions and neg. charged CNCs. The sensing performance illustrates that the CNC-Cu(II)125 film was sensitive to ammonia gas which could merge into nematic layers of CNCs and trigger-sensed to copper ions chelated on CNCs, consequently arousing a red shift of reflective wavelength as well as an effective colorimetric transition. Such a hybrid film is anticipated to boost a new gas sensing regime for fast and effective on-site qual. studies.
- 173Song, W.; Lee, J.-K.; Gong, M. S.; Heo, K.; Chung, W.-J.; Lee, B. Y. Cellulose Nanocrystal-Based Colored Thin Films for Colorimetric Detection of Aldehyde Gases. ACS Appl. Mater. Interfaces 2018, 10, 10353– 10361, DOI: 10.1021/acsami.7b19738Google Scholar173Cellulose Nanocrystal-Based Colored Thin Films for Colorimetric Detection of Aldehyde GasesSong, Wonbin; Lee, Jong-Kwon; Gong, Mi Sic; Heo, Kwang; Chung, Woo-Jae; Lee, Byung YangACS Applied Materials & Interfaces (2018), 10 (12), 10353-10361CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)The authors demonstrate a controllable and reliable process for manifesting color patterns on solid substrates using cellulose nanocrystals (CNCs) without the use of any other chem. pigments. The color can be controlled by adjusting the assembly conditions of the CNC soln. during a dip-and-pull process while aiding the close packing of CNCs on a solid surface with the help of ionic-liq. (1-butyl-3-methylimidazolium) mols. that screen the repelling electrostatic charges between CNCs. By controlling the pulling speed from 3 to 9 μm/min during the dip-and-pull process, the authors were able to control the film thickness from 100 to 300 nm, resulting in films with different colors in the visible range. The optical properties were in good agreement with the finite-difference time-domain simulation results. By functionalizing these films with amine groups, the authors developed colorimetric sensors that can change in color when exposed to aldehyde gases such as formaldehyde or propanal. A principal component anal. showed that the authors can differentiate between different aldehyde gases and other interfering mols. The authors expect that the authors' approach will enable inexpensive and rapid volatile org. compd. detection with on-site monitoring capabilities.
- 174Zhao, G.; Zhang, Y.; Zhai, S.; Sugiyama, J.; Pan, M.; Shi, J.; Lu, H. Dual Response of Photonic Films with Chiral Nematic Cellulose Nanocrystals: Humidity and Formaldehyde. ACS Appl. Mater. Interfaces 2020, 12, 17833– 17844, DOI: 10.1021/acsami.0c00591Google Scholar174Dual Response of Photonic Films with Chiral Nematic Cellulose Nanocrystals: Humidity and FormaldehydeZhao, Guomin; Zhang, Yin; Zhai, Shengcheng; Sugiyama, Junji; Pan, Mingzhu; Shi, Jingbo; Lu, HongyiACS Applied Materials & Interfaces (2020), 12 (15), 17833-17844CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)Manipulating functional stimuli-responsive materials has been a hot topic in the research of smart sensors and anticounterfeiting encryption. Here, a novel functional chiral nematic cellulose nanocrystal (CNC) film showing dual responsiveness to humidity and formaldehyde gas was fabricated. The chiral nematic CNC iridescent film could respond to environmental humidity and formaldehyde gas changes by reversible motion. Interestingly, the humidity sensitivity of the CNC iridescent film could be gated by exposing the film to formaldehyde gas. At the same time, the formaldehyde-responsive behavior is strongly affected by the relative humidity (RH), and the response range could be tuned by changing the RH over a wide range. Importantly, the formaldehyde-induced color change could be altered from invisible to visible by the naked eye when the film was exposed to a humid environment. The mechanism of this dual response of the CNC iridescent film is ascribed to the synergistic effect of cooperation and competition between water and formaldehyde mols. by constructing phys. crosslinking networks by hydrogen bonds among water, formaldehyde, and CNCs. Furthermore, the "RH-concn. of formaldehyde gas-color" ternary colorimetric system was simulated, which is thought to endow the CNC iridescent film with great potential to act as a sensor in the convenient visible detection of gaseous formaldehyde. Furthermore, this work provided a promising strategy to design multi-gas-sensitive devices with convenient detection, good stability, and excellent reversibility.
- 175Zhang, Z.-L.; Dong, X.; Fan, Y.-N.; Yang, L.-M.; He, L.; Song, F.; Wang, X.-L.; Wang, Y.-Z. Chameleon-Inspired Variable Coloration Enabled by a Highly Flexible Photonic Cellulose Film. ACS Appl. Mater. Interfaces 2020, 12, 46710– 46718, DOI: 10.1021/acsami.0c13551Google Scholar175Chameleon-Inspired Variable Coloration Enabled by a Highly Flexible Photonic Cellulose FilmZhang, Ze-Lian; Dong, Xiu; Fan, Yi-Ning; Yang, Lu-Ming; He, Lu; Song, Fei; Wang, Xiu-Li; Wang, Yu-ZhongACS Applied Materials & Interfaces (2020), 12 (41), 46710-46718CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)Due to spontaneous organization of cellulose nanocrystals (CNCs) into the chiral nematic structure that can selectively reflect circularly polarized light within a visible-light region, fabricating stretching deformation-responsive CNC materials is of great interest but is still a big challenge, despite such a function widely obsd. from existing creatures, like a chameleon, because of the inherent brittleness. Here, a flexible network structure is introduced in CNCs, exerting a bridge effect for the rigid nanomaterials. The as-prepd. films display high flexibility with a fracture strain of up to 39%. Notably, stretching-induced structural color changes visible to the naked eye are realized, for the first time, for CNC materials. In addn., the soft materials show humidity- and compression-responsive properties in terms of changing apparent structural colors. Colored marks left by ink-free writing can be shown or hidden by controlling the environmental humidities. This biobased photonic film, acting as a new "smart skin", is potentially used with multifunctions of chromogenic sensing, encryption, and anti-counterfeit.
- 176Lu, R.; Wen, Z.; Zhang, P.; Chen, Y.; Wang, H.; Jin, H.; Zhang, L.; Chen, Y.; Wang, S.; Pan, S. Color-Tunable Perovskite Nanomaterials with Intense Circularly Polarized Luminescence and Tailorable Compositions. Small 2024, 20, 2311013 DOI: 10.1002/smll.202311013Google ScholarThere is no corresponding record for this reference.
- 177Nguyen, T.-D.; Lizundia, E.; Niederberger, M.; Hamad, W. Y.; MacLachlan, M. J. Self-Assembly Route to TiO2 and TiC with a Liquid Crystalline Order. Chem. Mater. 2019, 31, 2174– 2181, DOI: 10.1021/acs.chemmater.9b00462Google Scholar177Self-Assembly Route to TiO2 and TiC with a Liquid Crystalline OrderNguyen, Thanh-Dinh; Lizundia, Erlantz; Niederberger, Markus; Hamad, Wadood Y.; MacLachlan, Mark J.Chemistry of Materials (2019), 31 (6), 2174-2181CODEN: CMATEX; ISSN:0897-4756. (American Chemical Society)We report the liq. cryst. self-assembly of cellulose nanocrystals (CNCs) with peroxotitanate to replicate large freestanding mesoporous films of TiO2 and chiral nematic TiC structures. The compatibility of cellulose liq. crystals with water-sol. peroxotitanate enabled them to self-assemble into flexible chiral nematic TiO2/cellulose composite films. The highly compatible peroxotitanate/CNC mixt. is a new liq. cryst. system to investigate the development of photonic films with tunable optical properties and structural replication by varying the ratio of constituents. Iridescent peroxotitanate/CNC composites were heated under hydrothermal conditions and calcined to generate layered mesoporous anatase TiO2 replicas that are robust, semitransparent films. Through magnesiothermic redn., we transformed carbonized peroxotitanate/CNC assemblies to mesoporous TiC with a chiral nematic order. Our work shows the potential of the mesoporous TiC to function as a long-life cycle rechargeable lithium-ion battery anode material and may extend this route to other peroxometallate compds.
- 178Kim, M.; Han, M. J.; Lee, H.; Flouda, P.; Bukharina, D.; Pierce, K. J.; Adstedt, K. M.; Buxton, M. L.; Yoon, Y. H.; Heller, W. T.; Singamaneni, S.; Tsukruk, V. V. Bio-Templated Chiral Zeolitic Imidazolate Framework for Enantioselective Chemoresistive Sensing. Angew. Chem., Int. Ed. 2023, 62, e202305646 DOI: 10.1002/anie.202305646Google ScholarThere is no corresponding record for this reference.
- 179Dujardin, E.; Blaseby, M.; Mann, S. Synthesis of Mesoporous Silica by Sol-Gel Mineralisation of Cellulose Nanorod Nematic Suspensions. J. Mater. Chem. 2003, 13, 696– 699, DOI: 10.1039/b212689cGoogle Scholar179Synthesis of mesoporous silica by sol-gel mineralization of cellulose nanorod nematic suspensionsDujardin, Erik; Blaseby, Matthew; Mann, StephenJournal of Materials Chemistry (2003), 13 (4), 696-699CODEN: JMACEP; ISSN:0959-9428. (Royal Society of Chemistry)Mesoporous silica was synthesized by sol-gel mineralization using nematic liq. cryst. templates consisting of partially ordered suspensions of cellulose rod-like nanocrystals, ca. 145 × 13 nm in size. The nanorods were prepd. by acid hydrolysis of cellulose powder and concd. droplets evapd. onto glass slides to form nematic liq. crystals. Addn. of an aq. alk. soln. of pre-hydrolyzed tetramethoxysilane to the droplets resulted in a birefringent cellulose-silica composite that was subsequently calcined at 400°C for 2 h. Removal of the cellulose nanorod template produced a birefringent silica replica that exhibited patterned mesoporosity due to the presence of co-aligned cylindrical pores, ∼15 nm in diam. and 10 nm in wall thickness. TEM studies suggest that a chiral imprint of the helically ordered cellulose nanorods was imposed on the silica structure, although further studies are required to confirm these preliminary observations. As cellulose nanorods can be prepd. from renewable, inexpensive sources, they offer a cost-effective, environmentally benign route to the template-directed synthesis of mesoporous materials.
- 180Gesesse, G. D.; Li, C.; Paineau, E.; Habibi, Y.; Remita, H.; Colbeau-Justin, C.; Ghazzal, M. N. Enhanced Photogenerated Charge Carriers and Photocatalytic Activity of Biotemplated Mesoporous TiO2 Films with a Chiral Nematic Structure. Chem. Mater. 2019, 31, 4851– 4863, DOI: 10.1021/acs.chemmater.9b01465Google Scholar180Enhanced photogenerated charge carriers and photocatalytic activity of biotemplated mesoporous TiO2 films with a chiral nematic structureGesesse, Getaneh Diress; Li, Chunyu; Paineau, Erwan; Habibi, Youssef; Remita, Hynd; Colbeau-Justin, Christophe; Ghazzal, Mohamed NawfalChemistry of Materials (2019), 31 (13), 4851-4863CODEN: CMATEX; ISSN:0897-4756. (American Chemical Society)Improving the photogeneration and the lifetime of charge carriers assocd. with light harvesting is among the main challenges facing materials for photocatalysis. We report here the synthesis of mesoporous TiO2 contg. a replica of a chiral nematic structure (CNS) as a photocatalyst with improved light harvesting and photogenerated charge carriers under UV illumination. The CNS of cellulose nanocrystal photonic films, obtained by an evapn.-induced self-assembly method, were successfully transferred into an inorg. TiO2 film by sol-gel mineralization of the biotemplate. The stopband of the photonic films was adjusted by controlling the amt. of added D-glucose. The improvement of the kinetics of phenol photocatalytic degrdn. and H2 prodn. and the enhancement of the TiO2 photocond. as measured by time-resolved microwave cond., compared to mesoporous TiO2, strongly suggest an increase in light harvesting. The CNS microdomains in TiO2 increase the light scattering within the nanostructure and, thus, the absorption factor of TiO2, resulting in higher photoefficiency. This peculiar structure is used for the deposition of gold nanoparticles (AuNPs) inside the mesopores that are left by the mineralization of the biotemplate. AuNPs act as cocatalysts by leveraging highly photogenerated charge carriers for the prodn. of H2. This straightforward method opens up new opportunities, esp. for a wide range of materials, where converting photons into energy remains a major challenge.
- 181Andrew, L. J.; Gillman, E. R.; Walters, C. M.; Lizundia, E.; MacLachlan, M. J. Multi-Responsive Supercapacitors from Chiral Nematic Cellulose Nanocrystal-Based Activated Carbon Aerogels. Small 2023, 19, 2301947 DOI: 10.1002/smll.202301947Google ScholarThere is no corresponding record for this reference.
- 182Khan, M. K.; Giese, M.; Yu, M.; Kelly, J. A.; Hamad, W. Y.; MacLachlan, M. J. Flexible Mesoporous Photonic Resins with Tunable Chiral Nematic Structures. Angew. Chem., Int. Ed. 2013, 52, 8921– 8924, DOI: 10.1002/anie.201303829Google Scholar182Flexible Mesoporous Photonic Resins with Tunable Chiral Nematic StructuresKhan, Mostofa K.; Giese, Michael; Yu, Marcus; Kelly, Joel A.; Hamad, Wadood Y.; MacLachlan, Mark J.Angewandte Chemie, International Edition (2013), 52 (34), 8921-8924CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)Herein we report a mesoporous phenol-formaldehyde (PF) resin that exhibits the chiral nematic order of the CNCs, leading to colorful polymer films. In comparison to other CNC-templated solids, the flexibility and responsive swelling behavior of the mesoporous films make them appealing for potential application in sensing and optics. This PF resin is the first of a family of plastic materials whose tunable properties might favorably combine chiral nematic coloration and mesoporosity.
- 183Sun, J.; Ji, X.; Li, G.; Zhang, Y.; Liu, N.; Li, H.; Qin, M.; Yuan, Z. Chiral Nematic Latex-GO Composite Films with Synchronous Response of Color and Actuation. J. Mater. Chem. C 2019, 7, 104– 110, DOI: 10.1039/C8TC04319AGoogle ScholarThere is no corresponding record for this reference.
- 184Yang, N.; Ji, X.; Sun, J.; Zhang, Y.; Xu, Q.; Fu, Y.; Li, H.; Qin, M.; Yuan, Z. Photonic Actuators with Predefined Shapes. Nanoscale 2019, 11, 10088– 10096, DOI: 10.1039/C9NR02294EGoogle Scholar184Photonic actuators with predefined shapesYang, Na; Ji, Xingxiang; Sun, Juanjuan; Zhang, Yu; Xu, Qinghua; Fu, Yingjuan; Li, Hongguang; Qin, Menghua; Yuan, ZaiwuNanoscale (2019), 11 (20), 10088-10096CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)Developing actuators with multi-responsibility, large deformation, and predefined shapes is crit. for the application of actuators in the field of artificial intelligence. Herein, we report the prepn. of a new type of unimorph actuators contg. phenol-formaldelyde resin (PFR) and graphene oxide (GO) using the chiral nematic structure of cellulose nanocrystals (CNCs) as the template. The so-obtained PFR/GO films have a unimorph structure with an asym. distribution of GO across the film. They exhibit synchronous responses of both photonic properties and actuation to humidifying/dehumidifying. Moreover, PFR/GO films can be forged into desired shapes by aldehyde treatment, and thereby are able to produce complex movements. In addn., the objects with predetd. shapes show good shape recovery capability upon many wetting-drying cycles, esp. through the treatment with formaldehyde. A mechanism model for shape predetn. by aldehyde treatment is suggested based on exptl. details. By further designing the predetd. shapes and patterns, such PFR/GO actuators may hold great promise for smart actuation devices of highly complex movements.
- 185Khan, M. K.; Bsoul, A.; Walus, K.; Hamad, W. Y.; MacLachlan, M. J. Photonic Patterns Printed in Chiral Nematic Mesoporous Resins. Angew. Chem., Int. Ed. 2015, 54, 4304– 4308, DOI: 10.1002/anie.201410411Google Scholar185Photonic Patterns Printed in Chiral Nematic Mesoporous ResinsKhan, Mostofa K.; Bsoul, Anas; Walus, Konrad; Hamad, Wadood Y.; MacLachlan, Mark J.Angewandte Chemie, International Edition (2015), 54 (14), 4304-4308CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)Chiral nematic mesoporous phenol-formaldehyde resins, which were prepd. using cellulose nanocrystals as a template, can be used as a substrate to produce latent photonic images. These resins undergo swelling, which changes their reflected color. By writing on the films with chem. inks, the d. of methylol groups in the resin changes, subsequently affecting their degree of swelling and, consequently, their color. Writing on the films gives latent images that are revealed only upon swelling of the films. Using inkjet printing, it is possible to make higher resoln. photonic patterns both as text and images that can be visualized by swelling and erased by drying. This novel approach to printing photonic patterns in resin films may be applied to anti-counterfeit tags, signage, and decorative applications.
- 186Khan, M. K.; Hamad, W. Y.; MacLachlan, M. J. Tunable Mesoporous Bilayer Photonic Resins with Chiral Nematic Structures and Actuator Properties. Adv. Mater. 2014, 26, 2323– 2328, DOI: 10.1002/adma.201304966Google Scholar186Tunable Mesoporous Bilayer Photonic Resins with Chiral Nematic Structures and Actuator PropertiesKhan, Mostofa K.; Hamad, Wadood Y.; MacLachlan, Mark J.Advanced Materials (Weinheim, Germany) (2014), 26 (15), 2323-2328CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)Novel bilayer formaldehyde-phenol resin films were developed with mesoporosity and chiral nematic structures exhibiting photonic and actuator properties simultaneously. Chiral nematic structures were embedded into these materials in a scalable and straightforward layer-by-layer synthetic method using cellulose nanocrystals as a template. The concurrence of stimuli-responsive actuation and variation in photonic properties makes these materials appealing for applications in optics and soft robotics.
- 187Nishimura, T.; Ito, T.; Yamamoto, Y.; Yoshio, M.; Kato, T. Macroscopically Ordered Polymer/CaCO3 Hybrids Prepared by Using a Liquid-Crystalline Template. Angew. Chem., Int. Ed. 2008, 47, 2800– 2803, DOI: 10.1002/anie.200705062Google Scholar187Macroscopically ordered polymer/CaCO3 hybrids prepared by using a liquid-crystalline templateNishimura, Tatsuya; Ito, Takahiro; Yamamoto, Yuya; Yoshio, Masafumi; Kato, TakashiAngewandte Chemie, International Edition (2008), 47 (15), 2800-2803CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)Unidirectionally aligned hybrids consisting of chitin and calcite were obtained by template crystn. of CaCO3 in an ordered chitin film with nematic liq.-cryst. mol. alignment. The picture shows the resulting chitin matrix contg. CaCO3 rods, schematically and in the form of an optical micrograph, and the selected-area electron diffraction pattern of a thin section of a single rod.
- 188Matsumura, S.; Kajiyama, S.; Nishimura, T.; Kato, T. Formation of Helically Structured Chitin/CaCO3 Hybrids through an Approach Inspired by the Biomineralization Processes of Crustacean Cuticles. Small 2015, 11, 5127– 5133, DOI: 10.1002/smll.201501083Google Scholar188Formation of Helically Structured Chitin/CaCO3 Hybrids through an Approach Inspired by the Biomineralization Processes of Crustacean CuticlesMatsumura, Shunichi; Kajiyama, Satoshi; Nishimura, Tatsuya; Kato, TakashiSmall (2015), 11 (38), 5127-5133CODEN: SMALBC; ISSN:1613-6810. (Wiley-VCH Verlag GmbH & Co. KGaA)Chitin/CaCO3 hybrids with helical structures are formed through a biomineralization-inspired crystn. process under ambient conditions. Liq.-cryst. chitin whiskers are used as helically ordered templates. The liq.-cryst. structures are stabilized by acidic polymer networks which interact with the chitin templates. The crystn. of CaCO3 is conducted by soaking the templates in the colloidal suspension of amorphous CaCO3 (ACC) at room temp. At the initial stage of crystn., ACC particles are introduced inside the templates, and they crystallize to CaCO3 nanocrystals. The acidic polymer networks induce CaCO3 crystn. The characterization of the resultant hybrids reveals that they possess helical order and homogeneous hybrid structures of chitin and CaCO3, which resemble the structure and compn. of the exoskeleton of crustaceans.
- 189Belamie, E.; Boltoeva, M. Y.; Yang, K.; Cacciaguerra, T.; Alonso, B. Tunable Hierarchical Porosity from Self-Assembled Chitin-Silica Nano-Composites. J. Mater. Chem. 2011, 21, 16997– 17006, DOI: 10.1039/c1jm12110cGoogle Scholar189Tunable hierarchical porosity from self-assembled chitin-silica nano-compositesBelamie, Emmanuel; Boltoeva, Maria Yu; Yang, Ke; Cacciaguerra, Thomas; Alonso, BrunoJournal of Materials Chemistry (2011), 21 (42), 16997-17006CODEN: JMACEP; ISSN:0959-9428. (Royal Society of Chemistry)We studied new mesoporous materials with original properties and obtained from self-assembled chitin-silica nano-composites. Our novel synthesis allows the controlled colloidal assembly of α-chitin nanorods (bundles of elongated chitin monocrystals) and siloxane oligomers. Calcination of nano-composites results in mesoporous silica materials. Their pore vol. fraction [phis]POR (0-0.52) is strongly correlated to the initial chitin content. Using N2 sorption and TEM data, we identify and characterize primary and secondary textural units related to the imprints of chitin monocrystals (2.5 nm wide) and nanorods (20-30 nm wide) resp. Primary textural units are preserved over a wide [phis]POR range (linear relationship between pore vol. and sp. surface area). The coating of monocrystals by siloxane oligomers leads to a siloxane network of fractal nature as deduced from complementary SAXS data. Beyond a crit. value [phis]POR' estd. near 0.2, the coating is partial, and the porosity becomes more open and connected. At larger scales, the arrangements of secondary textural units result in complex textures and long-range ordering, showing similarities with textural features found in natural materials. We discuss the competition between entropy-driven transitions typical of anisotropic particles and kinetic arrest due to colloidal gelation and inorg. condensation. Finally, a schematic model for texture formation is given.
- 190Nguyen, T.-D.; Shopsowitz, K. E.; MacLachlan, M. J. Mesoporous Silica and Organosilica Films Templated by Nanocrystalline Chitin. Chem.─Eur. J. 2013, 19, 15148– 15154, DOI: 10.1002/chem.201301929Google ScholarThere is no corresponding record for this reference.
- 191Nguyen, T.-D.; Shopsowitz, K. E.; MacLachlan, M. J. Mesoporous Nitrogen-Doped Carbon from Nanocrystalline Chitin Assemblies. J. Mater. Chem. A 2014, 2, 5915– 5921, DOI: 10.1039/c3ta15255cGoogle Scholar191Mesoporous nitrogen-doped carbon from nanocrystalline chitin assembliesNguyen, Thanh-Dinh; Shopsowitz, Kevin E.; MacLachlan, Mark J.Journal of Materials Chemistry A: Materials for Energy and Sustainability (2014), 2 (16), 5915-5921CODEN: JMCAET; ISSN:2050-7496. (Royal Society of Chemistry)Nanocryst. chitin has been used both as a soft template and as the carbon and nitrogen sources for prepg. mesoporous nitrogen-doped carbon materials with a layered structure. The chitin nanorods prepd. by sequential deacetylation and hydrolysis of fibrils isolated from king crab shells organized into a nematic liq.-cryst. phase. Silica/chitin composites obtained by sol-gel condensation of silica in the presence of liq.-cryst. chitin were carbonized and etched to yield mesoporous nitrogen-doped carbon films that replicate the layered nematic organization of the nanocryst. chitin films. The high degree of mesoporosity and nitrogen doping in the liq.-cryst. biopolymer-derived carbon replicas allows them to function as efficient supercapacitor electrode materials. Films embedded with tin oxide nanoparticles displayed superior performance for supercapacitor electrodes.
- 192Xiong, R.; Yu, S.; Kang, S.; Adstedt, K. M.; Nepal, D.; Bunning, T. J.; Tsukruk, V. V. Integration of Optical Surface Structures with Chiral Nanocellulose for Enhanced Chiroptical Properties. Adv. Mater. 2020, 32, 1905600 DOI: 10.1002/adma.201905600Google Scholar192Integration of Optical Surface Structures with Chiral Nanocellulose for Enhanced Chiroptical PropertiesXiong, Rui; Yu, Shengtao; Kang, Saewon; Adstedt, Katarina M.; Nepal, Dhriti; Bunning, Timothy J.; Tsukruk, Vladimir V.Advanced Materials (Weinheim, Germany) (2020), 32 (2), 1905600CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)The integration of chiral organization with photonic structures found in many living creatures enables unique chiral photonic structures with a combination of selective light reflection, light propagation, and CD. Inspired by these natural integrated nanostructures, hierarchical chiroptical systems that combine imprinted surface optical structures with the natural chiral organization of cellulose nanocrystals are fabricated. Different periodic photonic surface structures with rich diffraction phenomena, including various optical gratings and microlenses, are replicated into nanocellulose film surfaces over large areas. The resulting films with embedded optical elements exhibit vivid, controllable structural coloration combined with highly asym. broadband CD and a microfocusing capability not typically found in traditional photonic bioderived materials without compromising their mech. strength. The strategy of imprinting surface optical structures onto chiral biomaterials facilitates a range of prospective photonic applications, including stereoscopic displays, polarization encoding, chiral polarizers, and colorimetric chiral biosensing.
- 193Rofouie, P.; Alizadehgiashi, M.; Mundoor, H.; Smalyukh, I. I.; Kumacheva, E. Self-Assembly of Cellulose Nanocrystals into Semi-Spherical Photonic Cholesteric Films. Adv. Funct. Mater. 2018, 28, 1803852 DOI: 10.1002/adfm.201803852Google ScholarThere is no corresponding record for this reference.
- 194Kim, M.; Pierce, K.; Krecker, M.; Bukharina, D.; Adstedt, K.; Nepal, D.; Bunning, T.; Tsukruk, V. V. Monolithic Chiral Nematic Organization of Cellulose Nanocrystals under Capillary Confinement. ACS Nano 2021, 15, 19418– 19429, DOI: 10.1021/acsnano.1c05988Google Scholar194Monolithic Chiral Nematic Organization of Cellulose Nanocrystals under Capillary ConfinementKim, Minkyu; Pierce, Kellina; Krecker, Michelle; Bukharina, Daria; Adstedt, Katarina; Nepal, Dhriti; Bunning, Timothy; Tsukruk, Vladimir V.ACS Nano (2021), 15 (12), 19418-19429CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)We demonstrate bioenabled crack-free chiral nematic films prepd. via a unidirectional flow of cellulose nanocrystals (CNCs) in the capillary confinement. To facilitate the uniform long-range nanocrystal organization during drying, we utilized tunicate-inspired hydrogen-bonding-rich 3,4,5-trihydroxyphenethylamine hydrochloride (TOPA) for phys. crosslinking of nanocrystals with enhanced hydrogen bonding and polyethylene glycol (PEG) as a relaxer of internal stresses in the vicinity of the capillary surface. The CNC/TOPA/PEG film is organized as a left-handed chiral structure parallel to flat walls, and the inner vol. of the films displayed transitional herringbone organization across the interfacial region. The resulting thin films also exhibit high mech. performance compared to brittle films with multiple cracks commonly obsd. for capillary-formed pure CNC films. The chiral nematic ordering of modified TOPA-PEG-CNC material propagates through the entire thickness of robust monolithic films and across centimeter-sized surface areas, facilitating consistent, vivid iridescence, and enhanced circular polarization. The best performance that prevents the cracks was achieved for a CNC/TOPA/PEG film with a minimal, 3% amt. of TOPA. Overall, we suggest that intercalation of small highly adhesive mols. to cellulose nanocrystal-polymer matrixes can facilitate uniform flow of liq. crystal phase and drying inside the capillary, resulting in improvement of the ultimate tensile strength and toughness (77% and 100% increase, resp.) with controlled uniform optical reflection and enhanced circular polarization unachievable during regular drying conditions.
- 195Chu, G.; Qu, D.; Camposeo, A.; Pisignano, D.; Zussman, E. When Nanocellulose Meets Diffraction Grating: Freestanding Photonic Paper with Programmable Optical Coupling. Mater. Horiz. 2020, 7, 511– 519, DOI: 10.1039/C9MH01485CGoogle Scholar195When nanocellulose meets diffraction grating: freestanding photonic paper with programmable optical couplingChu, Guang; Qu, Dan; Camposeo, Andrea; Pisignano, Dario; Zussman, EyalMaterials Horizons (2020), 7 (2), 511-519CODEN: MHAOBM; ISSN:2051-6355. (Royal Society of Chemistry)Photonic crystals based on plasmonic or dielec. periodic structures have attracted considerable interest owing to their capabilities to control light-matter interactions with tailored precision. By using a nanocellulose derived chiral liq. crystal as a building block, here we demonstrate a bio-inspired dual photonic structure that contains the combination of microscopic periodic 1D surface grating and nanoscopic helical organization, giving rise to programmable color mixing and polarization rotation. We show that a variation in the photonic band-gap in the bulk matrix leads to simultaneous control over the reflection and diffraction of light with controllable iridescence.
- 196Droguet, B. E.; Liang, H.-L.; Frka-Petesic, B.; Parker, R. M.; De Volder, M. F. L.; Baumberg, J. J.; Vignolini, S. Large-Scale Fabrication of Structurally Coloured Cellulose Nanocrystal Films and Effect Pigments. Nat. Mater. 2022, 21, 352– 358, DOI: 10.1038/s41563-021-01135-8Google Scholar196Large-scale fabrication of structurally coloured cellulose nanocrystal films and effect pigmentsDroguet, Benjamin E.; Liang, Hsin-Ling; Frka-Petesic, Bruno; Parker, Richard M.; De Volder, Michael F. L.; Baumberg, Jeremy J.; Vignolini, SilviaNature Materials (2022), 21 (3), 352-358CODEN: NMAACR; ISSN:1476-1122. (Nature Portfolio)Cellulose nanocrystals are renewable plant-based colloidal particles capable of forming photonic films by solvent-evapn.-driven self-assembly. So far, the cellulose nanocrystal self-assembly process has been studied only at a small scale, neglecting the limitations and challenges posed by the continuous deposition processes that are required to exploit this sustainable material in an industrial context. Here, we addressed these limitations by using roll-to-roll deposition to produce large-area photonic films, which required optimization of the formulation of the cellulose nanocrystal suspension and the deposition and drying conditions. Furthermore, we showed how metre-long structurally colored films can be processed into effect pigments and glitters that are dispersible, even in water-based formulations. These promising effect pigments are an industrially relevant cellulose-based alternative to current products that are either micro-polluting (for example, non-biodegradable microplastic glitters) or based on carcinogenic, unsustainable or unethically sourced compds. (for example, titania or mica).
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Abstract
Figure 1
Figure 1. Schematic diagram showing the main contents of this review from the introduction and self-assembly of PNs to the potential applications of the self-assembled materials. Responsive photonic materials. Reprinted with permission from ref (6). Copyright 2017 Wiley-VCH. Reprinted with permission under a Creative Commons Attribution (CC BY) License from ref (7). Copyright 2019 Springer Nature. Photonic encryption. Reprinted with permission from refs (8) and (9). Copyright 2020 Wiley-VCH. Copyright 2023 Wiley-VCH. Mesoporous materials. Reprinted with permission from refs (10) and (11). Copyright 2010 Springer Nature. Copyright 2012 Wiley-VCH. Others. Reprinted with permission from ref (12). Copyright 2020 Wiley-VCH. Reprinted with permission under a Creative Commons Attribution (CC BY) License from ref (13). Copyright 2022 Springer Nature.
Figure 2
Figure 2. a) Schematic diagram showing the isolation of CNCs from plants. Reprinted with permission from ref (33). Copyright 2021 Wiley-VCH. TEM images of CNCs extracted from b) bacterial cellulose, c) wood pulp, and d) tunicate. b) Reprinted with permission from ref (34). Copyright 2023 Elsevier. c) Reprinted with permission from ref (35). Copyright 2020 American Chemical Society. d) Reprinted with permission from ref (36). Copyright 2024 Elsevier.
Figure 3
Figure 3. a) Schematic illustration of the hierarchical organization of the exoskeleton of lobster. Reprinted with permission from ref (53). Copyright 2022 Wiley-VCH. b) TEM image of ChNCs extracted from the chitin of crab shell through acid hydrolysis. Reprinted with permission from ref (54). Copyright 2020 American Chemical Society. c) TEM image of ChNCs extracted from the chitin of crab shell through TEMPO-mediated oxidation. Reprinted with permission from ref (55). Copyright 2022 Elsevier. d) TEM image of ChNCs after periodate oxidation from shrimp chitin. Reprinted with permission from ref (56). Copyright 2021 Royal Society of Chemistry.
Figure 4
Figure 4. a) Helicoidal arrangement of molecules in chiral nematic liquid crystals. Reprinted with permission from ref (68). Copyright 2018 Wiley-VCH. b) Photograph of Danaea nodosa. Reprinted with permission from ref (69). Copyright 2007 University of Chicago Press. c) Cross-sectional TEM image of the cell wall of a juvenile Danaea nodosa leaf. Reprinted with permission from ref (70). Copyright 1993 Wiley-VCH. d) TEM image of helicoidal cell wall of Elaphoglossum herminieri. Reprinted with permission under a Creative Commons Attribution (CC BY) License from ref (71). Copyright 2024 Oxford University Press. e) Photograph of Microsorum thailandicum. f) TEM image of the adaxial cell wall. Reprinted with permission from ref (72). Copyright 2018 Royal Society. g) Photograph of Mapania caudata. h) TEM image of the adaxial wall near the surface. i) TEM image of the central part of the adaxial wall. Reprinted with permission from ref (73). Copyright 2013 Oxford University Press.
Figure 5
Figure 5. a) Picture of a Pollia condensata fruit. b,c) Microscope image in the two circular polarization channels showing the strongly pointillistic coloration originating in individually colored cells of the epicarp. d) TEM image of the epicarp showing the typical helicoidal motif (red line shows one pitch). Reprinted with permission from ref (78). Copyright 2012 National Academy of Sciences. e) Picture of Margaritaria nobilis fruits. f,g) Microscope image of a fresh fruit in different circular polarization configurations. h) TEM image of the cell wall of Margaritaria nobilis fruits. Reprinted with permission under a Creative Commons Attribution 4.0 International License from ref (79). Copyright 2016, The Royal Society.
Figure 6
Figure 6. a) Photograph of the beetle Chrysina gloriosa under a left circular polarizer. b) Photograph of the beetle Chrysina gloriosa under a right circular polarizer. c) A microscopy image shows the exoskeleton of beetle Chrysina gloriosa. Reprinted with permission from ref (81). Copyright 2021 Optica Publishing Group. d) Cross-sectional SEM image of green stripes. e) Cross-sectional SEM image of silver stripes. Reprinted with permission from ref (82). Copyright 2017 Elsevier. f) Photograph of Plusiotis resplendens. Reprinted with permission from ref (83). Copyright 2005 Springer Nature. g) Electron micrograph showing a cross-section of the reflective layer of Plusiotis resplendens. Reprinted with permission from ref (84). Copyright 1971 The Royal Society.
Figure 7
Figure 7. a) Phase diagram illustrating the transition of isotropic-to-chiral nematic phase and the corresponding equilibrium pitch with the increasing of CNC concentration. Reprinted with permission under a Creative Commons Attribution (CC BY) License from ref (18). Copyright 2017 Wiley-VCH. b) Regions show the (I) planar texture and (II) fingerprint texture. Reprinted with permission under a Creative Commons Attribution (CC BY) License from ref (85). Copyright 2015 MDPI. c) Schematic diagram showing the chiral nematic structures formed by CNCs that can selectively reflect CPL. Reprinted with permission from ref (86). Copyright 2019 Royal Society of Chemistry.
Figure 8
Figure 8. a) PLM images of the bulk chiral nematic phase at 10 and 43 °C. Reprinted with permission from ref (20). Copyright 2018 American Chemical Society. b) PLM images of CNC-X films under different annealing temperatures and annealing times. The annealing times from left to right in each group of images are 0 h, 30 min, 1, 3, 6, 12, 18, 24, and 48 h. Scale bar: 100 μm. Reprinted with permission from ref (124). Copyright 2021 Elsevier. c) PLM images and cross-sectional SEM images of CNC iridescent films with different ultrasonic time. d) Schematic illustration of the mechanism of sonication-driven increase in pitch. Reprinted with permission from ref (125). Copyright 2024 Wiley-VCH. e) Schematic illustration of the evolution of particle distribution under sonication. Scale bar 200 nm. f) The relationship between relative volume fraction of each particle subpopulation and sonication dose. g) Modulation of chiral strength with relative dopant volume fraction. Reprinted with permission under a Creative Commons Attribution (CC BY) License from ref (29). Copyright 2022 Springer Nature. h) Schematic illustration of the fabrication of Mn2+ doped C–CNC iridescent films and images of the color of the prepared iridescent films as a function of ultrasound time. i) Schematic diagram of the mechanism of ultrasonic destruction of C–CNC agglomerates. Reprinted with permission from ref (126). Copyright 2022 Elsevier.
