The dynamics of entangled polymer melts not only is of fundamental theoretical interest but also has wide-reaching consequences for developing a theoretical foundation for investigating biological macromolecules and complex systems relevant to material sciences. Despite several decades of intensive experimental and theoretical research in this field, open questions remain regarding segmental dynamics over the wide range of time scales from local to global motion. This work employs a novel approach based on nuclear magnetic relaxation to scrutinize the character of dipolar interactions in entangled polymer melts, thereby accessing unique information about segmental diffusion and rotation. The main focus is set on the separate consideration of intra- and intermolecular contributions to the proton dipolar interactions, which have been previously shown to possess a different, nontrivial time dependence. A combination of well-established field-cycling T₁ relaxometry and recently developed methods based on spin echo is utilized to investigate dipolar couplings in entangled poly(ethylene oxide) melts of various molecular weights. Isolation of the intermolecular contributions to the corresponding experimental quantities provides a means to observe segmental translations taking place during more than 6 orders of magnitude in time. Time dependences of the mean-square displacement obtained in this way revealed apparent exponents of the power laws significantly deviating from predictions of the widely used tube-reptation model of polymer dynamics in the regime of entangled motion. In addition to that, the relative ratio of intermolecular dipolar interactions over the intramolecular counterpart is probed through their corresponding contributions to the transverse relaxation rate. A strong deviation from the tube-reptation model predictions for the evolution of this quantity is observed in the whole range probed experimentally. The obtained data do not reflect the restricted character of segmental motion anticipated in the corresponding time regime. It is emphasized that similar results, both in amplitude and in qualitative behavior, have been previously demonstrated in polybutadiene and polyethylene-alt-propylene, thereby allowing to discuss the universality of the observed deviation.

We demonstrated for the first time a facile and reproducible preparation of large-scale (∼40 m²) initiator layers for surface-initiated atom transfer radical polymerization (SI-ATRP) using a simple sol–gel solution of (p-chloromethyl)phenyltrimethoxysilane and tetraethoxysilane. Highly smooth and transparent initiator layers could be formed on various inorganic/organic substrates via a spin-, wire-bar-, or roll-to-roll-coating without any marked change in surface morphology or bulk properties at room temperature. Combining the advantages of this sol–gel approach and subsequent “paint on” SI-ATRP using a variety of waterborne monomers, we have succeeded in the formation of polymer brushes on large-scale real-life substrates (i.e., maximum 50 × 50 cm²) under ambient conditions (room temperature and open to the air) without any complicated apparatus or harsh reaction conditions.

Dual-responsive (light and pH) yolk–shell structured drug delivery nanocapsules, each consisting of a movable upconversion nanoparticle (UCNP) core and a shrinkable poly(methacrylic acid) (PMAA) shell, were prepared by distillation precipitation polymerization. Monodispersed NaYF₄: Yb³⁺/Tm³⁺ UCNPs were synthesized and encapsulated in silica templates, followed by coating to form PMAA shells. Subsequently, the silica templates were dissolved to form nanocavities for drug loading. The PMAA shell contains pH and ultraviolet (UV) light sensing moieties, enabling a control release upon the exposure of nanocapsules to these stimuli. The near-infrared (NIR)-to-UV feature of UCNPs allows azobenzene isomerization to be light triggered remotely to control contraction and swelling of PMAA shells. The loading efficiency of the anticancer drug doxorubicin (DXR) was up to 17 wt % due to the unique nanoporous structure of PMAA shells. The values of the diffusion coefficient under different release conditions were determined using the Baker–Lonsdale model to facilitate the design of dual-responsive drug release devices or systems.

