Designed for Circularity: Chemically Recyclable and Enzymatically Degradable Biorenewable Schiff Base Polyester-IminesClick to copy article linkArticle link copied!
- Sathiyaraj SubramaniyanSathiyaraj SubramaniyanDepartment of Fibre and Polymer Technology, KTH Royal Institute of Technology, Teknikringen 58, 100 44 Stockholm, SwedenWallenberg Wood Science Center (WWSC), KTH Royal Institute of Technology, Teknikringen 58, 100 44 Stockholm, SwedenMore by Sathiyaraj Subramaniyan
- Nasim NajjarzadehNasim NajjarzadehDepartment of Fibre and Polymer Technology, KTH Royal Institute of Technology, Teknikringen 58, 100 44 Stockholm, SwedenWallenberg Wood Science Center (WWSC), KTH Royal Institute of Technology, Teknikringen 58, 100 44 Stockholm, SwedenBiotechnology and Health, Science for Life Laboratory, KTH Royal Institute of Technology, Teknikringen 58, 100 44 Stockholm, SwedenMore by Nasim Najjarzadeh
- Sudarsana Reddy VangaSudarsana Reddy VangaBiotechnology and Health, Science for Life Laboratory, KTH Royal Institute of Technology, Teknikringen 58, 100 44 Stockholm, SwedenMore by Sudarsana Reddy Vanga
- Anna LiguoriAnna LiguoriDepartment of Fibre and Polymer Technology, KTH Royal Institute of Technology, Teknikringen 58, 100 44 Stockholm, SwedenMore by Anna Liguori
- Per-Olof SyrénPer-Olof SyrénDepartment of Fibre and Polymer Technology, KTH Royal Institute of Technology, Teknikringen 58, 100 44 Stockholm, SwedenWallenberg Wood Science Center (WWSC), KTH Royal Institute of Technology, Teknikringen 58, 100 44 Stockholm, SwedenBiotechnology and Health, Science for Life Laboratory, KTH Royal Institute of Technology, Teknikringen 58, 100 44 Stockholm, SwedenMore by Per-Olof Syrén
- Minna Hakkarainen*Minna Hakkarainen*Email: [email protected]Department of Fibre and Polymer Technology, KTH Royal Institute of Technology, Teknikringen 58, 100 44 Stockholm, SwedenWallenberg Wood Science Center (WWSC), KTH Royal Institute of Technology, Teknikringen 58, 100 44 Stockholm, SwedenMore by Minna Hakkarainen
Abstract
Bio-based plastics potentially have several positive impacts on the environment; however, in order to make a real difference, they need to have managed and sustainable end of life. This means they should from the start be designed for chemical, mechanical, and/or organic (biological) recycling. Development of energy-efficient and selective chemical recycling processes is a necessary part in reaching truly circular plastic flows. Polyesters are generally well suited for chemical recycling due to the presence of reversible ester bonds. Utilization of dynamic covalent chemistry to include a second, even more easily reversed bond, such as Schiff base (SB, imine bond), could further facilitate chemical recycling, enabling depolymerization back to monomeric products under mild conditions. Here, we present the synthesis of three vanillin-derived SB monomers SBM1, SBM2, and SBM3 and the corresponding polymers SBP3a–b, SBP4a–b, and SBP5a–b. Three different diamines and two potentially bio-sourced diesters were utilized to yield altogether six different polyester-imines with different aliphatic/aromatic contents. All the obtained SB-based polyesters were thermally stable at ∼290–330 °C and had a high char yield during the pyrolysis, which may indicate inherent flame resistance. All the polyesters were amorphous with glass transition temperatures from 36 to 76 °C. The chemical recyclability and hydrolytic degradation of the synthesized polyesters was evaluated by using real-time 1H NMR spectroscopy. Finally, the susceptibility of the synthesized polyester-imines to enzymatic degradation by PETase was demonstrated. The experimental results were further supported by induced-fit docking experiments to theoretically evaluate the potential productive binding of the produced polyester-imines and intermediates thereof to the active site of PETase.
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License Summary*
You are free to share(copy and redistribute) this article in any medium or format and to adapt(remix, transform, and build upon) the material for any purpose, even commercially within the parameters below:
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Attribution (BY): Credit must be given to the creator.
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Synopsis
Biobased polyester-imines exhibiting enzymatic degradability and closed-loop chemical recyclability under mild conditions provide a step toward circular bioeconomy.
Introduction
Experimental Section
Materials
Analytical Methods
Nuclear Magnetic Resonance Spectroscopy
Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy
Size Exclusion Chromatography
Thermogravimetric Analysis
Differential Scanning Calorimetry
Synthesis
Synthesis of 4-(2-Hydroxyethoxy)-2-methoxybenzaldehyde (1)
General Procedure for Synthesis of Schiff Base Monomers (SBM1–3)
Monomer SBM1
Monomer SBM2
Monomer SBM3
General Procedure for Synthesis of Schiff Base Polymers (SBP1a–b to SBP3a–b)
Polyester SBP3a
Polyester SBP3b
Polyester SBP4a
Polyester SBP4b
Polyester SBP5a
Polyester SBP5b
General Procedure for the Chemical Recyclability Studies
Recycled Product RP1
Recycled Product RP2
Mapping Chemical Recycling Process by Real-Time 1H NMR (66)
Enzymatic Degradation
Enzyme Production and Purification
Enzymatic Degradation of the Schiff Base Polymers
Molecular Docking
Results and Discussion
Synthesis of Monomers and Polyesters
Figure 1
Figure 1. 1H NMR (400.13 MHz, DMSO-d6) spectra of (A) monomer SBM2 (4) and (B,C) its corresponding polymers SBP4a–b, received after reaction with DMS and DMT, respectively.
Figure 2
Figure 2. 13C NMR (100.61 MHz, DMSO-d6) spectra of (A) monomer SBM2 (4) and (B,C) its corresponding polymers SBP4a–b formed after reaction with DMS and DMT, respectively.