Figure 9
Figure 9. a) Evolution of iridescence in chiral nematic suspension with increasing electric field. Reprinted with permission from ref (123). Copyright 2017 Wiley-VCH. b) Schematic diagram of the reversible electrical response properties of CNC tactoid and PLM images of tactoid with increasing E. Reprinted with permission from ref (137). Copyright 2020, American Chemical Society. c) Schematic diagram of the self-assembly of CNC by electrophoretic deposition. d) Photographs of the electrodeposited CNC film on a flexible substrate. e–f) SEM images of CNC film illustrating the chiral nematic structures under different magnifications. Reprinted with permission from ref (138). Copyright 2022, Wiley-VCH.
Figure 10
Figure 10. a) Films produced by slow evaporation of aqueous CNC suspension in a dish placed on NdFeB magnets. Reprinted with permission under a Creative Commons Attribution (CC BY) License from ref (140). Copyright 2017 Wiley-VCH. b) SEM images of CNC films under magnetic fields with varying strength. Reprinted with permission from ref (141). Copyright 2020 American Chemical Society. c) PLM image showing the phase separation of a CNC/MNP dispersion in a vertical gradient magnetic field. d) 3D model showing the phase separation and orientation of tactoids when the magnet was placed under the vial. e) 3D model showing the phase separation and orientation of tactoids when the magnet was placed on the right side of the vial. Reprinted with permission from ref (142). Copyright 2019 Elsevier.
Figure 11
Figure 11. a) Photographs and PLM images of iridescent CNC films fabricated with the EISA technique (left) and the VASA technique (right). Reprinted with permission from ref (147). Copyright 2019, Elsevier. b) Schematic illustration of pressure-directed self-assembly of chiral pearlescent CNC films. c) Cross-sectional SEM image of the chiral pearlescent CNC films. Reprinted with permission from ref (94). Copyright 2023 Wiley-VCH. d) Schematic illustration of VASA of CNCs. Reprinted with permission from ref (148). Copyright 2020 Elsevier. e) Schematic illustration of the CNC/PEG/GO film fabrication process. Reprinted with permission from ref (149). Copyright 2024 Elsevier.
Figure 12
Figure 12. a) Schematic illustration of CNC suspensions from rest to increasing applied shear rates. Reprinted with permission from ref (152). Copyright 2021 Elsevier. Schematic illustration of the reorientation of CNCs by shear flow b) in-plane unwinding process and c) later vertical helical unwinding process. Reprinted with permission from ref (153). Copyright 2023 American Chemical Society. d) The CNC particles were reoriented from a chiral nematic state to an aligned structure via stretching. Reprinted with permission under a Creative Commons Attribution (CC BY) License from ref (7). Copyright 2019 Springer Nature. e) Schematic illustration of the hydrodynamic alignment of CNCs in dynamic hydrogels under stretching. Reprinted with permission from ref (154). Copyright 2019 American Chemical Society.
Figure 13
Figure 13. a) Schematic illustration of the sequential programming and recovery of CNC-SMP. Photos of the CNC-SMP pressed at b) 0 N, c) 140 N, d) 180 N, and e) 230 N. Reprinted with permission from ref (156). Copyright 2021 Wiley-VCH. f) Pressure-responsive property of the hydrogel. Reprinted with permission from ref (157). Copyright 2023 Wiley-VCH.
Figure 14
Figure 14. a) PLM images of 5.0 wt % ChNC aqueous suspension with different salt concentrations. b) PLM images of 5.0 wt % ChNC aqueous suspensions with different pH values. Reprinted with permission from ref (159). Copyright 2019 Elsevier. c) TEM images of ChNCs with different deacetylation time. d) PLM images of ChNC suspensions. Reprinted with permission from ref (160). Copyright 2023 American Chemical Society. e) Photograph and optical microscopy image of the ChNC film before (A, B) and after alkaline treatment (C, D). f) Reflection spectra under crossed polarizers of (B) and (D). Reprinted with permission under a Creative Commons Attribution (CC BY) License from ref (92). Copyright 2022 Wiley-VCH.
Figure 15
Figure 16
Figure 16. a) Schematic diagram showing the structure of iridescent films changed with humidity. Reprinted with permission from ref (165). Copyright 2017, American Chemical Society. b) Dot matrix image of a “Christmas tree” observed by circular polarizer. c) CNC microfilm obtained on a flexible PDMS substrate. d) CNC photonic array transferred to adhesive tape. e) Response of CNC microfilms to humidity changes. Reprinted with permission under a Creative Commons Attribution (CC BY) License from ref (166). Copyright 2019, Wiley-VCH.
Figure 17
Figure 17. a) Schematic diagram of the coassembly process of the CNC-based composite films. b) Response of composite films to light at different relative humidities. Reprinted with permission from ref (167). Copyright 2020 American Chemical Society. c) Schematic diagram of the production of bioinspired composite films. d) A smart “mimosa” responded to moisture and NIR light. Reprinted with permission under a Creative Commons Attribution (CC BY) License from ref (168). Copyright 2021 Wiley-VCH. e) CNC composite film was used as humidity-responsive color-changing paper. Reprinted with permission from ref (169). Copyright 2019 American Chemical Society.
Figure 18
Figure 18. a) Schematic diagram of the structure and color-tuning mechanism of CNC or CNC-Cu(II) films. Reprinted with permission from ref (172). Copyright 2017 Elsevier. b) Schematic diagram of the production of the CNC-based films. c) Images of a CNC colorimetric sensor before (left) and after (right) exposure to formaldehyde at a concentration of 100 ppm. Reprinted with permission from ref (173). Copyright 2018 American Chemical Society. d) Optical images of a CNC film at different RHs. e) Optical images of a CNC film at different concentrations of formaldehyde gas. Reprinted with permission from ref (174). Copyright 2020 American Chemical Society.
Figure 19
Figure 19. a) Schematic diagram showing the fabrication of CNC composite films with uniform and tunable colors. b) Ten fundamental elements, representing 0–9 decimal, were formed by stacking patterned composite films between the crossed polarizers. c) A 3D code for information storage and encryption through the combination of fundamental elements. Reprinted with permission from ref (8). Copyright 2020 Wiley-VCH. d) The potential of chiral photonic CNC films for polarization-based encryption. Reprinted with permission from ref (21). Copyright 2018 Wiley-VCH. e) Integrated five-channel encryption of CNC/bioAuNCs biolabels. Reprinted with permission from ref (9). Copyright 2023 Wiley-VCH.
Figure 20
Figure 20. a) Photograph of mesoporous silica films with different colors. b–c) Photograph of a mesoporous silica film taken at different incidences. Reprinted with permission from ref (10). Copyright 2010 Springer Nature. d) Schematic diagram of in situ confined growth of PNCs within CNC film. Reprinted with permission from ref (176). Copyright 2024 Wiley-VCH. e) Photo of TiC film. f) PLM image of the TiC film. Reprinted with permission from ref (177). Copyright 2019 American Chemical Society. g) Schematic illustration of the production of templated ZIF. h) Typical I–V curve of templated ZIF to l-Ala and d-Ala at 400 μM. i) Current change (ΔI/I0) plot of templated ZIF at different l- and d-Ala concentrations from 50 to 400 μM. Reprinted with permission from ref (178). Copyright 2023 Wiley-VCH.
Figure 21
Figure 21. a) Schematic diagram showing the synthesis of mesoporous chiral nematic phenol-formaldehyde resins. b) Photographs of a sample under left-handed circular polarizer (left) and right-handed polarizer (right). c) Schematic illustration (top) and photographs (bottom) of the samples in water and ethanol mixtures. Reprinted with permission from ref (182). Copyright 2013, Wiley-VCH. d) Schematic illustration of the fabrication of latex-GO composite film. e) Photographs of the film strips immersed in the mixtures of H2O/n-PrOH with different VH2O. Reprinted with permission from ref (183). Copyright 2019 Royal Society of Chemistry. f) Illustration and photographs of the film strips with predetermined shapes treated by FoA and their responses to the wetting-drying circle. Reprinted with permission from ref (184). Copyright 2019 Royal Society of Chemistry. g) Photographs of mesoporous polymer resin films in a mixture of water and ethanol with different proportions. h) Complicated image patterned on a mesoporous film, and the pattern can be revealed by swelling in water. i) Complicated image patterned on a mesoporous film, and the pattern can be revealed by swelling in 20/80 (v/v) water/ethanol mixture. Reprinted with permission from ref (185). Copyright 2015, Wiley-VCH.
Figure 22
Figure 22. a) Schematic illustration of the self-assembly of chiral CNC photonic structures with surface gratings. b) Photographs of CNC film patterned with the grating periodicity of 1.6 μm under no polarizers (left), left-hand circular polarizer (middle), and right-hand circular polarizer (right). Reprinted with permission from ref (192). Copyright 2019 Wiley-VCH. c) Fabrication of scalable LMC fibers. d) Schematic illustration showing the formation of the chiral nematic liquid crystalline phase within the LMC fibers and the mechanism of the self-organization of LMCs in a dynamically confined, cylindrical geometry. e) PLM-λ images of the LMC fibers with different optical appearances by applying external stress. f) PLM-λ images of two crossed LMC fibers showing different combinations of optical appearances at the position of right-rotated 45°. g) Schematic illustration of the advanced fabrics showing different colors for identification. Reprinted with permission from ref (12). Copyright 2020 Wiley-VCH. h) Photographs of four curved films with a radius R = 2 mm (top) and the corresponding polarized optical microscopy images of these films (down). Reprinted with permission from ref (193). Copyright 2018 Wiley-VCH. i) PLM images of pure and composite CNC films drying in the rectangular capillaries. Reprinted with permission from ref (194). Copyright 2021 American Chemical Society. j) Photographs of cellulosic photonic pigments. Reprinted with permission under a Creative Commons Attribution (CC BY) License from ref (13). Copyright 2022 Springer Nature.
Figure 23
Figure 23. a) Flowchart describing the key steps in the fabrication of photonic CNC particles. b) Photograph of the corona etching step. c) Photograph of the slot-die coating of CNC suspension onto the web. d) Photograph of static drying at 20 °C. e) Photograph of continuous progressive drying at 60 °C. f) In-line peeling of a CNC film from the web. g) CNC films deposited onto a black PET web. h) Photograph of a free-standing R2R-cast CNC film. i) Untreated (left) and heat-treated (right) photonic CNC particles embedded in transparent varnish before size sorting. j) Heat-treated photonic CNC particles (pigments) immersed in ethanol and 50% aqueous ethanol (from left to right). Reprinted with permission from ref (196). Copyright 2022 Springer Nature.
References
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- 6Yao, K.; Meng, Q.; Bulone, V.; Zhou, Q. Flexible and Responsive Chiral Nematic Cellulose Nanocrystal/Poly(ethylene glycol) Composite Films with Uniform and Tunable Structural Color. Adv. Mater. 2017, 29, 1701323 DOI: 10.1002/adma.201701323There is no corresponding record for this reference.
- 7Kose, O.; Tran, A.; Lewis, L.; Hamad, W. Y.; MacLachlan, M. J. Unwinding a Spiral of Cellulose Nanocrystals for Stimuli-Responsive Stretchable Optics. Nat. Commun. 2019, 10, 510, DOI: 10.1038/s41467-019-08351-67Unwinding a spiral of cellulose nanocrystals for stimuli-responsive stretchable opticsKose, Osamu; Tran, Andy; Lewis, Lev; Hamad, Wadood Y.; MacLachlan, Mark J.Nature Communications (2019), 10 (1), 510CODEN: NCAOBW; ISSN:2041-1723. (Nature Research)Cellulose nanocrystals (CNCs) derived from biomass spontaneously organize into a helical arrangement, termed a chiral nematic structure. This structure mimics the organization of chitin found in the exoskeletons of arthropods, where it contributes to their remarkable mech. strength. Here, we demonstrate a photonic sensory mechanism based on the reversible unwinding of chiral nematic CNCs embedded in an elastomer, leading the materials to display stimuli-responsive stretchable optics. Vivid interference colors appear as the film is stretched and disappear when the elastomer returns to its original shape. This reversible optical effect is caused by a mech.-induced transition of the CNCs between a chiral nematic and pseudo-nematic arrangement.
- 8Yang, Y.; Wang, X.; Huang, H.; Cui, S.; Chen, Y.; Wang, X.; Zhang, K. Modular Nanocomposite Films with Tunable Physical Organization of Cellulose Nanocrystals for Photonic Encryption. Adv. Opt. Mater. 2020, 8, 2000547 DOI: 10.1002/adom.2020005478Modular Nanocomposite Films with Tunable Physical Organization of Cellulose Nanocrystals for Photonic EncryptionYang, Yang; Wang, Xiaojie; Huang, Heqin; Cui, Shiqiang; Chen, Ye; Wang, Xiaohui; Zhang, KaiAdvanced Optical Materials (2020), 8 (12), 2000547CODEN: AOMDAX; ISSN:2195-1071. (Wiley-VCH Verlag GmbH & Co. KGaA)Reported herein is the novel achievement of uniform and tunable interference colors of nanocomposite films contg. organized cellulose nanocrystals (CNCs) from dynamic hydrogel precursors. Homogeneous and amendable interference colors with broad range are obtained either by stacking the nanocomposite films to adjust the amt. of CNCs in the propagation pathway of light or by regulating the rotation angles between the individual films to alter the relative organization of CNCs within the system. Moreover, the precise and controllable patterned CNC composite films with multicolors in one film are facilely fabricated for the first time from the patterned hydrogel precursors. Based on this stacking/rotation-method, these patterned nanocomposite films with tunable interference colors can be further applied as fundamental elements for optical encryption by establishing a ternary-coded decimal system with encoded decimal numerals, paving the way for the development of photonic functional materials based on CNCs.
- 9Zhou, Y.; Lu, C.; Lu, Z.; Guo, Z.; Ye, C.; Tsukruk, V. V.; Xiong, R. Chiroptical Nanocellulose Bio-Labels for Independent Multi-Channel Optical Encryption. Small 2023, 19, 2303064 DOI: 10.1002/smll.2023030649Chiroptical Nanocellulose Bio-Labels for Independent Multi-Channel Optical EncryptionZhou, Yi; Lu, Canhui; Lu, Zhixing; Guo, Zhen; Ye, Chunhong; Tsukruk, Vladimir V.; Xiong, RuiSmall (2023), 19 (32), 2303064CODEN: SMALBC; ISSN:1613-6810. (Wiley-VCH Verlag GmbH & Co. KGaA)Advanced multiplexing optical labels with multiple information channels provide a powerful strategy for large-capacity and high-security information encryption. However, current optical labels face challenges of difficulty to realize independent multi-channel encryption, cumbersome design, and environmental pollution. Herein, multiplexing chiroptical bio-labels integrating with multiple optical elements, including structural color, photoluminescence (PL), circular polarized light activity, humidity-responsible color, and micro/nano phys. patterns, are constructed in complex design based on host-guest self-assembly of cellulose nanocrystals and bio-gold nanoclusters. The thin nanocellulose labels exhibit tunable circular polarized structural color crossover the entire visible wavelength and circularly polarized PL with the highest-recorded dissymmetry factor up to 1.05 due to the well-ordered chiral organization of templated gold nanoclusters. Most importantly, these elements can independently encode customized anti-counterfeiting information to achieve five independent channels of high-level anti-counterfeiting, which are rarely achieved in traditional materials and design counterparts. Considering the exceptional seamless integration of five independent encryption channels and the recyclable features of labels, the bio-labels have great potential for the next generation anti-counterfeiting materials technol.
- 10Shopsowitz, K. E.; Qi, H.; Hamad, W. Y.; MacLachlan, M. J. Free-Standing Mesoporous Silica Films with Tunable Chiral Nematic Structures. Nature 2010, 468, 422– 425, DOI: 10.1038/nature0954010Free-standing mesoporous silica films with tunable chiral nematic structuresShopsowitz, Kevin E.; Qi, Hao; Hamad, Wadood Y.; MacLachlan, Mark J.Nature (London, United Kingdom) (2010), 468 (7322), 422-425CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)Chirality at the mol. level is found in diverse biol. structures, such as polysaccharides, proteins and DNA, and is responsible for many of their unique properties. Introducing chirality into porous inorg. solids may produce new types of materials that could be useful for chiral sepn., stereospecific catalysis, chiral recognition (sensing) and photonic materials. Template synthesis of inorg. solids using the self-assembly of lyotropic liq. crystals offers access to materials with well-defined porous structures, but only recently has chirality been introduced into hexagonal mesostructures through the use of a chiral surfactant. Efforts to impart chirality at a larger length scale using self-assembly are almost unknown. Here we describe the development of a photonic mesoporous inorg. solid that is a cast of a chiral nematic liq. crystal formed from nanocryst. cellulose. These materials may be obtained as free-standing films with high surface area. The peak reflected wavelength of the films can be varied across the entire visible spectrum and into the near-IR through simple changes in the synthetic conditions. To the best of our knowledge these are the first materials to combine mesoporosity with long-range chiral ordering that produces photonic properties. Our findings could lead to the development of new materials for applications in, for example, tuneable reflective filters and sensors. In addn., this type of material could be used as a hard template to generate other new materials with chiral nematic structures.
- 11Shopsowitz, K. E.; Stahl, A.; Hamad, W. Y.; MacLachlan, M. J. Hard Templating of Nanocrystalline Titanium Dioxide with Chiral Nematic Ordering. Angew. Chem., Int. Ed. 2012, 51, 6886– 6890, DOI: 10.1002/anie.20120111311Hard Templating of Nanocrystalline Titanium Dioxide with Chiral Nematic OrderingShopsowitz, Kevin E.; Stahl, Alexander; Hamad, Wadood Y.; MacLachlan, Mark J.Angewandte Chemie, International Edition (2012), 51 (28), 6886-6890, S6886/1-S6886/9CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)Chiral nematic mesoporous silica can be used as a template to synthesize titania. In this hard-templating method, structural features are replicated at several length scales: (1) the titania is mesoporous with a surface area and pore size that is detd. by the porosity of the starting silica template; (2) the material obtained selectively reflects left-handed circularly polarized light, which indicates a chiral nematic organization of the titania crystallites; and (3) the titania is obtained as films with similar dimensions as the original silica films.
- 12Liu, Y.; Wu, P. Bioinspired Hierarchical Liquid-Metacrystal Fibers for Chiral Optics and Advanced Textiles. Adv. Funct. Mater. 2020, 30 (27), 2002193 DOI: 10.1002/adfm.20200219312Bioinspired Hierarchical Liquid-Metacrystal Fibers for Chiral Optics and Advanced TextilesLiu, Yanjun; Wu, PeiyiAdvanced Functional Materials (2020), 30 (27), 2002193CODEN: AFMDC6; ISSN:1616-301X. (Wiley-VCH Verlag GmbH & Co. KGaA)The organization of nanoparticles in constrained geometries has attracted increasing attention due to their promising structures and topologies. However, the control of hierarchical structures with tailored periodicity at different length scales and topol. stabilization in a dynamic environment are very limited and challenging. Herein, through self-assembly of cellulose nanocrystals (CNCs) within an in situ formed hydrogel sheath using a simple microfluidic strategy, a new breed of liq. crystal (LC) fibers with hierarchical core-sheath architectures, metaperiodic cholesteric alignments, and 3D topol. defects, termed as liq. metacrystal (LMC) fibers, is created. The resulting LMC fibers not only exhibit vivid, tunable interference colors, and even inverse optical activity but also have a unique ability to precisely regulate linearly and circularly polarized light in a half-sync/half-async form. Furthermore, robust hydrogel sheath enables the LMCs with alignment stability and configuration programmability during drying, which endows the unprecedented freedom to tailor different optical appearances for polarization-based encryption and recognition. This work opens an avenue toward the fabrication of length-scale colloidal LCs with continuous and stable topologies and expands the application regimes of LC materials in chiral optics and smart textiles.
- 13Parker, R. M.; Zhao, T. H.; Frka-Petesic, B.; Vignolini, S. Cellulose Photonic Pigments. Nat. Commun. 2022, 13, 3378, DOI: 10.1038/s41467-022-31079-913Cellulose photonic pigmentsParker, Richard M.; Zhao, Tianheng H.; Frka-Petesic, Bruno; Vignolini, SilviaNature Communications (2022), 13 (1), 3378CODEN: NCAOBW; ISSN:2041-1723. (Nature Portfolio)When pursuing sustainable approaches to fabricate photonic structures, nature can be used as a source of inspiration for both the nanoarchitecture and the constituent materials. Although several biomaterials have been promised as suitable candidates for photonic materials and pigments, their fabrication processes have been limited to the small to medium-scale prodn. of films. Here, by employing a substrate-free process, structurally colored microparticles are produced via the confined self-assembly of a cholesteric cellulose nanocrystal (CNC) suspension within emulsified microdroplets. Upon drying, the droplets undergo multiple buckling events, which allow for greater contraction of the nanostructure than predicted for a spherical geometry. This buckling, combined with a solvent or thermal post-treatment, enables the prodn. of dispersions of vibrant red, green, and blue cellulose photonic pigments. The hierarchical structure of these pigments enables the deposition of coatings with angular independent color, offering a consistent visual appearance across a wide range of viewing angles.
- 14Habibi, Y.; Lucia, L. A.; Rojas, O. J. Cellulose Nanocrystals: Chemistry, Self-Assembly, and Applications. Chem. Rev. 2010, 110, 3479– 3500, DOI: 10.1021/cr900339w14Cellulose Nanocrystals: Chemistry, Self-Assembly, and ApplicationsHabibi, Youssef; Lucia, Lucian A.; Rojas, Orlando J.Chemical Reviews (Washington, DC, United States) (2010), 110 (6), 3479-3500CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)A review discussing chem. and phys. features of the most dominant fundamental building block in the biosphere, cellulose nanocrystals. A brief introduction to cellulose was followed by the discussion of morphol., chem., including prepn. and chem. routes for functionalization, and self-assembly in various media under various conditions, and applications in the nanocomposites.
- 15Bai, L.; Liu, L.; Esquivel, M.; Tardy, B. L.; Huan, S.; Niu, X.; Liu, S.; Yang, G.; Fan, Y.; Rojas, O. J. Nanochitin: Chemistry, Structure, Assembly, and Applications. Chem. Rev. 2022, 122, 11604– 11674, DOI: 10.1021/acs.chemrev.2c0012515Nanochitin: Chemistry, Structure, Assembly, and ApplicationsBai, Long; Liu, Liang; Esquivel, Marianelly; Tardy, Blaise L.; Huan, Siqi; Niu, Xun; Liu, Shouxin; Yang, Guihua; Fan, Yimin; Rojas, Orlando J.Chemical Reviews (Washington, DC, United States) (2022), 122 (13), 11604-11674CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)A review. Chitin, a fascinating biopolymer found in living organisms, fulfills current demands of availability, sustainability, biocompatibility, biodegradability, functionality, and renewability. A feature of chitin is its ability to structure into hierarchical assemblies, spanning the nano- and macroscales, imparting toughness and resistance (chem., biol., among others) to multicomponent materials as well as adding adaptability, tunability, and versatility. Retaining the inherent structural characteristics of chitin and its colloidal features in dispersed media has been central to its use, considering it as a building block for the construction of emerging materials. Top-down chitin designs have been reported and differentiate from the traditional mol.-level, bottom-up synthesis and assembly for material development. Such topics are the focus of this Review, which also covers the origins and biol. characteristics of chitin and their influence on the morphol. and phys.-chem. properties. We discuss recent achievements in the isolation, deconstruction, and fractionation of chitin nanostructures of varying axial aspects (nanofibrils and nanorods) along with methods for their modification and assembly into functional materials. We highlight the role of nanochitin in its native architecture and as a component of materials subjected to multiscale interactions, leading to highly dynamic and functional structures. We introduce the most recent advances in the applications of nanochitin-derived materials and industrialization efforts, following green manufg. principles. Finally, we offer a crit. perspective about the adoption of nanochitin in the context of advanced, sustainable materials.
- 16Tran, A.; Boott, C. E.; MacLachlan, M. J. Understanding the Self-Assembly of Cellulose Nanocrystals-Toward Chiral Photonic Materials. Adv. Mater. 2020, 32, 1905876 DOI: 10.1002/adma.20190587616Understanding the Self-Assembly of Cellulose Nanocrystals-Toward Chiral Photonic MaterialsTran, Andy; Boott, Charlotte E.; MacLachlan, Mark J.Advanced Materials (Weinheim, Germany) (2020), 32 (41), 1905876CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)Review. Over millions of years, animals and plants have evolved complex mols. and structures that endow them with vibrant colors. Among the sources of natural coloration, structural color is prominent in insects, bird feathers, snake skin, plants, and other organisms, where the color arises from the interaction of light with nanoscale features rather than absorption from a pigment. Cellulose nanocrystals (CNCs) are a biorenewable resource that spontaneously organize into chiral nematic liq. crystals having a hierarchical structure that resembles the Bouligand structure of arthropod shells. The periodic, chiral nematic organization of CNC films leads them to diffract light, making them appear iridescent. Over the past two decades, there have been many advances to develop the photonic properties of CNCs for applications ranging from cosmetics to sensors. Here, the origin of color in CNCs, the control of photonic properties of CNC films, the development of new composite materials of CNCs that can yield flexible photonic structures, and the future challenges in this field are discussed. In particular, recent efforts to make flexible photonic materials using CNCs are highlighted.
- 17Wang, P.-X.; Hamad, W. Y.; MacLachlan, M. J. Structure and Transformation of Tactoids in Cellulose Nanocrystal Suspensions. Nat. Commun. 2016, 7, 11515, DOI: 10.1038/ncomms1151517Structure and transformation of tactoids in cellulose nanocrystal suspensionsWang, Pei-Xi; Hamad, Wadood Y.; MacLachlan, Mark J.Nature Communications (2016), 7 (), 11515pp.CODEN: NCAOBW; ISSN:2041-1723. (Nature Publishing Group)Cellulose nanocrystals obtained from natural sources are of great interest for many applications. In water, cellulose nanocrystals form a liq. cryst. phase whose hierarchical structure is retained in solid films after drying. Although tactoids, one of the most primitive components of liq. crystals, are thought to have a significant role in the evolution of this phase, they have evaded structural study of their internal organization. Here we report the capture of cellulose nanocrystal tactoids in a polymer matrix. This method allows us to visualize, for the first time, the arrangement of cellulose nanocrystals within individual tactoids by electron microscopy. Furthermore, we can follow the structural evolution of the liq. cryst. phase from tactoids to iridescent-layered films. Our insights into the early nucleation events of cellulose nanocrystals give important information about the growth of cholesteric liq. cryst. phases, esp. for cellulose nanocrystals, and are crucial for prepg. photonics-quality films.
- 18Parker, R. M.; Guidetti, G.; Williams, C. A.; Zhao, T.; Narkevicius, A.; Vignolini, S.; Frka-Petesic, B. The Self-Assembly of Cellulose Nanocrystals: Hierarchical Design of Visual Appearance. Adv. Mater. 2018, 30, e1704477 DOI: 10.1002/adma.201704477There is no corresponding record for this reference.
- 19Tardy, B. L.; Ago, M.; Guo, J.; Borghei, M.; Kämäräinen, T.; Rojas, O. J. Optical Properties of Self-Assembled Cellulose Nanocrystals Films Suspended at Planar-Symmetrical Interfaces. Small 2017, 13, 1702084 DOI: 10.1002/smll.201702084There is no corresponding record for this reference.
- 20Nyström, G.; Arcari, M.; Adamcik, J.; Usov, I.; Mezzenga, R. Nanocellulose Fragmentation Mechanisms and Inversion of Chirality from the Single Particle to the Cholesteric Phase. ACS Nano 2018, 12, 5141– 5148, DOI: 10.1021/acsnano.8b0051220Nanocellulose fragmentation mechanisms and inversion of chirality from single particle to cholesteric phaseNystrom, Gustav; Arcari, Mario; Adamcik, Jozef; Usov, Ivan; Mezzenga, RaffaeleACS Nano (2018), 12 (6), 5141-5148CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)Understanding how nanostructure and nanomechanics influence phys. material properties on the micro- and macroscale is an essential goal in soft condensed matter research. Mechanisms governing fragmentation and chirality inversion of filamentous colloids are of specific interest because of their crit. role in load-bearing and self-organizing functionalities of soft nanomaterials. Here we provide a fundamental insight into the self-organization across several length scales of nanocellulose, an important biocolloid system with wide-ranging applications as structural, insulating, and functional material. Through a combined microscopic and statistical anal. of nanocellulose fibrils at the single particle level, we show how mech. and chem. induced fragmentations proceed in this system. Moreover, by studying the bottom-up self-assembly of fragmented carboxylated cellulose nanofibrils into cholesteric liq. crystals, we show via direct microscopic observations that the chirality is inverted from right-handed at the nanofibril level to left-handed at the level of the liq. crystal phase. These results improve our fundamental understanding of nanocellulose and provide an important rationale for its application in colloidal systems, liq. crystals, and nanomaterials.
- 21Zheng, H.; Li, W.; Li, W.; Wang, X.; Tang, Z.; Zhang, S. X.-A.; Xu, Y. Uncovering the Circular Polarization Potential of Chiral Photonic Cellulose Films for Photonic Applications. Adv. Mater. 2018, 30, 1705948 DOI: 10.1002/adma.201705948There is no corresponding record for this reference.
- 22Narkevicius, A.; Steiner, L. M.; Parker, R. M.; Ogawa, Y.; Frka-Petesic, B.; Vignolini, S. Controlling the Self-Assembly Behavior of Aqueous Chitin Nanocrystal Suspensions. Biomacromolecules 2019, 20, 2830– 2838, DOI: 10.1021/acs.biomac.9b0058922Controlling the Self-Assembly Behavior of Aqueous Chitin Nanocrystal SuspensionsNarkevicius, Aurimas; Steiner, Lisa M.; Parker, Richard M.; Ogawa, Yu; Frka-Petesic, Bruno; Vignolini, SilviaBiomacromolecules (2019), 20 (7), 2830-2838CODEN: BOMAF6; ISSN:1525-7797. (American Chemical Society)As with many other biosourced colloids, chitin nanocrystals (ChNCs) can form liq. cryst. phases with chiral nematic ordering. In this work, we demonstrate that it is possible to finely tune the liq. cryst. behavior of aq. ChNC suspensions finely. Such control was made possible by carefully studying how the hydrolysis conditions and suspension treatments affect the colloidal and self-assembly properties of ChNCs. Specifically, we systematically investigated the effects of duration and acidity of chitin hydrolysis required to ext. ChNCs, as well as the effects of the tip sonication energy input, degree of acetylation, pH and ionic strength. Finally, we show that by controlled water evapn., it is possible to retain and control the helicoidal ordering in dry films, leading to a hierarchical architecture analogous to that found in nature, e.g. in crab shells. We believe that this work serves as a comprehensive insight into ChNC prepn. and handling which is required to unlock the full potential of this material in both a scientific and industrial context.
- 23Rofouie, P.; Galati, E.; Sun, L.; Helmy, A. S.; Kumacheva, E. Hybrid Cholesteric Films with Tailored Polarization Rotation. Adv. Funct. Mater. 2019, 29, 1905552 DOI: 10.1002/adfm.20190555223Hybrid Cholesteric Films with Tailored Polarization RotationRofouie, Pardis; Galati, Elizabeth; Sun, Lu; Helmy, Amr S.; Kumacheva, EugeniaAdvanced Functional Materials (2019), 29 (43), 1905552CODEN: AFMDC6; ISSN:1616-301X. (Wiley-VCH Verlag GmbH & Co. KGaA)Incorporation of metal nanoparticles in chiral (Ch) films of cellulose nanocrystals (CNCs) enhances nanoparticle plasmon resonances, due to the coupling of the intrinsic properties of the plasmonic guest and the photonic properties of the Ch-CNC host. In contrast with previous reports, the properties of the Ch-CNC host are focused and an effective strategy is developed for tuning the optical polarization rotation of the composite films formed by the CNCs and gold nanoparticles. A twofold enhancement in the polarization rotation power of the composite Ch-CNC films, with an insignificant change in the incurred optical losses, is achieved by varying the d. and dimensions of gold nanoparticles embedded in the Ch-CNC films. For such films, a new approach is developed to obtain broadband CD by fabricating films from mixts. of CNC suspensions ultrasonicated for different time intervals. These new findings enable fine-tuning of the power and spectral range of the polarization rotation and offer a novel strategy for the fabrication of broadband reflectors and polarizers, smart solar windows, and detectors for circularly polarized light.
- 24Xiong, R.; Yu, S.; Smith, M. J.; Zhou, J.; Krecker, M.; Zhang, L.; Nepal, D.; Bunning, T. J.; Tsukruk, V. V. Self-Assembly of Emissive Nanocellulose/Quantum Dot Nanostructures for Chiral Fluorescent Materials. ACS Nano 2019, 13, 9074– 9081, DOI: 10.1021/acsnano.9b0330524Self-Assembly of Emissive Nanocellulose/Quantum Dot Nanostructures for Chiral Fluorescent MaterialsXiong, Rui; Yu, Shengtao; Smith, Marcus J.; Zhou, Jing; Krecker, Michelle; Zhang, Lijuan; Nepal, Dhriti; Bunning, Timothy J.; Tsukruk, Vladimir V.ACS Nano (2019), 13 (8), 9074-9081CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)Chiral fluorescent materials with fluorescent nanoparticles assembled into a chiral structure represent a grand challenge. Here, we report self-assembled emissive needle-like nanostructures through decorating cellulose nanocrystals (CNCs) with carbon quantum dots (CQDs). This assembly is facilitated by the heterogeneous amphiphilic interactions between natural and synthetic components. These emissive nanostructures can self-organize into chiral nematic solid-state materials with enhanced mech. performance. The chiral CQD/CNC films demonstrate an intense iridescent appearance superimposed with enhanced luminescence that is significantly higher than that for CQD films and other reported CQD/CNC films. A characteristic fluorescent fingerprint signature is obsd. in the CQD/CNC film, proving the well-defined chiral organization of fluorescent nanostructures. The chiral organization of CQDs enables the solid CQD/CNC film to form a right-hand chiral fluorescence with an asym. factor of -0.2. Addnl., we developed chem. 2D printing and soft lithog. patterning techniques to fabricate the freestanding chiral fluorescent patterns that combines mech. integrity and chiral nematic structure with light diffraction and emission.
- 25Guo, J.; Haehnle, B.; Hoenders, D.; Creusen, G.; Jiao, D.; Kuehne, A. J. C.; Walther, A. Biodegradable Laser Arrays Self-Assembled from Plant Resources. Adv. Mater. 2020, 32, 2002332 DOI: 10.1002/adma.20200233225Biodegradable Laser Arrays Self-Assembled from Plant ResourcesGuo, Jiaqi; Haehnle, Bastian; Hoenders, Daniel; Creusen, Guido; Jiao, Dejin; Kuehne, Alexander J. C.; Walther, AndreasAdvanced Materials (Weinheim, Germany) (2020), 32 (29), 2002332CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)The transition toward future sustainable societies largely depends on disruptive innovations in biobased materials to substitute nonsustainable advanced functional materials. In the field of optics, advanced devices (e.g., lasers or metamaterial devices) are typically manufd. using top-down engineering and synthetic materials. This work breaks with such concepts and switchable lasers self-assembled from plant-based cellulose nanocrystals and fluorescent polymers at room temp. and from water are shown. Controlled structure formation allows laser-grade cholesteric photonic bandgap materials, in which the photonic bandgap is matched to the fluorescence emission to function as an efficient resonator for low threshold multimode lasing. The lasers can be switched on and off using humidity, and can be printed into pixelated arrays. Addnl., the materials exhibit stiffness above typical thermoplastic polymers and biodegradability in soil. The concept showcases that highly advanced functions can be encoded into biobased materials, and opens the design space for future sustainable optical devices of unprecedented function.
- 26Lizundia, E.; Nguyen, T.-D.; Winnick, R. J.; MacLachlan, M. J. Biomimetic Photonic Materials Derived from Chitin and Chitosan. J. Mater. Chem. C 2021, 9, 796– 817, DOI: 10.1039/D0TC05381C26Biomimetic photonic materials derived from chitin and chitosanLizundia, Erlantz; Nguyen, Thanh-Dinh; Winnick, Rebecca J.; MacLachlan, Mark J.Journal of Materials Chemistry C: Materials for Optical and Electronic Devices (2021), 9 (3), 796-817CODEN: JMCCCX; ISSN:2050-7534. (Royal Society of Chemistry)A review. Insight into the hierarchical structures of carbohydrate nanofibrils such as chitin and cellulose is important in order to exploit their unique geometrical features for materials innovation and emerging applications. Chitin nanofibrils are responsible for the outstanding mech. strength in exoskeletons of some animals, and for the iridescence of some insects. The appearance of structural colors in chitin-constituted insect shells inspires scientists to mimic their photonic properties in artificial analogs, paving the path towards new optical technologies. Although the intricate organization of chitin nanofibrils in these structures was recognized several decades ago, the use of chitin nanofibrils in biomimetic templating, to transfer their sophisticated structures into solid-state materials, has only recently been exploited. Cellulose nanocrystals (CNCs) are high aspect ratio nanomaterials prepd. by acid hydrolysis of the most abundant carbohydrate in plants. Similar to chitin nanofibrils, CNCs are readily dispersible in water and present an intriguing self-assembly behavior that can be exploited as a lyotropic liq.-cryst. template to fabricate photonic materials. Extended efforts of this research strategy are necessary to seek new organized structures of carbohydrate nanofibrils and to develop synthetic methods that offer access to novel biomimetic materials that combine chirality, coloration, and mesoporosity through colloidal templating and self-assembly. This Review summarizes recent progress to create functional optical materials templated by nanochitin and compares it with developments using nanocellulose.