We report the propagation-inspired initiation of sodium N-phenethyl-3-phenylpropanamide (NaPEPPA), an aliphatic sodium amidate, for the living anionic homo- and copolymerization of isocyanates. This initiator was compared with sodium benzanilide (NaBA), an aromatic sodium amidate, in the living anionic homopolymerization of n-hexyl isocyanate (HIC). Only NaPEPPA attained the initiation efficiencies close to unity at the early stage of propagation. The homopolymerization with [HIC]₀/[NaPEPPA]₀ = 38.9/85.1/203 led to poly(n-hexyl isocyanate)s (PHICs) with predictable MWs and low dispersities (M_n,theo = 5.12/10.7/24.7 kDa; M_n = 5.22/11.1/27.4 kDa; Đ = 1.11/1.10/1.06). NaPEPPA was also used to initiate the living anionic copolymerization of HIC and furfuryl isocyanate (FIC). As a result, poly(furfuryl isocyanate-block-n-hexyl isocyanate) (P(FIC-b-HIC)) was afforded by the blocky monomer sequence distribution. Based on the copolymerization kinetics, a series of polyisocyanate-based multiblock copolymers, P(FIC-b-HIC)₁/P(FIC-b-HIC)₂/P(FIC-b-HIC)₃/P(FIC-b-HIC)₄ (M_n,theo = 5.47/10.6/15.8/20.8 kDa; M_n = 5.59/11.5/16.3/20.3 kDa; Đ = 1.10/1.03/1.03/1.03), were afforded by the repetitive sequential addition of comonomers.

A novel approach is reported for self-healing of polybenzoxazine thermosets based on both supramolecular attractions and metal–ligand interactions. The relating smart material was synthesized by using bis(3-aminopropyl)-terminated polydimethylsiloxane, formaldehyde, and bisphenol A. The films of the obtained main-chain polybenzoxazine precursor (Poly(Si-Bz)) containing 2% FeCl₃ were prepared and cured at low temperatures (100–120 °C). The structures of the precursors and final products were characterized by spectral analysis. The curing and thermal stability of the related materials were investigated by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). Self-healing efficiency was studied by stress–strain measurements. Potential shape recovery (SR) behavior was also demonstrated by preparing curled or spiral fixed shapes, and the transformation of temporary shapes to these fixed shapes was verified.

The development of highly efficient and rapid photoinitiating systems for free radical photopolymerization under the irradiation of visible light has attracted increasing attention due to their widespread potential applications in, for example, 3D printing or dental polymers. Unfortunately, currently available visible-light-sensitive photoinitiators are not efficient enough for 3D printing applications suffering from low printing speeds. Here we describe a series of photoinitiating systems consisting of disubstituted aminoanthraquinone derivatives (i.e., 1-amino-4-hydroxyanthraquinone, 1,4-diaminoanthraquinone, and 1,5-diaminoanthraquinone) and various additives (e.g., tertiary amine and phenacyl bromide) toward the free radical photopolymerization of various acrylate monomers (such as commercial 3D resin) under the irradiation of blue to red LEDs. It is shown that the type and position of substituents of the aminoanthraquinone derivative can significantly affect its photoinitiation properties. The most efficient disubstituted aminoanthraquinone derivative-based photoinitiating system was selected and used for the 3D printing of a commercial 3D resin in a 3D printer with polychromatic visible light as the irradiation source. It is shown that its printing speed was dramatically enhanced compared to a commercial photoinitiator 2,4,6-trimethylbenzoyldiphenylphosphine oxide (TPO).

Clay aerogel composites have high potential to be used in the construction industry as an insulation material; however, their hydrophilic nature may result in an amount of moisture absorption that could significantly hinder both physical and mechanical properties. This study develops hydrophobic clay aerogel composites using an environmentally friendly freeze-drying process. This was achieved by using three water dispersible repellent components: WDisRep1, WDisRep3, and WDisRep4. Microstructure, wettability, moisture resistance, mechanical properties, and thermal conductivity of the developed clay aerogel composites were fully characterized to understand working mechanisms and performance. The composites exhibited superior mechanical and physical properties in which the composites’ moisture absorbance was reduced by up to 40%, while maintaining excellent dimensional stability. The aerogel composites achieved a contact angle of 140° with a 93% reduction in water absorption. The composites achieved a compressive modulus as high as 3.2 MPa while maintaining low thermal conductivity at 0.038 W/(m K).