Scheme 1
aFirst, the synthesis of SB diol monomers SBM1–SBM3 (3–5) starting by reaction between modified vanillin [4-(2-hydroxyethoxy)-2-methoxybenzaldehyde] and EDA (2a), BDA (2b) or m-xylylenediamine (XylDA, 2c), respectively, followed by polymerizations of the diol monomers with aliphatic or aromatic diester, DMS (6a) and DMT (6b), respectively, yielding polyesters (SBP3a–b and SBP5a–b) with different aliphatic/aromatic contents.
samples | Mn (kg mol–1) | Mw (kg mol–1) | Đ | Tg (°C) | T5 (°C) | Td (°C) | CY (%) |
---|---|---|---|---|---|---|---|
SBP3a | 13.6 | 29.7 | 2.18 | 51 | 296 | 316, 374 | 34.2 |
SBP3b | 7.8 | 18.3 | 2.34 | 66 | 300 | 309, 350 | 35.3 |
SBM1 (3) | 287 | 307, 375 | 29.0 | ||||
SBP4a | 19.7 | 47.0 | 2.38 | 36 | 289 | 283, 399 | 32.1 |
SBP4b | 10.6 | 18.0 | 1.69 | 57 | 315 | 278, 390 | 33.6 |
SBM2 (4) | 275 | 297, 357 | 31.7 | ||||
SBP5a | 6.8 | 9.3 | 1.21 | 58 | 318 | 330, 390 | 40.1 |
SBP5b | 6.5 | 9.4 | 1.44 | 78 | 330 | 340, 457 | 43.7 |
SBM3 (5) | 307 | 321, 402 | 41.4 |
Mn, Mw, and Đ were measured by SEC in DMSO. Tg values were obtained from the second heating scan of DSC analysis. T5 (temperature for 5% mass loss) and Td (temperature for the maximal decomposition rate) were obtained from TGA analysis.
Thermal Properties of the Schiff Base-Based Polyesters
Figure 3
Figure 3. TGA curves showing the weight loss (A,C,E) and first derivative weight loss curves (B,D,F) of monomers SBM1 (3), SBM2 (4), and SBM3 (5) and polyesters SBP3a–b, SBP4a–b, and SBP5a–b.
Figure 4
Figure 4. DSC thermograms from the second heating of polyesters SBP3a–b, SBP4a–b, and SBP5a–b.
Chemical Recyclability of the Synthesized Polyesters
Figure 5
Figure 5. 1H (400.13 MHz, DMSO-d6) and 13C NMR (100.61 MHz, DMSO-d6) spectra of the recycled products RP1 (A,C) and RP2 (B,D) respectively.
Figure 6
Figure 6. Real-time 1H NMR spectra of (A) original SBP4a and (B) SBP4a after 30 min in acidic solution. (C) SBP4a after 24 h in acidic solution illustrating the chemical recycling of polyester SBP4a in 0.1 M HCl solution (methanol-d4 and water = 8:2 ratio v/v) at room temperature during 24 h. Reference spectra for (D) BDA and (E) recycled dialdehyde product (RP1).
First Evaluation of Susceptibility to Enzymatic Degradation of SB Polyesters
Figure 7
Figure 7. (A) Chemical structures and molecular weights of the expected aldehydes formed from SBP3a, SBP4a, and SBP5b by opening of the imine bonds and hydrolysis of ester bonds. The degradation products DP1 and DP2 formed by opening of the imine bond have same chemical structure than the recycled products RP1 and RP2. Comparative analysis of (B) degradation product DP3 released from all three polymers and (C) degradation product DP4 released from SBP3a and SBP4a and DP5 released from SBP5b after 1 and 24 h with or without (control) enzymes.
Figure 8
Figure 8. Binding mode of the degradation products, DP1 (panel A; green) and DP4 (panel B; blue), are shown. Key residues are represented in cyan color lines.
Figure 9
Figure 9. Binding mode of polymers SBP3a (panel A,D; magenta), SBP4a (panel B,E; yellow), and SBP5b (panel C,F; orange) obtained in the induced-fit docking calculations of PETase (PDB ID: 6EQE) in poses A and B, respectively. Key residues are represented in cyan color lines.
Conclusions
Supporting Information
The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acssuschemeng.2c06935.
1D and 2D NMR and FT-IR spectra of monomers [SBM1 (3), SBM2 (4), and SBM3 (5)] and their corresponding polymers (SBP3a–b and SBP5a–b), the recycled products (RP1 and RP2), real-time 1H NMR spectra of SBP4a, SBP4b and SBP5b, SDS-PAGE of purified PETase after expression in E. coli, LC–MS calibration curve of DP3, and a table presenting the total number of binding poses obtained in each category (PDF)
Terms & Conditions
Most electronic Supporting Information files are available without a subscription to ACS Web Editions. Such files may be downloaded by article for research use (if there is a public use license linked to the relevant article, that license may permit other uses). Permission may be obtained from ACS for other uses through requests via the RightsLink permission system: http://pubs.acs.org/page/copyright/permissions.html.
Acknowledgments
Authors are grateful for the financial support from the Wallenberg Wood Science Center (WWSC) financed by the Knut and Alice Wallenberg Foundation. Authors also acknowledge the financial support from the Kamprad Family Foundation (grant no. 20200076) and the Novo Nordisk Foundation (grant no. NNF20OC0064972). We thank Luyao Zhao for helping with the SDS-page gel.
References
This article references 80 other publications.
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- 4Welsby, D.; Price, J.; Pye, S.; Ekins, P. Unextractable Fossil Fuels in a 1.5 °C World. Nature 2021, 597, 230– 234, DOI: 10.1038/s41586-021-03821-8Google Scholar4https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhvFyntrzI&md5=d0514d16c17af6f4fe9e0a792d08c559Unextractable fossil fuels in a 1.5°C worldWelsby, Dan; Price, James; Pye, Steve; Ekins, PaulNature (London, United Kingdom) (2021), 597 (7875), 230-234CODEN: NATUAS; ISSN:0028-0836. (Nature Portfolio)Parties to the 2015 Paris Agreement pledged to limit global warming to well below 2° and to pursue efforts to limit the temp. increase to 1.5° relative to pre-industrial times. However, fossil fuels continue to dominate the global energy system and a sharp decline in their use must be realized to keep the temp. increase below 1.5°. Here we use a global energy systems model to assess the amt. of fossil fuels that would need to be left in the ground, regionally and globally, to allow for a 50 per cent probability of limiting warming to 1.5°. By 2050, we find that nearly 60 per cent of oil and fossil methane gas, and 90 per cent of coal must remain unextd. to keep within a 1.5° carbon budget. This is a large increase in the unextractable ests. for a 2° carbon budget, particularly for oil, for which an addnl. 25 per cent of reserves must remain unextd. Furthermore, we est. that oil and gas prodn. must decline globally by 3 per cent each year until 2050. This implies that most regions must reach peak prodn. now or during the next decade, rendering many operational and planned fossil fuel projects unviable. We probably present an underestimate of the prodn. changes required, because a greater than 50 per cent probability of limiting warming to 1.5° requires more carbon to stay in the ground and because of uncertainties around the timely deployment of neg. emission technologies at scale.