- 27Lee, S. R.; Reichmanis, E.; Srinivasarao, M. Anisotropic Responsive Microgels Based on the Cholesteric Phase of Chitin Nanocrystals. ACS Macro Lett. 2022, 11, 96– 102, DOI: 10.1021/acsmacrolett.1c00675There is no corresponding record for this reference.
- 28Liu, P.; Wang, J.; Qi, H.; Koddenberg, T.; Xu, D.; Liu, S.; Zhang, K. Biomimetic Confined Self-Assembly of Chitin Nanocrystals. Nano Today 2022, 43, 101420 DOI: 10.1016/j.nantod.2022.10142028Biomimetic confined self-assembly of chitin nanocrystalsLiu, Peiwen; Wang, Jiaxiu; Qi, Houjuan; Koddenberg, Tim; Xu, Dan; Liu, Siyuan; Zhang, KaiNano Today (2022), 43 (), 101420CODEN: NTAOCG; ISSN:1748-0132. (Elsevier Ltd.)It is a longstanding challenge to aptly describe the natural assembly process of chitin Bouligand organization as well as biomimetic construct these position-dependent structures with the isolated chitin nanodomains. Here, we report a fixed-boundary evapn.-induced self-assembly (FB-EISA) modality using chitin nanocrystals (ChNCs) in the capillaries, where the generation of continuous and ordered anisotropic phase relies on the growth of phase boundary towards the opposite direction of water evapn. Distinct from the previous EISA modalities with the moving evapn. interface, the pinned air-liq. interface at the end of capillaries in a confined environment acts as the evapn. interface and initial deposition site of ChNCs simultaneously. During the whole self-assembly process via successive evapn., the generation of droplets-like ChNCs clusters known as tactoids is suppressed. Therefore, continuous birefringent multi-layers as nested multiple paraboloid structures of ChNCs with a d. gradient are gradually generated, before cylindrical tubes are formed finally. The FB-EISA process can be accelerated by heat and maintains stable regardless of vibration or different capillary opening directions relative to gravity direction. This FB-EISA modality in confined geometry allows rapid formation of ChNCs-based photonics-quality structure of larger length scales and enables us to deepen our understanding of the natural self-assembly process in diverse biol. species.
- 29Parton, T. G.; Parker, R. M.; van de Kerkhof, G. T.; Narkevicius, A.; Haataja, J. S.; Frka-Petesic, B.; Vignolini, S. Chiral Self-Assembly of Cellulose Nanocrystals Is Driven by Crystallite Bundles. Nat. Commun. 2022, 13, 2657, DOI: 10.1038/s41467-022-30226-629Chiral self-assembly of cellulose nanocrystals is driven by crystallite bundlesParton, Thomas G.; Parker, Richard M.; van de Kerkhof, Gea T.; Narkevicius, Aurimas; Haataja, Johannes S.; Frka-Petesic, Bruno; Vignolini, SilviaNature Communications (2022), 13 (1), 2657CODEN: NCAOBW; ISSN:2041-1723. (Nature Portfolio)The transfer of chirality across length-scales is an intriguing and universal natural phenomenon. However, connecting the properties of individual building blocks to the emergent features of their resulting large-scale structure remains a challenge. In this work, we investigate the origins of mesophase chirality in cellulose nanocrystal suspensions, whose self-assembly into chiral photonic films has attracted significant interest. By correlating the ensemble behavior in suspensions and films with a quant. morphol. anal. of the individual nanoparticles, we reveal an inverse relationship between the cholesteric pitch and the abundance of laterally-bound composite particles. These 'bundles' thus act as colloidal chiral dopants, analogous to those used in mol. liq. crystals, providing the missing link in the hierarchical transfer of chirality from the mol. to the colloidal scale.
- 30Peng, Z.; Lin, Q.; Tai, Y.-A. A.; Wang, Y. Applications of Cellulose Nanomaterials in Stimuli-Responsive Optics. J. Agric. Food Chem. 2020, 68, 12940– 12955, DOI: 10.1021/acs.jafc.0c0474230Applications of Cellulose Nanomaterials in Stimuli-Responsive OpticsPeng, Zhiwei; Lin, Qinglin; Tai, Yu-An Angela; Wang, YuHuangJournal of Agricultural and Food Chemistry (2020), 68 (46), 12940-12955CODEN: JAFCAU; ISSN:0021-8561. (American Chemical Society)A Review. As one of the most abundant biopolymers, cellulose has been a basic but essential building block of human society, with its use dating back thousands of years. With recent developments in nanotechnol. and increasing environmental concerns, cellulose-based nanomaterials are now gaining attention as promising green material candidates for many high-value applications as a result of their biocompatibility and advantageous phys. and chem. properties. In particular, cellulose nanocrystals are notable for their optical properties that can respond to various environmental stimuli as a result of the unique chiral nematic structure of the material. Compositing cellulosic materials with functional polymers, small mols., and other nanomaterials can further stabilize and amplify these responsive optical signals and introduce multiple new functionalities. On the basis of these capabilities, many advanced applications of cellulose nanomaterials have been proposed, including chem. sensors, photonic papers, decorative coatings, data security, and smart textiles. In this review, we discuss and summarize recent advances in this emerging field of stimuli-responsive optics based on cellulose nanomaterials.
- 31Duan, C.; Cheng, Z.; Wang, B.; Zeng, J.; Xu, J.; Li, J.; Gao, W.; Chen, K. Chiral Photonic Liquid Crystal Films Derived from Cellulose Nanocrystals. Small 2021, 17, 2007306 DOI: 10.1002/smll.20200730631Chiral Photonic Liquid Crystal Films Derived from Cellulose NanocrystalsDuan, Chengliang; Cheng, Zheng; Wang, Bin; Zeng, Jinsong; Xu, Jun; Li, Jinpeng; Gao, Wenhua; Chen, KefuSmall (2021), 17 (30), 2007306CODEN: SMALBC; ISSN:1613-6810. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. As a nanoscale renewable resource derived from lignocellulosic materials, cellulose nanocrystals (CNCs) have the features of high purity, high crystallinity, high aspect ratio, high Young's modulus, and large sp. surface area. The most interesting trait is that they can form the entire films with bright structural colors through the evapn.-induced self-assembly (EISA) process under certain conditions. Structural color originates from micro-nano structure of CNCs matrixes via the interaction of nanoparticles with light, rather than the absorption and reflection of light from the pigment. CNCs are the new generation of photonic liq. crystal materials of choice due to their simple and convenient prepn. processes, environmentally friendly fabrication approaches, and intrinsic chiral nematic structure. Therefore, understanding the forming mechanism of CNCs in nanoarchitectonics is crucial to multiple fields of physics, chem., materials science, and engineering application. Herein, a timely summary of the chiral photonic liq. crystal films derived from CNCs is systematically presented. The relationship of CNC, structural color, chiral nematic structure, film performance, and applications of chiral photonic liq. crystal films is discussed. The review article also summarizes the most recent achievements in the field of CNCs-based photonic functional materials along with the faced challenges.
- 32Xu, C.; Huang, C.; Huang, H. Recent Advances in Structural Color Display of Cellulose Nanocrystal Materials. Appl. Mater. Today 2021, 22, 100912 DOI: 10.1016/j.apmt.2020.100912There is no corresponding record for this reference.
- 33Pei, Y.; Wang, L.; Tang, K.; Kaplan, D. L. Biopolymer Nanoscale Assemblies as Building Blocks for New Materials: A Review. Adv. Funct. Mater. 2021, 31, 2008552 DOI: 10.1002/adfm.20200855233Biopolymer Nanoscale Assemblies as Building Blocks for New Materials: A ReviewPei, Ying; Wang, Lu; Tang, Keyong; Kaplan, David L.Advanced Functional Materials (2021), 31 (15), 2008552CODEN: AFMDC6; ISSN:1616-301X. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. Biopolymers, a class of fascinating polymers from biomass provide sustainability, biodegradability, availability, biocompatibility, and unique properties. A ubiquitous feature of biopolymers is their hierarchical structure, with the presence of well-organized structures from the nanoscale to macroscopic dimensions. This structural organization endows biopolymers with toughness, defect resistance, and bucking adaptability. To retain these inherent structural features, nano-structural assemblies isolated from biomass have been applied as building blocks to construct new biopolymer-based materials. This top-down processing strategy is distinct from the more traditional mol.-level bottom-up design and assembly approach for new materials. In this review, the hierarchical structures of several representative biopolymers (cellulose, chitin, silk, collagen) are introduced with a focus on these nanoscale building blocks, as well as highlighting the similarities and differences in the resp. chemistries and structures. Recent progress in prodn. strategies of these natural building blocks are summarized, covering methods and treatments used for isolations. Finally, approaches and emerging applications of biopolymer-based materials using these natural nano- and meso-scale building blocks are demonstrated in areas of biomedicine, electronics, environmental, packaging, sensing, foods, and cosmetics.
- 34Xia, J.; Sun, X.; Jia, P.; Li, L.; Xu, K.; Cao, Y.; Lü, X.; Wang, L. Multifunctional Sustainable Films of Bacterial Cellulose Nanocrystal-Based, Three-Phase Pickering Nanoemulsions: A Promising Active Food Packaging for Cheese. Chem. Eng. J. 2023, 466, 143295 DOI: 10.1016/j.cej.2023.143295There is no corresponding record for this reference.
- 35Jiang, J.; Carrillo-Enríquez, N. C.; Oguzlu, H.; Han, X.; Bi, R.; Song, M.; Saddler, J. N.; Sun, R.-C.; Jiang, F. High Production Yield and More Thermally Stable Lignin-Containing Cellulose Nanocrystals Isolated Using a Ternary Acidic Deep Eutectic Solvent. ACS Sustainable Chem. Eng. 2020, 8, 7182– 7191, DOI: 10.1021/acssuschemeng.0c0172435High Production Yield and More Thermally Stable Lignin-Containing Cellulose Nanocrystals Isolated Using a Ternary Acidic Deep Eutectic SolventJiang, Jungang; Carrillo-Enriquez, Nancy C.; Oguzlu, Hale; Han, Xushen; Bi, Ran; Song, Mingyao; Saddler, Jack N.; Sun, Run-Cang; Jiang, FengACS Sustainable Chemistry & Engineering (2020), 8 (18), 7182-7191CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)From the aspects of green chem. and sustainability, the using of green and sustainable materials and reagents for nanocellulose prodn. is highly desirable. In this study, an acidic deep eutectic solvent (DES) pretreatment process was developed to fabricate lignin contg. cellulose nanocrystals (LCNCs) from undervalued thermo-mech. pulp (TMP). LCNCs were successfully obtained by using both binary DES (choline chloride - oxalic acid, 1:1 molar ratio), and ternary DES (choline chloride - oxalic acid - p-toluenesulfonic acid, 2:1:1 molar ratio) followed by a mild mech. disintegration process. The LCNCs with width around 6 nm, thickness of 3.3 nm, retained cellulose I crystallinity of 57.4%, high lignin content of 47.8%, and high yield of 66% were obtained under the optimum conditions using ternary DES at 80°C for 3 h pretreatment. Meanwhile, the LCNCs obtained from this process showed a high thermal stability (Tmax of 358°C), which exhibited a promising potential for further applications. The results demonstrate that the environmentally friendly DES is a promising solvent, which can provide a prospective future for both lignocellulosic material utilization and LCNCs isolation. Undervalued thermo-mech. pulp can be facially converted to thermally stable lignin contg. cellulose nanocrystals at 66% yield using a ternary deep eutectic solvent.
- 36Lv, X.; Yu, H.; Han, J.; Hou, Y.; Sun, Y.; Liu, K.; Zhou, W.; Chen, J. Tunicate Cellulose Nanocrystals Reinforced Modified Calcium Sulfate Bone Cement with Enhanced Mechanical Properties for Bone Repair. Carbohydr. Polym. 2024, 323, 121380 DOI: 10.1016/j.carbpol.2023.121380There is no corresponding record for this reference.
- 37Li, T.; Chen, C.; Brozena, A. H.; Zhu, J. Y.; Xu, L.; Driemeier, C.; Dai, J.; Rojas, O. J.; Isogai, A.; Wågberg, L.; Hu, L. Developing Fibrillated Cellulose As a Sustainable Technological Material. Nature 2021, 590, 47– 56, DOI: 10.1038/s41586-020-03167-737Developing fibrillated cellulose as a sustainable technological materialLi, Tian; Chen, Chaoji; Brozena, Alexandra H.; Zhu, J. Y.; Xu, Lixian; Driemeier, Carlos; Dai, Jiaqi; Rojas, Orlando J.; Isogai, Akira; Wagberg, Lars; Hu, LiangbingNature (London, United Kingdom) (2021), 590 (7844), 47-56CODEN: NATUAS; ISSN:0028-0836. (Nature Research)A review. Cellulose is the most abundant biopolymer on Earth, found in trees, waste from agricultural crops and other biomass. The fibers that comprise cellulose can be broken down into building blocks, known as fibrillated cellulose, of varying, controllable dimensions that extend to the nanoscale. Fibrillated cellulose is harvested from renewable resources, so its sustainability potential combined with its other functional properties (mech., optical, thermal and fluidic, for example) gives this nanomaterial unique technol. appeal. Here we explore the use of fibrillated cellulose in the fabrication of materials ranging from composites and macrofibres, to thin films, porous membranes and gels. We discuss research directions for the practical exploitation of these structures and the remaining challenges to overcome before fibrillated cellulose materials can reach their full potential. Finally, we highlight some key issues towards successful manufg. scale-up of this family of materials.
- 38Bethke, K.; Palantöken, S.; Andrei, V.; Roß, M.; Raghuwanshi, V. S.; Kettemann, F.; Greis, K.; Ingber, T. T. K.; Stückrath, J. B.; Valiyaveettil, S.; Rademann, K. Functionalized Cellulose for Water Purification, Antimicrobial Applications, and Sensors. Adv. Funct. Mater. 2018, 28, 1800409 DOI: 10.1002/adfm.201800409There is no corresponding record for this reference.
- 39Zhang, L.; Liao, Y.; Wang, Y.-C.; Zhang, S.; Yang, W.; Pan, X.; Wang, Z. L. Cellulose II Aerogel-Based Triboelectric Nanogenerator. Adv. Funct. Mater. 2020, 30 (28), 2001763 DOI: 10.1002/adfm.20200176339Cellulose II Aerogel-Based Triboelectric NanogeneratorZhang, Lei; Liao, Yang; Wang, Yi-Cheng; Zhang, Steven; Yang, Weiqing; Pan, Xuejun; Wang, Zhong LinAdvanced Functional Materials (2020), 30 (28), 2001763CODEN: AFMDC6; ISSN:1616-301X. (Wiley-VCH Verlag GmbH & Co. KGaA)Cellulose-based triboelec. nanogenerators (TENGs) have gained increasing attention. In this study, a novel method is demonstrated to synthesize cellulose-based aerogels and such aerogels are used to fabricate TENGs that can serve as mech. energy harvesters and self-powered sensors. The cellulose II aerogel is fabricated via a dissoln.-regeneration process in a green inorg. molten salt hydrate solvent (lithium bromide trihydrate). The as-fabricated cellulose II aerogel exhibits an interconnected open-pore 3D network structure, higher degree of flexibility, high porosity, and a high surface area of 221.3 m2 g-1. Given its architectural merits, the cellulose II aerogel-based TENG presents an excellent mech. response sensitivity and high elec. output performance. By blending with other natural polysaccharides, i.e., chitosan and alginic acid, electron-donating and electron-withdrawing groups are introduced into the composite cellulose II aerogels, which significantly improves the triboelec. performance of the TENG. The cellulose II aerogel-based TENG is demonstrated to light up light-emitting diodes, charge com. capacitors, power a calculator, and monitor human motions. This study demonstrates the facile fabrication of cellulose II aerogel and its application in TENG, which leads to a high-performance and eco-friendly energy harvesting and self-powered system.
- 40Ong, X.-R.; Chen, A. X.; Li, N.; Yang, Y. Y.; Luo, H.-K. Nanocellulose: Recent Advances Toward Biomedical Applications. Small Sci. 2023, 3, 2200076 DOI: 10.1002/smsc.20220007640Review on nanocellulose: recent advances toward biomedical applicationsOng, Xuan-Ran; Chen, Adrielle Xianwen; Li, Ning; Yang, Yi Yan; Luo, He-KuanSmall Science (2023), 3 (2), 2200076CODEN: SSMCBJ; ISSN:2688-4046. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. Sustainable materials are key to the continual improvement of living stds. on this planet with minimal environmental impacts. Nanocellulose combines the fascinating features of nanomaterials with favorable properties of the abundantly available cellulose biopolymer, which in recent years has gained much attention toward biomedical applications by virtue of its unique surface chem., remarkable phys. features, and inherent biol. attributes. Herein, the recent advances in nanocellulose-based biomedical materials, with foci on biomol. immobilization, drug delivery, cell culture and tissue engineering (TE), antimicrobial strategy, wound healing, and biomedical implants are summarized. Each topic is elaborated with representative examples to present the significance of nanocelluloses in their resp. material design principles utilizing different sub-types, including cellulose nanofibers (CNFs), cellulose nanocrystals (CNCs), and bacterial nanocellulose (BNC). The current state of large-scale prodn. of nanocellulose and accelerated development by artificial intelligence and machine learning are also briefly discussed, before ending with its future prospects and potential challenges.
- 41Thomas, B.; Raj, M. C.; B, A. K.; H, R. M.; Joy, J.; Moores, A.; Drisko, G. L.; Sanchez, C. Nanocellulose, a Versatile Green Platform: From Biosources to Materials and Their Applications. Chem. Rev. 2018, 118, 11575– 11625, DOI: 10.1021/acs.chemrev.7b0062741Nanocellulose, a Versatile Green Platform: From Biosources to Materials and Their ApplicationsThomas, Bejoy; Raj, Midhun C.; B, Athira K.; H, Rubiyah M.; Joy, Jithin; Moores, Audrey; Drisko, Glenna L.; Sanchez, ClementChemical Reviews (Washington, DC, United States) (2018), 118 (24), 11575-11625CODEN: CHREAY; ISSN:0009-2665. (American Chemical Society)A review. With increasing environmental and ecol. concerns due to the use of petroleum-based chems. and products, the synthesis of fine chems. and functional materials from natural resources is of great public value. Nanocellulose may prove to be one of the most promising green materials of modern times due to its intrinsic properties, renewability, and abundance. In this review, we present nanocellulose-based materials from sourcing, synthesis, and surface modification of nanocellulose, to materials formation and applications. Nanocellulose can be sourced from biomass, plants, or bacteria, relying on fairly simple, scalable, and efficient isolation techniques. Mech., chem., and enzymic treatments, or a combination of these, can be used to ext. nanocellulose from natural sources. The properties of nanocellulose are dependent on the source, the isolation technique, and potential subsequent surface transformations. Nanocellulose surface modification techniques are typically used to introduce either charged or hydrophobic moieties, and include amidation, esterification, etherification, silylation, polymn., urethanization, sulfonation, and phosphorylation. Nanocellulose has excellent strength, high Young's modulus, biocompatibility, and tunable self-assembly, thixotropic, and photonic properties, which are essential for the applications of this material. Nanocellulose participates in the fabrication of a large range of nanomaterials and nanocomposites, including those based on polymers, metals, metal oxides, and carbon. In particular, nanocellulose complements org.-based materials, where it imparts its mech. properties to the composite. Nanocellulose is a promising material whenever material strength, flexibility, and/or specific nanostructuration are required. Applications include functional paper, optoelectronics, and antibacterial coatings, packaging, mech. reinforced polymer composites, tissue scaffolds, drug delivery, biosensors, energy storage, catalysis, environmental remediation, and electrochem. controlled sepn. Phosphorylated nanocellulose is a particularly interesting material, spanning a surprising set of applications in various dimensions including bone scaffolds, adsorbents, and flame retardants and as a support for the heterogenization of homogeneous catalysts.
- 42Lv, P.; Lu, X.; Wang, L.; Feng, W. Nanocellulose-Based Functional Materials: From Chiral Photonics to Soft Actuator and Energy Storage. Adv. Funct. Mater. 2021, 31, 2104991 DOI: 10.1002/adfm.20210499142Nanocellulose-Based Functional Materials: From Chiral Photonics to Soft Actuator and Energy StorageLv, Pengfei; Lu, Xiaomin; Wang, Ling; Feng, WeiAdvanced Functional Materials (2021), 31 (45), 2104991CODEN: AFMDC6; ISSN:1616-301X. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. Nanocellulose is currently in the limelight of extensive research from fundamental science to technol. applications owing to its renewable and carbon-neutral nature, superior biocompatibility, tailorable surface chem., and unprecedented optical and mech. properties. Herein, an up-to-date account of the recent advancements in nanocellulose-derived functional materials and their emerging applications in areas of chiral photonics, soft actuators, energy storage, and biomedical science is provided. The fundamental design and synthesis strategies for nanocellulose-based functional materials are discussed. Their unique properties, underlying mechanisms, and potential applications are highlighted. Finally, this review provides a brief conclusion and elucidates both the challenges and opportunities of the intriguing nanocellulose-based technologies rooted in materials and chem. science. This review is expected to provide new insights for nanocellulose-based chiral photonics, soft robotics, advanced energy, and novel biomedical technologies, and promote the rapid development of these highly interdisciplinary fields, including nanotechnol., nanoscience, biol., physics, synthetic chem., materials science, and device engineering.
- 43Nasseri, R.; Deutschman, C. P.; Han, L.; Pope, M. A.; Tam, K. C. Cellulose Nanocrystals in Smart and Stimuli-Responsive Materials: A Review. Mater. Today Adv. 2020, 5, 100055 DOI: 10.1016/j.mtadv.2020.100055There is no corresponding record for this reference.
- 44Mali, P.; Sherje, A. P. Cellulose Nanocrystals: Fundamentals and Biomedical Applications. Carbohydr. Polym. 2022, 275, 118668 DOI: 10.1016/j.carbpol.2021.11866844Cellulose nanocrystals: Fundamentals and biomedical applicationsMali, Prajakta; Sherje, Atul P.Carbohydrate Polymers (2022), 275 (), 118668CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)A review. The present review explores the recent developments of cellulose nanocrystals, a class of captivating nanomaterials in variety of applications. CNCs are made by acid hydrolyzing cellulosic materials like wood, cotton, tunicate, flax fibers by sonochem. It has many desirable properties, including a high tensile strength, wide surface area, stiffness, exceptional colloidal stability, and the ability to be modified. CNCs are colloidally stable, hydrophilic, and rigid rod-shaped bio-based nanomaterials in the form of rigid rods with high strength and surface area that has a diverse set of applications and properties. The intriguing features emerging from numerous fibers studies, such as renewable character and biodegradability, piqued the curiosity of many researchers who worked on lowering the size of these fibers. Physicochem. properties such as rheol., mech., thermal, lipid cryst., swelling capacity, microstructural properties result in affecting surface-area to vol. ratio and crystallinity of cellulose nanocrystals. The present article highlights the fundamentals of cellulose nanocrystals such as sources, isolation, fabrication, properties and surface modification with an emphasis on plethora of biomedical applications. Selected nanocellulose studies with significant findings on cellular labeling and bioimaging, tissue engineering, biosensors, gene delivery, anti-viral property, anti-bacterial property, ocular delivery, modified drug release, anti-cancer activity and enzyme immobilization are emphasized.
- 45Mahmud, M. M.; Perveen, A.; Jahan, R. A.; Matin, M. A.; Wong, S. Y.; Li, X.; Arafat, M. T. Preparation of Different Polymorphs of Cellulose from Different Acid Hydrolysis Medium. Int. J. Biol. Macromol. 2019, 130, 969– 976, DOI: 10.1016/j.ijbiomac.2019.03.02745Preparation of different polymorphs of cellulose from different acid hydrolysis mediumMahmud, Md Musavvir; Perveen, Asma; Jahan, Rumana A.; Matin, Md Abdul; Wong, Siew Yee; Li, Xu; Arafat, M. TarikInternational Journal of Biological Macromolecules (2019), 130 (), 969-976CODEN: IJBMDR; ISSN:0141-8130. (Elsevier B.V.)In this study, medical cotton was subjected to acid hydrolysis in sulfuric, hydrochloric and phosphoric acid medium to prep. cellulose nanocrystals (CNC) with different morphologies and polymorphism. Morphol. of the prepd. CNC samples revealed fiber shaped morphol. for sulfuric and hydrochloric acid hydrolyzed samples, whereas, spherical shaped for phosphoric acid hydrolyzed samples. The size of the spherical shaped CNC decreased with the increase of hydrolysis time, from 853 nm for 12 h to 187 nm for 48 h. X-ray Diffraction anal. showed that hydrochloric acid hydrolyzed CNC is cellulose I (CI), phosphoric acid hydrolyzed CNC is cellulose II (CII) and sulfuric acid hydrolyzed CNC contain both CI and CII. The crystallinity of sulfuric and hydrochloric acid hydrolysis samples was 91%, whereas, the crystallinity of phosphoric acid hydrolysis samples was between 43 and 60% depending on hydrolysis time. Thermal properties were also affected by the hydrolysis medium. Thus cellulose nanocrystals were prepd. with different morphologies and phys. characteristics through a facile method.
- 46Zhang, H.; Chen, Y.; Wang, S.; Ma, L.; Yu, Y.; Dai, H.; Zhang, Y. Extraction and Comparison of Cellulose Nanocrystals from Lemon (Citrus Limon) Seeds Using Sulfuric Acid Hydrolysis and Oxidation Methods. Carbohydr. Polym. 2020, 238, 116180 DOI: 10.1016/j.carbpol.2020.11618046Extraction and comparison of cellulose nanocrystals from lemon (Citrus limon) seeds using sulfuric acid hydrolysis and oxidation methodsZhang, Huan; Chen, Yuan; Wang, Shanshan; Ma, Liang; Yu, Yong; Dai, Hongjie; Zhang, YuhaoCarbohydrate Polymers (2020), 238 (), 116180CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)In this study, the lemon (Citrus limon) seeds as typical agricultural processing wastes were utilized to ext. cellulose nanocrystals (CNCs) by sulfuric acid hydrolysis (S-LSCNC), ammonium persulfate oxidn. (A-LSCNC) and TEMPO oxidn. (T-LSCNC). The properties of CNCs were comparatively investigated by Fourier transform IR spectroscopy (FTIR), XPS, X-ray diffraction (XRD), thermogravimetric anal. (TG), and at. force microscope (AFM), and the application in Pickering emulsions was also preliminarily studied. The results showed that all CNCs maintained cellulose Iβ structure and had a good dispersion regardless of extn. methods. Differently, T-LSCNC had a higher yield, larger size and lower CrI than A-LSCNC and S-LSCNC. Comparatively, A-LSCNC showed the highest CrI and S-LSCNC showed the lowest size. For the application of Pickering emulsions, S-LSCNC and A-LSCNC showed a better ability as Pickering stabilizers than T-LSCNC. This study is beneficial for developing the potential utilization of CNCs from lemon byproducts.
- 47Tang, Y.; Yang, H.; Vignolini, S. Recent Progress in Production Methods for Cellulose Nanocrystals: Leading to More Sustainable Processes. Adv. Sustainable Syst. 2022, 6, 2100100 DOI: 10.1002/adsu.20210010047Recent Progress in Production Methods for Cellulose Nanocrystals: Leading to More Sustainable ProcessesTang, Yimian; Yang, Han; Vignolini, SilviaAdvanced Sustainable Systems (2022), 6 (3), 2100100CODEN: ASSDAN; ISSN:2366-7486. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. Cellulose nanocrystals (CNCs) are a new class of biodegradable nanomaterial derived from the most abundant and renewable biomass on the planet: cellulose. Due to their potential as a low carbon footprint nanomaterial, CNCs have received significant interest in the community for a wide variety of applications. In this review, the most recent strategies exploited to produce CNCs are therefore summarized, focusing on the "greener" isolation methods aiming at minimizing the environmental impact of their prodn. The environmental impact of each CNCs prodn. method is qual. evaluated and the properties of the CNCs obtained are discussed. Finally, the necessary steps to address the development of the field in the industrial context are discussed, focusing on the type of applications where the CNCs can be exploited.
- 48Vanderfleet, O. M.; Cranston, E. D. Production Routes to Tailor the Performance of Cellulose Nanocrystals. Nat. Rev. Mater. 2021, 6, 124– 144, DOI: 10.1038/s41578-020-00239-y48Production routes to tailor the performance of cellulose nanocrystalsVanderfleet, Oriana M.; Cranston, Emily D.Nature Reviews Materials (2021), 6 (2), 124-144CODEN: NRMADL; ISSN:2058-8437. (Nature Research)A review. Cellulose nanocrystals (CNCs) are bio-based, high aspect ratio nanoparticles that are industrially produced in tonne-per-day quantities across the globe. CNCs can be used to improve the performance of a large range of materials such as emulsions and foams, biomedical devices, electronics and sensors, high-viscosity fluids and polymer composites. Their ability to do so, however, is highly dependent on the way they are produced. In this Review, we assess the properties of CNCs from more than 30 prodn. routes and 40 biomass sources to help CNC users select the right material for their desired application. CNCs produced by various methods are evaluated against three target properties: colloidal stability, size and crystallinity index. Alternative prodn. routes and/or starting materials are suggested to overcome challenges assocd. with CNC use, including increasing compatibility with hydrophobic materials, resistance to thermal degrdn. and colloidal stability in high ionic strength environments. Addnl., we discuss industrial prodn. of CNCs, as well as considerations for increasing the yield and reducing the environmental impact of these processes. Overall, this Review guides researchers and CNC users towards a deeper understanding of how prodn. processes can be modified to control CNC properties and subsequently tailor their performance.
- 49Lv, D.; Du, H.; Che, X.; Wu, M.; Zhang, Y.; Liu, C.; Nie, S.; Zhang, X.; Li, B. Tailored and Integrated Production of Functional Cellulose Nanocrystals and Cellulose Nanofibrils via Sustainable Formic Acid Hydrolysis: Kinetic Study and Characterization. ACS Sustainable Chem. Eng. 2019, 7, 9449– 9463, DOI: 10.1021/acssuschemeng.9b0071449Tailored and Integrated Production of Functional Cellulose Nanocrystals and Cellulose Nanofibrils via Sustainable Formic Acid Hydrolysis: Kinetic Study and CharacterizationLv, Dong; Du, Haishun; Che, Xinpeng; Wu, Meiyan; Zhang, Yuedong; Liu, Chao; Nie, Shuangxi; Zhang, Xinyu; Li, BinACS Sustainable Chemistry & Engineering (2019), 7 (10), 9449-9463CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)Cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) are of great interest to researchers due to their outstanding properties and wide application potentials. However, green and sustainable prodn. of CNCs and CNFs is still challenging. In this work, the integrated and sustainable prodn. of functional CNCs and CNFs was achieved by formic acids (FA) hydrolysis. Kinetic study for FA hydrolysis of cellulosic pulp was performed to investigate the hydrolysis mechanism. FA concn. of 80-98 wt %, reaction temp. of 70-100°, and reaction duration up to 24 h were employed to capture the feature of the coexistence of a diversity of reaction products, i.e., CNCs, cellulose solid residue (CSR), cellulose formate (CF), xylose, glucose, and furfural. The sepd. CSR was further fibrillated to CNFs by homogenization. It was found that the yield, morphol., crystallinity, thermal stability, and degree of esterification of CNCs and CNFs were significantly affected by hydrolysis conditions (particularly for acid concn.). Detailed characterization indicated that the as-prepd. CNCs exhibited high thermal stability (maximal wt. loss temp. of 375°) and high crystallinity index of 79%. Both the resultant CNCs and CNFs showed good dispersibility in dimethylacetamide due to the introduction of ester groups on cellulose surface during FA hydrolysis. More interestingly, the regenerated CF was also a kind of functional CNFs with more ester groups. These ester groups would enable the CNCs/CNFs to be potentially used in polymeric materials due to the hydrophobic surface. Therefore, this study provided fundamental knowledge for the sustainable and integrated prodn. of thermally stable and functional CNCs and CNFs with tailored characteristics.
- 50Pereira, B.; Arantes, V. Production of Cellulose Nanocrystals Integrated into a Biochemical Sugar Platform Process via Enzymatic Hydrolysis at High Solid Loading. Ind. Crops Prod. 2020, 152, 112377 DOI: 10.1016/j.indcrop.2020.11237750Production of cellulose nanocrystals integrated into a biochemical sugar platform process via enzymatic hydrolysis at high solid loadingPereira, Barbara; Arantes, ValdeirIndustrial Crops and Products (2020), 152 (), 112377CODEN: ICRDEW; ISSN:0926-6690. (Elsevier B.V.)This work evaluated the viability of integrating the isolation of cellulose nanocrystals (CNCs) via enzymic hydrolysis at a high solid loading into the biochem. platform process for the prodn. of sugars from sugarcane bagasse (SCB). SCB was first processed at a biochem. conversion pilot plant and bleached to yield a cellulose-rich pulp, which was enzymically hydrolyzed at high solid and low enzyme loadings. The resulting hydrolyzate had high sugar concn. (>120 g/L glucose) and the CNCs (20 nm in diam.) isolated directly from the hydrolysis residue showed superior properties (higher thermal stability, higher crystallinity index, and higher particle diam. uniformity) than the CNCs prepd. from com. bleached eucalyptus Kraft pulp. These findings demonstrate the tech. viability of the proposed integrated process that combined with the high CNCs yield (approx.50%) and the no need for the costly ultrasonic dispersion treatment step to obtain nanoparticles can further contribute for improving the economic and environmental viability of the proposed enzyme-mediated isolation process.
- 51Ferreira, P. F. O.; Pereira, A. L. S.; Rosa, M. F.; de Santiago-Aguiar, R. S. Lignin-Rich Cellulose Nanocrystals from Coir Fiber Treated with Ionic Liquids: Preparation and Evaluation as Pickering Emulsifier. Ind. Crops Prod. 2022, 186, 115119 DOI: 10.1016/j.indcrop.2022.11511951Lignin-rich cellulose nanocrystals from coir fiber treated with ionic liquids: Preparation and evaluation as pickering emulsifierFerreira, Priscilla F. O.; Pereira, Andre L. S.; Rosa, Morsyleide F.; de Santiago-Aguiar, Rilvia S.Industrial Crops and Products (2022), 186 (), 115119CODEN: ICRDEW; ISSN:0926-6690. (Elsevier B.V.)Lignocellulosic materials are promising sources of energy and biomaterials. In this context, the biomass from the mesocarp of the green coconut can be used to produce nanocellulose. For this purpose, this work proposed approaches for pretreatment of coconut biomass using protic ionic liqs. (PILs), which are solvents that have specific characteristics and less environmental impact, followed by acid hydrolysis to obtain lignin-contg. nanocellulose. Thus, three PILs were produced, and two pretreatment methodologies were evaluated. The results showed that, when using the ionic liq. 2-HEAA and Methodol. B, there was a delignification of 17.4%, a redn. of 14% of hemicelluloses and a gain of 50.8% of cellulose. Furthermore, acid hydrolysis provided a stable suspension of lignin-contg. cellulose nanocrystals (zeta potential of -34.6 mV) with particles in the nanometer scale and more thermally resistant. When testing these lignin-contg. cellulose nanocrystals as a stabilizer for oil-in-water emulsions, satisfactory results were obtained at a concn. of 0.50%, which generated a stable emulsion for 14 days (-47.5 mV of zeta potential and mean diam. of 6.23μm).
- 52Gao, M.; Shang, Y.; Li, B.; Du, H. Sustainable Preparation of Cellulose Nanocrystals: State of the Art and Perspectives. Green Chem. 2022, 24, 9346– 9372, DOI: 10.1039/D2GC03003A52Sustainable preparation of cellulose nanocrystals: state of the art and perspectivesGao, Mengge; Shang, Yazhuo; Li, Bin; Du, HaishunGreen Chemistry (2022), 24 (24), 9346-9372CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)A review. As sustainable and advanced nanomaterials, cellulose nanocrystals (CNCs) attract extensive attention from both academia and industry due to their superior phys. and chem. properties. Strong inorg. acid (e.g., H2SO4) hydrolysis is the most common method for the prepn. of CNCs because of its high efficiency. However, inorg. acid hydrolysis faces several limitations such as severe equipment corrosion, over-degrdn. of cellulose, pollution of the environment, and the use of a large amt. of water. This review comprehensively summarizes sustainable strategies invented in recent years for the prepn. of CNCs, including the oxidn. method, ionic liq. treatment, deep eutectic solvent treatment, enzymic hydrolysis, inorg. solid acid hydrolysis, org. acid hydrolysis, supercrit. water hydrolysis, HCl vapor/gas hydrolysis, and the electron beam radiation method. It is believed that CNCs, as green and renewable nanomaterials, have broad application prospects in the future, and the realization of the green, low-cost, and sustainable prepn. of CNCs will be the prerequisite guarantee for the large-scale application of CNCs.