The ring-opening polymerization (ROP) kinetics of ε-caprolactone and lactide with various H-bonding organocatalysts, (thio)ureas paired with an amine cocatalyst, were evaluated at temperatures up to 110 °C. In nonpolar solvent, most cocatalyst systems exhibit decomposition at high temperatures, while only two, a monourea and bis-urea H-bond donor plus base cocatalyst, are stable up to 110 °C. The onset temperature of cocatalyst decomposition must be measured under reaction conditions. In polar solvent, when the more active imidate form of the (thio)urea is favored, most cocatalyst systems become thermally stable up to 110 °C, exhibiting linear Eyring behavior, including some that were unstable in toluene. The very progress of an ROP is shown to influence the nature of the catalysts as the solution polarity changes from highly polar (at 0% conversion) to less polar at full conversion. Activation parameters are discussed, and a mechanistic explanation of the observations is proposed.

The development of polyimides (PIs) with a superheat resistance and a high thermal dimensional stability is required urgently for application in the rapidly growing area of flexible-display substrates. Based on an enhanced intermolecular interaction, 2,2′-p-phenylenebis(5-aminobenzimidazole) (DP) that contains bis-benzimidazole was synthesized, and two series of its copolyimides (PI-a and PI-b) were prepared by copolycondensation with 5-amino-2-(4-aminobenzene)benzimidazole (PABZ) and 5-amino-2-(3-aminobenzene)benzimidazole (i-PABZ), respectively. The high density and packing coefficient of the resulting PIs caused by the strong intermolecular interaction from the hydrogen bonds and the charge-transfer complex provided the PI films with a very high glass-transition temperature (T_g > 450 °C) and an extremely low coefficient of thermal expansion (CTE) below 10 ppm/K for PI-a. Such good thermal properties expand their application as high thermostable materials. Furthermore, the PI-b had a higher T_g than PI-a, whereas the latter had lower CTE values because of the configuration difference of their polymer chains. These data indicate that the resultant thermostable copolyimides have potential application as a flexible-display substrate and provide a feasible method to improve the thermal properties by incorporating bis-benzimidazole moieties.

A series of linear thermosensitive amphiphilic pentablock terpolymers PNIPAM_x-b-PtBA₉₀-b-PPO₃₆-b-PtBA₉₀-b-PNIPAM_x (N_xT₉₀O₃₆T₉₀N_x) with various lengths x of PNIPAM block (x = 111, 107, 95, 58, 33, and 26) were synthesized via a two-step atom transfer radical polymerization (ATRP) using modified poly(propylene oxide) (PPO₃₆) as the macroinitiator, tert-butyl acrylate (tBA) as the first monomer, and N-isopropylacrylamide (NIPAM) as the second monomer. The N_xT₉₀O₃₆T₉₀N_x pentablock terpolymers form micelles in dilute aqueous solution, whose structure and morphology are dependent on the length x of PNIPAM block and solution temperature. At 14 °C, below the lower critical solution temperature (LCST) of PNIPAM block, the morphology of N_xT₉₀O₃₆T₉₀N_x micelles changes from core–corona spherical micelles with homogeneous hydrophobic core to rodlike micelles, core–shell–corona spherical micelles with clear boundaries, core–shell–corona spherical micelles with blurry boundaries, and finally large compound spherical micelles with embedded hydrophilic chains in the hydrophobic region when x decreases from 111 to 26. This morphology change might be attributed to the different stretching factors of hydrophobic PPO and PtBA blocks in the micelles, which varied differently with length x of PNIPAM block and hence resulted in the change of compatibility of the two hydrophobic blocks. A scaling relationship between the length L₀ of hydrophilic corona and the length x of PNIPAM block is found to be L₀ ∼ x^0.77±0.08, which falls in the range 0.5–0.86 theoretically predicted for the micelles of diblock copolymers. The size of hydrophobic regions increases with decreasing x. At 60 °C above the LCST of PNIPAM block, all N_xT₉₀O₃₆T₉₀N_x pentablock terpolymers form spherical micelles with uniform structure and size distribution in aqueous solution regardless of the length x of PNIPAM block.