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- 6Zhu, Y.; Romain, C.; Williams, C. K. Sustainable Polymers from Renewable Resources. Nature 2016, 540, 354– 362, DOI: 10.1038/nature21001Google Scholar6https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XitVyru7%252FP&md5=1a3419dd9b1a7e1643b4671cdf42553fSustainable polymers from renewable resourcesZhu, Yunqing; Romain, Charles; Williams, Charlotte K.Nature (London, United Kingdom) (2016), 540 (7633), 354-362CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)Renewable resources are used increasingly in the prodn. of polymers. In particular, monomers such as carbon dioxide, terpenes, vegetable oils and carbohydrates can be used as feedstocks for the manuf. of a variety of sustainable materials and products, including elastomers, plastics, hydrogels, flexible electronics, resins, engineering polymers and composites. Efficient catalysis is required to produce monomers, to facilitate selective polymns. and to enable recycling or upcycling of waste materials. There are opportunities to use such sustainable polymers in both high-value areas and in basic applications such as packaging. Life-cycle assessment can be used to quantify the environmental benefits of sustainable polymers.
- 7Gregory, G. L.; Williams, C. K. Exploiting Sodium Coordination in Alternating Monomer Sequences to Toughen Degradable Block Polyester Thermoplastic Elastomers. Macromolecules 2022, 55, 2290– 2299, DOI: 10.1021/acs.macromol.2c00068Google Scholar7https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XlsVKrt78%253D&md5=6e9185e9e7b97342b86aae50a7465aafExploiting Sodium Coordination in Alternating Monomer Sequences to Toughen Degradable Block Polyester Thermoplastic ElastomersGregory, Georgina L.; Williams, Charlotte K.Macromolecules (Washington, DC, United States) (2022), 55 (6), 2290-2299CODEN: MAMOBX; ISSN:0024-9297. (American Chemical Society)Thermoplastic elastomers (TPEs) that are closed-loop recyclable are needed in a circular material economy, but many current materials degrade during recycling, and almost all are pervasive hydrocarbons. Here, well-controlled block polyester TPEs featuring regularly placed sodium/lithium carboxylate side chains are described. They show significantly higher tensile strengths than unfunctionalized analogs, with high elasticity and elastic recovery. The materials are prepd. using controlled polymns., exploiting a single catalyst that switches between different polymn. cycles. ABA block polyesters of high molar mass (60-100 kg mol-1; 21 wt. % A-block) are constructed using the ring-opening polymn. of ε-decalactone (derived from castor oil; B-block), followed by the alternating ring-opening copolymn. of phthalic anhydride with 4-vinyl-cyclohexene oxide (A-blocks). The polyesters undergo efficient functionalization to install regularly placed carboxylic acids onto the A blocks. Reacting the polymers with sodium or lithium hydroxide controls the extent of ionization (0-100%); ionized polymers show a higher tensile strength (20 MPa), elasticity (>2000%), and elastic recovery (>80%). In one case, sodium functionalization results in 35x higher stress at break than the carboxylic acid polymer; in all cases, changing the quantity of sodium tunes the properties. A leading sample, 2-COONa75 (Mn 100 kg mol-1, 75% sodium), shows a wide operating temp. range (-52 to 129°C) and is recycled (x3) by hot-pressing at 200°C, without the loss of mech. properties. Both the efficient synthesis of ABA block polymers and precision ionization in perfectly alternating monomer sequences are concepts that can be generalized to many other monomers, functional groups, and metals. These materials are partly bioderived and have degradable ester backbone chemistries, deliver useful properties, and allow for thermal reprocessing; these features are attractive as future sustainable TPEs.
- 8Tu, Y. M.; Wang, X. M.; Yang, X.; Fan, H. Z.; Gong, F. L.; Cai, Z.; Zhu, J. B. Biobased High-Performance Aromatic-Aliphatic Polyesters with Complete Recyclability. J. Am. Chem. Soc. 2021, 143, 20591– 20597, DOI: 10.1021/jacs.1c10162Google Scholar8https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXis1Wns7rJ&md5=16e514059bbbbf791092cb5d52d86ff2Biobased High-Performance Aromatic-Aliphatic Polyesters with Complete RecyclabilityTu, Yi-Min; Wang, Xue-Mei; Yang, Xing; Fan, Hua-Zhong; Gong, Fu-Long; Cai, Zhongzheng; Zhu, Jian-BoJournal of the American Chemical Society (2021), 143 (49), 20591-20597CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)The development of high-performance recyclable polymers represents a circular plastics economy to address the urgent issues of plastic sustainability. Herein, we design a series of biobased seven-membered-ring esters contg. arom. and aliph. moieties. Ring-opening polymn. studies showed that they readily polymerize with excellent activity (TOF up to 2.1 × 105 h-1) at room temp. and produce polymers with high mol. wt. (Mn up to 438 kg/mol). The variety of functionalities allows us to investigate the substitution effect on polymerizability/recyclability of monomers and properties of polymers (such as Tgs from -1 to 79°C). Remarkably, a stereocomplexed P(M2) exhibited significantly increased Tm and crystn. rate. More importantly, product P(M)s were capable of depolymg. into their monomers in soln. or bulk with high efficiency, thus establishing their circular life cycle.