- 53Lee, S.; Hao, L. T.; Park, J.; Oh, D. X.; Hwang, D. S. Nanochitin and Nanochitosan: Chitin Nanostructure Engineering with Multiscale Properties for Biomedical and Environmental Applications. Adv. Mater. 2023, 35, 2203325 DOI: 10.1002/adma.20220332553Review on nanochitin and nanochitosan and chitin nanostructure engineering with multiscale properties for biomedical and environmental applicationsLee, Suyoung; Hao, Lam Tan; Park, Jeyoung; Oh, Dongyeop X.; Hwang, Dong SooAdvanced Materials (Weinheim, Germany) (2023), 35 (4), 2203325CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. Nanochitin and nanochitosan (with random-copolymer-based multiscale architectures of glucosamine and N-acetylglucosamine units) have recently attracted immense attention for the development of green, sustainable, and advanced functional materials. Nanochitin and nanochitosan are multiscale materials from small oligomers, rod-shaped nanocrystals, longer nanofibers, to hierarchical assemblies of nanofibers. Various phys. properties of chitin and chitosan depend on their mol.- and nanostructures; translational research has utilized them for a wide range of applications (biomedical, industrial, environmental, and so on). Instead of reviewing the entire extensive literature on chitin and chitosan, here, recent developments in multiscale-dependent material properties and their applications are highlighted; immune, medical, reinforcing, adhesive, green electrochem. materials, biol. scaffolds, and sustainable food packaging are discussed considering the size, shape, and assembly of chitin nanostructures. In summary, new perspectives for the development of sustainable advanced functional materials based on nanochitin and nanochitosan by understanding and engineering their multiscale properties are described.
- 54Bai, L.; Kämäräinen, T.; Xiang, W.; Majoinen, J.; Seitsonen, J.; Grande, R.; Huan, S.; Liu, L.; Fan, Y.; Rojas, O. J. Chirality from Cryo-Electron Tomograms of Nanocrystals Obtained by Lateral Disassembly and Surface Etching of Never-Dried Chitin. ACS Nano 2020, 14, 6921– 6930, DOI: 10.1021/acsnano.0c0132754Chirality from Cryo-Electron Tomograms of Nanocrystals Obtained by Lateral Disassembly and Surface Etching of Never-Dried ChitinBai, Long; Kamarainen, Tero; Xiang, Wenchao; Majoinen, Johanna; Seitsonen, Jani; Grande, Rafael; Huan, Siqi; Liu, Liang; Fan, Yimin; Rojas, Orlando J.ACS Nano (2020), 14 (6), 6921-6930CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)The complex nature of typical colloids and corresponding interparticle interactions pose a challenge in understanding their self-assembly. This specifically applies to biol. nanoparticles, such as those obtained from chitin, which typically are hierarchical and multidimensional. In this study, we obtain chitin nanocrystals by one-step heterogeneous acid hydrolysis of never-dried crab residues. Partial deacetylation facilitates control over the balance of electrostatic charges (ζ-potential in the range between +58 and +75 mV) and therefore affords chitin nanocrystals (DE-ChNC) with axial aspect (170-350 nm in length), as detd. by cryogenic transmission electron microscopy and at. force microscopy. We find that the surface amines generated by deacetylation, prior to hydrolysis, play a crit. role in the formation of individual chitin nanocrystals by the action of a dual mechanism. We directly access the twisting feature of chitin nanocrystals using electron tomog. (ET) and uncover the distinctive morphol. differences between chitin nanocrystals extd. from nondeacetylated chitin, ChNC, which are bundled and irregular, and DE-ChNC (single, straight nanocrystals). Whereas chitin nanocrystals obtained from dried chitin precursors are known to be twisted and form chiral nematic liq. crystals, our ET measurements indicate no dominant twisting or handedness for the nanocrystals obtained from the never-dried source. Moreover, no sepn. into typical isotropic and anisotropic phases occurs after 2 mo at rest. Altogether, we highlight the crit. role of drying the precursors or the nanopolysaccharides to develop chirality.
- 55Liu, L.; Chen, H.; Zou, Y.; Chen, F.; Fan, Y.; Yong, Q. Zwitterionic Chitin Nanocrystals Mediated Composite and Self-Assembly with Cellulose Nanofibrils. Int. J. Biol. Macromol. 2022, 223, 108– 119, DOI: 10.1016/j.ijbiomac.2022.10.23555Zwitterionic chitin nanocrystals mediated composite and self-assembly with cellulose nanofibrilsLiu, Liang; Chen, Huangjingyi; Zou, Yujun; Chen, Feier; Fan, Yimin; Yong, QiangInternational Journal of Biological Macromolecules (2022), 223 (Part_A), 108-119CODEN: IJBMDR; ISSN:0141-8130. (Elsevier B.V.)Zwitterionic dispersed chitin nanocrystals and TEMPO oxidized cellulose nanofibrils can be well mixed and self-assembled to be hydrogels/membranes. Active carboxyl groups ensure the well mixing of zwitterionic chitin nanocrystals and cellulose nanofibrils under neutral and alk. condition. Electrostatic attraction between amino groups in chitin nanocrystals and carboxyl groups in chitin nanocrystals and cellulose nanofibrils further endows self-assemble property of composite suspensions. Simple standing for 12 h at room temp. is found enough for prepg. self-assembled composite hydrogels. By 1-(3-dimethy-laminopropyl)-3-ethylcarbodiimide hydrochloride/N-hydroxy succinimide (EDC/NHS) mediated chem. crosslinking, the storage modulus of composite hydrogel can achieve almost 8 times higher than self-assembled hydrogel. Well dispersed composite suspensions also can be transformed to be membranes via filtration treatment. The strain increases almost 2.3 times higher with similar tensile strength for cellulose nanofibril rich samples, and chitin nanocrystals mainly contributes to the enhancement in strain of composite membranes.
- 56Liu, P.; Liu, H.; Schäfer, T.; Gutmann, T.; Gibhardt, H.; Qi, H.; Tian, L.; Zhang, X. C.; Buntkowsky, G.; Zhang, K. Unexpected Selective Alkaline Periodate Oxidation of Chitin for the Isolation of Chitin Nanocrystals. Green Chem. 2021, 23, 745– 751, DOI: 10.1039/D0GC04054A56Unexpected selective alkaline periodate oxidation of chitin for the isolation of chitin nanocrystalsLiu, Peiwen; Liu, Huan; Schaefer, Timmy; Gutmann, Torsten; Gibhardt, Holger; Qi, Houjuan; Tian, Lin; Zhang, Xizhou Cecily; Buntkowsky, Gerd; Zhang, KaiGreen Chemistry (2021), 23 (2), 745-751CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)Periodate oxidn. reaction occurring directly on chitin has been neglected in polysaccharide chem. so far. Herein, we present the first direct alk. periodate oxidn. of chitin, which demonstrates at the same time a novel approach for the prepn. of chitin nanocrystals (ChNCs). This oxidn. is based on an unprecedented selective reaction of non-ordered domains of chitin by the dimeric orthoperiodate ions (H2I2O104-) as the major species in alk. surroundings. Nearly 50 wt% of non-ordered regions are dissolved after sequential accelerated partial deacetylation, periodate oxidn. and β-alkoxy fragmentation, which allows the isolation of up to 50 wt% of uniform anisotropic zwitterionic ChNCs.
- 57El Knidri, H.; Belaabed, R.; Addaou, A.; Laajeb, A.; Lahsini, A. Extraction, Chemical Modification and Characterization of Chitin and Chitosan. Int. J. Biol. Macromol. 2018, 120, 1181– 1189, DOI: 10.1016/j.ijbiomac.2018.08.13957Extraction, chemical modification and characterization of chitin and chitosanEl Knidri, Hakima; Belaabed, Raja; Addaou, Abdellah; Laajeb, Ali; Lahsini, AhmedInternational Journal of Biological Macromolecules (2018), 120 (Part_A), 1181-1189CODEN: IJBMDR; ISSN:0141-8130. (Elsevier B.V.)Chitin is the second most common polymer after cellulose in earth, existing in the shells of crustaceans like crab and shrimp. Chitosan is a natural amino-polysaccharide derived from chitin, known as one of the most abundant org. materials in nature, it has been widely used in several applications due to its natural origin and exceptional properties such as biocompatibility, biodegradability, non-toxicity, and chelating of metal ions. Chitin and chitosan are characterized by deacetylation degree, one of the most important chem. characteristics that can influence the performance of chitosan in many applications. Chitosan is usually prepd. by a thermochem. method, consuming time, energy and reagents. In this review, various methods of chitosan extn. will be approached and compared; the importance of a new method of ecol. extn. will be emphasized. Moreover, in order to improve the chitosan functionality, and better control these physicochem. properties, several chem. modifications have been reported. These chem. modifications lead to a broad range of derivs. with a wide range of applications in many fields. Recent examples of the distinct applications, with particular emphasis on environmental applications, have been presented.
- 58Mohan, K.; Ganesan, A. R.; Ezhilarasi, P. N.; Kondamareddy, K. K.; Rajan, D. K.; Sathishkumar, P.; Rajarajeswaran, J.; Conterno, L. Green and Eco-Friendly Approaches for the Extraction of Chitin and Chitosan: A review. Carbohydr. Polym. 2022, 287, 119349 DOI: 10.1016/j.carbpol.2022.11934958Green and eco-friendly approaches for the extraction of chitin and chitosan: A reviewMohan, Kannan; Ganesan, Abirami Ramu; Ezhilarasi, P. N.; Kondamareddy, Kiran Kumar; Rajan, Durairaj Karthick; Sathishkumar, Palanivel; Rajarajeswaran, Jayakumar; Conterno, LorenzaCarbohydrate Polymers (2022), 287 (), 119349CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)A review. Chitin is one of the most diverse and naturally occurring biopolymers, and it is mainly present in crustaceans, insects, and fungi. Chitosan is derived from chitin by deacetylation process. It is important to note that the conventional chem. method of extg. chitin includes disadvantages and it poses various environmental issues. Recently, the green extn. techniques have perceived substantial development in the field of polymer chem. A variety of methods have been successfully developed using green extn. techniques for extg. chitin and chitosan from various resources. It includes the use of ionic liqs. (ILs), deep eutectic solvents (DES), microbial fermn., enzyme-assisted extn. (EAE), microwave-assisted extn. (MAE), ultrasonic-assisted extn. (UAE), subcrit. water extn. (SWE), and electrochem. extn. (ECE). In this review, the extn. of chitin and chitosan using greener approaches were summarized. In addn., challenges, opportunities and future perspectives of green extn. methods have also been narrated.
- 59Zhou, R.; Zhao, L.; Wang, Y.; Hameed, S.; Ping, J.; Xie, L.; Ying, Y. Recent Advances in Food-Derived Nanomaterials Applied to Biosensing. TrAC Trends Anal. Chem. 2020, 127, 115884 DOI: 10.1016/j.trac.2020.115884There is no corresponding record for this reference.
- 60Shahidi, F.; Arachchi, J. K. V.; Jeon, Y.-J. Food Applications of Chitin and Chitosans. Trends Food Sci. Technol. 1999, 10, 37– 51, DOI: 10.1016/S0924-2244(99)00017-560Food applications of chitin and chitosansShahidi, Fereidoon; Arachchi, Janak Kamil Vidana; Jeon, You-JinTrends in Food Science & Technology (1999), 10 (2), 37-51CODEN: TFTEEH; ISSN:0924-2244. (Elsevier Science Ltd.)A review with 143 refs. Chitin is the second most abundant natural biopolymer after cellulose. The chem. structure of chitin is similar to that of cellulose with 2-acetamido-2-deoxy-β-D-glucose (NAG) monomers attached via β(1→4) linkages. Chitosan is the deacetylated (to varying degrees) form of chitin, which, unlike chitin, is sol. in acidic solns. Application of chitinous products in foods and pharmaceuticals as well as processing aids has received considerable attention in recent years as exotic synthetic compds. are losing their appeal. This review summarizes some of the important developments related to food applications of chitin, chitosan and their derivs.
- 61Kumar, S.; Foroozesh, J. Chitin Nanocrystals Based Complex Fluids: A Green Nanotechnology. Carbohydr. Polym. 2021, 257, 117619 DOI: 10.1016/j.carbpol.2021.11761961Chitin nanocrystals based complex fluids: A green nanotechnologyKumar, Sunil; Foroozesh, JalalCarbohydrate Polymers (2021), 257 (), 117619CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)A review. Chitin biopolymer has received significant attention recently by many industries as a green technol. Nanotechnol. has been used to make chitin nanocrystals (ChiNCs) that are rod-shaped natural nanomaterials with nanoscale size. Owing to the unique features such as biodegradability, biocompatibility, renewability, rod-shape, and excellent surface and interfacial, physiochem., and thermo-mech. properties; ChiNCs have been green and attractive products with wide applications specifically in medical and pharmaceutical, food and packaging, cosmetic, elec., and electronic, and also in the oil and gas industry. This review aims to give a comprehensive and applied insight into ChiNCs technol. It starts with reviewing different sources of chitin and their extn. methods followed by the characterization of ChiNCs. Furthermore, a detailed investigation into various complex fluids (dispersions, emulsions, foams, and gels) stabilized by ChiNCs and their characterization have been thoroughly deliberated. Finally, the current status including ground-breaking applications, untapped investigations, and future prospective have been presented.
- 62Claverie, M.; McReynolds, C.; Petitpas, A.; Thomas, M.; Fernandes, S. C. M. Marine-Derived Polymeric Materials and Biomimetics: An Overview. Polymers 2020, 12, 1002, DOI: 10.3390/polym12051002There is no corresponding record for this reference.
- 63Kaya, M.; Mujtaba, M.; Ehrlich, H.; Salaberria, A. M.; Baran, T.; Amemiya, C. T.; Galli, R.; Akyuz, L.; Sargin, I.; Labidi, J. On Chemistry of γ-Chitin. Carbohydr. Polym. 2017, 176, 177– 186, DOI: 10.1016/j.carbpol.2017.08.07663On chemistry of γ-chitinKaya, Murat; Mujtaba, Muhammad; Ehrlich, Hermann; Salaberria, Asier M.; Baran, Talat; Amemiya, Chris T.; Galli, Roberta; Akyuz, Lalehan; Sargin, Idris; Labidi, JalelCarbohydrate Polymers (2017), 176 (), 177-186CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)The biol. material, chitin, is present in nature in three allomorphic forms: α, β and γ. Whereas most studies have dealt with α- and β-chitin, only few investigations have focused on γ-chitin, whose structural and physicochem. properties have not been well delineated. In this study, chitin obtained for the first time from the cocoon of the moth (Orgyia dubia) was subjected to extensive physicochem. analyses and examd., in parallel, with α-chitin from exoskeleton of a freshwater crab and β-chitin from cuttlebone of the common cuttlefish. Our results, which are supported by 13C CP-MAS NMR, XRD, FT-IR, Raman spectroscopy, TGA, DSC, SEM, AFM, chitinase digestive test and elemental anal., verify the authenticity of γ-chitin. Further, quantum chem. calcns. were conducted on all three allomorphic forms, and, together with our physicochem. analyses, demonstrate that γ-chitin is distinct, yet closer in structure to α-chitin than β-chitin.
- 64Huang, W.; Restrepo, D.; Jung, J.-Y.; Su, F. Y.; Liu, Z.; Ritchie, R. O.; McKittrick, J.; Zavattieri, P.; Kisailus, D. Multiscale Toughening Mechanisms in Biological Materials and Bioinspired Designs. Adv. Mater. 2019, 31, 1901561 DOI: 10.1002/adma.20190156164Multiscale toughening mechanisms in biological materials and bioinspired designsHuang, Wei; Restrepo, David; Jung, Jae-Young; Su, Frances Y.; Liu, Zengqian; Ritchie, Robert O.; McKittrick, Joanna; Zavattieri, Pablo; Kisailus, DavidAdvanced Materials (Weinheim, Germany) (2019), 31 (43), 1901561CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. Biol. materials found in Nature such as nacre and bone are well recognized as light-wt., strong, and tough structural materials. The remarkable toughness and damage tolerance of such biol. materials are conferred through hierarchical assembly of their multiscale (i.e., at.- to macroscale) architectures and components. Herein, the toughening mechanisms of different organisms at multilength scales are identified and summarized: macromol. deformation, chem. bond breakage, and biomineral crystal imperfections at the at. scale; biopolymer fibril reconfiguration/deformation and biomineral nanoparticle/nanoplatelet/nanorod translation, and crack reorientation at the nanoscale; crack deflection and twisting by characteristic features such as tubules and lamellae at the microscale; and structure and morphol. optimization at the macroscale. In addn., the actual loading conditions of the natural organisms are different, leading to energy dissipation occurring at different time scales. These toughening mechanisms are further illustrated by comparing the exptl. results with computational modeling. Modeling methods at different length and time scales are reviewed. Examples of biomimetic designs that realize the multiscale toughening mechanisms in engineering materials are introduced. Indeed, there is still plenty of room mimicking the strong and tough biol. designs at the multilength and time scale in Nature.
- 65Yang, T.; Qi, H.; Liu, P.; Zhang, K. Selective Isolation Methods for Cellulose and Chitin Nanocrystals. ChemPlusChem. 2020, 85, 1081– 1088, DOI: 10.1002/cplu.20200025065Selective Isolation Methods for Cellulose and Chitin NanocrystalsYang, Ting; Qi, Houjuan; Liu, Peiwen; Zhang, KaiChemPlusChem (2020), 85 (5), 1081-1088CODEN: CHEMM5; ISSN:2192-6506. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. This Minireview focuses on the selective isolation methods for the prepn. of cellulose nanocrystals (CNCs) and chitin nanocrystals (ChNCs). Various selective prepn. strategies with specific prepn. conditions and reaction mechanisms are summarized. In particular, these selective reaction routes include controlled acid hydrolysis and selective oxidns. at specific positions of cellulose or chitin fibers as well as particular reaction sites of the repeating monosaccharide building blocks of their main chains. These lead to selective cleavage of the ordered and non-ordered regions of cellulose and chitin and result in efficient prodn. of CNCs and ChNCs.
- 66Oun, A. A.; Rhim, J.-W. Effect of Isolation Methods of Chitin Nanocrystals on the Properties of Chitin-Silver Hybrid Nanoparticles. Carbohydr. Polym. 2018, 197, 349– 358, DOI: 10.1016/j.carbpol.2018.06.03366Effect of isolation methods of chitin nanocrystals on the properties of chitin-silver hybrid nanoparticlesOun, Ahmed A.; Rhim, Jong-WhanCarbohydrate Polymers (2018), 197 (), 349-358CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)Chitin nanocrystal (ChNC) was isolated using sulfuric acid hydrolysis (ChNCH2SO4), TEMPO-oxidn. (ChNCTEMPO), and ammonium persulfate (ChNCAPS) methods, and used for the prepn. of hybrid nanoparticles of ChNC/silver nanoparticles (AgNP). The ChNC exhibited a needle-shaped structure with a sulfate group content of 135 μmol/g for ChNCH2SO4 and carboxyl content of 0.71 and 1.42 mmol/g for ChNCTEMPO and ChNCAPS, resp. ChNC worked as a reducing and stabilizing agent for the prodn. of AgNP and reduced the size of AgNP from 23.9 nm to 6.3 nm in the ChNC/AgNP hybrid. The carboxyl content of ChNC played a significant role for the nucleation, size distribution, and antibacterial activity of ChNC/AgNP. ChNC/AgNP hybrid, esp. ChNCAPS/AgNP, exhibited strong antibacterial activity against food-borne pathogenic Gram-neg. (E. coli) and Gram-pos. (L. monocytogenes) bacteria. The prepd. ChNC/AgNP hybrid nanomaterials have a high potential for the application to be used as a nanofiller to improve the properties of food packaging materials to extend the shelf-life of packaged food.
- 67Nguyen, H. V. D.; de Vries, R.; Stoyanov, S. D. Chitin Nanowhiskers with Improved Properties Obtained Using Natural Deep Eutectic Solvent and Mild Mechanical Processing. Green Chem. 2022, 24, 3834– 3844, DOI: 10.1039/D2GC00305HThere is no corresponding record for this reference.
- 68Wang, L.; Urbas, A. M.; Li, Q. Nature-Inspired Emerging Chiral Liquid Crystal Nanostructures: From Molecular Self-Assembly to DNA Mesophase and Nanocolloids. Adv. Mater. 2020, 32, 1801335 DOI: 10.1002/adma.20180133568Nature-Inspired Emerging Chiral Liquid Crystal Nanostructures: From Molecular Self-Assembly to DNA Mesophase and NanocolloidsWang, Ling; Urbas, Augustine M.; Li, QuanAdvanced Materials (Weinheim, Germany) (2020), 32 (41), 1801335CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. Liq. crystals (LCs) are omnipresent in living matter, whose chirality is an elegant and distinct feature in certain plant tissues, the cuticles of crabs, beetles, arthropods, and beyond. Taking inspiration from nature, researchers have recently devoted extensive efforts toward developing chiral liq. cryst. materials with self-organized nanostructures and exploring their potential applications in diverse fields ranging from dynamic photonics to energy and safety issues. In this review, an account on the state of the art of emerging chiral liq. cryst. nanostructured materials and their technol. applications is provided. First, an overview on the significance of chiral liq. cryst. architectures in various living systems is given. Then, the recent significant progress in different chiral liq. cryst. systems including thermotropic LCs (cholesteric LCs, cubic blue phases, achiral bent-core LCs, etc.) and lyotropic LCs (DNA LCs, nanocellulose LCs, and graphene oxide LCs) is showcased. The review concludes with a perspective on the future scope, opportunities, and challenges in these truly advanced functional soft materials and their promising applications.
- 69Lee, D. W. Nature’s Palette: The Science of Plant Color; The University of Chicago Press: Chicago, Illinois, USA, 2007.There is no corresponding record for this reference.
- 70Graham, R. M.; Lee, D. W.; Norstog, K. Physical and Ultrastructural Basis of Blue Leaf Iridescence in Two Neotropical Ferns. Am. J. Bot. 1993, 80, 198– 203, DOI: 10.1002/j.1537-2197.1993.tb13789.xThere is no corresponding record for this reference.
- 71Lundquist, C. R.; Rudall, P. J.; Sukri, R. S.; Conejero, M.; Smith, A.; Lopez-Garcia, M.; Vignolini, S.; Metali, F.; Whitney, H. M. Living Jewels: Iterative Evolution of Iridescent Blue Leaves from Helicoidal Cell Walls. Ann. Bot. 2024, 134, 131– 150, DOI: 10.1093/aob/mcae045There is no corresponding record for this reference.
- 72Steiner, L. M.; Ogawa, Y.; Johansen, V. E.; Lundquist, C. R.; Whitney, H.; Vignolini, S. Structural Colours in the Frond of Microsorum thailandicum. Interface Focus 2019, 9, 20180055 DOI: 10.1098/rsfs.2018.0055There is no corresponding record for this reference.
- 73Strout, G.; Russell, S. D.; Pulsifer, D. P.; Erten, S.; Lakhtakia, A.; Lee, D. W. Silica Nanoparticles Aid in Structural Leaf Coloration in the Malaysian Tropical Rainforest Understorey Herb Mapania Caudata. Ann. Bot. 2013, 112, 1141– 1148, DOI: 10.1093/aob/mct17273Silica nanoparticles aid in structural leaf coloration in the Malaysian tropical rainforest understory herb Mapania caudataStrout, Greg; Russell, Scott D.; Pulsifer, Drew P.; Erten, Sema; Lakhtakia, Akhlesh; Lee, David W.Annals of Botany (Oxford, United Kingdom) (2013), 112 (6), 1141-1148CODEN: ANBOA4; ISSN:0305-7364. (Oxford University Press)Background and Aims Blue-green iridescence in the tropical rainforest understory sedge Mapania caudata creates structural coloration in its leaves through a novel photonic mechanism. Known structures in plants producing iridescent blues consist of altered cellulose layering within cell walls and in special bodies, and thylakoid membranes in specialized plastids. This study was undertaken in order to det. the origin of leaf iridescence in this plant, with particular attention to nano-scale components contributing to this coloration. Methods Adaxial walls of leaf epidermal cells were characterized using high-pressure-frozen freeze-substituted specimens, which retain their native dimensions during observations using transmission and scanning microscopy, accompanied by energy-dispersive X-ray spectroscopy to identify the role of biogenic silica in wall-based iridescence. Biogenic silica was exptl. removed using aq. Na2CO3 and optical properties were compared using spectral reflectance. Key Results and Conclusions Blue iridescence is produced in the adaxial epidermal cell wall, which contains helicoid lamellae. The blue iridescence from cell surfaces is left-circularly polarized. The position of the silica granules is entrained by the helicoid microfibrillar layers, and granules accumulate at a uniform position within the helicoids, contributing to the structure that produces the blue iridescence, as part of the unit cell responsible for 2 ° Bragg scatter. Removal of silica from the walls eliminated the blue color. Addn. of silica nanoparticles on existing cellulosic lamellae is a novel mechanism for adding structural color in organisms.
- 74He, Y.; Lin, S.; Guo, J.; Li, Q. Circularly Polarized Luminescent Self-Organized Helical Auperstructures: From Materials and Stimulus-Responsiveness to Applications. Aggregate 2021, 2, e141 DOI: 10.1002/agt2.141There is no corresponding record for this reference.
- 75Echeverría-Alar, S.; Clerc, M. G.; Bordeu, I. Emergence of Disordered Branching Patterns in Confined Chiral Nematic Liquid Crystals. Proc. Natl. Acad. Sci. U. S. A. 2023, 120, e2221000120 DOI: 10.1073/pnas.2221000120There is no corresponding record for this reference.
- 76Mitov, M. Cholesteric Liquid Crystals in Living Matter. Soft Matter 2017, 13, 4176– 4209, DOI: 10.1039/C7SM00384F76Cholesteric liquid crystals in living matterMitov, MichelSoft Matter (2017), 13 (23), 4176-4209CODEN: SMOABF; ISSN:1744-6848. (Royal Society of Chemistry)Liq. crystals play an important role in biol. because the combination of order and mobility is a basic requirement for self-organization and structure formation in living systems. Cholesteric liq. crystals are omnipresent in living matter under both in vivo and in vitro conditions and address the major types of mols. essential to life. In the animal and plant kingdoms, the cholesteric structure is a recurring design, suggesting a convergent evolution to an optimized left-handed helix. Herein, we review the recent advances in the cholesteric organization of DNA, chromatin, chitin, cellulose, collagen, viruses, silk and cholesterol ester deposition in atherosclerosis. Cholesteric structures can be found in bacteriophages, archaea, eukaryotes, bacterial nucleoids, chromosomes of unicellular algae, sperm nuclei of many vertebrates, cuticles of crustaceans and insects, bone, tendon, cornea, fish scales and scutes, cuttlebone and squid pens, plant cell walls, virus suspensions, silk produced by spiders and silkworms, and arterial wall lesions. This article specifically aims at describing the consequences of the cholesteric geometry in living matter, which are far from being fully defined and understood, and discusses various perspectives. The roles and functions of biol. cholesteric liq. crystals include maximisation of packing efficiency, morphogenesis, mech. stability, optical information, radiation protection and evolution pressure.
- 77Almeida, A. P. C.; Canejo, J. P.; Almeida, P. L.; Godinho, M. H. Cholesteric-Type Cellulosic Structures: From Plants to Applications. Liq. Cryst. 2019, 46, 1937– 1949, DOI: 10.1080/02678292.2019.164090477Cholesteric-type cellulosic structures: from plants to applicationsAlmeida, Ana P. C.; Canejo, Joao P.; Almeida, Pedro L.; Godinho, Maria HelenaLiquid Crystals (2019), 46 (13-14), 1937-1949CODEN: LICRE6; ISSN:0267-8292. (Taylor & Francis Ltd.)A review. The structural support of plant cells is provided by the cell wall, which major load-bearing component is an array of hierarchical orientedhierarchical-oriented cellulose nano-, micro- and meso-structures of cellulose microfibrils. Cellulosic structures can respond to humidity changes by expanding or shrinking and this allows, for example, the dispersion of seeds. Previous studies have shown that nanorods, extd. from cell walls, can generate lyotropic liq. crystals that are at the origin of solid cholesteric-like arrangements. Not only photonic films, but also right and left helical filaments, anisotropic films with the ability to bend back and forth under the action of a moisture gradient at room temp., are some of the materials that were produced from cellulose liq. crystal systems. This work is a review that focus on liq. cryst.-based structures obtained from cellulosic materials and how small perturbations on their structures affect significantly the response to external stimulus and interactions with the environment. Special emphasis is given to cholesteric-like organization of cellulose structures existing in plants, which are an inspiration for the prodn. of the next generation of soft interactive materials.
- 78Vignolini, S.; Rudall, P. J.; Rowland, A. V.; Reed, A.; Moyroud, E.; Faden, R. B.; Baumberg, J. J.; Glover, B. J.; Steiner, U. Pointillist Structural Color in Pollia Fruit. Proc. Natl. Acad. Sci. U. S. A. 2012, 109, 15712– 15715, DOI: 10.1073/pnas.121010510978Pointillist structural color in Pollia fruitVignolini, Silvia; Rudall, Paula J.; Rowland, Alice V.; Reed, Alison; Moyroud, Edwige; Faden, Robert B.; Baumberg, Jeremy J.; Glover, Beverley J.; Steiner, UllrichProceedings of the National Academy of Sciences of the United States of America (2012), 109 (39), 15712-15715, S15712/1-S15712/2CODEN: PNASA6; ISSN:0027-8424. (National Academy of Sciences)Biol. communication by means of structural color has existed for at least 500 million years. Structural color is commonly obsd. in the animal kingdom, but has been little studied in plants. We present a striking example of multilayer-based strong iridescent coloration in plants, in the fruit of Pollia condensatea. The color is caused by Bragg reflection of helicoidally stacked cellulose micro- fibrils that form multilayers in the cell walls of the epicarp. We demonstrate that animals and plants have convergently evolved multilayer-based photonic structures to generate colors using en- tirely distinct materials. The bright blue coloration of this fruit is more intense than that of any previously described biol. material. Uniquely in nature, the reflected color differs from cell to cell, as the layer thicknesses in the multilayer stack vary, giving the fruit a striking pixelated or pointillist appearance. Because the multilayers form with both helicoidicities, optical characterization reveals that the reflected light from every epidermal cell is polarized circularly either to the left or to the right, a feature that has never previously been obsd. in a single tissue.
- 79Vignolini, S.; Gregory, T.; Kolle, M.; Lethbridge, A.; Moyroud, E.; Steiner, U.; Glover, B. J.; Vukusic, P.; Rudall, P. J. Structural Colour from Helicoidal Cell-Wall Architecture in Fruits of Margaritaria Nobilis. J. R. Soc. Interface 2016, 13, 20160645 DOI: 10.1098/rsif.2016.0645There is no corresponding record for this reference.
- 80Airoldi, C. A.; Ferria, J.; Glover, B. J. The Cellular and Genetic Basis of Structural Colour in Plants. Curr. Opin. Plant Biol. 2019, 47, 81– 87, DOI: 10.1016/j.pbi.2018.10.002There is no corresponding record for this reference.
- 81Lee, S.; Kim, H.; Jeong, Y. Angular Distribution of Luminescence Dissymmetry Observed from a Random Laser Built upon the Exocuticle of the Scarab Beetle Chrysina Gloriosa. Opt. Express 2021, 29, 37712– 37721, DOI: 10.1364/OE.43869781Angular distribution of luminescence dissymmetry observed from a random laser built upon the exocuticle of the scarab beetle Chrysina gloriosaLee, Seungsu; Kim, Hansol; Jeong, YoonchanOptics Express (2021), 29 (23), 37712-37721CODEN: OPEXFF; ISSN:1094-4087. (Optica Publishing Group)We investigate the angular distribution of luminescence dissymmetry of random lasing in the mixt. of rhodamine 6G and titanium dioxide nanoparticles upon a biocompatible natural material substrate, i.e., the elytron of the scarab beetle Chrysina gloriosa. We look into both green and gold-colored areas of the elytron that exhibit distinctly different CD properties. The fabricated sample asym. emits both left- and right-handed circularly polarized light at 570 nm when pumped at 532 nm, depending on the direction of emission and the angle of the pump incidence. We characterize the light via measuring the angular distribution of its luminescence dissymmetry factor (glum), which reaches an unusually high maximal value of 0.90 or -0.50 at some specific angle depending on the handedness of its polarization. This random laser source can be used in numerous potential optoelectronic applications which require light emission of distributed luminescence dissymmetry or of high luminescence dissymmetry.
- 82Agez, G.; Bayon, C.; Mitov, M. Multiwavelength Micromirrors in the Cuticle of Scarab Beetle Chrysina Gloriosa. Acta Biomater. 2017, 48, 357– 367, DOI: 10.1016/j.actbio.2016.11.03382Multiwavelength micromirrors in the cuticle of scarab beetle Chrysina gloriosaAgez, Gonzague; Bayon, Chloe; Mitov, MichelActa Biomaterialia (2017), 48 (), 357-367CODEN: ABCICB; ISSN:1742-7061. (Elsevier Ltd.)Beetles from the genus Chrysina show vivid reflections from bright green to metallic silver-gold as a consequence of the cholesteric liq. crystal organization of chitin mols. Particularly, the cuticle of Chrysina gloriosa exhibits green and silver stripes. By combining confocal microscopy and spectrophotometry, SEM and numerical simulations, the relationship between the reflectance and the structural parameters for both stripes at the micro- and nanoscales are established. Over the visible and near IR spectra, polygonal cells in tessellated green stripes behave as multiwavelength selective micro-mirrors and the silver stripes as specular broadband mirrors. Thermoregulation, conspecifics or intra-species communication, or camouflage against predators are discussed as possible functions. As a prerequisite to bio-inspired artificial replicas, the phys. characteristics of the polygonal texture in Chrysina gloriosa cuticle are compared to their equiv. in synthetic cholesteric oligomers and their fundamental differences are ascertained. It is shown that the cuticle has concave cells whereas the artificial films have convex cells, contrary to expectation and assumption in the literature. The present results may provide inspiration for fabricating multiwavelength selective micromirrors or spatial wavelength-specific light modulators. Many insects own a tessellated carapace with bumps, pits or indentations. Little is known on the phys. properties of these geometric variations and biol. functions are unknown or still debated. We show that the polygonal cells in scarab beetle Chrysina gloriosa behave as multiwavelength selective micromirrors over the visible and IR spectra, with a variety of spatial patterns. In the context of biomimetic materials, we demonstrate that the carapace has concave cells whereas the artificial films have convex cells, contrary to expectation in the literature. Thermoregulation, communication or camouflage are discussed as advanced functions. Results may provide inspiration for fabricating spatial wavelength-specific light modulators and optical packet switching in routing technologies.
- 83Hwang, J.; Song, M. H.; Park, B.; Nishimura, S.; Toyooka, T.; Wu, J. W.; Takanishi, Y.; Ishikawa, K.; Takezoe, H. Electro-Tunable Optical Diode Based on Photonic Bandgap Liquid-Crystal Heterojunctions. Nat. Mater. 2005, 4, 383– 387, DOI: 10.1038/nmat137783Electro-tunable optical diode based on photonic bandgap liquid-crystal heterojunctionsHwang, Jisoo; Song, Myoung Hoon; Park, Byoungchoo; Nishimura, Suzushi; Toyooka, Takehiro; Wu, J. W.; Takanishi, Yoichi; Ishikawa, Ken; Takezoe, HideoNature Materials (2005), 4 (5), 383-387CODEN: NMAACR; ISSN:1476-1122. (Nature Publishing Group)Manipulation of light is in strong demand in information technologies. Among the wide range of linear and nonlinear optical devices that have been used, growing attention has been paid to photonic crystals that possess a periodic modulation of dielec. function. Among many photonic bandgap (PBG) structures, liq. crystals with periodic structures are very attractive as self-assembled photonic crystals, leading to optical devices such as dye lasers. Here we report a new hetero-PBG structure consisting of an anisotropic nematic layer sandwiched between two cholesteric liq.-crystal layers with different helical pitches. We optically visualized the dispersion relation of this structure, displaying the optical diode performance: i.e., the non-reciprocal transmission of circular polarized light at the photonic-bandgap regions. Transmittance spectra with circularly polarized light also reveal the diode performance, which is well simulated in calcns. that include an electro-tunable diode effect. Lasing action was also confirmed to show the diode effect with a particular directionality.