The chain conformation of a β-glucan extracted from black fungus (BFP) was studied by static/dynamic light scattering, viscometry, atomic force microscopy (AFM), and molecular dynamics (MD) simulation. The Mark–Houwink equation and the relationship between M_w and R_g of BFP in water at 25 °C were determined to be [η] = 1.78 × 10^–7M_w^1.6 and R_g = 5 × 10^–4M_w^0.9, and the molar mass per unit contour length (M_L) and the persistence length (q) were 2724 ± 276 nm^–1 and 230 ± 30 nm, respectively, indicating triple-helix conformation. Moreover, the stiff-chain lengths of the BFP fractions were visualized with AFM images, and their M_L values were estimated to give a mean of 2212 nm^–1, consistent with the above. Importantly, MD simulation confirmed that the triple helix was the most stable conformation of BFP. We identified, for the first time, the triple-helix chain conformation of BFP and also offered an alternative method for the characterization of the rigid macromolecules.

We report the synthesis of nanoparticle (NP) networks in a variety of sizes through the controlled cross-linking reaction of ketone groups integrated into linear polyester backbones and a difunctionalized aminooxy ethylene cross-linker. In contrast to previous work forming nanonetworks from linear components with pendant reactive groups, the ketone functional group is part of the polymer backbone accomplished by copolymerization of 2-oxepane-1,5-dione (OPD) monomers together with δ-valerolactone. This process precludes postpolymerization reactions, modifying pendant functional groups in the polyester component, and provides direct access to the cross-linking entity. Reactions with bis(aminooxy)poly(ethylene glycol) form networks in a rapidly proceeding process with linear precursors containing 4%, 8%, and 14% of OPD, in a ratio of two aminooxy groups per keto group. The concentration of the OPD unit in solution is another critical factor contributing to the controlled production of these particles as investigated in two conditions to yield a set of six particles in well-defined dimensions ranging from 39 to 173 nm. Ketoxime linkages are pH-responsive and provide an alternative faster degradation mechanism together with a hydrolysis of the polymer backbone. The reduction of the ketoxime linkages after nanoparticle formation resulted in an additional set of six particles in comparable sizes with stable alkoxyamine groups limiting the degradation to a slower hydrolysis. In this work, we prepared a series of twelve particles in a two- or three-step process starting from the synthesis of three different OPD-containing polymers and controlled cross-linking in two reaction concentrations, with or without reduction of the ketoxime connective group. These particles are promising drug delivery systems as a practical synthesis is combined with a tunable degradation leading to expanded options for drug release and is demonstrated in the release of the natural product Brefeldin A.

Polyolefin-containing block copolymers were catalytically synthesized using a postpolymerization modification strategy. A traditional olefin polymerization followed by a tandem hydroformylation/hydrogenation of the olefinic terminated polymer was implemented to yield a hydroxyl terminated polyolefin. The hydroxyl terminated polyolefin was then used as a macroinitiator for the ring-opening polymerization of cyclic esters to yield the corresponding diblock copolymer. This methodology was applied to an array of different polyolefins and two cyclic monomers (ε-caprolactone and lactide) showcasing the versatility of the protocol. Most noticeably, isotactic polypropylene was quantitatively incorporated into block copolymers. Additionally, the hydrophobicity of polyethylene films was successfully decreased by the addition of small amounts of a block copolymer.

We have studied the effect of cross-linking on the tribological behavior of polymer brushes using a combined experimental and theoretical approach. Tribological and indentation measurements on poly(glycidyl methacrylate) brushes and gels in the presence of dimethylformamide solvent were obtained by means of atomic force microscopy. To complement experiments, we have performed corresponding molecular dynamics (MD) simulations of a generic bead–spring model in the presence of explicit solvent and cross-linkers. Our study shows that cross-linking leads to an increase in friction between polymer brushes and a counter-surface. The coefficient of friction increases with increasing degree of cross-linking and decreases with increasing length of the cross-linker chains. We find that the brush-forming polymer chains in the outer layer play a significant role in reducing friction at the interface.

Although the tube models have attained remarkable success, development of a simulation method for entangled branch polymer dynamics is still a challenge. In this study, the multichain slip-spring model has been examined to branch polymers for the first time. In the model, the bead–spring chains are dispersed in the simulation box, and the entanglement is mimicked by the virtual spring, so-called slip-spring, which connects the chains and hops along the chain. The slip-springs are created and destructed only at the chain ends. Besides, for the relaxation of entanglements formed between the backbone chains in the branch polymers, the hopping of the slip-spring across the branch point (SHAB) is additionally allowed when the branching arm relaxes. The simulation results for symmetric and asymmetric star and H branch polymers are in semiquantitative agreement with experimental and earlier simulation data extracted from the literature. Although the proposed simulation is compatible with the data for scarcely entangled systems, due to the computational difficulties the test against well-entangled systems remained unperformed, and the details of SHAB implementation remain open.