- 9Vilela, C.; Sousa, A. F.; Fonseca, A. C.; Serra, A. C.; Coelho, J. F. J.; Freire, C. S. R.; Silvestre, A. N. D. The Quest for Sustainable Polyesters-Insights into the Future. Polym. Chem. 2014, 5, 3119– 3141, DOI: 10.1039/C3PY01213AGoogle Scholar9https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXlt1Siur4%253D&md5=1bf365b5d2bfe29b6080f6f5b421b30eThe quest for sustainable polyesters - insights into the futureVilela, Carla; Sousa, Andreia F.; Fonseca, Ana C.; Serra, Armenio C.; Coelho, Jorge F. J.; Freire, Carmen S. R.; Silvestre, Armando J. D.Polymer Chemistry (2014), 5 (9), 3119-3141CODEN: PCOHC2; ISSN:1759-9962. (Royal Society of Chemistry)A review. Polyesters from renewable resources are an expanding area with a burgeoning scientific activity, nevertheless little has been reviewed about this particular class of polymers. The present appraisal intends to contribute to fill this literature gap by reviewing recent aspects related to the most promising renewable-based polyesters. Emphasis will be placed on bio-based polyesters that, given their comparable properties, may replace polymers derived from fossil fuel feedstock, and on bio-based polyesters with completely innovative properties for novel applications. Furthermore, the sources of renewable monomers will also be reviewed, together with the most relevant eco-friendly synthetic approaches used in polycondensation reactions leading to polyesters.
- 10Boyer, C.; Liu, J.; Wong, J.; Tippett, M.; Bulmus, V.; Davis, T. P. Stability and Utility of Pyridyl Disulfide Functionality in RAFT and Conventional Radical Polymerizations. J. Polym. Sci., Part A: Polym. Chem. 2008, 46, 7207– 7224, DOI: 10.1002/pola.23028Google Scholar10https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXhsVSnur%252FE&md5=80410dd2e4377c98e90a92ad07cfeec0Stability and utility of pyridyl disulfide functionality in RAFT and conventional radical polymerizationsBoyer, Cyrille; Liu, Jingquan; Wong, Lingjiun; Tippett, Michael; Bulmus, Volga; Davis, Thomas P.Journal of Polymer Science, Part A: Polymer Chemistry (2008), 46 (21), 7207-7224CODEN: JPACEC; ISSN:0887-624X. (John Wiley & Sons, Inc.)Two RAFT (reversible addn. fragmentation chain transfer) agents, suitable for inducing living radical polymn. in water, have been synthesized. Both RAFT agents were shown to be effective over the temp. range 25°-70°. One RAFT agent was functionalized with a pyridyl disulfide group. RAFT efficacy was demonstrated for the polymns. of N-iso-Pr acrylamide (NIPAAM) and poly(ethylene oxide)-acrylate (PEG-A) in both water and acetonitrile. The kinetic data indicates that the pyridyl disulfide functionality is largely benign in free radical polymns., remaining intact for subsequent reaction with thiol groups. This result was confirmed by studying conventional radical polymns. in the presence of hydroxyethyl pyridyl disulfide. The utility of the pyridyl disulfide functionality at the terminus of the polymers was demonstrated by synthesizing polymer-BSA (bovine serum albumin) conjugates.
- 11Vecchiato, S.; Ahrens, J.; Pellis, A.; Scaini, D.; Mueller, B.; Herrero Acero, E.; Guebitz, G. M. Enzymatic Functionalization of HMLS-Polyethylene Terephthalate Fabrics Improves the Adhesion to Rubber. ACS Sustainable Chem. Eng. 2017, 5, 6456– 6465, DOI: 10.1021/acssuschemeng.7b00475Google Scholar11https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtVCktr7J&md5=cd51f0455e009600c70a03fc6ff1f859Enzymatic Functionalization of HMLS-Polyethylene Terephthalate Fabrics Improves the Adhesion to RubberVecchiato, Sara; Ahrens, Jennifer; Pellis, Alessandro; Scaini, Denis; Mueller, Bernhard; Herrero Acero, Enrique; Guebitz, Georg M.ACS Sustainable Chemistry & Engineering (2017), 5 (8), 6456-6465CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)Among synthetic thermoplastic fiber materials for reinforcement, high modulus and low shrinkage poly(ethylene terephthalate) (HMLS-PET) became the major carcass material for the low to medium-end tire segment. Usually cords are coated with a resorcinol-formaldehyde latex (RFL) dip to achieve acceptable power transmission. However, the low concn. of polar groups on the PET's surface requires an addnl. activation with costly and potentially toxic chems. to create addnl. nucleophilic groups prior to RFL dipping. Here, a green enzyme based alternative to chem. HMLS-PET activation was investigated. Four different cutinase variants from Thermobifida cellulosilytica were shown to hydrolyze HMLS-PET-cords creating new carboxylic and hydroxyl groups with distinct exoendo wise selectivity. The highest degree of enzymic functionalization reached a concn. of 0.51 nmol mm-2 of COOH with a release of 1.35 mM of sol. products after 72 h. The chem. treatment with 1 M NaOH released more sol. products leading up to a 10% decrease of the tensile strength while the functionalization degree achieved was only 0.21 nmol mm-2. This clearly indicates a more endowise mode of hydrolysis for the enzymic treatment when compared to chem. hydrolysis. SEM of the fibers confirmed the aggressiveness of the chem. treatment, whereas the enzymic approach only led to 0.7% solubilization of the polymer with no loss of mech. properties and crystallinity changes. The newly created groups were chem. accessible and reactive in the dipping step and lead after the vulcanization to a significant improvement of the adhesion between the polymer and a representative carcass rubber-compd. according to the peel tests.
- 12Brown, A. E.; Reinhart, A. K. Polyester Fiber : From Its Invention to Its Present Position. Science 1971, 173, 287– 293, DOI: 10.1126/science.173.3994.287Google Scholar12https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaE3MXlsFakurk%253D&md5=cc942112d6a5a938003d28a772bd0e65Polyester fiber. From its invention to its present positionBrown, Alfred E.; Reinhart, Kenneth A.Science (Washington, DC, United States) (1971), 173 (3994), 287-93CODEN: SCIEAS; ISSN:0036-8075.Developments in polyester fibers since their invention 30 years ago were reviewed with 27 refs. emphasising the polymer chemistry, mol. structure, properties, and end uses.
- 13Mashiur, R. Degradation of Polyester in Medical Applications. In Polyester; Saleh, H. M., Ed.; IntechOpen, 2012; Chapter 5, pp 1– 35.Google ScholarThere is no corresponding record for this reference.