- 84Caveney, S. Cuticle Reflectivity and Optical Activity in Scarab Beetles: the Role of Uric Acid. Proc. R. Soc. London, Ser. B 1971, 178, 205– 25, DOI: 10.1098/rspb.1971.006284Cuticle reflectivity and optical activity in scarab beetles: role of uric acidCaveney, S.Proceedings of the Royal Society of London, Series B: Biological Sciences (1971), 178 (1051), 205-25CODEN: PRLBA4; ISSN:0962-8452.The iridescent cuticle of certain rutelian scarab beetles, which is optically active and selectively reflects circularly polarized light, contained an NH4OH-extractable component identified as uric acid (I). All species of Plusiotis examd. had I in their reflecting layers, as did several species of Anoplognathus. P. respendens had a reflecting layer with a I vol. fraction of 0.7, and P. optima a vol. fraction of 0.6. The reflecting layer of the former had a counter-clockwise helicoidal architecture, the optical thickness of the helicoidal pitch being such that it constructively interfered with visible light wavelengths. A counter-clockwise helicoid constructively interferes with only the left circularly polarized component of incident light, right circularly polarized light being transmitted without attenuation. P. respendens had a 1.8 μ thick unidirectional layer embedded within the helicoid which functioned as a perfect halfwave retardation plate for wavelength 590 nm, enabling the helicoidal reflector to reflect both left and right circularly polarized components of incident light. After passing through the halfwave plate, transmitted right circularly polarized light became left circularly polarized; this light was reflected and emerged from the cuticle right circularly polarized, after passing back through the halfwave plate. Consequently the total reflectivity of circularly polarized incident light was greater in P. resplendens than in any other species examd.; the plate also reduced multiple internal reflections. Interferometric anal. of the refractive properties of the helicoidal reflectors in species of Plusiotis showed that the ordered incorporation of I increased the birefringence of the system 5-fold. As the coeff. of reflection of a helicoidal reflector is directly proportional to the birefringence of the individual planes comprising the helicoid, beetles incorporating I into their reflecting surfaces reflected circularly polarized light far more efficiently than beetles lacking I. Although I is a common cytoplasmic reflecting material in arthropods, this is the first record of its presence in an extracellular (cuticular) reflector.
- 85Gray, D. G.; Mu, X. Chiral Nematic Structure of Cellulose Nanocrystal Suspensions and Films; Polarized Light and Atomic Force Microscopy. Materials 2015, 8, 7873– 7888, DOI: 10.3390/ma811542785Chiral nematic structure of cellulose nanocrystal suspensions and films; polarized light and atomic force microscopyGray, Derek G.; Mu, XiaoyueMaterials (2015), 8 (11), 7873-7888CODEN: MATEG9; ISSN:1996-1944. (MDPI AG)Cellulosic liq. cryst. solns. and suspensions form chiral nematic phases that show a rich variety of optical textures in the liq. cryst. state. These ordered structures may be preserved in solid films prepd. by evapn. of solvent or suspending medium. Film formation from aq. suspensions of cellulose nanocrystals (CNC) was investigated by polarized light microscopy, optical profilometry and at. force microscopy (AFM). An attempt is made to interpret qual. the obsd. textures in terms of the orientation of the cellulose nanocrystals in the suspensions and films, and the changes in orientation caused by the evaporative process. Mass transfer within the evapg. droplet resulted in the formation of raised rings whose magnitude depended on the degree of pinning of the receding contact line. AFM of dry films at short length scales showed a radial orientation of the CNC at the free surface of the film, along with a radial height variation with a period of approx. P/2, ascribed to the anisotropic shrinkage of the chiral nematic structure.
- 86Giese, M.; Spengler, M. Cellulose Nanocrystals in Nanoarchitectonics-towards Photonic Functional Materials. Mol. Syst. Des. Eng. 2019, 4, 29– 48, DOI: 10.1039/C8ME00065DThere is no corresponding record for this reference.
- 87Marchessault, R.; Morehead, F.; Walter, N. Liquid Crystal Systems from Fibrillar Polysaccharides. Nature 1959, 184, 632– 633, DOI: 10.1038/184632a087Liquid crystal systems from fibrillar polysaccharidesMarchessault, R. H.; Morehead, F. F.; Walter, N. M.Nature (London, United Kingdom) (1959), 184 (Suppl. No. 9), 632-3CODEN: NATUAS; ISSN:0028-0836.A suspension of crystallite particles of chitin was prepd. by treating purified chitin from crab shells with HCl under reflux. Electron micrographs showed the presence of rodlike particles. The methods used for the prepn. of liquid crystals from such a suspension and from a suspension of cellulose are described, and micrographs are given.
- 88Revol, J. F.; Bradford, H.; Giasson, J.; Marchessault, R. H.; Gray, D. G. Helicoidal Self-Ordering of Cellulose Microfibrils in Aqueous Suspension. Int. J. Biol. Macromol. 1992, 14, 170– 172, DOI: 10.1016/S0141-8130(05)80008-X88Helicoidal self-ordering of cellulose microfibrils in aqueous suspensionRevol, J.-F.; Bradford, H.; Giasson, J.; Marchessault, R. H.; Gray, D. G.International Journal of Biological Macromolecules (1992), 14 (3), 170-2CODEN: IJBMDR; ISSN:0141-8130.In many skeletal support systems of plants and animals, cellulose, chitin, and collagen occur in the form of microfibrils ordered in a chiral nematic fashion (helicoids). However, these structures remain poorly understood due to the many constituents present in biol. tissues. Here an in vitro system is reported that is attractive for its simplicity. Only one chem. component, cellulose, is present in the form of fibrillar fragments dispersed in water. Above a crit. concn. the colloidal dispersion separates spontaneously into a chiral nematic liq. cryst. phase. On drying, this phase solidifies into regularly twisted fibrillar layers that mimic the structural organization of helicoids in nature.
- 89Edgar, C. D.; Gray, D. G. Induced Circular Dichroism of Chiral Nematic Cellulose Films. Cellulose 2001, 8, 5– 12, DOI: 10.1023/A:101662433045889Induced circular dichroism of chiral nematic cellulose filmsEdgar, Catherine D.; Gray, Derek G.Cellulose (Dordrecht, Netherlands) (2001), 8 (1), 5-12CODEN: CELLE8; ISSN:0969-0239. (Kluwer Academic Publishers)Colloidal chiral nematic suspensions of cellulose (I) were prepd. from dissolving grade wood pulp. Upon evapn. of the water, the suspension dries down to give iridescent I films. The optical properties of the films may be characterized by incorporating dyes in the films, and following the ordering of the dye mols. by measurement of induced CD (ICD). Structural changes to the films, e.g. decreasing the chiral nematic pitch by increasing the salt content and increasing the chiral nematic order through magnetic alignment, can be monitored by measuring the changes in ICD.
- 90Mu, X.; Gray, D. G. Formation of Chiral Nematic Films from Cellulose Nanocrystal Suspensions Is a Two-Stage Process. Langmuir 2014, 30, 9256– 9260, DOI: 10.1021/la501741r90Formation of Chiral Nematic Films from Cellulose Nanocrystal Suspensions Is a Two-Stage ProcessMu, Xiaoyue; Gray, Derek G.Langmuir (2014), 30 (31), 9256-9260CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)The evapn. of aq. suspensions of cellulose nanocrystals (CNCs) gives iridescent chiral nematic films with reflection colors at visible wavelengths. A key problem is controlling the chiral nematic pitch, P, and hence the reflection colors of CNC films. By adding D-(+)-glucose to the suspension, the change in P during evapn. occurs in 2 distinct stages. The 1st stage is the decrease in P as the concn. of CNC in the chiral nematic suspension increases due to evapn.; the addn. of glucose causes a decrease in P at this stage. In a 2nd stage, a concn. of CNC is reached where the formation of ordered gels and glasses prevents further major changes in P. The addn. of glucose lowers the CNC concn. at which this occurs, increasing P and hence an overall shift to the red end of the spectrum in the final film.
- 91Coles, H. in Handbook of Liquid Crystals, Demus, D.; Goodby, J.; Gray, G.W.; Spiess, H.-W.; Vill, V., Eds.; Wiley-VCH: Weinheim, Germany, 1998.There is no corresponding record for this reference.
- 92Narkevicius, A.; Parker, R. M.; Ferrer-Orri, J.; Parton, T. G.; Lu, Z.; van de Kerkhof, G. T.; Frka-Petesic, B.; Vignolini, S. Revealing the Structural Coloration of Self-Assembled Chitin Nanocrystal Films. Adv. Mater. 2022, 34, 2203300 DOI: 10.1002/adma.20220330092Revealing the Structural Coloration of Self-Assembled Chitin Nanocrystal FilmsNarkevicius, Aurimas; Parker, Richard M.; Ferrer-Orri, Jordi; Parton, Thomas G.; Lu, Zihao; van de Kerkhof, Gea T.; Frka-Petesic, Bruno; Vignolini, SilviaAdvanced Materials (Weinheim, Germany) (2022), 34 (31), 2203300CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)The structural coloration of arthropods often arises from helicoidal structures made primarily of chitin. Although it is possible to achieve analogous helicoidal architectures by exploiting the self-assembly of chitin nanocrystals (ChNCs), to date no evidence of structural coloration has been reported from such structures. Previous studies are identified to have been constrained by both the exptl. inability to access sub-micrometer helicoidal pitches and the intrinsically low birefringence of cryst. chitin. To expand the range of accessible pitches, here, ChNCs are isolated from two phylogenetically distinct sources of alpha-chitin, namely fungi and shrimp, while to increase the birefringence, an in situ alk. treatment is performed, increasing the intensity of the reflected color by nearly two orders of magnitude. By combining this treatment with precise control over ChNC suspension formulation, structurally colored chitin-based films are demonstrated with reflection tunable from blue to near IR.
- 93Andrew, L. J.; Walters, C. M.; Hamad, W. Y.; MacLachlan, M. J. Coassembly of Cellulose Nanocrystals and Neutral Polymers in Iridescent Chiral Nematic Films. Biomacromolecules 2023, 24, 896– 908, DOI: 10.1021/acs.biomac.2c0132593Coassembly of Cellulose Nanocrystals and Neutral Polymers in Iridescent Chiral Nematic FilmsAndrew, Lucas J.; Walters, Christopher M.; Hamad, Wadood Y.; MacLachlan, Mark J.Biomacromolecules (2023), 24 (2), 896-908CODEN: BOMAF6; ISSN:1525-7797. (American Chemical Society)Photonic materials based on composite films of cellulose nanocrystals (CNCs) and polymers are promising as they can be renewable and show tunable optical and mech. properties. However, the influence of polymers on CNC self-assembly is not always well understood, and conflicting results are present in the literature. In this study, we incorporate three neutral, water-sol. polymers-poly(ethylene glycol) (PEG), poly(vinyl pyrrolidone) (PVP), and poly(acrylic acid) (PAA)-with different mol. wts. into CNC suspensions at various concns. prior to obtaining iridescent composite thin films by solvent evapn. Through spectroscopic, potentiometric, and rheol. analyses, we find that PVP phys. adsorbs to the surface of CNCs resulting in a bathochromic shift in film color with both increasing concn. and polymer mol. wt. In contrast, PEG induces depletion interactions that result in a decrease in the size of chiral nematic CNC domains, with a negligible change in film color. Finally, PAA hydrogen bonds to the hydroxyl groups of CNCs, resulting in a bathochromic color shift along with interesting rheol. and liq.-state properties. This work demonstrates a deeper understanding of CNC-polymer interactions during coassembly and formation of iridescent chiral nematic films, allowing for greater control over optical properties of future CNC-based materials.
- 94Wang, Z.; Chu, J.; Shi, L.; Xing, T.; Gao, X.; Xu, Y. Chiral Pearlescent Cellulose Nanocrystals Films with Broad-Range Tunable Optical Properties for Anti-Counterfeiting Applications. Small 2024, 20, 2306810 DOI: 10.1002/smll.202306810There is no corresponding record for this reference.
- 95He, J.; Bian, K.; Piao, G. Self-Assembly Properties of Carboxylated Tunicate Cellulose Nanocrystals Prepared by Ammonium Persulfate Oxidation and Subsequent Ultrasonication. Carbohydr. Polym. 2020, 249, 116835 DOI: 10.1016/j.carbpol.2020.11683595Self-assembly properties of carboxylated tunicate cellulose nanocrystals prepared by ammonium persulfate oxidation and subsequent ultrasonicationHe, Jintao; Bian, Kaiqiang; Piao, GuangzheCarbohydrate Polymers (2020), 249 (), 116835CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)Tunicate cellulose, extd. from the marine animal, has drawn increasing attention as the high crystallinity and aspect ratio. However, it is hard to prep. tunicate cellulose nanocrystals (tCNCs) with narrow size distribution in the traditional way, esp. for the carboxylated samples, which also affects their lyotropic liq. crystal behavior to a certain extent. Herein, carboxylated tCNCs with uniform nanoscale dimensions and high surface charges d. were prepd. through ammonium persulfate (APS) oxidn. and ultrasonic post-processing. Of particular interest, the formation of carboxylated tCNCs lyotropic chiral nematic liq. crystals was obsd. for the first time, which displayed obvious birefringence and fingerprint texture. Meanwhile, it was found that the crit. concn. of phase sepn. for tCNCs suspension was around 3.5 wt% from the phase diagram. This study provides an efficient way to fabricate carboxylated tCNCs, and the self-assembly properties may lead to great potential applications in constructing advanced functional materials.
- 96Raghuwanshi, V. S.; Browne, C.; Batchelor, W.; Garnier, G. Self-Assembly of Cellulose Nanocrystals of Different Lengths. J. Colloid Interface Sci. 2023, 630, 249– 259, DOI: 10.1016/j.jcis.2022.10.10096Self-assembly of cellulose nanocrystals of different lengthsRaghuwanshi, Vikram Singh; Browne, Christine; Batchelor, Warren; Garnier, GilJournal of Colloid and Interface Science (2023), 630 (Part_B), 249-259CODEN: JCISA5; ISSN:0021-9797. (Elsevier B.V.)The self-assembly (SA) of cellulose nanocrystals (CNC) in suspensions is important both from the fundamental and advanced technol. development perspective. CNC of different lengths self-assemble differently in suspensions by balancing attractive and repulsive interactions which depends strongly on morphol., surface chem. and concns. Two different com. CNC samples (CNC-M and CNC-C) of different lengths were dispersed in Milli-Q water at different concns. (0.5-10 wt%). CNC-M is provided as a gel at a solid concn. of 10.3 wt% which was dild. in Milli-Q water. CNC-C is sold as a powder which was dispersed in Milli-Q water with a mixer to achieve the desired concns. TEM was used to det. morphol. of CNC. Polarised optical microscopy is performed to get microscale visualisation of the chiral nematic self-assembly. High flux synchrotron SAXS is applied to evaluate and compare the nanoscale self-assembly mechanisms of CNC of different lengths. The SA of two different types of CNC rods of similar diam. but different lengths is investigated. SAXS anal. shows the short rods in suspension form an isotropic phase (randomly oriented) at lower concn. (0-4 wt%); as concn. is increased, the rods become systematically aligned in a nematic phase. The interrod distance d varies as c-0.33 at the lower concn., which changes to c-0.5 and even c-1 at the higher concns. In contrast, the long rods in suspension remain in the isotropic phase throughout the measured concn. range from 0.5 to 10 wt%. The interrod distance also follows the isotropic power law slope of c-0.33. Suspensions made of the short CNC rods show long range order and large interrod distance compared to those formed by the long rods. POM agrees with the SAXS results. A specific equil. between attractive and repulsive forces is required to maintain SA and ordering of the rods. DLVO calcns. reveal that the long rods maintain van der Waal attractive force dominating over the electrostatic repulsion, which hinders rods alignment in an ordered manner. However, for the short rods, the weaker attractive interactions are well compensated by the repulsive force which aligns rods in an ordered assembly. This fundamental understanding of the SA of rods in suspensions facilitates the engineering of novel CNC composites of unique optical properties which enables novel applications such as in sensors and bio-diagnostics.
- 97Zhao, G.; Zhang, S.; Zhai, S.; Pan, M. Fabrication and Characterization of Photonic Cellulose Nanocrystal Films with Structural Colors Covering Full Visible Light. J. Mater. Sci. 2020, 55, 8756– 8767, DOI: 10.1007/s10853-020-04616-4There is no corresponding record for this reference.
- 98Wang, N.; Ding, E.; Cheng, R. Preparation and Liquid Crystalline Properties of Spherical Cellulose Nanocrystals. Langmuir 2008, 24, 5– 8, DOI: 10.1021/la702923w98Preparation and Liquid Crystalline Properties of Spherical Cellulose NanocrystalsWang, Neng; Ding, Enyong; Cheng, RongshiLangmuir (2008), 24 (1), 5-8CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)A novel kind of spherical cellulose nanocrystal (SCNC) suspension was prepd. by hydrolysis of microcryst. cellulose with a mixt. of sulfuric acid and hydrochloric acid under ultrasonic treatment. The mechanism of SCNC formation and the liq. cryst. properties of their suspensions were investigated. A suspension of spherical particles was usually inclined to form crystn. colloids rather than liq. crystals at high concn. However, a SCNC suspension with high polydispersity (49%) was obsd. to form the liq. cryst. phase, and the liq. cryst. textures changed with increasing concn. This observation offers an approach to the liq. crystal formation of highly polydisperse spherical nanoparticles.
- 99Verma, C.; Chhajed, M.; Gupta, P.; Roy, S.; Maji, P. K. Isolation of cellulose nanocrystals from different waste bio-mass collating their liquid crystal ordering with morphological exploration. Int. J. Biol. Macromol. 2021, 175, 242– 253, DOI: 10.1016/j.ijbiomac.2021.02.03899Isolation of cellulose nanocrystals from different waste bio-mass collating their liquid crystal ordering with morphological explorationVerma, Chhavi; Chhajed, Monika; Gupta, Pragya; Roy, Sunanda; Maji, Pradip K.International Journal of Biological Macromolecules (2021), 175 (), 242-253CODEN: IJBMDR; ISSN:0141-8130. (Elsevier B.V.)Cellulose nanocrystals (CNCs) have been recognized as one of the most promising nanofillers in modern science and technol. owing to their outstanding characteristics of renewability, biodegradability, excellent mech. strength, and liq. cryst. behavior. Interestingly, these properties are dependent on their genetic and also on the isolation process. Therefore, this research aimed to unveil how the biol. variations of cellulose can influence on the phys. properties of the extd. CNCs. A std. optimized extn. process was adopted to isolate the CNCs from different sources. Extd. CNCs were compared through characterization tools, including Fourier transformation IR spectroscopy (FTIR), X-ray Diffraction (XRD), thermogravimetry anal. (TGA), dynamic light scattering (DLS), field emission SEM (FE-SEM), at. force microscopy (AFM), and polarized optical microscopy (POM). Different self-assembly patterns were obsd. for different CNCs, owing to their biol. variations. The resultant nanocrystals displayed variable morphologies such as spherical, rod, and needle shape. The hydrodynamic diam., crystallinity index, decompn. temp., liq. crystallinity, and storage modulus were varied. Nanocrystals isolated from non-wood feedstock have shown a higher d.p. of 108.2 and a high crystllinity Index (C.I.) of 55.1%. The rod-like morphol. with the liq. cryst. pattern was obtained at 3 wt% concn. for SCNC.
- 100Abitbol, T.; Kam, D.; Levi-Kalisman, Y.; Gray, D. G.; Shoseyov, O. Surface Charge Influence on the Phase Separation and Viscosity of Cellulose Nanocrystals. Langmuir 2018, 34, 3925– 3933, DOI: 10.1021/acs.langmuir.7b04127100Surface Charge Influence on the Phase Separation and Viscosity of Cellulose NanocrystalsAbitbol, Tiffany; Kam, Doron; Levi-Kalisman, Yael; Gray, Derek G.; Shoseyov, OdedLangmuir (2018), 34 (13), 3925-3933CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)A series of four cellulose nanocrystal (CNC) suspensions were prepd. from bleached softwood kraft pulp using different conditions of sulfuric acid hydrolysis. The CNCs were identical in size (95 nm in length × 5 nm in width) but had different surface charges corresponding to the harshness of the hydrolysis conditions. Consequently, it was possible to isolate the effects of surface charge on the self-assembly and viscosity of the CNC suspensions across surface charges ranging from 0.27%S to 0.89%S. The four suspensions (never-dried, free of added electrolyte) all underwent liq. cryst. phase sepn., but the concn. onset for the emergence of the chiral nematic phase shifted to higher values with increasing surface charge. Similarly, suspension viscosity was also influenced by surface charge, with suspensions of lower surface charge CNCs more viscous and tending to gel at lower concns. The properties of the suspensions were interpreted in terms of the increase in effective diam. of the nanocrystals due to the surface electrostatic repulsion of the neg. sulfate half-esters, as modified by the screening effects of the H+ counterions in the suspensions. The results suggest that there is a threshold surface charge d. (∼0.3%S) above which effective vol. considerations are dominant across the concn. range relevant to liq. cryst. phase formation. Above this threshold value, phase sepn. occurs at the same effective vol. fraction of CNCs (∼10 vol. %), with a corresponding increase in crit. concn. due to the decrease in effective diam. that occurs with increasing surface charge. Below or near this threshold value, the formation of end-to-end aggregates may favor gelation and interfere with ordered phase formation.
- 101Salajkova, M.; Berglund, L. A.; Zhou, Q. Hydrophobic Cellulose Nanocrystals Modified with Quaternary Ammonium Salts. J. Mater. Chem. 2012, 22, 19798– 19805, DOI: 10.1039/c2jm34355j101Hydrophobic cellulose nanocrystals modified with quaternary ammonium saltsSalajkova, Michaela; Berglund, Lars A.; Zhou, QiJournal of Materials Chemistry (2012), 22 (37), 19798-19805CODEN: JMACEP; ISSN:0959-9428. (Royal Society of Chemistry)An environmentally friendly procedure in aq. soln. for the surface modification of cellulose nanocrystals (CNCs) using quaternary ammonium salts via adsorption was developed as inspired by organomodified layered silicates. CNCs with a high carboxylate content of 1.5 mmol g-1 were prepd. by a new route, direct hydrochloric acid hydrolysis of 2,2,6,6-tetramethylpiperidine-1-oxyl radical (TEMPO)-oxidized nanofibrillated cellulose from a softwood pulp, and characterized by at. force microscopy (AFM) and X-ray diffraction (XRD). Four quaternary ammonium cation surfactants bearing long alkyl, Ph, glycidyl, and diallyl groups were successfully used to modify CNCs carrying carboxylic acid groups as characterized by Fourier transform IR spectroscopy (FTIR). The modified CNCs can be redispersed and individualized in an org. solvent such as toluene as obsd. by scanning transmission electron microscopy (STEM). One may envision removing excess surfactant to obtain CNC with a monolayer of surfactant. The toluene suspension of the modified CNCs showed strong birefringence under crossed polars but no further chiral-nematic ordering was obsd. The model surface prepd. by the CNCs modified with quaternary ammonium salts bearing C18 alkyl chains showed a significant increase in water contact angle (71°) compared to that of unmodified CNCs (12°). This new series of modified CNCs can be dried from solvent and have the potential to form well-dispersed nanocomposites with non-polar polymers.
- 102Araki, J.; Wada, M.; Kuga, S. Steric Stabilization of a Cellulose Microcrystal Suspension by Poly(ethylene glycol) Grafting. Langmuir 2001, 17, 21– 27, DOI: 10.1021/la001070m102Steric Stabilization of a Cellulose Microcrystal Suspension by Poly(ethylene glycol) GraftingAraki, Jun; Wada, Masahisa; Kuga, ShigenoriLangmuir (2001), 17 (1), 21-27CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)A sterically stabilized aq. suspension of rodlike cellulose microcrystals was prepd. by the combination of acid hydrolysis of native cellulose, oxidative carboxylation of microcrystals, and grafting of poly(ethylene glycol) having a terminal amino group on one end (PEG-NH2, MW = 1000) using water-sol. carbodiimide. Chem. binding of PEG to the microcrystals was confirmed by wt. increase, diminishment of carboxyl groups, thermogravimetry, and IR spectroscopy, resulting in consumption of 20-30% of the initially introduced carboxyl groups. The amt. of bound PEG was 0.2-0.3 g/g of cellulose. The PEG-grafted cellulose microcrystals showed drastically enhanced dispersion stability, i.e., resistance to addn. of 2 M sodium chloride, and ability to redisperse into either water or chloroform from the freeze-dried state. The concd. aq. suspension of PEG-grafted microcrystals formed a chiral nematic mesophase through a phase sepn. similar to that of the ungrafted sample, but with a reduced spacing of the fingerprint pattern.
- 103He, J.; Liu, S.; Li, L.; Piao, G. Lyotropic Liquid Crystal Behavior of Carboxylated Cellulose Nanocrystals. Carbohydr. Polym. 2017, 164, 364– 369, DOI: 10.1016/j.carbpol.2017.01.080There is no corresponding record for this reference.
- 104Fan, W.; Li, J.; Wei, L.; Xu, Y. Carboxylated Cellulose Nanocrystal Films with Tunable Chiroptical Properties. Carbohydr. Polym. 2022, 289, 119442 DOI: 10.1016/j.carbpol.2022.119442104Carboxylated cellulose nanocrystal films with tunable chiroptical propertiesFan, Wei; Li, Jiaqi; Wei, Lihong; Xu, YanCarbohydrate Polymers (2022), 289 (), 119442CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)Carboxylated cellulose nanocrystals prepd. by TEMPO-mediated oxidn. exhibit a distinct ability to form nematic order, however, their ability to form chiral nematic films remains relatively unexplored. In this study, bleached cotton pulp hydrolyzed with hydrochloric acid and oxidized by TEMPO-mediated oxidn. produce carboxylated cellulose nanocrystals with different aspect ratios 33.1, 32.8, 30.9, 29.0 and 28.9, and surface charge densities 0.16, 0.56, 1.00, 1.25, and 1.42 e.nm2. By tuning the aspect ratio and surface charge d., the optimal carboxylated cellulose nanocrystals producing left-handed chiral nematic films by evapn.-induced self-assembly are obtained. The left-handed chiral nematic films enable selective reflection of left-handed circularly polarized light with the peak wavelength tunable from the visible to the near-IR regime by modifying the characteristics of nanorods and suspensions. Such carboxylated cellulose nanocrystal films transform spontaneous luminescence to right-handed circularly polarized luminescence with the peak luminescence dissymmetry factor of -0.51.
- 105Lin, C.; Wang, P.; Liu, Y.; Lv, Y.; Ye, X.; Liu, M.; Zhu, J. Y. Chiral Self-Assembly Behavior of Carboxylated Cellulose Nanocrystals Isolated by Recyclable Oxalic Acid from Degreasing Cotton. ACS Sustainable Chem. Eng. 2023, 11, 8035– 8043, DOI: 10.1021/acssuschemeng.3c00118There is no corresponding record for this reference.
- 106Risteen, B.; Delepierre, G.; Srinivasarao, M.; Weder, C.; Russo, P.; Reichmanis, E.; Zoppe, J. Thermally Switchable Liquid Crystals Based on Cellulose Nanocrystals with Patchy Polymer Grafts. Small 2018, 14, 1802060 DOI: 10.1002/smll.201802060There is no corresponding record for this reference.
- 107Xu, Q.; Yi, J.; Zhang, X.; Zhang, H. A Novel Amphotropic Polymer Based on Cellulose Nanocrystals Grafted with Azo Polymers. Eur. Polym. J. 2008, 44, 2830– 2837, DOI: 10.1016/j.eurpolymj.2008.06.010107A novel amphotropic polymer based on cellulose nanocrystals grafted with azo polymersXu, Qunxing; Yi, Jie; Zhang, Xuefei; Zhang, HailiangEuropean Polymer Journal (2008), 44 (9), 2830-2837CODEN: EUPJAG; ISSN:0014-3057. (Elsevier Ltd.)A novel amphotropic polymer which could exhibit liq.-cryst. behavior both in the solvent and in the heating process was synthesized through azo polymers grafting from cellulose nanocrystals (CNCs). The CNCs, prepd. by acid hydrolysis of filter paper, were characterized by At. Force Microscopy (AFM). Poly{6-[4-(4-methoxyphenylazo)phenoxy] hexyl methacrylate} (PMMAZO), which was a liq.-cryst. polymers (LCP), was successfully to graft from CNC via Atom transfer radical polymn. (ATRP). The structure and thermal properties of the PMMAZO-grafted CNC were investigated using FT-IR and thermogravimetric analyses (TGA). Its phase structures and transitions were studied by DSC and polarized optical microscopy (POM). The exptl. results showed that the PMMAZO-grafted CNC exhibited both types of liq. crystal formation, thermotropic and lyotropic.
- 108Yi, J.; Xu, Q.; Zhang, X.; Zhang, H. Chiral-Nematic Self-Ordering of Rodlike Cellulose Nanocrystals Grafted with Poly(styrene) in Both Thermotropic and Lyotropic States. Polymer 2008, 49, 4406– 4412, DOI: 10.1016/j.polymer.2008.08.008108Chiral-nematic self-ordering of rodlike cellulose nanocrystals grafted with poly(styrene) in both thermotropic and lyotropic statesYi, Jie; Xu, Qunxing; Zhang, Xuefei; Zhang, HailiangPolymer (2008), 49 (20), 4406-4412CODEN: POLMAG; ISSN:0032-3861. (Elsevier Ltd.)Graft copolymers of rodlike cellulose nanocrystals (CNC) with poly(styrene) (PSt) were synthesized through atom transfer radical polymn. (ATRP). The hydroxyl groups on CNC were esterified with 2-bromoisobutyrylbromide to yield 2-bromoisobutyryloxy groups, which were used to initiate the polymn. of poly(styrene). The graft copolymers were characterized by thermogravimetric anal. (TGA), fourier transform IR spectroscopy (FT-IR) and gel permeation chromatog. (GPC). The size of the original CNC is 10-40 nm in width and 100-400 nm in length, which was characterized by at. force microscopy (AFM). The thermal and liq. cryst. properties of the graft copolymers were investigated by differential scanning calorimeter (DSC) and polarizing optical microscope (POM). The graft copolymers exhibit fingerprint texture in both thermotropic and lyotropic states. In thermotropic state, the PSt-grafted CNC orient spontaneously in isotropic melt (PSt side chains acting as a solvent). The thermotropic liq. crystal phase behavior is similar to the lyotropic phase behavior.
- 109Delepierre, G.; Traeger, H.; Adamcik, J.; Cranston, E. D.; Weder, C.; Zoppe, J. O. Liquid Crystalline Properties of Symmetric and Asymmetric End-Grafted Cellulose Nanocrystals. Biomacromolecules 2021, 22, 3552– 3564, DOI: 10.1021/acs.biomac.1c00644109Liquid Crystalline Properties of Symmetric and Asymmetric End-Grafted Cellulose NanocrystalsDelepierre, Gwendoline; Traeger, Hanna; Adamcik, Jozef; Cranston, Emily D.; Weder, Christoph; Zoppe, Justin O.Biomacromolecules (2021), 22 (8), 3552-3564CODEN: BOMAF6; ISSN:1525-7797. (American Chemical Society)The hydrophilic polymer poly[2-(2-(2-methoxy ethoxy)ethoxy)ethylacrylate] (POEG3A) was grafted onto the reducing end-groups (REGs) of cellulose nanocrystal (CNC) allomorphs, and their liq. cryst. properties were investigated. The REGs on CNCs extd. from cellulose I (CNC-I) are exclusively located at one end of the crystallite, whereas CNCs extd. from cellulose II (CNC-II) feature REGs at both ends of the crystallite, so that grafting from the REGs affords asym. and sym. decorated CNCs, resp. To confirm the REG modification, several complementary anal. techniques were applied. The grafting of POEG3A onto the CNC REGs was evidenced by Fourier transform IR spectroscopy, at. force microscopy, and the coil-globule conformational transition of this polymer above 60°C, i.e., its lower crit. soln. temp. Furthermore, we investigated the self-assembly of end-tethered CNC-hybrids into chiral nematic liq. cryst. phases. Above a crit. concn., both end-grafted CNC allomorphs form chiral nematic tactoids. The introduction of POEG3A to CNC-I does not disturb the surface of the CNCs along the rods, allowing the modified CNCs to approach each other and form helicoidal textures. End-grafted CNC-II formed chiral nematic tactoids with a pitch observable by polarized optical microscopy. This is likely due to their increase in hydrodynamic radius or the introduced steric stabilization of the end-grafted polymer.
- 110Qin, J.; Wang, Z.; Hu, J.; Yuan, Y.; Liu, P.; Cheng, L.; Kong, Z.; Liu, K.; Yan, S.; Zhang, J. Distinct Liquid Crystal Self-Assembly Behavior of Cellulose Nanocrystals Functionalized with Ionic Liquids. Colloids Surf., A 2022, 632, 127790 DOI: 10.1016/j.colsurfa.2021.127790110Distinct liquid crystal self-assembly behavior of cellulose nanocrystals functionalized with ionic liquidsQin, Jinli; Wang, Zhaolu; Hu, Jie; Yuan, Yuan; Liu, Ping; Cheng, Li; Kong, Zhengqing; Liu, Ke; Yan, Shouke; Zhang, JianmingColloids and Surfaces, A: Physicochemical and Engineering Aspects (2022), 632 (), 127790CODEN: CPEAEH; ISSN:0927-7757. (Elsevier B.V.)Rod-like cellulose nanocrystals (CNCs) show the intriguing liq. crystal self-assembly ability. The understanding of the self-assembly behavior of CNCs is of fundamental importance for constructing cellulose-based functional materials. The presented work explores how the liq. crystal self-assembly behavior of CNCs is affected by the grafted ionic liqs. (IL) [VBIm][BF4]. The results demonstrate that the IL modified CNC (CNC-IL) with pos. charged form chiral nematic structure in suspensions, which was normally obsd. in neg. charged ones. Significantly, such liq.-cryst. organization can be obtained under much lower concn. (as low as 1.0 wt%) than that of the non-functionalized CNCs prepd. from paper pulp (∼ 3.0 wt%). Moreover, for CNC-IL concns. varying from 1.0 to 4.0 wt%, the tactoids (showing obvious fingerprint texture) coexist with the disordered CNC phase, rather than sepg. into two phases. Unlike original CNCs, the pitch of chiral nematic tactoids increases with increasing concn. of CNC-IL. Our study suggests that the distinct liq. crystal self-assembly behavior of CNC-IL is related to the restricted mobility of CNCs rods due to the increase in CNCs particle size and the high viscosity of CNC-IL suspension as the result of IL surface modification. The study of the liq. crystal assembly behavior of IL modified CNCs provides some new insight to understand the intriguing chiral nematic self-assembly of CNCs and for construction of CNC-IL reinforced nanocomposites.
- 111Momeni, A.; Walters, C. M.; Xu, Y.-T.; Hamad, W. Y.; MacLachlan, M. J. Concentric Chiral Nematic Polymeric Fibers from Cellulose Nanocrystals. Nanoscale Adv. 2021, 3, 5111– 5121, DOI: 10.1039/D1NA00425E111Concentric chiral nematic polymeric fibers from cellulose nanocrystalsMomeni, Arash; Walters, Christopher M.; Xu, Yi-Tao; Hamad, Wadood Y.; MacLachlan, Mark J.Nanoscale Advances (2021), 3 (17), 5111-5121CODEN: NAADAI; ISSN:2516-0230. (Royal Society of Chemistry)Hierarchical biol. materials, such as osteons and plant cell walls, are complex structures that are difficult to mimic. Here, we combine liq. crystal systems and polymn. techniques within confined systems to develop complex structures. A single-domain concentric chiral nematic polymeric fiber was obtained by confining cellulose nanocrystals (CNCs) and hydroxyethyl acrylate inside a capillary tube followed by UV-initiated polymn. The concentric chiral nematic structure continues uniformly throughout the length of the fiber. The pitch of the chiral nematic structure could be controlled by changing the CNC concn. We tracked the formation of the concentric structure over time and under different conditions with variation of the tube orientation, CNC concn., CNC type, and capillary tube size. We show that the inner radius of the capillary tube is important and a single-domain structure was only obtained inside small-diam. tubes. At low CNC concn., the concentric chiral nematic structure did not completely cover the cross-section of the fiber. The highly ordered structure was studied using imaging techniques and X-ray diffraction, and the mech. properties and structure of the chiral nematic fiber were compared to a pseudo-nematic fiber. CNC polymeric fibers could become a platform for many applications from photonics to complex hierarchical materials.
- 112Lagerwall, J. P. F.; Schütz, C.; Salajkova, M.; Noh, J.; Hyun Park, J.; Scalia, G.; Bergström, L. Cellulose Nanocrystal-Based Materials: From Liquid Crystal Self-Assembly and Glass Formation to Multifunctional Thin Films. NPG Asia Mater. 2014, 6, e80 DOI: 10.1038/am.2013.69112Cellulose nanocrystal-based materials: from liquid crystal self-assembly and glass formation to multifunctional thin filmsLagerwall, Jan P. F.; Schutz, Christina; Salajkova, Michaela; Noh, Jung Hyun; Park, Ji Hyun; Scalia, Giusy; Bergstrom, LennartNPG Asia Materials (2014), 6 (1), e80CODEN: NAMPCE; ISSN:1884-4057. (Nature Publishing Group)A review. Cellulose nanocrystals (CNCs), produced by the acid hydrolysis of wood, cotton or other cellulose-rich sources, constitute a renewable nanosized raw material with a broad range of envisaged uses: for example, in composites, cosmetics and medical devices. The intriguing ability of CNCs to self-organize into a chiral nematic (cholesteric) liq. crystal phase with a helical arrangement has attracted significant interest, resulting in much research effort, as this arrangement gives dried CNC films a photonic band gap. The films thus acquire attractive optical properties, creating possibilities for use in applications such as security papers and mirrorless lasing. In this crit. review, we discuss the sensitive balance between glass formation and liq. crystal self-assembly that governs the formation of the desired helical structure. We show that several as yet unclarified observations-some constituting severe obstacles for applications of CNCs-may result from competition between the two phenomena. Moreover, by comparison with the corresponding self-assembly processes of other rod-like nanoparticles, for example, carbon nanotubes and fd virus particles, we outline how further liq. crystal ordering phenomena may be expected from CNCs if the suspension parameters can be better controlled. Alternative interpretations of some unexpected phenomena are provided, and topics for future research are identified, as are new potential application strategies.