Understanding the ion transport mechanism in nanocomposite solid polymer electrolytes is necessary to develop next-generation electrochemical devices. We investigate the role of inorganic nanoparticle on ion conduction and segmental dynamics in cross-linked epoxy-based nanocomposite solid polymer electrolytes, complexed with Li⁺F₃CSO₂NSO₂CF₃^– (LiTFSI) salt and Al₂O₃ nanowire, using dielectric relaxation spectroscopy. The addition of Al₂O₃ not only increases the ionic conductivity σ_DC by up to ∼10 times but also accelerates the segmental α motion compared to the host electrolyte. Increasing Al₂O₃ content leads to a reduction in segmental α relaxation temperature T_α (fast dynamics), resulting in increased ion mobility as well as an enhancement in segmental α relaxation strength Δε_α, lowering ion dissociation energy, as revealed by density functional theory calculations, thereby providing more mobile ions for conduction. This ion transport investigation provides insights into the design of high-conductivity nanocomposite solid polymer electrolytes for energy applications.

The efficient and versatile click chemistry based on 1,2,4-triazoline-3,5-dione (TAD) was used as one of the most potential postfunctionalizing pathways to specially design polymer nanostructure for dielectric materials. The block copolymer was synthesized by tandem ring-opening metathesis polymerization and metathesis cyclopolymerization and self-assembled into the core–shell nanostructure in the selective solvent, which could be modified by TAD in a controlled manner by tuning the TAD feeding amount, enabling the Alder–ene reaction of TAD with the double bonds to occur first on the polynorbornene backbone in the shell and then the cascade Alder–ene and Diels–Alder reactions on the polyacetylene backbone bearing five-membered rings in the core. The modified block copolymers incorporating varied amount of urazole moieties exhibited enhanced dielectric constant from 16.2 to 20.3 and lowered dielectric loss from 0.031 to 0.013 to 0.009, which provides a new idea of the selective postfunctionalization of nanostructures in solution for regulating the polymer structure and properties.

We report a versatile and simple approach to produce cylindrical micelles by the direct dissolution of polymers in water. The developed strategy relies on a RAFT agent functionalized by a bisurea sticker that allowed to synthesize a series of α-bisurea-functionalized poly(N,N-dimethylacrylamide) (PDMAc), poly(acrylic acid) (PAA), polyacrylamide (PAM), and poly(2-(N,N-dimethylamino)ethyl acrylate) (PDMAEA) with number-average degrees of polymerization (DP_n) varying from about 10 to 50. Their spontaneous self-assembly in water was studied by electron microscopy (cryo-TEM), neutron scattering (SANS), and calorimetry (ITC) analyses which showed that long cylindrical micelles are spontaneously formed in water. The crucial role of the bisurea sticker end-groups was established by comparison with the corresponding bisurea-free model polymers that only formed spherical micelles. Finally, we have shown that it is possible to trigger reversibly the assembly/disassembly of the nanofibers by pH changes.

Nucleobase-containing polymers have received great attention for their complementary multiple hydrogen bonding between nucleobases. However, their polymerization is difficult due to poor solubility in a solvent. In this study, we successfully synthesized adenine-containing block copolymers, poly(9-(4-vinylbenzyl)adenine)-block-polystyrene (PVBA-b-PS), using reversible addition–fragmentation chain transfer (RAFT) polymerization in polar solvents of dimethyl sulfoxide and N,N-dimethylformamide and characterized them by size exclusion chromatography and nuclear magnetic resonance spectroscopy. We measured the temperature dependence of the Flory–Huggins interaction parameter (χ) between PVBA and PS as χ = 0.3847 + 55.763/T. The χ was very large (∼0.5 at 200 °C). The phase behavior of PVBA-b-PS with various volume fractions of PS block (f_PS) was investigated via small-angle X-ray scattering and transmission electron microscopy. With increasing f_PS from 0.1 to 0.8, body-centered-cubic spheres of PS, hexagonally packed (HEX) cylinders of PS, lamellae, and HEX cylinders of PVBA were observed. Interestingly, PVBA-b-PS with f_PS = 0.75 showed asymmetric lamellar microdomains. We also prepared a thin film of PVBA-b-PS on a substrate as a template for spatial arrangement of gold nanoparticles (AuNPs). When the surface of AuNPs was modified with thymine-containing polymer chains, AuNPs were selectively sequestered into PVBA microdomains through the complementary hydrogen bonding between thymine and adenine units.