- 14Oblak, P.; Gonzalez-Gutierrez, J.; Zupančič, B.; Aulova, A.; Emri, I. Processability and Mechanical Properties of Extensively Recycled High Density Polyethylene. Polym. Degrad. Stab. 2015, 114, 133– 145, DOI: 10.1016/j.polymdegradstab.2015.01.012Google Scholar14https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhvFCht7k%253D&md5=eb74f4072d3d06f8c8bfe5e5eb59c24fProcessability and mechanical properties of extensively recycled high density polyethyleneOblak, Pavel; Gonzalez-Gutierrez, Joamin; Zupancic, Barbara; Aulova, Alexandra; Emri, IgorPolymer Degradation and Stability (2015), 114 (), 133-145CODEN: PDSTDW; ISSN:0141-3910. (Elsevier Ltd.)In plastics industry it is a common practice to mech. recycle waste material arising from prodn. However, while plastics are mech. recycled, their mech. properties change. These changes may affect material processing conditions and quality of the end products; therefore they need to be quantified. In this study, mech. recycling of high d. polyethylene (HDPE) was simulated by one-hundred (100) consecutive extrusions cycles. During extrusion, processability of virgin HDPE and its recyclates was studied by recording the processing conditions, i.e. melt pressure and extrusion torque, while after prepn. of the recyclates, melt flow index measurements (MFI), small amplitude oscillatory shear tests (rheol. properties), and differential scanning calorimetry measurements (DSC) of thermal properties were performed. Also, mech. properties in solid state were characterized in terms of hardness and modulus measured by nanoindentation, and finally, shear creep compliance was measured to characterize the materials' time-dependent mech. properties and its durability in solid state. In addn., gel permeation chromatog. (GPC) and soly. tests were implemented to study changes in the material structure. The results on rheol. and MFI measurements indicate significant structural changes in the material that occurred during the first 30 extrusion cycles. Those changes affect material processability which is as well supported by the recorded processing pressure and torque. On the other hand, processing did not significantly affect material thermal properties. Results on hardness and modulus show deterioration of the material mech. properties after 10th reprocessing cycle. Similarly, shear creep compliance measurements showed an unfavorable effect of mech. recycling on the time-dependent mech. properties, particularly after the 30th extrusion cycle. In addn., results suggested chain branching as a dominating mechanism through first 30 extrusion cycles, domination of chain scission afterwards and also presence of crosslinking after 60th extrusion cycle.
- 15Rosenboom, J. G.; Langer, R.; Traverso, G. Bioplastics for a Circular Economy. Nat. Rev. Mater. 2022, 7, 117– 137, DOI: 10.1038/s41578-021-00407-8Google Scholar15https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BB2M7islGhtg%253D%253D&md5=7fa8c602781b3396112169c4bc4ca9a2Bioplastics for a circular economyRosenboom Jan-Georg; Langer Robert; Rosenboom Jan-Georg; Langer Robert; Traverso Giovanni; Rosenboom Jan-Georg; Traverso Giovanni; Traverso GiovanniNature reviews. Materials (2022), 7 (2), 117-137 ISSN:2058-8437.Bioplastics - typically plastics manufactured from bio-based polymers - stand to contribute to more sustainable commercial plastic life cycles as part of a circular economy, in which virgin polymers are made from renewable or recycled raw materials. Carbon-neutral energy is used for production and products are reused or recycled at their end of life (EOL). In this Review, we assess the advantages and challenges of bioplastics in transitioning towards a circular economy. Compared with fossil-based plastics, bio-based plastics can have a lower carbon footprint and exhibit advantageous materials properties; moreover, they can be compatible with existing recycling streams and some offer biodegradation as an EOL scenario if performed in controlled or predictable environments. However, these benefits can have trade-offs, including negative agricultural impacts, competition with food production, unclear EOL management and higher costs. Emerging chemical and biological methods can enable the 'upcycling' of increasing volumes of heterogeneous plastic and bioplastic waste into higher-quality materials. To guide converters and consumers in their purchasing choices, existing (bio)plastic identification standards and life cycle assessment guidelines need revision and homogenization. Furthermore, clear regulation and financial incentives remain essential to scale from niche polymers to large-scale bioplastic market applications with truly sustainable impact.
- 16Geyer, R.; Jambeck, J. R.; Law, K. L. Production , Use , and Fate of All Plastics Ever Made. Science 2017, 3, 25– 29, DOI: 10.1126/sciadv.1700782Google ScholarThere is no corresponding record for this reference.
- 17Chinthapalli, R.; Skoczinski, P.; Carus, M.; Baltus, W.; de Guzman, D. D.; Käb, H.; Raschka, A.; Ravenstijn, J. Bio-Based Building Blocks and Polymers─Global Capacities and Trends, 2018–2023. Ind. Biotechnol. 2019, 15, 237– 241, DOI: 10.1089/ind.2019.29179.rchGoogle ScholarThere is no corresponding record for this reference.
- 18Kratish, Y.; Marks, T. J. Efficient Polyester Hydrogenolytic Deconstruction via Tandem Catalysis. Angew. Chem., Int. Ed. 2022, 61, e202112576 DOI: 10.1002/anie.202112576Google Scholar18https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXislOns7nL&md5=ca486a806d432b38b18f84aaa628a3baEfficient Polyester Hydrogenolytic Deconstruction via Tandem CatalysisKratish, Yosi; Marks, Tobin J.Angewandte Chemie, International Edition (2022), 61 (9), e202112576CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)Using a mechanism-based solvent-free tandem catalytic approach, commodity polyester plastics such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN) are rapidly and selectively deconstructed by combining the two air- and moisture-stable catalysts, Hf(OTf)4 and Pd/C, under 1 atm H2, affording terephthalic acid (or naphthalene dicarboxylic acid for PEN) and ethane (or butane for PBT) in essentially quant. yield. This process is effective for both lab. grade and waste plastics, and comingled polypropylene remains unchanged. Combined exptl. and DFT mechanistic analyses indicate that Hf(OTf)4 catalyzes a mildly exergonic retro-hydroalkoxylation reaction in which an alkoxy C-O bond is first cleaved, yielding a carboxylic acid and alkene, and this process is closely coupled to an exergonic olefin hydrogenation step, driving the overall reaction forward.