- 113Klockars, K. W.; Tardy, B. L.; Borghei, M.; Tripathi, A.; Greca, L. G.; Rojas, O. J. Effect of Anisotropy of Cellulose Nanocrystal Suspensions on Stratification, Domain Structure Formation, and Structural Colors. Biomacromolecules 2018, 19, 2931– 2943, DOI: 10.1021/acs.biomac.8b00497113Effect of Anisotropy of Cellulose Nanocrystal Suspensions on Stratification, Domain Structure Formation, and Structural ColorsKlockars, Konrad W.; Tardy, Blaise L.; Borghei, Maryam; Tripathi, Anurodh; Greca, Luiz G.; Rojas, Orlando J.Biomacromolecules (2018), 19 (7), 2931-2943CODEN: BOMAF6; ISSN:1525-7797. (American Chemical Society)Outstanding optical and mech. properties can be obtained from hierarchical assemblies of nanoparticles. Herein, the formation of helically ordered, chiral nematic films obtained from aq. suspensions of cellulose nanocrystals (CNCs) were studied as a function of the initial suspension state. Specifically, nanoparticle organization and the structural colors displayed by the resultant dry films were investigated as a function of the anisotropic vol. fraction (AVF), which depended on the initial CNC concn. and equilibration time. The development of structural color and the extent of macroscopic stratification were studied by optical and SEM as well as UV-vis spectroscopy. Overall, suspensions above the crit. threshold required for formation of liq. crystals resulted in CNC films assembled with longer ranged order, more homogeneous pitches along the cross sections, and narrower specific absorption bands. This effect was more pronounced for the suspensions that were closer to equil. prior to drying. Thus, we show that high AVF and more extensive phase sepn. in CNC suspensions resulted in large, long-range ordered chiral nematic domains in dried films. Addnl., the av. CNC aspect ratio and size distribution in the two sepd. phases were measured and correlated to the formation of structured domains in the dried assemblies.
- 114Bukharina, D.; Kim, M.; Han, M. J.; Tsukruk, V. V. Cellulose Nanocrystals’ Assembly under Ionic Strength Variation: From High Orientation Ordering to a Random Orientation. Langmuir 2022, 38, 6363– 6375, DOI: 10.1021/acs.langmuir.2c00293114Cellulose Nanocrystals' Assembly under Ionic Strength Variation: From High Orientation Ordering to a Random OrientationBukharina, Daria; Kim, Minkyu; Han, Moon Jong; Tsukruk, Vladimir V.Langmuir (2022), 38 (20), 6363-6375CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)We discuss the effect of the ionic strength and effective charge d. on the final structural organization of cellulose nanocrystals (CNCs) after drying suspensions with different ionic strengths in terms of quant. characteristics of the orientation order, rarely considered to date. We obsd. that increasing the ionic strength in the initial suspension results in continuous shrinking of the helical pitch length that shifts the photonic band gap to a far UV region from the visible range (from 400 to 250 nm) because of the increase in the helical twisting power from 4 to 6μm-1 and doubling of the twisting angle between neighboring monolayers from 5.5 to 9°. As our estn. of the Coulombic interactions demonstrates, the redn. of the Debye charge screening length below a crit. value of 3 nm results in the loss of the long-range helicoidal order and the transition to a disordered morphol. with random packing of nanocrystals. Subsequently, very high orientation ordering with the 2D orientation factor, S, within the range 0.8-0.9, close to the theor. limit of 1, gradually decreased to a very low value of S = 0.1-0.2, a characteristic of random organization at high ionic strength. We suggest that the loss of the chiral ordering is a result of the redn. of repulsive forces, promoting direct phys. contact with the reduced contact area during Brownian motion, combined with increased repulsive Coulombic interactions of nanocrystals at nonparallel local packing. Notably, electrolyte addn. enhances chiral interactions to the point where the helical twisting power is too large and the resulting nanocrystal bundles can no longer compactly pack without creating unfavorably large free vol. We propose that the Debye charge screening length in suspensions can be used as a universal parameter for CNCs under different conditions and can be used to assess expected ordering characteristics in the solid films.
- 115Lin, M.; Singh Raghuwanshi, V.; Browne, C.; Simon, G. P.; Garnier, G. Modulating the Chiral Nanoarchitecture of Cellulose Nanocrystals Through Interaction with Salts and Polymer. J. Colloid Interface Sci. 2022, 613, 207– 217, DOI: 10.1016/j.jcis.2021.12.182115Modulating the chiral nanoarchitecture of cellulose nanocrystals through interaction with salts and polymerLin, Maoqi; Singh Raghuwanshi, Vikram; Browne, Christine; Simon, George P.; Garnier, GilJournal of Colloid and Interface Science (2022), 613 (), 207-217CODEN: JCISA5; ISSN:0021-9797. (Elsevier B.V.)The conditions to allow self-assembly of cellulose nanocrystal (CNC) suspensions into chiral nematic structures are based on aspect ratio, surface charge d. and a balance between repulsive and attractive forces between CNC particles. Three types of systems were characterized in suspensions and subsequently in their solid dried films: 1. neat water dialyzed CNC, 2. CNC combined with polyethylene glycol(PEG) (CNC/PEG), and 3. CNC with added salt (CNC/Salt). All suspensions were characterized by polarized optical microscope (POM) and small angle X-ray scattering (SAXS), while the resultant dried films were analyzed by reflectance spectrometer, scanning electron microscope (SEM) and SAXS. The presence of chiral nematic (CN*) structures was not obsd. in dialyzed aq. suspensions of CNC during water evapn. By introducing salts or a non-adsorbing polymer, chirality was apparent in both suspensions and films. The interaxial angle between CNC rods increased when the suspensions of CNC/PEG and CNC/salt were dried to solid films. The angle was found to be dependent on both species of ions and ionic strength, while the inter-particle distance was only related to the salt concn., as explained in terms of interaction energies. The CNC suspensions/film chirality can be modulated by controlling the colloidal forces.
- 116Cao, T.; Elimelech, M. Colloidal Stability of Cellulose Nanocrystals in Aqueous Solutions Containing Monovalent, Divalent, and Trivalent Inorganic Salts. J. Colloid Interface Sci. 2021, 584, 456– 463, DOI: 10.1016/j.jcis.2020.09.117116Colloidal stability of cellulose nanocrystals in aqueous solutions containing monovalent, divalent, and trivalent inorganic saltsCao, Tianchi; Elimelech, MenachemJournal of Colloid and Interface Science (2021), 584 (), 456-463CODEN: JCISA5; ISSN:0021-9797. (Elsevier B.V.)Aggregation kinetics and surface charging properties of rod-like sulfated cellulose nanocrystals (CNCs) have been investigated in aq. suspensions contg. monovalent, divalent, or trivalent inorg. salts. Electrophoresis and time-resolved dynamic light scattering (DLS) were used to characterize the surface charge and colloidal stability of the CNCs, resp. The surface charge and aggregation kinetics of the sulfated CNCs were found to be independent of soln. pH (pH range 2-10). For the monovalent salts (CsCl, KCl, NaCl, and LiCl), the crit. coagulation concn. (CCC) followed the order of Cs+ < K+ < Na+ < Li+, which follows the direct Hofmeister series, indicating specific interaction of the cations with the CNCs surface. The exptl. aggregation kinetics of CNCs were in very good agreement with predictions based on the classic Derjaguin-Landau-Verwey-Overbeek (DLVO) theory. A Hamaker const. of 3.6 x 10-20 J for the CNCs in aq. medium was derived, for the first time, from the colloidal stability curves with monovalent salts. This value is consistent with a previous value detd. by direct force measurements for cellulose surfaces in aq. solns. For the divalent salts (MgCl2, CaCl2, and BaCl2), the CCC values followed the order Mg2+ > Ca2+ > Ba2+, which is in the reverse order of the counterion ionic size. For the trivalent salts (LaCl3, AlCl3, and FeCl3), the CNCs suspension was destabilized much more effectively. The obsd. complex stability curves with AlCl3 and FeCl3 are attributed to charge neutralization and charge reversal imparted by the adsorption of aluminum and ferric hydrolysis species on the CNC surface. The significant charge reversal induced by the ferric hydrolysis species led to the restabilization of suspensions. Our results on the colloidal stability of CNCs are of central importance to the nanotechnol. and materials science communities working on various applications of CNCs.
- 117Chu, G.; Vasilyev, G.; Qu, D.; Deng, S.; Bai, L.; Rojas, O. J.; Zussman, E. Structural Arrest and Phase Transition in Glassy Nanocellulose Colloids. Langmuir 2020, 36, 979– 985, DOI: 10.1021/acs.langmuir.9b03570117Structural Arrest and Phase Transition in Glassy Nanocellulose ColloidsChu, Guang; Vasilyev, Gleb; Qu, Dan; Deng, Shengwei; Bai, Long; Rojas, Orlando J.; Zussman, EyalLangmuir (2020), 36 (4), 979-985CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)From drying blood to oil paint, the developing of a glassy phase from colloids is obsd. on a daily basis. Colloidal glass is solid soft matter that consists of two intertwined phases: a random packed particle network and a fluid solvent. By dispersing charged rod-like cellulose nanoparticles into a water-ethylene glycol cosolvent, here we demonstrate a new kind of colloidal glass with a high liq. cryst. order, namely, two general superstructures with nematic and cholesteric packing states are preserved and jammed inside the glass matrix. During the glass formation process, structural arrest and phase transition occur simultaneously at high particle concns., yielding solid-like behavior as well as a frozen liq. crystal texture that is because of caging of the charged colloids through neighboring long-ranged repulsive interactions.
- 118Bruel, C.; Davies, T. S.; Carreau, P. J.; Tavares, J. R.; Heuzey, M.-C. Self-Assembly Behaviors of Colloidal Cellulose Nanocrystals: A Tale of Stabilization Mechanisms. J. Colloid Interface Sci. 2020, 574, 399– 409, DOI: 10.1016/j.jcis.2020.04.049118Self-assembly behaviors of colloidal cellulose nanocrystals: A tale of stabilization mechanismsBruel, Charles; Davies, Tom S.; Carreau, Pierre J.; Tavares, Jason R.; Heuzey, Marie-ClaudeJournal of Colloid and Interface Science (2020), 574 (), 399-409CODEN: JCISA5; ISSN:0021-9797. (Elsevier B.V.)In solvent casting, colloidal nanocrystal self-assembly patterns are controlled by a mix of cohesive and repulsive interactions that promote destabilization-induced self-assembly (DISA) or evapn.-induced self-assembly (EISA). Tuning the strength and nature of the stabilization mechanisms may allow repulsive interactions to govern self-assembly during the casting of colloidal cellulose nanocrystal (CNC) suspensions. We propose a tool to classify the level of electrostatic and solvation-induced stabilizations based on two solvent parameters only: dielec. const., ε, and chem. affinity for CNCs, in terms of Hansen Soly. Parameters, Ra. These criteria are applied to study CNC self-assembly in solvent casting expts. in various media and binary mixts. In solvent casting of suspensions stabilized through a combination of electrostatic and solvation effects, the primarily governing mechanism is EISA, which leads to the formation of chiral nematic domains and optically active thin films. In electrostatically-stabilized suspensions, EISA and DISA are in competition and casting may yield anything from a continuous film to a powder. In other suspensions, DISA prevails and evapn. yields a powder of CNC agglomerates. By classifying media according to their stabilization mechanisms, this work establishes that the behavior of CNC suspensions in solvent casting may be predicted from solvent parameters only.
- 119Attia, D.; Cohen, N.; Ochbaum, G.; Levi-Kalisman, Y.; Bitton, R.; Yerushalmi-Rozen, R. Nano-to-Meso Structure of Cellulose Nanocrystal Phases in Ethylene-Glycol-Water Mixtures. Soft Matter 2020, 16, 8444– 8452, DOI: 10.1039/D0SM01025AThere is no corresponding record for this reference.
- 120Bruckner, J. R.; Kuhnhold, A.; Honorato-Rios, C.; Schilling, T.; Lagerwall, J. P. F. Enhancing Self-Assembly in Cellulose Nanocrystal Suspensions Using High-Permittivity Solvents. Langmuir 2016, 32, 9854– 9862, DOI: 10.1021/acs.langmuir.6b02647120Enhancing Self-Assembly in Cellulose Nanocrystal Suspensions Using High-Permittivity SolventsBruckner, Johanna R.; Kuhnhold, Anja; Honorato-Rios, Camila; Schilling, Tanja; Lagerwall, Jan P. F.Langmuir (2016), 32 (38), 9854-9862CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)Protic solvents with a high dielec. permittivity εr significantly speed up self-assembly (from days to hours) at high cellulose nanocrystals (CNCs) mass fraction and reduce the concn. dependence of the helix period (variation reducing from more than 30 μm to less than 1 μm). Computer simulations indicate that the degree of order at const. CNC content increases with increasing εr, leading to a shorter pitch and a reduced threshold for liq. crystallinity. In low-εr solvents, the onset of long-range orientational order is coupled to kinetic arrest, preventing the formation of a helical superstructure.
- 121Elazzouzi-Hafraoui, S.; Putaux, J.-L.; Heux, L. Self-Assembling and Chiral Nematic Properties of Organophilic Cellulose Nanocrystals. J. Phys. Chem. B 2009, 113, 11069– 11075, DOI: 10.1021/jp900122t121Self-assembling and Chiral Nematic Properties of Organophilic Cellulose NanocrystalsElazzouzi-Hafraoui, Samira; Putaux, Jean-Luc; Heux, LaurentJournal of Physical Chemistry B (2009), 113 (32), 11069-11075CODEN: JPCBFK; ISSN:1520-6106. (American Chemical Society)Cotton cellulose nanocrystals with different aspect ratios were dispersed in cyclohexane as a model apolar solvent, using surfactants. Above a crit. concn., which was higher than that in water, the suspensions spontaneously phase sepd. into a chiral nematic mesophase. According to Onsager's theory, the phase sepn. is controlled by the aspect ratio, while being influenced by the polydispersity. The sample with the highest aspect ratio did not show any phase sepn. but instead shows an anisotropic gel phase at high concn. Exptl. crit. concns. are much lower than the predicted ones, revealing an attractive interaction between the rods. Chiral nematic pitches ≥2 μm are much lower than those measured in water, due to stronger chiral interactions in the apolar medium.
- 122Saraiva, D. V.; Remiëns, S. N.; Jull, E. I. L.; Vermaire, I. R.; Tran, L. Flexible, Photonic Films of Surfactant-Functionalized Cellulose Nanocrystals for Pressure and Humidity Sensing. Small Struct. 2024, 5, 2400104 DOI: 10.1002/sstr.202400104There is no corresponding record for this reference.
- 123Frka-Petesic, B.; Radavidson, H.; Jean, B.; Heux, L. Dynamically Controlled Iridescence of Cholesteric Cellulose Nanocrystal Suspensions Using Electric Fields. Adv. Mater. 2017, 29, 1606208 DOI: 10.1002/adma.201606208There is no corresponding record for this reference.
- 124D’Acierno, F.; Ohashi, R.; Hamad, W. Y.; Michal, C. A.; MacLachlan, M. J. Thermal Annealing of Iridescent Cellulose Nanocrystal Films. Carbohydr. Polym. 2021, 272, 118468 DOI: 10.1016/j.carbpol.2021.118468124Thermal annealing of iridescent cellulose nanocrystal filmsD'Acierno, Francesco; Ohashi, Ryutaro; Hamad, Wadood Y.; Michal, Carl A.; MacLachlan, Mark J.Carbohydrate Polymers (2021), 272 (), 118468CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)The properties of chiral nematic and iridescent cellulose nanocrystal films with different monovalent cations (CNC-X) obtained through evapn.-induced self-assembly (EISA) can be modified by a variety of external stimuli. Here, we study the transformations of their optical and structural properties when the films are thermally annealed at 200°C and 240°C for up to 2 days. The chiral nematic structure of the most thermally stable films is not destroyed even after extensive heating due to the thermochem. stability of the cellulose backbone and the presence of surface alkali counterions, which suppress catalysis of early stage degrdn. Despite the resilience of the cholesteric structure and the overall integrity of heated CNC-X films, thermal annealing is often accompanied by redn. of iridescence, birefringence, and transparency, as well as formation of degrdn. products. The versatility, sustainability, and stability of CNC-X films highlight their potential as temp. indicators and photonic devices.
- 125Chen, H.; Zhang, X.; Zhou, T.; Hou, A.; Liang, J.; Ma, T.; Xie, K.; Gao, A. A Tunable Hydrophilic-Hydrophobic, Stimulus Responsive, and Robust Iridescent Structural Color Bionic Film with Chiral Photonic Crystal Nanointerface. Small 2024, 2311283 DOI: 10.1002/smll.202311283There is no corresponding record for this reference.
- 126Qin, J.; Li, N.; Jiang, M.; Zong, L.; Yang, H.; Yuan, Y.; Zhang, J. Ultrasonication Pretreatment Assisted Rapid Co-Assembly of Cellulose Nanocrystal and Metal Ion for Multifunctional Application. Carbohydr. Polym. 2022, 277, 118829 DOI: 10.1016/j.carbpol.2021.118829126Ultrasonication pretreatment assisted rapid co-assembly of cellulose nanocrystal and metal ion for multifunctional applicationQin, Jinli; Li, Na; Jiang, Min; Zong, Lu; Yang, Hongsheng; Yuan, Yuan; Zhang, JianmingCarbohydrate Polymers (2022), 277 (), 118829CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)Co-assembly of metal ion and cellulose nanocrystals (CNC) is a promising strategy to fabricate novel iridescent CNC materials with advanced applications. By combining ultrasonication pretreatment and vacuum-assisted self-assembly (VASA) technique, a facile and rapid strategy is proposed to prep. the Mn2+-doped carboxylated CNC (C-CNC) iridescent films with multifunctional application. The ultrasonication pretreatment temporarily disassembles the aggregates of C-CNC nanorods caused by the electrostatic interaction between neg. charged C-CNC and Mn2+. The subsequent VASA process accelerates the self-assembly of chiral liq. crystals prior to the re-agglomeration of C-CNC by the bridge effect of Mn2+. Furthermore, the as-prepd. Mn2+/CNC film exhibits a rapid and visible color change in ammonia atm. along with the formation of MnO2. The reversible change can be realized by the stimulation of reducing agent. The derived MnO2/C-CNC composite film displays efficient removal of methylene blue dye in aq. soln. by both of adsorption and degrdn. procedure.
- 127Vanderfleet, O. M.; Winitsky, J.; Bras, J.; Godoy-Vargas, J.; Lafitte, V.; Cranston, E. D. Hydrothermal Treatments of Aqueous Cellulose Nanocrystal Suspensions: Effects on Structure and Surface Charge Content. Cellulose 2021, 28, 10239– 10257, DOI: 10.1007/s10570-021-04187-w127Hydrothermal treatments of aqueous cellulose nanocrystal suspensions: effects on structure and surface charge contentVanderfleet, Oriana M.; Winitsky, Jaclyn; Bras, Julien; Godoy-Vargas, Jazmin; Lafitte, Valerie; Cranston, Emily D.Cellulose (Dordrecht, Netherlands) (2021), 28 (16), 10239-10257CODEN: CELLE8; ISSN:0969-0239. (Springer)Cellulose nanocrystals (CNCs) are ideal rheol. modifiers for aq. oil and gas extn. fluids. CNCs are typically produced with sulfuric acid and their aq. suspensions have uniform and predictable properties under ambient conditions; however, drastic changes occur at elevated temps. Herein, the effects of high temp. treatments (ranging from 80 to 180°C for 1 h to 7 days) on the properties (including uniformity, colloidal stability, and color) of sulfated, phosphated, and carboxylated CNC suspensions were studied. Addnl., cellulose mol. wt., and CNC surface charge content and crystallinity index were quantified before and after heating. CNCs underwent few morphol. changes; their mol. wt. and crystallinity index were largely unchanged under the conditions tested. Their surface charge content, however, was significantly decreased after heat treatment which resulted in loss of colloidal stability and aggregation of CNCs. The largest change in suspension properties was obsd. for sulfated CNCs whereas CNCs with a combination of sulfate and phosphate esters, or carboxylate groups, were less affected and maintained colloidal stability at higher temps. In fact, desulfation was found to occur rapidly at 80°C, while many carboxylate groups persisted at temps. up to 180°C; calcd. rate consts. (based on second order kinetics) suggested that desulfation is 20 times faster than decarboxylation but with a similar activation energy.
- 128Liu, D.; Wang, S.; Ma, Z.; Tian, D.; Gu, M.; Lin, F. Structure-Color Mechanism of Iridescent Cellulose Nanocrystal Films. RSC Adv. 2014, 4, 39322– 39331, DOI: 10.1039/C4RA06268J128Structure-color mechanism of iridescent cellulose nanocrystal filmsLiu, Dagang; Wang, Shuo; Ma, Zhongshi; Tian, Donglin; Gu, Mingyue; Lin, FengyingRSC Advances (2014), 4 (74), 39322-39331CODEN: RSCACL; ISSN:2046-2069. (Royal Society of Chemistry)Chirality and repulsion interactions among sulfate cellulose nanocrystals (CNCs) have vital impact on the formation of a cholesteric liq. crystal (CLC) phase in a suspension or solidified film. In this work, a facile sonication treatment was applied to change the structure and repulsion interactions of CNCs and consequently tune the chiroptical properties of the resultant films. The results show that increasing the sonication energy either by improving the input power or prolonging the aging time resulted in the redn. of particle size and surface charge d., thereby increasing the cholesteric pitch and red-shifting the reflective wavelength of the iridescent films. The optical properties of the film followed the regulation of Bragg reflection and thin-film interference. However, an over-energy input would result in the multi-dispersion of the CNCs according to the level of the surface charge d., thus leading to the formation of polydomain CLC instead of planar CLC because of multi-distributed intra-axial drive forces. Hence, a schematic model was built up to describe the structure transition, as well as the color variation and to correlate the mesoscopic behavior of CNCs and the microscopic interactions of electrostatic repulsions, hydrogen bonding affinity and chirality. Hence, we provide some meaningful information on building up a hierarchical organization assembled from charged rigid biol. rods, and help to recognize the structure-color mechanism of solidified films of polysaccharide nanocrystals.
- 129Beck, S.; Bouchard, J.; Chauve, G.; Berry, R. Controlled Production of Patterns in Iridescent Solid Films of Cellulose Nanocrystals. Cellulose 2013, 20, 1401– 1411, DOI: 10.1007/s10570-013-9888-4129Controlled production of patterns in iridescent solid films of cellulose nanocrystalsBeck, Stephanie; Bouchard, Jean; Chauve, Greg; Berry, RichardCellulose (Dordrecht, Netherlands) (2013), 20 (3), 1401-1411CODEN: CELLE8; ISSN:0969-0239. (Springer)A method to produce predefined patterns in solid iridescent films of cellulose nanocrystals (CNCs) by differential heating of aq. CNC suspensions during film casting has been discovered. Placing materials of different temps. beneath an evapg. CNC suspension results in watermark-like patterns of different reflection wavelength incorporated within the final film structure. The patterned areas are of different thickness and different chiral nematic pitch than the surrounding film; heating results in thicker areas of longer pitch. Thermal pattern creation in CNC films is proposed to be caused by differences in evapn. rates and thermal motion in the areas of the CNC suspension corresponding to the pattern-producing object and the surrounding, unperturbed suspension. Pattern formation was found to occur during the final stages of drying during film casting, once the chiral nematic structure is kinetically trapped in the gel state. It is thus possible to control the reflection wavelength of CNC films by an external process in the absence of additives.
- 130Guidetti, G.; Frka-Petesic, B.; Dumanli, A. G.; Hamad, W. Y.; Vignolini, S. Effect of Thermal Treatments on Chiral Nematic Cellulose Nanocrystal Films. Carbohydr. Polym. 2021, 272, 118404 DOI: 10.1016/j.carbpol.2021.118404130Effect of thermal treatments on chiral nematic cellulose nanocrystal filmsGuidetti, Giulia; Frka-Petesic, Bruno; Dumanli, Ahu G.; Hamad, Wadood Y.; Vignolini, SilviaCarbohydrate Polymers (2021), 272 (), 118404CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)The ability to manipulate the optical appearance of materials is essential in virtually all products and areas of technol. Structurally colored chiral nematic cellulose nanocrystal (CNC) films proved to be an excellent platform to design optical appearance, as their response can be molded by organizing them in hierarchical architectures. Here, we study how thermal treatments influence the optical appearance of structurally colored CNC films. We demonstrate that the CNCs helicoidal architecture and the chiral optical response can be maintained up to 250°C after base treatment and crosslinking with glutaraldehyde, while, alternatively, an exposure to vacuum allows for the helicoidal arrangement to be further preserved up to 900°C, thus producing arom. chiral carbon. The ability to retain the helicoidal arrangement, and thus the visual appearance, in CNC films up to 250°C is highly desirable for high temp. color-based industrial applications and for passive colorimetric heat sensors. Similarly, the prodn. of chiral carbon provides a new type of conductive carbon for electrochem. applications.
- 131Ji, H.; Xiang, Z.; Qi, H.; Han, T.; Pranovich, A.; Song, T. Strategy Towards One-Step Preparation of Carboxylic Cellulose Nanocrystals and Nanofibrils with High Yield, Carboxylation and Highly Stable Dispersibility Using Innocuous Citric Acid. Green Chem. 2019, 21, 1956– 1964, DOI: 10.1039/C8GC03493A131Strategy towards one-step preparation of carboxylic cellulose nanocrystals and nanofibrils with high yield, carboxylation and highly stable dispersibility using innocuous citric acidJi, Hui; Xiang, Zhouyang; Qi, Haisong; Han, Tingting; Pranovich, Andrey; Song, TaoGreen Chemistry (2019), 21 (8), 1956-1964CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)Acid hydrolysis using concd. mineral acids is currently the most applied method to prep. nanocellulose, specifically cellulose nanocrystals (CNCs). However, the method exhibits several crit. defects, namely it is hazardous to the environment and human body, causes corrosion to the process equipment and the overdegrdn. of raw cellulose material, is high cost, and so on. Moreover, chem. modification to the functional groups of the CNC products is usually needed for further applications, also leading to extra costs. In this work, an innocuous weak acid (citric acid) was applied to prep. cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) from bleached bagasse pulp accompanied by simultaneous modifications of the functional groups on their mol. interface. It was discovered that with the small aid of ultrasonication at the appropriate prepn. stage, citric acid could overcome the difficulties of hydrolyzing cellulose caused by its weak acidity, and CNCs were successfully produced with good nanoscales and high yield. CNCs with a diam. of 20-30 nm and length of 250-450 nm and CNFs with a diam. of 30-60 nm and length of 500-1000 nm were achieved. Up to 32.2% of the original bagasse pulp was converted to CNCs via citric acid hydrolysis with the assistance of ultrasonication, compared to only about 10.6% of the CNC yield without ultrasonication under the same hydrolysis conditions. At least one carboxylic group of the citric acid was simultaneously introduced to the cellulose via esterification during acid hydrolysis to form carboxylic CNCs and CNFs, which is important for further functionalization. Contents of carboxylic acid groups up to 0.65 mmol g-1 for CNCs and 0.30 mmol g-1 for CNFs were obtained, which endowed the CNCs and CNFs with highly stable dispersibility. Over 90% of the citric acid could be easily recovered through a rotary evaporator. The carboxylic CNCs and CNFs presented in this work offer com. success and lower toxic risks, which means they have the potential to find applications as environmentally friendly, sustainable, and new bio-based nanomaterials in high-tech fields, such as biomaterials.
- 132Zhu, S.; Sun, H.; Mu, T.; Li, Q.; Richel, A. Preparation of Cellulose Nanocrystals from Purple Sweet Potato Peels by Ultrasound-Assisted Maleic Acid Hydrolysis. Food Chem. 2023, 403, 134496 DOI: 10.1016/j.foodchem.2022.134496There is no corresponding record for this reference.
- 133Duan, R.; Lu, M.; Tang, R.; Guo, Y.; Zhao, D. Structural Color Controllable Humidity Response Chiral Nematic Cellulose Nanocrystalline Film. Biosensors 2022, 12, 707, DOI: 10.3390/bios12090707133Structural Color Controllable Humidity Response Chiral Nematic Cellulose Nanocrystalline FilmDuan, Ran; Lu, Mengli; Tang, Ruiqi; Guo, Yuanyuan; Zhao, DongyuBiosensors (2022), 12 (9), 707CODEN: BIOSHU; ISSN:2079-6374. (MDPI AG)Through self-assembly, environmentally friendly cellulose nanocrystals (CNCs) can form films with a photonic crystal structure whose pitch size can be adjusted in a variety of ways at the fabrication stage. Moreover, the films exhibit response performance to multiple stimuli, which offers extensive applications. Poly(ethylene glycol) (PEG) and CNCs combine to form a smaller chiral nematic domain that develops a solid film with a uniform spiral structure when slowly dried. By changing the compn. of CNCs and PEG, flexible and flat photonic composite films with uniform structural colors from blue to red are prepd. Benefiting from the change in pitch size by insertion and detachment of water mols. into the chiral nematic structure, CNCs films and CNC-PEG composite films exhibit a reversible structural color change in response to different humidity. In addn., the chiral nematic films formed by the combination of glycerol and CNCs have a reversible stimulation response to hydrochloric acid gas. Similarly, adjusting the ratio of glycerol can control the pitch size of the films and, thus, the reflective color. In summary, the pitch size of the photonic crystal structure of the films can be precisely tuned by regulating the additive ratio, and the two prepd. films have reversible responses to humidity and hydrochloric acid gas, resp. The CNC-based films show promise in the application of colorimetric biosensors.
- 134Dong, X. M.; Revol, J.-F.; Gray, D. G. Effect of Microcrystallite Preparation Conditions on the Formation of Colloid Crystals of Cellulose. Cellulose 1998, 5, 19– 32, DOI: 10.1023/A:1009260511939134Effect of microcrystallite preparation conditions on the formation of colloid crystals of celluloseDong, Xue Min; Revol, Jean-Francois; Gray, Derek G.Cellulose (London) (1998), 5 (1), 19-32CODEN: CELLE8; ISSN:0969-0239. (Blackie Academic & Professional)Stable colloidal suspensions of cellulose (I) microcrystallites were prepd. from filter paper by H2SO4 hydrolysis. Above a crit. concn., the suspensions formed a chiral nematic ordered phase, or "colloid crystal". The prepn. conditions governed the properties of the individual I microcrystallites, and hence,the liq. cryst. phase sepn. of the I suspensions. The particle properties and the phase sepn. of the suspensions were strongly dependent on the hydrolysis temp. and time, and on the intensity of the ultrasound irradn. used to disperse the particles. The particle size of the microcrystallites was characterized with transmission electron microscopy and photon correlation spectroscopy. The surface charge was detd. by conductometric titrn. It was possible to fractionate the microcrystallites by size using the partitioning between isotropic and liq. cryst. phases; the longer microcrystallites migrated to the liq. cryst. phase.
- 135Yang, H.; Choi, S.-E.; Kim, D.; Park, D.; Lee, D.; Choi, S.; Nam, Y. S.; Kim, J. W. Color-Spectrum-Broadened Ductile Cellulose Films for Vapor-pH-Responsive Colorimetric Sensors. J. Ind. Eng. Chem. 2019, 80, 590– 596, DOI: 10.1016/j.jiec.2019.08.039135Color-spectrum-broadened ductile cellulose films for vapor-pH-responsive colorimetric sensorsYang, Hakyeong; Choi, Song-Ee; Kim, Doyeon; Park, Daehwan; Lee, Duho; Choi, Sunyoung; Nam, Yoon Sung; Kim, Jin WoongJournal of Industrial and Engineering Chemistry (Amsterdam, Netherlands) (2019), 80 (), 590-596CODEN: JIECFI; ISSN:1226-086X. (Elsevier B.V.)We introduce a smart colorimetric sensor platform, in which iridescent chiral nematic films composed of oxidized cellulose nanocrystals (OxCNCs) exhibit pH-responsive color changes. To provide dried OxCNC films with the controlled reflection of circularly polarized lights at specific wavelengths, we manipulated the half-pitch distance from 145 to 270 nm by adjusting the surface charges of OxCNCs during 2,2,6,6-tetramethylpiperidine-1-oxyl-radical-mediated oxidn. Utilizing the controlled electrostatic repulsion generated by the difference in the surface charge of OxCNCs, the reflection wavelengths of the films could be tuned across a broad color spectrum. In addn., we improved flexibility or ductility of OxCNC composite films by coassembly with a hygroscopic polymer, polyethylene glycol, while maintaining their iridescent colors. We finally demonstrated that the OxCNC composite films could show reversible color changes in response to vapors of aq. solns. with different pH values, thus enabling the development of a vapor-pH-responsive colorimetric sensor technol.
- 136Sui, Y.; Li, X.; Chang, W.; Wan, H.; Li, W.; Yang, F.; Yu, Z.-Z. Multi-Responsive Nanocomposite Membranes of Cellulose Nanocrystals and Poly(N-isopropyl acrylamide) with Tunable Chiral Nematic Structures. Carbohydr. Polym. 2020, 232, 115778 DOI: 10.1016/j.carbpol.2019.115778136Multi-responsive nanocomposite membranes of cellulose nanocrystals and poly(N-isopropyl acrylamide) with tunable chiral nematic structuresSui, Yanqiu; Li, Xiaofeng; Chang, Wei; Wan, Hao; Li, Wei; Yang, Fan; Yu, Zhong-ZhenCarbohydrate Polymers (2020), 232 (), 115778CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)By imitating the unique structure of nature creatures, photonic membranes with periodic chiral helical structure can be assembled by cellulose nanocrystals (CNCs). It is still an issue to fabricate CNC photonic structures tunable in the entire visible spectrum with multiple stimuli-response capacities. Herein, a multi-responsive nanocomposite photonic membrane is fabricated by co-assembly of poly(N-iso-Pr acrylamide) (PNIPAM) grafted CNCs with waterborne polyurethane (WPU) latex on the basis of the chiral nematic structure of CNCs, the thermo-responsibility of PNIPAM, and the flexibility of WPU. The flexible photonic membranes with uniform structural colors from blue to red are obtained by tuning the PNIPAM content. The membrane exhibits reversible responses to solvents, and iridescence changes in response to relative humidity with excellent repeatability. Interestingly, the membrane can be transparent or opaque depending on the ambient temp. The photonic membranes are appealing in applications as humidity sensor, camouflage materials, and even smart windows.
- 137Qu, D.; Zussman, E. Electro-Responsive Liquid Crystalline Nanocelluloses with Reversible Switching. J. Phys. Chem. Lett. 2020, 11, 6697– 6703, DOI: 10.1021/acs.jpclett.0c01924137Electro-responsive Liquid Crystalline Nanocelluloses with Reversible SwitchingQu, Dan; Zussman, EyalJournal of Physical Chemistry Letters (2020), 11 (16), 6697-6703CODEN: JPCLCD; ISSN:1948-7185. (American Chemical Society)Liq. cryst. cellulose nanocrystals (CNCs) which can change their structural and optical properties in an elec. field could be a new choice for advanced optoelectronic devices. Unfortunately, the exploration of its performance in an elec. field is underdeveloped. Hence, we reveal some interesting dielec. coupling activities of liq. cryst. CNC in an elec. field. The CNC tactoid is shown to orient its helix axis normal to the elec. field direction. Then, as a function of the elec. field strength and frequency, the tactoid can be stretched along with a pitch increase, with a deformation mechanism significantly differing at varied frequencies, and finally untwists the helix axis to form a nematic structure upon increasing the elec. field strength. Moreover, a straightforward method to visualize the elec. field is demonstrated, by combining the CNC uniform lying helix textures with polarized optical microscopy. We envision these understandings could facilitate the development of liq. cryst. CNC in the design of electro-optical devices.
- 138Atifi, S.; Mirvakili, M.-N.; Williams, C. A.; Bay, M. M.; Vignolini, S.; Hamad, W. Y. Fast Self-Assembly of Scalable Photonic Cellulose Nanocrystals and Hybrid Films via Electrophoresis. Adv. Mater. 2022, 34, 2109170 DOI: 10.1002/adma.202109170138Fast Self-Assembly of Scalable Photonic Cellulose Nanocrystals and Hybrid Films via ElectrophoresisAtifi, Siham; Mirvakili, Mehr-Negar; Williams, Cyan A.; Bay, Melanie M.; Vignolini, Silvia; Hamad, Wadood Y.Advanced Materials (Weinheim, Germany) (2022), 34 (12), 2109170CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)Nano-enabled, bio-based, functional materials are key for the transition to a sustainable society as they can be used, owing to both their performance and nontoxicity, to gradually replace existing nonrenewable engineering materials. Cellulose nanocrystals (CNCs), produced by acid hydrolysis of cellulosic biomass, have been shown to possess distinct self-assembly, optical, and electromech. properties, and are anticipated to play an important role in the fabrication of photonic, optoelectronic, and functional hybrid materials. To facilitate CNCs' technol. viability, a method suitable for industrial exploitation is developed to produce photonic films possessing long-range chirality on conductive, rigid, or flexible, substrates within a few minutes. The approach is based on electrophoretic deposition (EPD)-induced self-assembly of CNCs, where photonic films of any size can be produced by controlling CNC surface properties and EPD parameters. CNC film coloration can be detd. by the CNC aq. suspension characteristics, while their reflected intensity can be tuned by changing the duration and no. of electrodeposition cycles. EPD-induced self-assembly of CNCs is compatible with in situ redn. of gold precursors without the need to use addnl. reducing agents (some of which are considered toxic), thereby allowing the prepn. of hybrid photonic films with tunable plasmonic response in a one-pot process.