A new generation of light-induced production of polymeric materials is presented here. In detail, we propose to use photoacidic catalysis during the well-known epoxy–amine polyaddition reaction: it is now referred to as “epoxy–amine photopolyaddition”. Soft irradiation (405 nm visible light, 150–450 mW/cm²) of a photosensitizer/iodonium salt system leads to the production of superacids (e.g., H⁺, PF₆^–) that spectacularly enhance state-of-the-art epoxy–amine polyaddition kinetics: <3 min is necessary to obtain full conversion when >3 h is required to complete the reaction without light. Also, photoactivation greatly enhances final epoxy and amine conversions which resulted in increases (+15 °C) of the glass transition temperature of the final 3D polymer networks. This work clearly shows the extremely versatile applications for epoxy–amine photopolyaddition: thin layers (40 μm), thick layers (up to 2.5 cm), and composites (45 wt % fillers). This work paves the path toward ultrafast production of epoxy–amine composites and adhesives.

Polymer degrafting is a process in which surface-attached polymer brushes are removed from the substrate by breaking a chemical bond in proximity to the substrate. This paper provides insight into the kinetics of degrafting poly(methyl methacrylate) (PMMA) brushes using tetrabutylammonium fluoride (TBAF) and demonstrates how the process can be modeled using a series of degrafting reactions. The trichlorosilane-based polymerization initiator utilized here to synthesize PMMA grafts by surface-initiated atom transfer radical polymerization anchors to the silica substrate by up to three potential attachment points. During the degrafting sequence this anchoring reduces to two and one chemical bond and finally results in complete liberation of the PMMA macromolecule from the substrate. We investigate the effect of TBAF concentration, the initial grafting density of PMMA grafts on the substrate, and TBAF exposure time on degrafting of PMMA by monitoring the instantaneous areal grafting density of PMMA on the substrate.

The living anionic copolymerization of isoprene and styrene in cyclohexane affords tapered block copolymers due to the highly disparate reactivity ratios of r_I = 12.8 and r_S = 0.051. Repeated addition of a mixture of these monomers was exploited to generate tapered multiblock copolymer architectures of the (AB)_n type with up to 10 blocks (1 ≤ n ≤ 5), thereby subdividing the polymer chains in alternating flexible polyisoprene (PI) and rigid polystyrene (PS) segments. Three series of well-defined tapered multiblock copolymers with approximate molecular weights of 80, 240, and 400 kg/mol were prepared on the 100 g scale. Via this synthetic strategy polymer chains were divided in di-, tetra-, hexa-, octa-, and decablock tapered multiblock structures. Because of the living nature of the polymerization, low dispersities in the range 1.06–1.28 (decablock) were obtained. To ensure full monomer conversion prior to the addition of the isoprene/styrene mixture, kinetic Monte Carlo simulation was employed, permitting to simulate chain growth in silico by employing the known polymerization rates and rate constants k_p. The synthesized tapered multiblock copolymers were characterized via SEC and selected samples via oxidative degradation of the polyisoprene block in solution, confirming the well-defined nature of the PS segments. Subsequently, the question was addressed, to which extent the tapered multiblock copolymers are capable of forming ordered nanosegregated morphologies. Detailed thermal, structural, and rheological investigations showed that the tapered multiblock copolymers with a molecular weight of 240 kg/mol formed ordered phases with the expected lamellar morphology. However, X-ray scattering data and transmission electron microscopy (TEM) images of the octablock and decablock copolymers reflect weakly ordered structures at ambient temperature. The domain spacing, d, was found to scale as d ∼ N^0.62, where N is the total degree of polymerization, suggesting stretching of chains and nonideal configurations. Following the structure factor, S(q), as a function of temperature revealed that the tapered multiblock copolymers undergo a fluctuation-induced first-order transition at the respective order-to-disorder transition temperature, T_ODT. The viscoelastic response of the tapered copolymers was controlled by the nanodomain structure, the degree of segregation, nanodomain-bridging configurations of blocks, and also the proximity to the glass temperature of the vitrified PS domains. Tapered hexablock copolymers were found to best combine structural integrity and mechanical toughness, while maintaining a large strain at break (>900%).