- 19Lange, J. P. Towards Circular Carbo-Chemicals-the Metamorphosis of Petrochemicals. Energy Environ. Sci. 2021, 14, 4358– 4376, DOI: 10.1039/D1EE00532DGoogle Scholar19https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXht1Citb7J&md5=1c7a8c0444c4b95d5b25017ea54d46baTowards circular carbo-chemicals - the metamorphosis of petrochemicalsLange, J.-P.Energy & Environmental Science (2021), 14 (8), 4358-4376CODEN: EESNBY; ISSN:1754-5706. (Royal Society of Chemistry)A review. The petrochem. industry grew to become one of the world's largest industries during the 20th century. It is expected that it will continue to grow, as the world's population gets wealthier, social dynamics change and people demand more affordable and useful materials. The industry recognizes that the Earth's carrying capacity is limited. It is adapting to seek to become a truly sustainable 'carbo'-chem. industry. This paper will address the three main challenges of this transition: shifting hydrocarbon stock, climate change and circular economy. As the energy sector transitions from oil, coal and eventually natural gas, it is expected that the chem. industry will have access to abundant hydrocarbon stocks for which it can find valuable uses. But rising CO2 prices and increasing upgrading costs will likely encourage greater use of alternative, low-carbon feedstocks. In particular, there may be a development of biomass for manufg. oxygenated chem. intermediates and bio-based materials. To help tackle climate change, the industry will need to reduce the CO2 emissions of its processes and utilities (energy sources). Ways to achieve this will include efficiency improvements, electrification of utilities and processes and switching to renewable H2; upgrading byproducts to chems.; and CO2 capture and storage or utilization (CCS/CCU). The issue of plastic waste pollution is combining with the challenges discussed above to push society and governments towards a more circular economy. Customer demand for sustainable products is growing. New regulations (and technologies) are being rolled out for waste collection, sorting and recycling. In addn., the industry is making pledges to produce and use more sustainably. However, it is expected that fresh carbon will still have to enter the material cycle. It will be needed to feed the growth of the chem. industry and to compensate for inevitable recycling losses. For a truly circular industry, this fresh carbon would come from a renewable source, i.e. from atm. CO2, initially via biomass and later possibly from direct CO2 capture and utilization (CCU).
- 20Geyer, R.; Jambeck, J. R.; Law, K. L. Production, Use, and Fate of All Plastics Ever Made. Sci. Adv. 2017, 3, 25– 29, DOI: 10.1126/sciadv.1700782Google ScholarThere is no corresponding record for this reference.
- 21Monsigny, L.; Berthet, J. C.; Cantat, T. Depolymerization of Waste Plastics to Monomers and Chemicals Using a Hydrosilylation Strategy Facilitated by Brookhart’s Iridium(III) Catalyst. ACS Sustainable Chem. Eng. 2018, 6, 10481– 10488, DOI: 10.1021/acssuschemeng.8b01842Google Scholar21https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXht1ejsrvO&md5=83de2d7600445886a6fed591619c08c5Depolymerization of Waste Plastics to Monomers and Chemicals Using a Hydrosilylation Strategy Facilitated by Brookhart's Iridium(III) CatalystMonsigny, Louis; Berthet, Jean-Claude; Cantat, ThibaultACS Sustainable Chemistry & Engineering (2018), 6 (8), 10481-10488CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)Plastic waste management is a major concern. While the societal demand for sustainability is growing, landfilling and incineration of waste plastics remain the norm and methods able to efficiently recycle these materials are desirable. Herein, we report the depolymn., under mild conditions, of oxygenated plastics in the presence of hydrosilanes with the cationic pincer complex [Ir(PCP)H(THF)][B(C6F5)4] (PCP=1,3-(tBu2P)2C6H3) as catalyst. The iridium catalyst, with a low loading (0.3-1 mol%), proves selective toward the formation of silyl ethers or the corresponding alkanes depending only on the reaction temp. The depolymn. of real household waste plastics such as PET (from plastic bottles) and polylactic acid (PLA) from 3D printer filaments is not altered by the presence of dye or other plastic's additives.
- 22Kim, D. H.; Han, D. O.; In Shim, K.; Kim, J. K.; Pelton, J. G.; Ryu, M. H.; Joo, J. C.; Han, J. W.; Kim, H. T.; Kim, K. H. One-Pot Chemo-Bioprocess of PET Depolymerization and Recycling Enabled by a Biocompatible Catalyst, Betaine. ACS Catal. 2021, 11, 3996– 4008, DOI: 10.1021/acscatal.0c04014Google Scholar22https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXmvV2nsL8%253D&md5=b655049ecbf843cdfa9eb03790065e19One-Pot Chemo-bioprocess of PET Depolymerization and Recycling Enabled by a Biocompatible Catalyst, BetaineKim, Dong Hyun; Han, Dong Oh; In Shim, Kyu; Kim, Jae Kyun; Pelton, Jeffrey G.; Ryu, Mi Hee; Joo, Jeong Chan; Han, Jeong Woo; Kim, Hee Taek; Kim, Kyoung HeonACS Catalysis (2021), 11 (7), 3996-4008CODEN: ACCACS; ISSN:2155-5435. (American Chemical Society)Poly(ethylene terephthalate) (PET) has been widely used in various industries due to its unique phys. properties. However, PET causes major environmental problems globally due to its low degradability and recycling rate. Since it is nearly impossible to replace PET with other materials, an efficient approach for PET recycling is necessary for a circular economy. Herein, for a paradigm shift toward the approach for resource recovery of PET components, we developed an integrated process for depolymg. PET and converting PET monomers to high-value products in a one-pot process. The key of our approach is the use of the biocompatible catalyst betaine in a glycolysis process that enables whole PET glycolysis slurry as a substrate to be directly applied to further bioprocesses. Based on the d. functional theory (DFT) anal., betaine effectively catalyzed PET depolymn. by two strong hydrogen interactions between betaine, EG, and PET as well as a synergetic effect by the anion and cation groups of betaine. Through the glycolysis of PET with betaine and the optimized enzymic hydrolytic process for the PET glycolysis slurry, PET was depolymd. to terephthalate (TPA, 31.0 g/L, 62.8%, mol./mol) and ethylene glycol (EG, 11.7 g/L, 63.3%, mol./mol) at a high titer value and high yield. This process was further applied to the bioconversion of TPA and EG present in the PET hydrolyzate to protocatechuic acid (PCA) and glycolic acid (GLA), resp. This one-pot chemo-bioprocess integrating chem. glycolysis, enzymic hydrolysis, and bioconversion for PET depolymn. and recycling was suggested to be highly applicable to the upcycling of waste PET.