- 139Bordel, D.; Putaux, J.-L.; Heux, L. Orientation of Native Cellulose in an Electric Field. Langmuir 2006, 22, 4899– 4901, DOI: 10.1021/la0600402139Orientation of Native Cellulose in an Electric FieldBordel, Damien; Putaux, Jean-Luc; Heux, LaurentLangmuir (2006), 22 (11), 4899-4901CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)Native cellulose has been oriented in an ac elec. field at both the macroscopic and colloidal level. Ramie fiber fragments suspended in chloroform have been shown to point along the field. Cellulose microcrystal suspensions in cyclohexane have also been allowed to evap. in an elec. field and have exhibited a high degree of orientation when further examd. by TEM and electron diffraction. Similarly, cellulose whisker suspensions showed increasing birefringence with increasing field strength and displayed interference Newton colors that satd. at around 2000 V cm-1. A high degree of order of this suspension was also obtained by evaluating the induced birefringence with color charts.
- 140Frka-Petesic, B.; Guidetti, G.; Kamita, G.; Vignolini, S. Controlling the Photonic Properties of Cholesteric Cellulose Nanocrystal Films with Magnets. Adv. Mater. 2017, 29, 1701469 DOI: 10.1002/adma.201701469There is no corresponding record for this reference.
- 141Chen, T.; Zhao, Q.; Meng, X.; Li, Y.; Peng, H.; Whittaker, A. K.; Zhu, S. Ultrasensitive Magnetic Tuning of Optical Properties of Films of Cholesteric Cellulose Nanocrystals. ACS Nano 2020, 14, 9440– 9448, DOI: 10.1021/acsnano.0c00506141Ultrasensitive Magnetic Tuning of Optical Properties of Films of Cholesteric Cellulose NanocrystalsChen, Tianxing; Zhao, Qinglan; Meng, Xin; Li, Yao; Peng, Hui; Whittaker, Andrew K.; Zhu, ShenminACS Nano (2020), 14 (8), 9440-9448CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)Chiral photonic crystals derived from the self-assembly of cellulose nanocrystals (CNCs) have found important applications in optical devices due to the capacity to adjust the chiral nematic phase under external stimulus, in particular an applied magnetic field. To date, strong magnetic fields have been required to induce an optical response in CNC films. In this work, the self-assembly of films of CNCs can be tuned by applying an ultrasmall magnetic field. The CNCs, decorated with Fe3O4 nanoparticles (Fe3O4/CNCs), were dispersed in suspensions of neat CNCs so as to alter the magnetic response of the CNCs. A subsequent process of dispersion not only prevents the clumping of the magnetic nanoparticles but also enhances the sensitivity to an applied magnetic field. A small magnetic field of 7 mT can tune the self-assembly and the microstructure of the CNCs. The pitch of the chiral structure decreased with an increase in applied magnetic field, from 302 to 206 nm, for fields from 7 to 15 mT. This phenomenon is opposite that obsd. for neat CNCs, in which the pitch is obsd. to increase with an increase in the external magnetic strength. The optical response under application of an ultrasmall magnetic field could help with theor. research and enable more applications, such as sensors or nanotemplating agents.
- 142Wang, P.-X.; Hamad, W. Y.; MacLachlan, M. J. Liquid Crystalline Tactoidal Microphases in Ferrofluids: Spatial Positioning and Orientation by Magnetic Field Gradients. Chem. 2019, 5, 681– 692, DOI: 10.1016/j.chempr.2018.12.010142Liquid Crystalline Tactoidal Microphases in Ferrofluids: Spatial Positioning and Orientation by Magnetic Field GradientsWang, Pei-Xi; Hamad, Wadood Y.; MacLachlan, Mark J.Chem (2019), 5 (3), 681-692CODEN: CHEMVE; ISSN:2451-9294. (Cell Press)Macroscopic manipulation of self-assembly in lyotropic systems, such as chiral nematic liq. crystals formed by cellulose nanocrystals, is kinetically hindered by the similarity between isotropic and anisotropic phases in compn. and phys. properties. By creating a significant difference in volumetric magnetic susceptibility between discrete liq. cryst. tactoids and continuous isotropic phases (based on the exclusion effects of tactoids on superparamagnetic doping nanoparticles), we achieved position and orientation control of liq. cryst. tactoids by magnetic field gradients as weak as several hundred gauss per cm, where the movement of tactoids is detd. by competition between magnetic and gravitational acceleration fields. We also undertook a preliminary examn. of the trapping of a liq. cryst. phase in the potential well of a quadrupole magnetic field. This method enabled us to control the phase sepn. rate and configuration, as well as the orientation of director fields in both tactoids and macroscopic ordered phases.
- 143Sugiyama, J.; Chanzy, H.; Maret, G. Orientation of Cellulose Microcrystals by Strong Magnetic Fields. Macromolecules 1992, 25, 4232– 4234, DOI: 10.1021/ma00042a032143Orientation of cellulose microcrystals by strong magnetic fieldsSugiyama, J.; Chanzy, H.; Maret, G.Macromolecules (1992), 25 (16), 4232-4CODEN: MAMOBX; ISSN:0024-9297.Orientation of cellulose (I) microcrystals in aq. suspension was achieved using homogeneous magnetic fields ≤7 T. Under these conditions, the crystals became strongly oriented with their long axis, as well as with the mean plane of their anhydro (1→4) β-D linked glucose moieties, perpendicular to the field. By drying the suspensions in the field, uniplanar-axial I films were obtained. They were analyzed by electron microscopy and electron and x-ray diffraction.
- 144De France, K. J.; Yager, K. G.; Hoare, T.; Cranston, E. D. Cooperative Ordering and Kinetics of Cellulose Nanocrystal Alignment in a Magnetic Field. Langmuir 2016, 32, 7564– 7571, DOI: 10.1021/acs.langmuir.6b01827144Cooperative Ordering and Kinetics of Cellulose Nanocrystal Alignment in a Magnetic FieldDe France, Kevin J.; Yager, Kevin G.; Hoare, Todd; Cranston, Emily D.Langmuir (2016), 32 (30), 7564-7571CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)Cellulose nanocrystals (CNCs) are emerging nanomaterials that form chiral nematic liq. crystals above a crit. concn. (C*) and addnl. orient within electromagnetic fields. The control over CNC alignment is significant for materials processing and end use; to date, magnetic alignment was demonstrated using only strong fields over extended or arbitrary time scales. This work studies the effects of comparatively weak magnetic fields (0-1.2 T) and CNC concn. (1.65-8.25%) on the kinetics and degree of CNC ordering using small-angle x-ray scattering. Interparticle spacing, correlation length, and orientation order parameters (η and S) increased with time and field strength following a sigmoidal profile. In a 1.2 T magnetic field for CNC suspensions above C*, partial alignment occurred in under 2 min followed by slower cooperative ordering to achieve nearly perfect alignment in under 200 min (S = -0.499 where S = -0.5 indicates perfect antialignment). At 0.56 T, nearly perfect alignment was also achieved, yet the ordering was 36% slower. Outside of a magnetic field, the order parameter plateaued at 52% alignment (S = -0.26) after 5 h, showcasing the drastic effects of relatively weak magnetic fields on CNC alignment. For suspensions below C*, no magnetic alignment was detected.
- 145Zhang, X.; Kang, S.; Adstedt, K.; Kim, M.; Xiong, R.; Yu, J.; Chen, X.; Zhao, X.; Ye, C.; Tsukruk, V. V. Uniformly Aligned Flexible Magnetic Films from Bacterial Nanocelluloses for Fast Actuating Optical Materials. Nat. Commun. 2022, 13, 5804, DOI: 10.1038/s41467-022-33615-z145Uniformly aligned flexible magnetic films from bacterial nanocelluloses for fast actuating optical materialsZhang, Xiaofang; Kang, Saewon; Adstedt, Katarina; Kim, Minkyu; Xiong, Rui; Yu, Juan; Chen, Xinran; Zhao, Xulin; Ye, Chunhong; Tsukruk, Vladimir V.Nature Communications (2022), 13 (1), 5804CODEN: NCAOBW; ISSN:2041-1723. (Nature Portfolio)Naturally derived biopolymers have attracted great interest to construct photonic materials with multi-scale ordering, adaptive birefringence, chiral organization, actuation and robustness. Nevertheless, traditional processing commonly results in non-uniform organization across large-scale areas. Here, we report magnetically steerable uniform biophotonic organization of cellulose nanocrystals decorated with superparamagnetic nanoparticles with strong magnetic susceptibility, enabling transformation from helicoidal cholesteric (chiral nematic) to uniaxial nematic phase with near-perfect orientation order parameter of 0.98 across large areas. We demonstrate that magnetically triggered high shearing rate of circular flow exceeds those for conventional evapn.-based assembly by two orders of magnitude. This high rate shearing facilitates unconventional unidirectional orientation of nanocrystals along gradient magnetic field and untwisting helical organization. These translucent magnetic films are flexible, robust, and possess anisotropic birefringence and light scattering combined with relatively high optical transparency reaching 75%. Enhanced mech. robustness and uniform organization facilitate fast, multimodal, and repeatable actuation in response to magnetic field, humidity variation, and light illumination.
- 146Cao, Y.; Wang, P.-X.; D’Acierno, F.; Hamad, W. Y.; Michal, C. A.; MacLachlan, M. J. Tunable Diffraction Gratings from Biosourced Lyotropic Liquid Crystals. Adv. Mater. 2020, 32, 1907376 DOI: 10.1002/adma.201907376146Tunable Diffraction Gratings from Biosourced Lyotropic Liquid CrystalsCao, Yuanyuan; Wang, Pei-Xi; D'Acierno, Francesco; Hamad, Wadood Y.; Michal, Carl A.; MacLachlan, Mark J.Advanced Materials (Weinheim, Germany) (2020), 32 (19), 1907376CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)Diffraction gratings are important for modern optical components, such as optical multiplexers and signal processors. Although liq. crystal (LC) gratings based on thermotropic LCs have been extensively explored, they often require expensive mols. and complicated manufg. processes. Lyotropic LCs, which can be broadly obtained from both synthetic and natural sources, have not yet been applied in optical gratings. Herein, a facile grating fabrication method using a biosourced lyotropic LC formed by cellulose nanocrystals (CNCs), a material extd. from plants, is reported. Hydrogel sheets with vertically aligned uniform periodic structures are obtained by fixing the highly oriented chiral nematic LC of CNCs in polymer networks under the cooperative effects of gravity on phase sepn. and a magnetic field on LC orientation. The hydrogel generates up to sixth-order diffraction spots and shows linear polarization selectivity, with tunable grating periodicity controlled through LC concn. regulation. This synthesis strategy can be broadly applied to various grating materials and opens up a new area of optical materials from lyotropic LCs.
- 147Wang, Z.; Li, N.; Zong, L.; Zhang, J. Recent Advances in Vacuum Assisted Self-Assembly of Cellulose Nanocrystals. Curr. Opin. Solid State Mater. Sci. 2019, 23, 142– 148, DOI: 10.1016/j.cossms.2019.03.001147Recent advances in vacuum assisted self-assembly of cellulose nanocrystalsWang, Zhaolu; Li, Na; Zong, Lu; Zhang, JianmingCurrent Opinion in Solid State & Materials Science (2019), 23 (3), 142-148CODEN: COSSFX; ISSN:1359-0286. (Elsevier Ltd.)Cellulose nanocrystals (CNC) iridescent films composed of the chiral nematic liq. crystal phase have attracted much attention owing to their fascinating optical properties. Herein, we summarized and discussed the recent advances in prepg. iridescent CNC film via vacuum-assisted self-assembly (VASA) method, which has the advantage to fabricate large area, highly oriented and structurally homogeneous CNC liq. crystal film. The discussed aspects include (i) Factors that influence the self-assembly behavior of CNC nanorods during VASA. (ii) The strategy for modifying the optical, thermal as well as the mech. properties of VASA assisted CNC iridescent film. (iii) Co-assembling of CNC liq. crystal phase and other functional nanoparticles by VASA technique. In all cases, key issues are highlighted and future developments that we consider as the most relevant are identified. Furthermore, future research activities are suggested in the conclusion.
- 148Wang, Z.; Yuan, Y.; Hu, J.; Yang, J.; Feng, F.; Yu, Y.; Liu, P.; Men, Y.; Zhang, J. Origin of Vacuum-Assisted Chiral Self-Assembly of Cellulose Nanocrystals. Carbohydr. Polym. 2020, 245, 116459 DOI: 10.1016/j.carbpol.2020.116459148Origin of vacuum-assisted chiral self-assembly of cellulose nanocrystalsWang, Zhaolu; Yuan, Yuan; Hu, Jian; Yang, Jiying; Feng, Fan; Yu, Yao; Liu, Ping; Men, Yongfeng; Zhang, JianmingCarbohydrate Polymers (2020), 245 (), 116459CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)To produce functional cellulose nanocrystal (CNC) films with desirable optical and mech. properties, it is crit. to understand and control the chiral self-assembly of CNCs during solvent removal. Here, the formation mechanism of CNC chiral nematic liq. crystal phase during vacuum-assisted self-assembly (VASA) was investigated. To elucidate the structural evolution of CNC aggregations on filter paper, CNC suspensions were "frozen" at various filtration stages in a polyacrylamide matrix. In addn., the flow rate of CNC suspension was monitored in situ. We found that disordered-to-ordered CNC self-assembly occurs at the interface between the filter paper and suspension over four stages. Tactoids develop in the concd. CNC suspension close to the filter paper, which is also obsd. in evapn.-induced self-assembly (EISA) of CNC films. However, compared to EISA, VASA promotes helical axes of CNC tactoids along the flow-field direction, leading to faster liq. crystal formation with long-range order via the nucleation growth.
- 149Xia, B.; Zeng, X.; Lan, W.; Zhang, M.; Huang, W.; Wang, H.; Liu, C. Cellulose Nanocrystal/Graphene Oxide One-Dimensional Photonic Crystal Film with Excellent UV-Blocking and Transparency. Carbohydr. Polym. 2024, 327, 121646 DOI: 10.1016/j.carbpol.2023.121646There is no corresponding record for this reference.
- 150Li, J.; Lu, C.; Ye, C.; Xiong, R. Structural, Optical, and Mechanical Insights into Cellulose Nanocrystal Chiral Nematic Film Engineering by Two Assembly Techniques. Biomacromolecules 2024, 25, 3507– 3518, DOI: 10.1021/acs.biomac.4c00169There is no corresponding record for this reference.
- 151Ren, Y.; Wang, T.; Chen, Z.; Li, J.; Tian, Q.; Yang, H.; Xu, Q. Liquid Crystal Behavior Induced Assembling Fabrication of Conductive Chiral MWCNTs@NCC Nanopaper. Appl. Surf. Sci. 2016, 385, 521– 528, DOI: 10.1016/j.apsusc.2016.05.146There is no corresponding record for this reference.
- 152Pignon, F.; Challamel, M.; De Geyer, A.; Elchamaa, M.; Semeraro, E. F.; Hengl, N.; Jean, B.; Putaux, J.-L.; Gicquel, E.; Bras, J.; Prevost, S.; Sztucki, M.; Narayanan, T.; Djeridi, H. Breakdown and Buildup Mechanisms of Cellulose Nanocrystal Suspensions under Shear and upon Relaxation Probed by SAXS and SALS. Carbohydr. Polym. 2021, 260, 117751 DOI: 10.1016/j.carbpol.2021.117751152Breakdown and buildup mechanisms of cellulose nanocrystal suspensions under shear and upon relaxation probed by SAXS and SALSPignon, Frederic; Challamel, Mathilde; De Geyer, Antoine; Elchamaa, Mohamad; Semeraro, Enrico F.; Hengl, Nicolas; Jean, Bruno; Putaux, Jean-Luc; Gicquel, Erwan; Bras, Julien; Prevost, Sylvain; Sztucki, Michael; Narayanan, Theyencheri; Djeridi, HendaCarbohydrate Polymers (2021), 260 (), 117751CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)The breakdown and buildup mechanisms in concd. cellulose nanocrystal (CNC) suspensions under shear and during relaxation upon cessation of shear were accessed by small-angle X-ray and light scattering combined with rheometry. The dynamic structural changes over nanometer to micrometer lengthscales were related to the well-known three-regime rheol. behavior. In the shear-thinning regime I, the large liq. cryst. domains were progressively fragmented into micrometer-sized tactoids, with their cholesteric axis aligned perpendicular to the flow direction. The viscosity plateau of regime II was assocd. to a further disruption into submicrometer-sized elongated tactoids oriented along the velocity direction. At high shear rate, regime III corresponded to the parallel flow of individual CNCs along the velocity direction. Upon cessation of flow, the relaxation process occurred through a three-step buildup mechanisms: (1) a fast reassembling of the individual CNCs into a nematic-like organization established up to micrometer lengthscales, (2) a slower formation of oriented large cholesteric domains, and (3) their isotropic redistribution.
- 153Feng, X.; Chen, B.; Kong, D.; Wang, T.; Cui, X.; Tian, Y. Visualizing the Shear Flow-Modulated Alignments in Cellulose Nanocrystal Films by the Mueller Matrix. J. Phys. Chem. C 2023, 127, 6974– 6980, DOI: 10.1021/acs.jpcc.3c00577153Visualizing the Shear Flow-Modulated Alignments in Cellulose Nanocrystal Films by the Mueller MatrixFeng, Xiaowei; Chen, Bo; Kong, Demei; Wang, Ting; Cui, Xiaoyan; Tian, YangJournal of Physical Chemistry C (2023), 127 (14), 6974-6980CODEN: JPCCCK; ISSN:1932-7447. (American Chemical Society)The microstructures of cellulose nanocrystal (CNC) films grown from their aq. suspensions are tuned by a shear flow during the formation of the films. The modulation of the chiral nematic organization of CNCs is visualized by the complete polarization anal. using Mueller matrix microscopy. Further optical simulation has ensured the comprehensive 3D structural anal. for the complex chiral structures of CNC films. As suggested by the optical investigation, regulating the helical structure under the shear flow involves two transition processes, an early in-plane unwinding, followed by a later helically vertical unwinding. We have also confirmed that sufficient shearing is required to reorient the helically aligned CNCs to form the nematic structure.
- 154Huang, H.; Wang, X.; Yu, J.; Chen, Y.; Ji, H.; Zhang, Y.; Rehfeldt, F.; Wang, Y.; Zhang, K. Liquid-Behaviors-Assisted Fabrication of Multidimensional Birefringent Materials from Dynamic Hybrid Hydrogels. ACS Nano 2019, 13, 3867– 3874, DOI: 10.1021/acsnano.9b00551154Liquid-Behaviors-Assisted Fabrication of Multidimensional Birefringent Materials from Dynamic Hybrid HydrogelsHuang, Heqin; Wang, Xiaojie; Yu, Jinchao; Chen, Ye; Ji, Hong; Zhang, Yumei; Rehfeldt, Florian; Wang, Yong; Zhang, KaiACS Nano (2019), 13 (4), 3867-3874CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)Liq.-solid transition is a widely used strategy to shape polymeric materials and encode their microstructures. However, it is still challenging to fully exploit liq. behaviors of material precursors. In particular, the dynamic and static liq. behaviors naturally conflict with each other, which makes it difficult to integrate their advantages in the same materials. Here, by utilizing a shear-thinning phenomenon in the dynamic hybrid hydrogels, we achieve a hydrodynamic alignment of cellulose nanocrystals (CNC) and preserve it in the relaxed hydrogel networks due to the much faster relaxation of polymer networks (within 500 s) than CNC after the unloading of external force. During the following drying process, the surface tension of hydrogels further enhances the orientation index of CNC up to 0.872 in confined geometry, and these anisotropic microstructures demonstrate highly tunable birefringence (up to 0.004 14). Due to the presence of the boundaries of dynamic hydrogels, diverse xerogels including fibers, films, and even complex three-dimensional structures with variable anisotropic microstructures can be fabricated without any external molds.
- 155Kose, O.; Boott, C. E.; Hamad, W. Y.; MacLachlan, M. J. Stimuli-Responsive Anisotropic Materials Based on Unidirectional Organization of Cellulose Nanocrystals in an Elastomer. Macromolecules 2019, 52, 5317– 5324, DOI: 10.1021/acs.macromol.9b00863155Stimuli-Responsive Anisotropic Materials Based on Unidirectional Organization of Cellulose Nanocrystals in an ElastomerKose, Osamu; Boott, Charlotte E.; Hamad, Wadood Y.; MacLachlan, Mark J.Macromolecules (Washington, DC, United States) (2019), 52 (14), 5317-5324CODEN: MAMOBX; ISSN:0024-9297. (American Chemical Society)Cellulose nanocrystals (CNCs) derived from biomass have unique properties, which have inspired their incorporation into a wide variety of materials. However, the no. of highly stretchable elastomers that have been prepd. with CNCs has been limited. Here, we report shear-aligned pseudonematic CNCs embedded in a poly(Et acrylate) elastomer, a homogeneous composite that exhibits reversible optical properties in response to mech. stimuli. Due to the long-range anisotropy of CNCs, the relaxed composite shows vivid interference color as it is viewed between crossed or parallel polarizers. When the pseudonematic CNC elastomer is stretched parallel to the CNC alignment direction, the CNCs become further aligned and the birefringence of the materials increases. In contrast, when the composite is stretched perpendicular to the CNC alignment direction, the CNCs become more disordered and the birefringence decreases. The extent of the CNC reorientation when the composite was stretched was detd. by calcn. of the birefringence of the material and two-dimensional X-ray diffraction anal. Furthermore, the aligned CNCs act as nanoreinforcement in the elastomer, which resulted in the pseudonematic CNC-poly(Et acrylate) elastomer having a tensile modulus up to 120 times higher than that of pure poly(Et acrylate).
- 156Boott, C. E.; Soto, M. A.; Hamad, W. Y.; MacLachlan, M. J. Shape-Memory Photonic Thermoplastics from Cellulose Nanocrystals. Adv. Funct. Mater. 2021, 31, 2103268 DOI: 10.1002/adfm.202103268156Shape-Memory Photonic Thermoplastics from Cellulose NanocrystalsBoott, Charlotte E.; Soto, Miguel A.; Hamad, Wadood Y.; MacLachlan, Mark J.Advanced Functional Materials (2021), 31 (43), 2103268CODEN: AFMDC6; ISSN:1616-301X. (Wiley-VCH Verlag GmbH & Co. KGaA)Responsive materials prepd. using shape-memory photonic crystals have potential applications in rewritable photonic devices, security features, and optical coatings. By embedding chiral nematic cellulose nanocrystals (CNCs) in a polyacrylate matrix, a shape-memory photonic crystal thermoplastic (CNC-SMP) allows reversible capture of different colored states is reported. In this system, the temp. is used to program the shape-memory response, while pressure is used to compress the helical pitch of the CNC chiral nematic organization. By increasing the force applied (≈140-230 N), the structural color can be tuned from red to blue. Then, on-demand, the CNC-SMP can recover to its original state by heating it above the glass transition temp. This cycle can be performed over 15 times without any loss of the shape-memory behavior or mech. degrdn. of the sample. In addn., multicolor readouts can be programmed into the chiral nematic CNC-SMP by using a patterned substrate to press the sample, while the glass transition temp. of the CNC-SMP can be tuned over a 90°C range by altering the monomer compn. used to prep. the polyacrylate matrix.
- 157Li, X.; Liu, J.; Zhang, X. Pressure/Temperature Dual-Responsive Cellulose Nanocrystal Hydrogels for On-Demand Schemochrome Patterning. Adv. Funct. Mater. 2023, 33, 2306208 DOI: 10.1002/adfm.202306208157Pressure/Temperature Dual-Responsive Cellulose Nanocrystal Hydrogels for On-Demand Schemochrome PatterningLi, Xinkai; Liu, Jize; Zhang, XinxingAdvanced Functional Materials (2023), 33 (47), 2306208CODEN: AFMDC6; ISSN:1616-301X. (Wiley-VCH Verlag GmbH & Co. KGaA)Cellulose nanocrystal (CNC) based optical devices with adjustable schemochrome have attracted immense interest. However, most of the previously reported structural colored CNC-based materials can only achieve simple stress-induced color change, which have difficulty achieving multimode control of complex patterning that can be accurately identified. Here, inspired by the nanostructure-based color-changing mechanism of neon tetra, this study presents a pressure/temp. dual-responsive CNC-based schemochrome hydrogel with adjustable dynamic chiral nematic structure. By incorporating abundant interfacial noncovalent interactions, dynamic correlations between adjustable helical pitch of the vertically stacked cholesteric liq. cryst. (LC) phase and responsiveness of flexible thermosensitive substrate are established, which further enable wide-range optical characteristic (12°-213° in HSV color model and 421-734 nm in the UV-Vis spectra) and identifiable visualized patterning. The resultant hydrogels are applied in proof-of-concept demonstrations of on-demand schemochrome patterning, including customizable patterned dual-encryption label, smart digital display, temp. monitor, and intelligent recognition/control system. This study envisages that the bioinspired construction of structural colored nanomaterials will have promising applications in smart responsive photonic equipment including smart display, anticounterfeiting, and intelligent control systems.
- 158Nguyen, T.-D.; Hamad, W. Y.; MacLachlan, M. J. Tuning the Iridescence of Chiral Nematic Cellulose Nanocrystals and Mesoporous Silica Films by Substrate Variation. Chem. Commun. 2013, 49, 11296– 11298, DOI: 10.1039/c3cc47337f158Tuning the iridescence of chiral nematic cellulose nanocrystals and mesoporous silica films by substrate variationNguyen, Thanh-Dinh; Hamad, Wadood Y.; MacLachlan, Mark J.Chemical Communications (Cambridge, United Kingdom) (2013), 49 (96), 11296-11298CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)The self-assembly of cellulose nanocrystals (CNCs) into chiral nematic phases varies significantly with the substrate and evapn. rate. These variables allow the reflectance peak of iridescent chiral nematic films of CNCs and mesoporous SiO2 templated from CNCs to be tuned over a wide range of wavelengths.
- 159Li, W.; Liu, W.; Wen, W.; Liu, H.; Liu, M.; Zhou, C.; Luo, B. The Liquid Crystalline Order, Rheology and Their Correlation in Chitin Whiskers Suspensions. Carbohydr. Polym. 2019, 209, 92– 100, DOI: 10.1016/j.carbpol.2019.01.006159The liquid crystalline order, rheology and their correlation in chitin whiskers suspensionsLi, Wenling; Liu, Wenjun; Wen, Wei; Liu, Hua; Liu, Mingxian; Zhou, Changren; Luo, BinghongCarbohydrate Polymers (2019), 209 (), 92-100CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)To explore the concn. range of chitin whiskers (CHWs) aq. suspensions with the liq. cryst. state, and the correlation between liq. cryst. characteristic and rheol. of CHWs suspensions, the CHWs aq. suspensions with different CHWs concn., pH value, ionic strength and temp. were prepd. The liq. cryst. characteristic and rheol. properties of the obtained suspensions were investigated by polarizing microscope and rotational rheometer. The results showed that the liq. cryst. state of the suspensions appeared at the CHWs concn. of 3.5 wt% and disappeared at 22.5 wt%. Increasing the CHWs concn., pH value and ionic strength, the values of elastic modulus (G') and viscous modulus (G") increased, and the liq. crystal texture basically became more and more regular and obvious. Moreover, the value of G"/G' was always less than 1, suggesting the elastic behavior of CHWs aq. suspension. Besides, the effect caused by heating on the elastic modulus was irreversible.
- 160Luo, Y.; Li, Y.; Liu, K.; Li, L.; Wen, W.; Ding, S.; Huang, Y.; Liu, M.; Zhou, C.; Luo, B. Modulating of Bouligand Structure and Chirality Constructed Bionically Based on the Self-Assembly of Chitin Whiskers. Biomacromolecules 2023, 24, 2942– 2954, DOI: 10.1021/acs.biomac.3c00419There is no corresponding record for this reference.
- 161Li, J.; Revol, J.; Marchessault, R. H. Effect of N-Sulfonation on the Colloidal and Liquid Crystal Behavior of Chitin Crystallites. J. Colloid Interface Sci. 1997, 192, 447– 457, DOI: 10.1006/jcis.1997.5003161Effect of N-Sulfonation on the Colloidal and Liquid Crystal Behavior of Chitin CrystallitesLi; Revol; MarchessaultJournal of colloid and interface science (1997), 192 (2), 447-57 ISSN:.Chitin crystallites were heterogeneously N-sulfonated in an aqueous medium using triethylamine/sulfur trioxide (TEA/SO3) or pyridine/sulfur trioxide. The extent of N-sulfonation of the crystallites has been controlled by the amount of TEA/SO3 added in the reaction. The concentration of sulfur in the crystallites after N-sulfonation was quantified using conductimetric titration and elemental analysis. The ratio of N-sulfonated amino groups to amino groups (S/N) was calculated based on the titration data. The presence of N-S bonds assumed to be at crystallite surfaces was demonstrated by X-ray photoelectron spectroscopy (XPS). After N-sulfonation, the crystallites have two ionizable groups at their surface: -NH3+ and -NHSO3H(Na). The former is pH dependent. The colloidal properties of the N-sulfonated crystallites having different S/N were investigated by plotting the zeta potential as a function of the pH of the suspension. The isoelectric point was found to change with the level of N-sulfonation. Transmission electron microscopy shows that the aggregation of crystallites depends strongly on the extent of N-sulfonation. Above a certain concentration, the original chitin crystallites form tactoids (chiral nematic domains) in an aqueous medium. This phenomenon was not observed for the crystallites with a low extent of surface N-sulfonation (below 70%). At about 80% N-sulfonation, the formation of tactoids was once again observed. Copyright 1997Academic Press
- 162Liu, D.; Chang, Y.; Tian, D.; Wu, W.; Lu, A.; Prempeh, N.; Tan, M.; Huang, Y. Lyotropic Liquid Crystal Self-Assembly of H2O2-Hydrolyzed Chitin Nanocrystals. Carbohydr. Polym. 2018, 196, 66– 72, DOI: 10.1016/j.carbpol.2018.04.098162Lyotropic liquid crystal self-assembly of H2O2-hydrolyzed chitin nanocrystalsLiu, Dagang; Chang, Yu; Tian, Donglin; Wu, Wenqi; Lu, Ang; Prempeh, Nana; Tan, Meijuan; Huang, YifengCarbohydrate Polymers (2018), 196 (), 66-72CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)H2O2 hydrolysis of mech.-defibrillated chitin nanofibrils was explored as a green way of fabricating rod-like chitin nanocrystals (H2O2-hydrolyzed CHNs) that have an av. length of 350 nm and width of 40 nm. We investigated the structure and morphol. of CHNs as well as the rheol. and lyotropic self-assembly behavior of its colloidal dispersions. The results show that although H2O2-hydrolyzed CHNs maintained the cryst. structure of α-chitin, surface charge of the nanorods was switched from pos. to neg. As a consequence, the colloidal nanocrystals were well-dispersed in neutral or alk. aq. media, and behaved as a lyotropic liq. crystal between two crit. concns. It is interesting that lyotropic liq. crystal transition was a spontaneously self-assembly from well-aligned nanofibers, to nanobelts, and to multi-layered lamellae. At high crit. concn., H2O2-hydrolyzed CHN colloids exhibited a sol-gel transition, which was discovered to be highly dependent on the storage time, concn., temp., and surface charge d. It is also suggested that nematic mesophases rather than gel could be effectively maintained by improving the surface charge d. or lowering the aging temp. and colloidal concn. of CHNs.
- 163Nge, T. T.; Hori, N.; Takemura, A.; Ono, H.; Kimura, T. Phase Behavior of Liquid Crystalline Chitin/Acrylic Acid Liquid Mixture. Langmuir 2003, 19, 1390– 1395, DOI: 10.1021/la020764n163Phase Behavior of Liquid Crystalline Chitin/Acrylic Acid Liquid MixtureNge, Thi T.; Hori, Naruhito; Takemura, Akio; Ono, Hirokuni; Kimura, TsunehisaLangmuir (2003), 19 (4), 1390-1395CODEN: LANGD5; ISSN:0743-7463. (American Chemical Society)Phase behavior of a liq. cryst. chitin/acrylic acid liq. mixt. was studied to fabricate a chitin-based composite with unique optical property. From phase sepn. studies, the authors can evaluate the ternary phase diagram of a chitin microfibril, H2O, and acrylic acid monomer system. A suitable starting liq. cryst. chitin concn. to obtain anisotropic monophase over a range of acrylic acid concn. (up to 33 (wt./wt.) %) was 14.62% (14-15%) by wt. At lower acrylic acid concn. range, cryst. microfibrillar fragments of chitin self-assembled to form upper isotropic phase and lower anisotropic liq. crystal phase at high enough concn. of chitin crystallites. The latter showed a characteristic chiral nematic order, a fingerprint-like texture. Above this chitin concn. and at higher acrylic acid concn. range, the system formed a monophasic stable flow-birefringence glassy phase, which displayed a nematic order. This phase occurred within a very limited range of chitin crystallites concn. of ∼6.22-6.41%, which provides a clear-cut boundary between isotropic phase and anisotropic phase as well as a metastable frozen-in state between chiral nematic order and nematic order.
- 164Nge, T. T.; Hori, N.; Takemura, A.; Ono, H.; Kimura, T. Synthesis and Orientation Study of a Magnetically Aligned Liquid-Crystalline Chitin/Poly(acrylic acid) Composite. J. Polym. Sci. B: Polym. Phys. 2003, 41, 711– 714, DOI: 10.1002/polb.10428164Synthesis and orientation study of a magnetically aligned liquid-crystalline chitin/poly(acrylic acid) compositeNge, Thi Thi; Hori, Naruhito; Takemura, Akio; Ono, Hirokuni; Kimura, TsunehisaJournal of Polymer Science, Part B: Polymer Physics (2003), 41 (7), 711-714CODEN: JPBPEM; ISSN:0887-6266. (John Wiley & Sons, Inc.)A high magnetic field of 5 T was used to fabricate a magnetically aligned, optically anisotropic, liq.-cryst. chitin/poly(acrylic acid) composite. The aligned mesophase was fixed by photoinitiated free-radical polymn. From an examn. of polarized optical micrographs and an x-ray diffraction study, a high degree of orientation of 0.70 was obsd. for the composite with a higher liq.-cryst. chitin concn. (10.70 wt. %); the orientation was reduced with a decreased chitin concn. at a given acrylic acid concn. The x-ray data for the developed composite showed a uniplanar orientation for the chitin crystallites, with its mol. long axes perpendicular to the direction of the magnetic field.
- 165Lu, T.; Pan, H.; Ma, J.; Li, Y.; Bokhari, S. W.; Jiang, X.; Zhu, S.; Zhang, D. Cellulose Nanocrystals/Polyacrylamide Composites of High Sensitivity and Cycling Performance to Gauge Humidity. ACS Appl. Mater. Interfaces 2017, 9, 18231– 18237, DOI: 10.1021/acsami.7b04590165Cellulose Nanocrystals/Polyacrylamide Composites of High Sensitivity and Cycling Performance To Gauge HumidityLu, Tao; Pan, Hui; Ma, Jun; Li, Yao; Bokhari, Syeda Wishal; Jiang, Xueliang; Zhu, Shenmin; Zhang, DiACS Applied Materials & Interfaces (2017), 9 (21), 18231-18237CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)Cellulose nanocrystals (CNCs) have attracted much interest due to their unique optical property, rich resource, environment friendliness, and templating potentials. CNCs have been reported as novel photonic humidity sensors, which are unfortunately limited by the dissoln. and unideal moisture absorption of CNCs. We, in this study, developed a high-performance photonic humidity composite sensor that consisted of CNCs and polyacrylamide; chem. bonding was induced between the two components by using glutaraldehyde as a bridging agent. The composites inherited the chiral nematic structure of CNCs and maintained it well through a cycling test. A distinct color change was obsd. for these composites used as a humidity indicator; the change was caused by polyacrylamide swelling with water and thus enlarging the helical pitch of the chiral nematic structure. The composites showed no degrdn. of the sensing performance through cycling. The excellent cycling stability was attributed to the bonding between polyacrylamide and CNCs. This composite strategy can extend to the development of other photonic indicators.
- 166Zhao, T. H.; Parker, R. M.; Williams, C. A.; Lim, K. T. P.; Frka-Petesic, B.; Vignolini, S. Printing of Responsive Photonic Cellulose Nanocrystal Microfilm Arrays. Adv. Funct. Mater. 2019, 29, 1804531 DOI: 10.1002/adfm.201804531There is no corresponding record for this reference.