The slow kinetics of block copolymer self-assembly may hinder, or even prevent, the realization of expected equilibrium ordered morphologies. Here we investigate the self-assembly kinetics of cylinder-forming polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) and its corresponding ternary blends with low molecular weight PS and PMMA in thin films ranging from <1 to several cylinder layers in thickness. In situ grazing-incidence X-ray scattering coupled with ex situ electron microscopy reveals pathway-dependent ordering substantially altered by homopolymer blending. In particular, the neat (unblended) block copolymer (BCP) is kinetically frustrated in films more than ∼1 cylinder layer thick and is unable to reach a state of ordered hexagonally packed cylinders during the annealing interval. On the other hand, while blends exhibit similar pattern coarsening behavior to neat BCPs for hexagonally ordered cylinders, reorientation transitions between vertical or horizontal cylinders are dramatically accelerated in blend thin films. We infer that more rapid early stage ordering observed in blends can be attributed in part to faster reorientation transitions.

Chain entanglements govern the dynamics of polymers and will therefore affect the processability and kinetics of ordering; it follows that through these parameters chain dynamics can also affect charge transport in conjugated polymers. The effect of nematic coupling on chain entanglements is probed by linear viscoelastic measurements on poly[N-9′-heptadecanyl-2,7-carbazole-alt-5,5-(4′,7′-di-2-thienyl-2′,1′,3′-benzothiadiazole)] (PCDTBT) and poly((9,9-dioctylfluorene-2,7-diyl)-alt-(4,7-di(thiophene-2-yl)-2,1,3-benzothiadiazole)-5′,5″-diyl) (PFTBT) with varying molecular weights. We first verify the existence of nematic phases in both PFTBT and PCDTBT and identify nematic–isotropic transition temperatures, T_IN, between 260 and 300 °C through a combination of differential scanning calorimetry, polarized optical microscopy, temperature-dependent X-ray scattering, and rheology. In addition, both PCDTBT and PFTBT show a glass transition temperature (T_g) and T_IN, whereas only PFTBT has a melting temperature T_m of 260 °C. Comparing the molecular weight dependence of T_IN with theoretical predictions of nematic phases in conjugated polymers yields the nematic coupling constant, α = (550 ± 80 K)/T + (2.1 ± 0.1), and the long-chain limit T_IN as 350 ± 10 °C for PFTBT. The entanglement molecular weight (M_e) in the isotropic phase is extracted to be 11 ± 1 kg/mol for PFTBT and 22 ± 2 kg/mol for PCDTBT by modeling the linear viscoelastic response. Entanglements are significantly reduced through the isotropic-to-nematic transition, leading to a 10-fold increase in M_e for PFTBT and a 15-fold increase for PCDTBT in the nematic phase.