- 23Han, X.; Liu, W.; Huang, J. W.; Ma, J.; Zheng, Y.; Ko, T. P.; Xu, L.; Cheng, Y. S.; Chen, C. C.; Guo, R. T. Structural Insight into Catalytic Mechanism of PET Hydrolase. Nat. Commun. 2017, 8, 2106, DOI: 10.1038/s41467-017-02255-zGoogle Scholar23https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC1MzgvFKltw%253D%253D&md5=97def04a6e570a4a7a37cb1941246d73Structural insight into catalytic mechanism of PET hydrolaseHan Xu; Liu Weidong; Ma Jiantao; Zheng Yingying; Chen Chun-Chi; Guo Rey-Ting; Huang Jian-Wen; Xu Limin; Cheng Ya-Shan; Ma Jiantao; Ko Tzu-PingNature communications (2017), 8 (1), 2106 ISSN:.PET hydrolase (PETase), which hydrolyzes polyethylene terephthalate (PET) into soluble building blocks, provides an attractive avenue for the bioconversion of plastics. Here we present the structures of a novel PETase from the PET-consuming microbe Ideonella sakaiensis in complex with substrate and product analogs. Through structural analyses, mutagenesis, and activity measurements, a substrate-binding mode is proposed, and several features critical for catalysis are elucidated.
- 24Wang, Z.; Jin, Y.; Wang, Y.; Tang, Z.; Wang, S.; Xiao, G.; Su, H. Cyanamide as a Highly Efficient Organocatalyst for the Glycolysis Recycling of PET. ACS Sustainable Chem. Eng. 2022, 10, 7965– 7973, DOI: 10.1021/acssuschemeng.2c01235Google Scholar24https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XhsVKgtbjJ&md5=9be27323d8a965d9b676a276119b008dCyanamide as a Highly Efficient Organocatalyst for the Glycolysis Recycling of PETWang, Zishuai; Jin, Yu; Wang, Yaoqiang; Tang, Zequn; Wang, Shaojie; Xiao, Gang; Su, HaijiaACS Sustainable Chemistry & Engineering (2022), 10 (24), 7965-7973CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)Due to the antibiodegradable properties, numerous plastics have been accumulated in the ecosystem and aggravate ecol. pollution. Poly (ethylene terephthalate) (PET) is among the most used plastics. Glycolysis of PET is a useful approach to solve the waste PET pollution and obtain bis(2-hydroxyethyl) terephthalate (BHET). In this paper, waste PET was efficiently depolymd. through glycolysis catalyzed by cyanamide. In particular, compared with the previously reported catalyst, cyanamide is more readily available and can be used directly in catalysis without a complex prepn. process. Under optimal conditions, PET was completely depolymd. with up to nearly 100% BHET yield. Even at a temp. as low as 150°C, a good BHET yield can be obtained. The application potential of this glycolysis procedure was demonstrated by its excellent performance in the glycolysis of various real PET wastes like transparent and opaque PET samples and polyester foam and by the high quality of the obtained BHET products. The mechanism was studied by 1H NMR anal., and DFT calcns. showed that the higher activity of cyanamide than its trimer, melamine, is due to the stronger hydrogen bonds formed between cyanamide and PET or ethylene glycol.
- 25Wei, R.; Tiso, T.; Bertling, J.; O’Connor, K.; Blank, L. M.; Bornscheuer, U. T. Possibilities and Limitations of Biotechnological Plastic Degradation and Recycling. Nat. Catal. 2020, 3, 867– 871, DOI: 10.1038/s41929-020-00521-wGoogle Scholar25https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXit1OrtLzF&md5=20e6b8a93db4a95f037d7318f2aed801Possibilities and limitations of biotechnological plastic degradation and recyclingWei, Ren; Tiso, Till; Bertling, Juergen; O'Connor, Kevin; Blank, Lars M.; Bornscheuer, Uwe T.Nature Catalysis (2020), 3 (11), 867-871CODEN: NCAACP; ISSN:2520-1158. (Nature Research)Considerable research achievements were made to address the plastic crisis using biotechnol., but this is still limited to polyesters. This Comment aims to clarify important aspects related to myths and realities about plastic biodegrdn. and suggests distinct strategies for a bio-based circular plastic economy in the future.
- 26Fernandes, A. C. Reductive Depolymerization of Plastic Waste Catalyzed by Zn(OAc)2 · 2H2O. ChemSusChem 2021, 14, 4228– 4233, DOI: 10.1002/cssc.202100130Google Scholar26https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXmt1eltbg%253D&md5=5835ec60b0d05383ba51b1db20870716Reductive Depolymerization of Plastic Waste Catalyzed by Zn(OAc)2 · 2H2OFernandes, Ana C.ChemSusChem (2021), 14 (19), 4228-4233CODEN: CHEMIZ; ISSN:1864-5631. (Wiley-VCH Verlag GmbH & Co. KGaA)Plastic pollution is one of the biggest problems all over the world. Beyond change/awareness of consumer behavior, there is an urgent need to search for efficient, economical and environmentally friendly catalysts for the valorization of plastic waste to value-added compds. This work describes the reductive depolymn. of several types of plastic waste into value-added compds., including 1,6-hexanediol, 1,2-propanediol, p-xylene and THF, in good yields using the eco-friendly, air-stable, com. available and very cheap catalyst Zn(OAc)2 · 2H2O. This is the first example of the reductive depolymn. of polyester waste catalyzed by a zinc catalyst. Moreover, the catalytic system silane/Zn(OAc)2 · 2H2O was successfully applied to the redn. of polycaprolactone (PCL) on the gram scale with good yield and also to the selective reductive depolymn. of plastic mixts. Finally, this work demonstrated that the catalyst Zn(OAc)2 · 2H2O can be used in at least 7 cycles with good yields.