- 167Chen, H.; Hou, A.; Zheng, C.; Tang, J.; Xie, K.; Gao, A. Light- and Humidity-Responsive Chiral Nematic Photonic Crystal Films Based on Cellulose Nanocrystals. ACS Appl. Mater. Interfaces 2020, 12, 24505– 24511, DOI: 10.1021/acsami.0c05139167Light- and humidity-responsive chiral nematic photonic crystal films based on cellulose nanocrystalsChen, Huanghuang; Hou, Aiqin; Zheng, Changwu; Tang, Jing; Xie, Kongliang; Gao, AiqinACS Applied Materials & Interfaces (2020), 12 (21), 24505-24511CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)Light- and humidity-responsive chiral nematic photonic crystal (PC) films contg. cellulose nanocrystals (CNCs) were fabricated. A photoactive polymer with hydrophilic groups, poly-(3,3'-benzophenone-4,4'-dicarboxylic acid dicarboxylate polyethylene glycol) ester, was coassembled with CNCs to form flexible iridescent films with a tunable chiral nematic order. In the coassembly process, the intermol. hydrogen bonds of CNCs were weakened, which facilitated the fine regulation of the chiral PC nanostructure. The PC films displayed sensitive responses to both light and humidity. With increasing humidity from 30 to 100%, the chiral nematic helix pitch increased from 328 to 422 nm. The color of the PC films changed from blue to green, yellow, orange, and dark red with increasing relative humidity. Over 15 min of light irradn., the absorption intensity of the films increased gradually. The light and humidity responses of the films were reversible. The films maintained their variable cholesteric liq. crystal texture and helical lamellar structure after light irradn. at different humidities. These PC films are expected to be useful in intelligent coatings and 3D printing.
- 168Li, X.; Liu, J.; Li, D.; Huang, S.; Huang, K.; Zhang, X. Bioinspired Multi-Stimuli Responsive Actuators with Synergistic Color- and Morphing-Change Abilities. Adv. Sci. 2021, 8, 2101295 DOI: 10.1002/advs.202101295There is no corresponding record for this reference.
- 169Sun, C.; Zhu, D.; Jia, H.; Lei, K.; Zheng, Z.; Wang, X. Humidity and Heat Dual Response Cellulose Nanocrystals/Poly(N-Isopropylacrylamide) Composite Films with Cyclic Performance. ACS Appl. Mater. Interfaces 2019, 11, 39192– 39200, DOI: 10.1021/acsami.9b14201169Humidity and Heat Dual Response Cellulose Nanocrystals/Poly(N-Isopropylacrylamide) Composite Films with Cyclic PerformanceSun, Chengyuan; Zhu, Dandan; Jia, Haiyan; Lei, Kun; Zheng, Zhen; Wang, XinlingACS Applied Materials & Interfaces (2019), 11 (42), 39192-39200CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)It has been widely reported that cellulose nanocrystals (CNCs) demonstrate a special structural color, which stems from chiral nematic domains. Herein, the humidity and heat dual response nanocomposite films with multilayered helical structure were prepd. by self-assembling of CNCs and hydrazone groups modified poly(N-isopropylacrylamide) (PNIPAM) copolymers. Furthermore, glutaraldehyde was involved to act as a chem. linker to improve cyclic stability by forming acylhydrazone bonds. The structural color of the films could be easily regulated by humidity, heat, or the content of modified PNIPAM copolymers. The absorption of water in higher humidity led to vol. expansion of the resin, resulting in a red shift for up to 145 nm. In contrast, the resin shrank under the temp. above the lower crit. soln. temp. of PNIPAM, leading to a blue shift for up to 87 nm. It was notable that the change of color can be easily captured by the naked eyes. Moreover, the films exhibited excellent stability and cyclicity in response to either vapor or liq. water due to the chem. linking between CNCs and resins. The as-prepd. CNCs/PNIPAM nanocomposite films with humidity or heat responsibilities are promising in stimuli-responsive sensors, printing industry, surface decorations, and so forth.
- 170Fan, J.; Xu, M.; Xu, Y.-T.; Hamad, W. Y.; Meng, Z.; MacLachlan, M. J. A Visible Multi-Response Electrochemical Sensor Based on Cellulose Nanocrystals. Chem. Eng. J. 2023, 457, 141175 DOI: 10.1016/j.cej.2022.141175There is no corresponding record for this reference.
- 171Meng, Y.; He, Z.; Dong, C.; Long, Z. Multi-Stimuli-Responsive Photonics Films Based on Chiral Nematic Cellulose Nanocrystals. Carbohydr. Polym. 2022, 277, 118756 DOI: 10.1016/j.carbpol.2021.118756171Multi-stimuli-responsive photonics films based on chiral nematic cellulose nanocrystalsMeng, Yahui; He, Zhibin; Dong, Cuihua; Long, ZhuCarbohydrate Polymers (2022), 277 (), 118756CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)Multiple-stimuli-responsive bio-based materials have received considerable attention for intelligent packaging and anti-counterfeiting applications. Herein, we present a unique biobased photonics film with multi-stimuli responsive behavior based on cellulose nanocrystals (CNCs), sorbitol (S) and anthocyanin (Anth). The resulting photonics film exhibits multi-stimuli responsive behavior to humidity, solvent and pH stimuli. Notably, the photonics film showed dramatic invertible color from blue to fuchsia and high sensitivity at a relative humidity from 50% to 100%. Moreover, the photonics film exhibited fast response and good reversibility under different ethanol concns. Significant color changes of the photonics film were also obsd. in response to pH change in the range of 2 to 12. Particularly, the humidity, solvent and pH responsiveness of the photonics film did not interfere with each other.
- 172Dai, S.; Prempeh, N.; Liu, D.; Fan, Y.; Gu, M.; Chang, Y. Cholesteric Film of Cu(II)-Doped Cellulose Nanocrystals for Colorimetric Sensing of Ammonia Gas. Carbohydr. Polym. 2017, 174, 531– 539, DOI: 10.1016/j.carbpol.2017.06.098172Cholesteric film of Cu(II)-doped cellulose nanocrystals for colorimetric sensing of ammonia gasDai, Shidong; Prempeh, Nana; Liu, Dagang; Fan, Yimin; Gu, Mingyue; Chang, YuCarbohydrate Polymers (2017), 174 (), 531-539CODEN: CAPOD8; ISSN:0144-8617. (Elsevier Ltd.)With the increasing demand of environmental monitoring for toxic and odorous ammonia gas it is desired to develop specific green, cost-effective and in situ passive colorimetric alternatives to current complex instrumentations. The authors designed an ammonia gas sensor based on cholesteric liq. crystal films of copper(II)-doped cellulose nanocrystals (CNC-Cu(II)) whose structure, optical and sensing properties were studied. The hybrid films using the low doping Cu(II) as a color-tuning agent inherited the chiral nematic signature and optical activity of CNCs, suggesting a strong chelation between copper ions and neg. charged CNCs. The sensing performance illustrates that the CNC-Cu(II)125 film was sensitive to ammonia gas which could merge into nematic layers of CNCs and trigger-sensed to copper ions chelated on CNCs, consequently arousing a red shift of reflective wavelength as well as an effective colorimetric transition. Such a hybrid film is anticipated to boost a new gas sensing regime for fast and effective on-site qual. studies.
- 173Song, W.; Lee, J.-K.; Gong, M. S.; Heo, K.; Chung, W.-J.; Lee, B. Y. Cellulose Nanocrystal-Based Colored Thin Films for Colorimetric Detection of Aldehyde Gases. ACS Appl. Mater. Interfaces 2018, 10, 10353– 10361, DOI: 10.1021/acsami.7b19738173Cellulose Nanocrystal-Based Colored Thin Films for Colorimetric Detection of Aldehyde GasesSong, Wonbin; Lee, Jong-Kwon; Gong, Mi Sic; Heo, Kwang; Chung, Woo-Jae; Lee, Byung YangACS Applied Materials & Interfaces (2018), 10 (12), 10353-10361CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)The authors demonstrate a controllable and reliable process for manifesting color patterns on solid substrates using cellulose nanocrystals (CNCs) without the use of any other chem. pigments. The color can be controlled by adjusting the assembly conditions of the CNC soln. during a dip-and-pull process while aiding the close packing of CNCs on a solid surface with the help of ionic-liq. (1-butyl-3-methylimidazolium) mols. that screen the repelling electrostatic charges between CNCs. By controlling the pulling speed from 3 to 9 μm/min during the dip-and-pull process, the authors were able to control the film thickness from 100 to 300 nm, resulting in films with different colors in the visible range. The optical properties were in good agreement with the finite-difference time-domain simulation results. By functionalizing these films with amine groups, the authors developed colorimetric sensors that can change in color when exposed to aldehyde gases such as formaldehyde or propanal. A principal component anal. showed that the authors can differentiate between different aldehyde gases and other interfering mols. The authors expect that the authors' approach will enable inexpensive and rapid volatile org. compd. detection with on-site monitoring capabilities.
- 174Zhao, G.; Zhang, Y.; Zhai, S.; Sugiyama, J.; Pan, M.; Shi, J.; Lu, H. Dual Response of Photonic Films with Chiral Nematic Cellulose Nanocrystals: Humidity and Formaldehyde. ACS Appl. Mater. Interfaces 2020, 12, 17833– 17844, DOI: 10.1021/acsami.0c00591174Dual Response of Photonic Films with Chiral Nematic Cellulose Nanocrystals: Humidity and FormaldehydeZhao, Guomin; Zhang, Yin; Zhai, Shengcheng; Sugiyama, Junji; Pan, Mingzhu; Shi, Jingbo; Lu, HongyiACS Applied Materials & Interfaces (2020), 12 (15), 17833-17844CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)Manipulating functional stimuli-responsive materials has been a hot topic in the research of smart sensors and anticounterfeiting encryption. Here, a novel functional chiral nematic cellulose nanocrystal (CNC) film showing dual responsiveness to humidity and formaldehyde gas was fabricated. The chiral nematic CNC iridescent film could respond to environmental humidity and formaldehyde gas changes by reversible motion. Interestingly, the humidity sensitivity of the CNC iridescent film could be gated by exposing the film to formaldehyde gas. At the same time, the formaldehyde-responsive behavior is strongly affected by the relative humidity (RH), and the response range could be tuned by changing the RH over a wide range. Importantly, the formaldehyde-induced color change could be altered from invisible to visible by the naked eye when the film was exposed to a humid environment. The mechanism of this dual response of the CNC iridescent film is ascribed to the synergistic effect of cooperation and competition between water and formaldehyde mols. by constructing phys. crosslinking networks by hydrogen bonds among water, formaldehyde, and CNCs. Furthermore, the "RH-concn. of formaldehyde gas-color" ternary colorimetric system was simulated, which is thought to endow the CNC iridescent film with great potential to act as a sensor in the convenient visible detection of gaseous formaldehyde. Furthermore, this work provided a promising strategy to design multi-gas-sensitive devices with convenient detection, good stability, and excellent reversibility.
- 175Zhang, Z.-L.; Dong, X.; Fan, Y.-N.; Yang, L.-M.; He, L.; Song, F.; Wang, X.-L.; Wang, Y.-Z. Chameleon-Inspired Variable Coloration Enabled by a Highly Flexible Photonic Cellulose Film. ACS Appl. Mater. Interfaces 2020, 12, 46710– 46718, DOI: 10.1021/acsami.0c13551175Chameleon-Inspired Variable Coloration Enabled by a Highly Flexible Photonic Cellulose FilmZhang, Ze-Lian; Dong, Xiu; Fan, Yi-Ning; Yang, Lu-Ming; He, Lu; Song, Fei; Wang, Xiu-Li; Wang, Yu-ZhongACS Applied Materials & Interfaces (2020), 12 (41), 46710-46718CODEN: AAMICK; ISSN:1944-8244. (American Chemical Society)Due to spontaneous organization of cellulose nanocrystals (CNCs) into the chiral nematic structure that can selectively reflect circularly polarized light within a visible-light region, fabricating stretching deformation-responsive CNC materials is of great interest but is still a big challenge, despite such a function widely obsd. from existing creatures, like a chameleon, because of the inherent brittleness. Here, a flexible network structure is introduced in CNCs, exerting a bridge effect for the rigid nanomaterials. The as-prepd. films display high flexibility with a fracture strain of up to 39%. Notably, stretching-induced structural color changes visible to the naked eye are realized, for the first time, for CNC materials. In addn., the soft materials show humidity- and compression-responsive properties in terms of changing apparent structural colors. Colored marks left by ink-free writing can be shown or hidden by controlling the environmental humidities. This biobased photonic film, acting as a new "smart skin", is potentially used with multifunctions of chromogenic sensing, encryption, and anti-counterfeit.
- 176Lu, R.; Wen, Z.; Zhang, P.; Chen, Y.; Wang, H.; Jin, H.; Zhang, L.; Chen, Y.; Wang, S.; Pan, S. Color-Tunable Perovskite Nanomaterials with Intense Circularly Polarized Luminescence and Tailorable Compositions. Small 2024, 20, 2311013 DOI: 10.1002/smll.202311013There is no corresponding record for this reference.
- 177Nguyen, T.-D.; Lizundia, E.; Niederberger, M.; Hamad, W. Y.; MacLachlan, M. J. Self-Assembly Route to TiO2 and TiC with a Liquid Crystalline Order. Chem. Mater. 2019, 31, 2174– 2181, DOI: 10.1021/acs.chemmater.9b00462177Self-Assembly Route to TiO2 and TiC with a Liquid Crystalline OrderNguyen, Thanh-Dinh; Lizundia, Erlantz; Niederberger, Markus; Hamad, Wadood Y.; MacLachlan, Mark J.Chemistry of Materials (2019), 31 (6), 2174-2181CODEN: CMATEX; ISSN:0897-4756. (American Chemical Society)We report the liq. cryst. self-assembly of cellulose nanocrystals (CNCs) with peroxotitanate to replicate large freestanding mesoporous films of TiO2 and chiral nematic TiC structures. The compatibility of cellulose liq. crystals with water-sol. peroxotitanate enabled them to self-assemble into flexible chiral nematic TiO2/cellulose composite films. The highly compatible peroxotitanate/CNC mixt. is a new liq. cryst. system to investigate the development of photonic films with tunable optical properties and structural replication by varying the ratio of constituents. Iridescent peroxotitanate/CNC composites were heated under hydrothermal conditions and calcined to generate layered mesoporous anatase TiO2 replicas that are robust, semitransparent films. Through magnesiothermic redn., we transformed carbonized peroxotitanate/CNC assemblies to mesoporous TiC with a chiral nematic order. Our work shows the potential of the mesoporous TiC to function as a long-life cycle rechargeable lithium-ion battery anode material and may extend this route to other peroxometallate compds.
- 178Kim, M.; Han, M. J.; Lee, H.; Flouda, P.; Bukharina, D.; Pierce, K. J.; Adstedt, K. M.; Buxton, M. L.; Yoon, Y. H.; Heller, W. T.; Singamaneni, S.; Tsukruk, V. V. Bio-Templated Chiral Zeolitic Imidazolate Framework for Enantioselective Chemoresistive Sensing. Angew. Chem., Int. Ed. 2023, 62, e202305646 DOI: 10.1002/anie.202305646There is no corresponding record for this reference.
- 179Dujardin, E.; Blaseby, M.; Mann, S. Synthesis of Mesoporous Silica by Sol-Gel Mineralisation of Cellulose Nanorod Nematic Suspensions. J. Mater. Chem. 2003, 13, 696– 699, DOI: 10.1039/b212689c179Synthesis of mesoporous silica by sol-gel mineralization of cellulose nanorod nematic suspensionsDujardin, Erik; Blaseby, Matthew; Mann, StephenJournal of Materials Chemistry (2003), 13 (4), 696-699CODEN: JMACEP; ISSN:0959-9428. (Royal Society of Chemistry)Mesoporous silica was synthesized by sol-gel mineralization using nematic liq. cryst. templates consisting of partially ordered suspensions of cellulose rod-like nanocrystals, ca. 145 × 13 nm in size. The nanorods were prepd. by acid hydrolysis of cellulose powder and concd. droplets evapd. onto glass slides to form nematic liq. crystals. Addn. of an aq. alk. soln. of pre-hydrolyzed tetramethoxysilane to the droplets resulted in a birefringent cellulose-silica composite that was subsequently calcined at 400°C for 2 h. Removal of the cellulose nanorod template produced a birefringent silica replica that exhibited patterned mesoporosity due to the presence of co-aligned cylindrical pores, ∼15 nm in diam. and 10 nm in wall thickness. TEM studies suggest that a chiral imprint of the helically ordered cellulose nanorods was imposed on the silica structure, although further studies are required to confirm these preliminary observations. As cellulose nanorods can be prepd. from renewable, inexpensive sources, they offer a cost-effective, environmentally benign route to the template-directed synthesis of mesoporous materials.
- 180Gesesse, G. D.; Li, C.; Paineau, E.; Habibi, Y.; Remita, H.; Colbeau-Justin, C.; Ghazzal, M. N. Enhanced Photogenerated Charge Carriers and Photocatalytic Activity of Biotemplated Mesoporous TiO2 Films with a Chiral Nematic Structure. Chem. Mater. 2019, 31, 4851– 4863, DOI: 10.1021/acs.chemmater.9b01465180Enhanced photogenerated charge carriers and photocatalytic activity of biotemplated mesoporous TiO2 films with a chiral nematic structureGesesse, Getaneh Diress; Li, Chunyu; Paineau, Erwan; Habibi, Youssef; Remita, Hynd; Colbeau-Justin, Christophe; Ghazzal, Mohamed NawfalChemistry of Materials (2019), 31 (13), 4851-4863CODEN: CMATEX; ISSN:0897-4756. (American Chemical Society)Improving the photogeneration and the lifetime of charge carriers assocd. with light harvesting is among the main challenges facing materials for photocatalysis. We report here the synthesis of mesoporous TiO2 contg. a replica of a chiral nematic structure (CNS) as a photocatalyst with improved light harvesting and photogenerated charge carriers under UV illumination. The CNS of cellulose nanocrystal photonic films, obtained by an evapn.-induced self-assembly method, were successfully transferred into an inorg. TiO2 film by sol-gel mineralization of the biotemplate. The stopband of the photonic films was adjusted by controlling the amt. of added D-glucose. The improvement of the kinetics of phenol photocatalytic degrdn. and H2 prodn. and the enhancement of the TiO2 photocond. as measured by time-resolved microwave cond., compared to mesoporous TiO2, strongly suggest an increase in light harvesting. The CNS microdomains in TiO2 increase the light scattering within the nanostructure and, thus, the absorption factor of TiO2, resulting in higher photoefficiency. This peculiar structure is used for the deposition of gold nanoparticles (AuNPs) inside the mesopores that are left by the mineralization of the biotemplate. AuNPs act as cocatalysts by leveraging highly photogenerated charge carriers for the prodn. of H2. This straightforward method opens up new opportunities, esp. for a wide range of materials, where converting photons into energy remains a major challenge.
- 181Andrew, L. J.; Gillman, E. R.; Walters, C. M.; Lizundia, E.; MacLachlan, M. J. Multi-Responsive Supercapacitors from Chiral Nematic Cellulose Nanocrystal-Based Activated Carbon Aerogels. Small 2023, 19, 2301947 DOI: 10.1002/smll.202301947There is no corresponding record for this reference.
- 182Khan, M. K.; Giese, M.; Yu, M.; Kelly, J. A.; Hamad, W. Y.; MacLachlan, M. J. Flexible Mesoporous Photonic Resins with Tunable Chiral Nematic Structures. Angew. Chem., Int. Ed. 2013, 52, 8921– 8924, DOI: 10.1002/anie.201303829182Flexible Mesoporous Photonic Resins with Tunable Chiral Nematic StructuresKhan, Mostofa K.; Giese, Michael; Yu, Marcus; Kelly, Joel A.; Hamad, Wadood Y.; MacLachlan, Mark J.Angewandte Chemie, International Edition (2013), 52 (34), 8921-8924CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)Herein we report a mesoporous phenol-formaldehyde (PF) resin that exhibits the chiral nematic order of the CNCs, leading to colorful polymer films. In comparison to other CNC-templated solids, the flexibility and responsive swelling behavior of the mesoporous films make them appealing for potential application in sensing and optics. This PF resin is the first of a family of plastic materials whose tunable properties might favorably combine chiral nematic coloration and mesoporosity.
- 183Sun, J.; Ji, X.; Li, G.; Zhang, Y.; Liu, N.; Li, H.; Qin, M.; Yuan, Z. Chiral Nematic Latex-GO Composite Films with Synchronous Response of Color and Actuation. J. Mater. Chem. C 2019, 7, 104– 110, DOI: 10.1039/C8TC04319AThere is no corresponding record for this reference.
- 184Yang, N.; Ji, X.; Sun, J.; Zhang, Y.; Xu, Q.; Fu, Y.; Li, H.; Qin, M.; Yuan, Z. Photonic Actuators with Predefined Shapes. Nanoscale 2019, 11, 10088– 10096, DOI: 10.1039/C9NR02294E184Photonic actuators with predefined shapesYang, Na; Ji, Xingxiang; Sun, Juanjuan; Zhang, Yu; Xu, Qinghua; Fu, Yingjuan; Li, Hongguang; Qin, Menghua; Yuan, ZaiwuNanoscale (2019), 11 (20), 10088-10096CODEN: NANOHL; ISSN:2040-3372. (Royal Society of Chemistry)Developing actuators with multi-responsibility, large deformation, and predefined shapes is crit. for the application of actuators in the field of artificial intelligence. Herein, we report the prepn. of a new type of unimorph actuators contg. phenol-formaldelyde resin (PFR) and graphene oxide (GO) using the chiral nematic structure of cellulose nanocrystals (CNCs) as the template. The so-obtained PFR/GO films have a unimorph structure with an asym. distribution of GO across the film. They exhibit synchronous responses of both photonic properties and actuation to humidifying/dehumidifying. Moreover, PFR/GO films can be forged into desired shapes by aldehyde treatment, and thereby are able to produce complex movements. In addn., the objects with predetd. shapes show good shape recovery capability upon many wetting-drying cycles, esp. through the treatment with formaldehyde. A mechanism model for shape predetn. by aldehyde treatment is suggested based on exptl. details. By further designing the predetd. shapes and patterns, such PFR/GO actuators may hold great promise for smart actuation devices of highly complex movements.
- 185Khan, M. K.; Bsoul, A.; Walus, K.; Hamad, W. Y.; MacLachlan, M. J. Photonic Patterns Printed in Chiral Nematic Mesoporous Resins. Angew. Chem., Int. Ed. 2015, 54, 4304– 4308, DOI: 10.1002/anie.201410411185Photonic Patterns Printed in Chiral Nematic Mesoporous ResinsKhan, Mostofa K.; Bsoul, Anas; Walus, Konrad; Hamad, Wadood Y.; MacLachlan, Mark J.Angewandte Chemie, International Edition (2015), 54 (14), 4304-4308CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)Chiral nematic mesoporous phenol-formaldehyde resins, which were prepd. using cellulose nanocrystals as a template, can be used as a substrate to produce latent photonic images. These resins undergo swelling, which changes their reflected color. By writing on the films with chem. inks, the d. of methylol groups in the resin changes, subsequently affecting their degree of swelling and, consequently, their color. Writing on the films gives latent images that are revealed only upon swelling of the films. Using inkjet printing, it is possible to make higher resoln. photonic patterns both as text and images that can be visualized by swelling and erased by drying. This novel approach to printing photonic patterns in resin films may be applied to anti-counterfeit tags, signage, and decorative applications.
- 186Khan, M. K.; Hamad, W. Y.; MacLachlan, M. J. Tunable Mesoporous Bilayer Photonic Resins with Chiral Nematic Structures and Actuator Properties. Adv. Mater. 2014, 26, 2323– 2328, DOI: 10.1002/adma.201304966186Tunable Mesoporous Bilayer Photonic Resins with Chiral Nematic Structures and Actuator PropertiesKhan, Mostofa K.; Hamad, Wadood Y.; MacLachlan, Mark J.Advanced Materials (Weinheim, Germany) (2014), 26 (15), 2323-2328CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)Novel bilayer formaldehyde-phenol resin films were developed with mesoporosity and chiral nematic structures exhibiting photonic and actuator properties simultaneously. Chiral nematic structures were embedded into these materials in a scalable and straightforward layer-by-layer synthetic method using cellulose nanocrystals as a template. The concurrence of stimuli-responsive actuation and variation in photonic properties makes these materials appealing for applications in optics and soft robotics.
- 187Nishimura, T.; Ito, T.; Yamamoto, Y.; Yoshio, M.; Kato, T. Macroscopically Ordered Polymer/CaCO3 Hybrids Prepared by Using a Liquid-Crystalline Template. Angew. Chem., Int. Ed. 2008, 47, 2800– 2803, DOI: 10.1002/anie.200705062187Macroscopically ordered polymer/CaCO3 hybrids prepared by using a liquid-crystalline templateNishimura, Tatsuya; Ito, Takahiro; Yamamoto, Yuya; Yoshio, Masafumi; Kato, TakashiAngewandte Chemie, International Edition (2008), 47 (15), 2800-2803CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)Unidirectionally aligned hybrids consisting of chitin and calcite were obtained by template crystn. of CaCO3 in an ordered chitin film with nematic liq.-cryst. mol. alignment. The picture shows the resulting chitin matrix contg. CaCO3 rods, schematically and in the form of an optical micrograph, and the selected-area electron diffraction pattern of a thin section of a single rod.
- 188Matsumura, S.; Kajiyama, S.; Nishimura, T.; Kato, T. Formation of Helically Structured Chitin/CaCO3 Hybrids through an Approach Inspired by the Biomineralization Processes of Crustacean Cuticles. Small 2015, 11, 5127– 5133, DOI: 10.1002/smll.201501083188Formation of Helically Structured Chitin/CaCO3 Hybrids through an Approach Inspired by the Biomineralization Processes of Crustacean CuticlesMatsumura, Shunichi; Kajiyama, Satoshi; Nishimura, Tatsuya; Kato, TakashiSmall (2015), 11 (38), 5127-5133CODEN: SMALBC; ISSN:1613-6810. (Wiley-VCH Verlag GmbH & Co. KGaA)Chitin/CaCO3 hybrids with helical structures are formed through a biomineralization-inspired crystn. process under ambient conditions. Liq.-cryst. chitin whiskers are used as helically ordered templates. The liq.-cryst. structures are stabilized by acidic polymer networks which interact with the chitin templates. The crystn. of CaCO3 is conducted by soaking the templates in the colloidal suspension of amorphous CaCO3 (ACC) at room temp. At the initial stage of crystn., ACC particles are introduced inside the templates, and they crystallize to CaCO3 nanocrystals. The acidic polymer networks induce CaCO3 crystn. The characterization of the resultant hybrids reveals that they possess helical order and homogeneous hybrid structures of chitin and CaCO3, which resemble the structure and compn. of the exoskeleton of crustaceans.
- 189Belamie, E.; Boltoeva, M. Y.; Yang, K.; Cacciaguerra, T.; Alonso, B. Tunable Hierarchical Porosity from Self-Assembled Chitin-Silica Nano-Composites. J. Mater. Chem. 2011, 21, 16997– 17006, DOI: 10.1039/c1jm12110c189Tunable hierarchical porosity from self-assembled chitin-silica nano-compositesBelamie, Emmanuel; Boltoeva, Maria Yu; Yang, Ke; Cacciaguerra, Thomas; Alonso, BrunoJournal of Materials Chemistry (2011), 21 (42), 16997-17006CODEN: JMACEP; ISSN:0959-9428. (Royal Society of Chemistry)We studied new mesoporous materials with original properties and obtained from self-assembled chitin-silica nano-composites. Our novel synthesis allows the controlled colloidal assembly of α-chitin nanorods (bundles of elongated chitin monocrystals) and siloxane oligomers. Calcination of nano-composites results in mesoporous silica materials. Their pore vol. fraction [phis]POR (0-0.52) is strongly correlated to the initial chitin content. Using N2 sorption and TEM data, we identify and characterize primary and secondary textural units related to the imprints of chitin monocrystals (2.5 nm wide) and nanorods (20-30 nm wide) resp. Primary textural units are preserved over a wide [phis]POR range (linear relationship between pore vol. and sp. surface area). The coating of monocrystals by siloxane oligomers leads to a siloxane network of fractal nature as deduced from complementary SAXS data. Beyond a crit. value [phis]POR' estd. near 0.2, the coating is partial, and the porosity becomes more open and connected. At larger scales, the arrangements of secondary textural units result in complex textures and long-range ordering, showing similarities with textural features found in natural materials. We discuss the competition between entropy-driven transitions typical of anisotropic particles and kinetic arrest due to colloidal gelation and inorg. condensation. Finally, a schematic model for texture formation is given.
- 190Nguyen, T.-D.; Shopsowitz, K. E.; MacLachlan, M. J. Mesoporous Silica and Organosilica Films Templated by Nanocrystalline Chitin. Chem.─Eur. J. 2013, 19, 15148– 15154, DOI: 10.1002/chem.201301929There is no corresponding record for this reference.
- 191Nguyen, T.-D.; Shopsowitz, K. E.; MacLachlan, M. J. Mesoporous Nitrogen-Doped Carbon from Nanocrystalline Chitin Assemblies. J. Mater. Chem. A 2014, 2, 5915– 5921, DOI: 10.1039/c3ta15255c191Mesoporous nitrogen-doped carbon from nanocrystalline chitin assembliesNguyen, Thanh-Dinh; Shopsowitz, Kevin E.; MacLachlan, Mark J.Journal of Materials Chemistry A: Materials for Energy and Sustainability (2014), 2 (16), 5915-5921CODEN: JMCAET; ISSN:2050-7496. (Royal Society of Chemistry)Nanocryst. chitin has been used both as a soft template and as the carbon and nitrogen sources for prepg. mesoporous nitrogen-doped carbon materials with a layered structure. The chitin nanorods prepd. by sequential deacetylation and hydrolysis of fibrils isolated from king crab shells organized into a nematic liq.-cryst. phase. Silica/chitin composites obtained by sol-gel condensation of silica in the presence of liq.-cryst. chitin were carbonized and etched to yield mesoporous nitrogen-doped carbon films that replicate the layered nematic organization of the nanocryst. chitin films. The high degree of mesoporosity and nitrogen doping in the liq.-cryst. biopolymer-derived carbon replicas allows them to function as efficient supercapacitor electrode materials. Films embedded with tin oxide nanoparticles displayed superior performance for supercapacitor electrodes.
- 192Xiong, R.; Yu, S.; Kang, S.; Adstedt, K. M.; Nepal, D.; Bunning, T. J.; Tsukruk, V. V. Integration of Optical Surface Structures with Chiral Nanocellulose for Enhanced Chiroptical Properties. Adv. Mater. 2020, 32, 1905600 DOI: 10.1002/adma.201905600192Integration of Optical Surface Structures with Chiral Nanocellulose for Enhanced Chiroptical PropertiesXiong, Rui; Yu, Shengtao; Kang, Saewon; Adstedt, Katarina M.; Nepal, Dhriti; Bunning, Timothy J.; Tsukruk, Vladimir V.Advanced Materials (Weinheim, Germany) (2020), 32 (2), 1905600CODEN: ADVMEW; ISSN:0935-9648. (Wiley-VCH Verlag GmbH & Co. KGaA)The integration of chiral organization with photonic structures found in many living creatures enables unique chiral photonic structures with a combination of selective light reflection, light propagation, and CD. Inspired by these natural integrated nanostructures, hierarchical chiroptical systems that combine imprinted surface optical structures with the natural chiral organization of cellulose nanocrystals are fabricated. Different periodic photonic surface structures with rich diffraction phenomena, including various optical gratings and microlenses, are replicated into nanocellulose film surfaces over large areas. The resulting films with embedded optical elements exhibit vivid, controllable structural coloration combined with highly asym. broadband CD and a microfocusing capability not typically found in traditional photonic bioderived materials without compromising their mech. strength. The strategy of imprinting surface optical structures onto chiral biomaterials facilitates a range of prospective photonic applications, including stereoscopic displays, polarization encoding, chiral polarizers, and colorimetric chiral biosensing.
- 193Rofouie, P.; Alizadehgiashi, M.; Mundoor, H.; Smalyukh, I. I.; Kumacheva, E. Self-Assembly of Cellulose Nanocrystals into Semi-Spherical Photonic Cholesteric Films. Adv. Funct. Mater. 2018, 28, 1803852 DOI: 10.1002/adfm.201803852There is no corresponding record for this reference.
- 194Kim, M.; Pierce, K.; Krecker, M.; Bukharina, D.; Adstedt, K.; Nepal, D.; Bunning, T.; Tsukruk, V. V. Monolithic Chiral Nematic Organization of Cellulose Nanocrystals under Capillary Confinement. ACS Nano 2021, 15, 19418– 19429, DOI: 10.1021/acsnano.1c05988194Monolithic Chiral Nematic Organization of Cellulose Nanocrystals under Capillary ConfinementKim, Minkyu; Pierce, Kellina; Krecker, Michelle; Bukharina, Daria; Adstedt, Katarina; Nepal, Dhriti; Bunning, Timothy; Tsukruk, Vladimir V.ACS Nano (2021), 15 (12), 19418-19429CODEN: ANCAC3; ISSN:1936-0851. (American Chemical Society)We demonstrate bioenabled crack-free chiral nematic films prepd. via a unidirectional flow of cellulose nanocrystals (CNCs) in the capillary confinement. To facilitate the uniform long-range nanocrystal organization during drying, we utilized tunicate-inspired hydrogen-bonding-rich 3,4,5-trihydroxyphenethylamine hydrochloride (TOPA) for phys. crosslinking of nanocrystals with enhanced hydrogen bonding and polyethylene glycol (PEG) as a relaxer of internal stresses in the vicinity of the capillary surface. The CNC/TOPA/PEG film is organized as a left-handed chiral structure parallel to flat walls, and the inner vol. of the films displayed transitional herringbone organization across the interfacial region. The resulting thin films also exhibit high mech. performance compared to brittle films with multiple cracks commonly obsd. for capillary-formed pure CNC films. The chiral nematic ordering of modified TOPA-PEG-CNC material propagates through the entire thickness of robust monolithic films and across centimeter-sized surface areas, facilitating consistent, vivid iridescence, and enhanced circular polarization. The best performance that prevents the cracks was achieved for a CNC/TOPA/PEG film with a minimal, 3% amt. of TOPA. Overall, we suggest that intercalation of small highly adhesive mols. to cellulose nanocrystal-polymer matrixes can facilitate uniform flow of liq. crystal phase and drying inside the capillary, resulting in improvement of the ultimate tensile strength and toughness (77% and 100% increase, resp.) with controlled uniform optical reflection and enhanced circular polarization unachievable during regular drying conditions.
- 195Chu, G.; Qu, D.; Camposeo, A.; Pisignano, D.; Zussman, E. When Nanocellulose Meets Diffraction Grating: Freestanding Photonic Paper with Programmable Optical Coupling. Mater. Horiz. 2020, 7, 511– 519, DOI: 10.1039/C9MH01485C195When nanocellulose meets diffraction grating: freestanding photonic paper with programmable optical couplingChu, Guang; Qu, Dan; Camposeo, Andrea; Pisignano, Dario; Zussman, EyalMaterials Horizons (2020), 7 (2), 511-519CODEN: MHAOBM; ISSN:2051-6355. (Royal Society of Chemistry)Photonic crystals based on plasmonic or dielec. periodic structures have attracted considerable interest owing to their capabilities to control light-matter interactions with tailored precision. By using a nanocellulose derived chiral liq. crystal as a building block, here we demonstrate a bio-inspired dual photonic structure that contains the combination of microscopic periodic 1D surface grating and nanoscopic helical organization, giving rise to programmable color mixing and polarization rotation. We show that a variation in the photonic band-gap in the bulk matrix leads to simultaneous control over the reflection and diffraction of light with controllable iridescence.
- 196Droguet, B. E.; Liang, H.-L.; Frka-Petesic, B.; Parker, R. M.; De Volder, M. F. L.; Baumberg, J. J.; Vignolini, S. Large-Scale Fabrication of Structurally Coloured Cellulose Nanocrystal Films and Effect Pigments. Nat. Mater. 2022, 21, 352– 358, DOI: 10.1038/s41563-021-01135-8196Large-scale fabrication of structurally coloured cellulose nanocrystal films and effect pigmentsDroguet, Benjamin E.; Liang, Hsin-Ling; Frka-Petesic, Bruno; Parker, Richard M.; De Volder, Michael F. L.; Baumberg, Jeremy J.; Vignolini, SilviaNature Materials (2022), 21 (3), 352-358CODEN: NMAACR; ISSN:1476-1122. (Nature Portfolio)Cellulose nanocrystals are renewable plant-based colloidal particles capable of forming photonic films by solvent-evapn.-driven self-assembly. So far, the cellulose nanocrystal self-assembly process has been studied only at a small scale, neglecting the limitations and challenges posed by the continuous deposition processes that are required to exploit this sustainable material in an industrial context. Here, we addressed these limitations by using roll-to-roll deposition to produce large-area photonic films, which required optimization of the formulation of the cellulose nanocrystal suspension and the deposition and drying conditions. Furthermore, we showed how metre-long structurally colored films can be processed into effect pigments and glitters that are dispersible, even in water-based formulations. These promising effect pigments are an industrially relevant cellulose-based alternative to current products that are either micro-polluting (for example, non-biodegradable microplastic glitters) or based on carcinogenic, unsustainable or unethically sourced compds. (for example, titania or mica).