The segregation kinetics of deuterated polystyrene (d-PS) within the grain boundary regions of a lamellar poly(styrene-b-isoprene) copolymer is analyzed using a combination of electron imaging and grain mapping as well as ultrasmall and small-angle neutron scattering. Solute segregation is limited to high-angle grain boundaries (that is, boundaries between grains having misorientations that exceed a threshold value). The accumulation of d-PS is found to be uniform across high-angle boundaries, reaching an equilibrium local concentration of solute within the boundary regions of about 52 vol %. This is interpreted as a consequence of d-PS segregation enabling the relaxation of perturbed chain conformations in the boundary regions, thus reducing the elastic strain energy that is stored in high-angle boundaries. The elastic strain energy is estimated using a continuum layer deformation model and compared to the experimental (relative) boundary tension that is determined by analysis of dihedral angles at grain boundary triple junctions. A McLean-type interface adsorption model is demonstrated to quantitatively capture both the kinetics and the extent of solute accumulation within boundary regions. The model reveals that the rate of segregation is sensitive to the mobility of the solute while the limiting concentration of solute within high-angle boundaries is determined by the energy of grain boundary defects. The results provide a basis for the interpretation of structure coarsening processes in block copolymer blend systems that are often found to result in more granular microstructures (featuring smaller grain sizes) as compared to the pristine block copolymer analogues and inform the development of processes for the strategic decoration of defects to enable new functionalities in block copolymer-based materials.

We determine the mechanism that governs polymerization during a process in which solid monomer is polymerized with a vapor-phase initiator. Gel permeation chromatography data show a bimodal molecular weight distribution at all processing conditions which can be attributed to two different polymerization mechanisms. Smaller chains form by polymerization at the vapor–solid interface, and larger chains form by polymerization within the solid. The monomer mobility and sublimation rate affect the polymerization rate and thereby affect the membrane structure. The molecular weight of the larger chains can be increased by increasing the polymerization temperature and the polymerization time. The ability to vary the polymerization time allows for tuning the solubility of the membranes. The process–structure–property relationships elucidated in this study can enable the fabrication of porous polymer membranes for applications in filtration, textiles, and sensors.

Understanding and designing nanoscale interfaces are essential to advancing the thermomechanical performance of polymer nanocomposites reinforced by nanocellulose. In this context, it remains to be understood how disorder introduced on the surfaces of crystals as filler materials during extraction and processing influences interfacial adhesion with glassy polymers. Using atomistic molecular dynamics (MD) simulations, here we systematically explore the interfacial adhesion between nanocellulose and poly(methyl methacrylate) (PMMA) by comparing an ordered cellulose nanocrystal (CNC) interface to a disordered amorphous cellulose (AC) interface. Using a bilayer system that consists of a cellulose underlayer and a polymer upper layer, our simulations show that the AC–PMMA interface can achieve about 50%–60% greater interfacial adhesion energy than that of the CNC–PMMA interface. We uncover that the improved adhesion primarily arises from a larger number of hydrogen bonds formed between the cellulose and polymer chains. Remarkably, the greater adhesion energy and smaller filler–filler surface energy achieved by the AC lead to significantly improved dispersive capability of nanofiller in polymer matrices in comparison with the CNC. Further analyses reveal that while the polymer chain configurations are characteristically different near the two interfaces, where stronger ordering and denser packing of chains are observed near the CNC, their relaxation dynamics are quite similar for the two interfaces. We attribute this observation to the competing effects between the interfacial adhesion and chain packing on polymer relaxation. Our study provides fundamental insights into the interfacial mechanisms of polymer–nanocellulose interfaces at a molecular level and reveals that surface disorder inevitably introduced during production may serve to improve interfacial adhesion energy with the polymer matrix while also enhancing nanofiller dispersion within polymer nanocomposites.

The combinatorial functionalization in a single molecular framework by structural integration utilizing multiple functional materials to create predefined structural morphology and multistimuli-responsive smart materials has attracted intensive attention. Herein, we constructed intrinsically porous and dual-responsive supramolecule, TeDA, by introducing a photopolymerizable diacetylene template (10,12-pentacosadiynoic acid) to the sterically rigid tetrahedral tetraphenylmethane (TPM) core. The self-assembled monomeric TeDA is transformed into the covalently cross-linked blue-phase polydiacetylene (TePDA) by UV irradiation (UV 254 nm). The BET measurement and examination of SEM images confirm the mesoporous characteristic for TeDA/PDA. Very interestingly, the blue-phase TePDA produces a naked-eye detectable colorimetric response to heat and VOCs (liquid and vapor phase). Most importantly, TePDA exhibits reversible thermochromism and excellent colorimetric response to chloroform vapors. To signify the structural influence of TPM on material properties, we also studied non-TPM derivatives. The TeDA/PDA integrated system demonstrates potential applications in developing multistimuli-responsive sensors.