- 27López-Fonseca, R.; Duque-Ingunza, I.; de Rivas, B. D.; Arnaiz, S.; Gutiérrez-Ortiz, J. I. Chemical Recycling of Post-Consumer PET Wastes by Glycolysis in the Presence of Metal Salts. Polym. Degrad. Stab. 2010, 95, 1022– 1028, DOI: 10.1016/j.polymdegradstab.2010.03.007Google Scholar27https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXlsFCrurg%253D&md5=98706e0420cdf812405847975213be15Chemical recycling of post-consumer PET wastes by glycolysis in the presence of metal saltsLopez-Fonseca, R.; Duque-Ingunza, I.; de Rivas, B.; Arnaiz, S.; Gutierrez-Ortiz, J. I.Polymer Degradation and Stability (2010), 95 (6), 1022-1028CODEN: PDSTDW; ISSN:0141-3910. (Elsevier Ltd.)Chem. recycling of poly(ethylene terephthalate) (PET) has been the subject of increased interest as a valuable feedstock for different chem. processes. In this work, glycolysis of PET waste granules was carried out using excess ethylene glycol in the presence of different simple chems. acting as catalysts, namely zinc acetate, sodium carbonate, sodium bicarbonate, sodium sulfate and potassium sulfate. Comparable high yields (≈70%) of the monomer bis(2-hydroxyethyl terephthalate) were obtained with zinc acetate and sodium carbonate as depolymn. catalysts at 196 °C with a PET:catalyst molar ratio of 100:1 in the presence of a large excess of glycol. The purified monomer was characterized by elemental anal., differential scanning calorimetry, IR spectroscopy, and NMR. The purified monomer was characterized by elemental anal., differential scanning calorimetry, IR spectroscopy, and NMR. Also an exploratory study on the application of this catalytic recycling technol. for complex PET wastes, namely highly colored and multi-layered PET, was performed.
- 28Pham, D. D.; Cho, J. Low-Energy Catalytic Methanolysis of Poly(Ethyleneterephthalate). Green Chem. 2021, 23, 511– 525, DOI: 10.1039/D0GC03536JGoogle Scholar28https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXisFWrt73I&md5=54474c6ca08c40c435cd6ec1474ceadfLow-energy catalytic methanolysis of poly(ethyleneterephthalate)Pham, Duong Dinh; Cho, JoungmoGreen Chemistry (2021), 23 (1), 511-525CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)Methanolysis is a chem. pathway for depolymg. post-consumer PET plastic waste into monomeric feedstock, which can be utilized as a starting component to produce polymer materials with the same quality as the original polymer or other valuable products. In general, conventional methanolysis is carried out at a high reaction temp. under high pressure, demanding high capital and operating costs and in turn leading to an adverse effect on the environment from CO2 emissions. In this study, we developed a low-energy catalytic route for methanolysis to convert PET resin to di-Me terephthalate (DMT). Potassium carbonate (K2CO3), which is an inexpensive and nontoxic salt, was used as a catalyst, and the effects of cosolvents on the catalytic performance were investigated to develop a new decompn. pathway towards DMT at ambient temp. Compared to existing methanolysis processes, the overall reaction rate of the proposed system was relatively slow and steady, but the PET resins were completely decompd. into monomers within 24 h. Intriguingly, a high selectivity of DMT was obtained at a mild temp. range of 20-35°C. The yield of DMT, obtained by methanolysis at 25°C, was 93.1% as the molar ratios of methanol, dichloromethane and K2CO3 to PET repeating units were 50, 50, and 0.2, resp. In this exptl. setup, the initial molar ratio of moisture to PET repeating units was adjusted to be 0.4. 2-Hydroxyethyl Me terephthalate and monomethyl terephthalate were the major byproducts created during the process. It was demonstrated that the ideal conversion of PET into DMT could be achieved by controlling the moisture level. In addn. to several anal. methods for product characterization, we performed a parametric study to probe the most likely reaction steps and to observe the reaction behavior of PET methanolysis. Based on the proposed mechanism, a kinetic model was developed and compared with the exptl. data to est. kinetic parameters. In the reaction system, PET depolymn. apparently proceeded through two series of reaction steps, and the degrdn. of PET had a relatively low activation energy of 66.5 kJ mol-1, which was accountable for catalytic methanolysis of PET at ambient conditions.
- 29Bäckström, E.; Odelius, K.; Hakkarainen, M. Ultrafast Microwave Assisted Recycling of PET to a Family of Functional Precursors and Materials. Eur. Polym. J. 2021, 151, 110441, DOI: 10.1016/j.eurpolymj.2021.110441Google ScholarThere is no corresponding record for this reference.
- 30Fukushima, K.; Lecuyer, J. M.; Wei, D. S.; Horn, H. W.; Jones, G. O.; Al-Megren, H. A.; Alabdulrahman, A. M.; Alsewailem, F. D.; McNeil, M. A.; Rice, J. E.; Hedrick, J. L. Advanced Chemical Recycling of Poly(Ethylene Terephthalate) through Organocatalytic Aminolysis. Polym. Chem. 2013, 4, 1610– 1616, DOI: 10.1039/C2PY20793AGoogle Scholar30https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXit1Wju7o%253D&md5=7fadbc098571fe3762b730a509b07522Advanced chemical recycling of poly(ethylene terephthalate) through organocatalytic aminolysisFukushima, Kazuki; Lecuyer, Julien M.; Wei, Di S.; Horn, Hans W.; Jones, Gavin O.; Al-Megren, Hamid A.; Alabdulrahman, Abdullah M.; Alsewailem, Fares D.; McNeil, Melanie A.; Rice, Julia E.; Hedrick, James L.Polymer Chemistry (2013), 4 (5), 1610-1616CODEN: PCOHC2; ISSN:1759-9962. (Royal Society of Chemistry)We report the effective organocatalysis of the aminolytic depolymn. of waste poly(ethylene terephthalate) (PET) using 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) producing a broad range of cryst. terephthalamides. This diverse set of monomers possesses great potential as building blocks for high performance materials with desirable thermal and mech. properties deriving from the terephthalic moiety and amide hydrogen bonding. Further, a computational study established mechanistic insight into self-catalyzed and organocatalyzed aminolysis of terephthalic esters, suggesting that the bifunctionality of TBD particularly concerning activation of the carbonyl group differentiates TBD from other org. bases.
- 31Fuentes, J. A.; Smith, S. M.; Scharbert, M. T.; Carpenter, I.; Cordes, D. B.; Slawin, A. M. Z.; Clarke, M. L. On the Functional Group Tolerance of Ester Hydrogenation and Polyester Depolymerisation Catalysed by Ruthenium Complexes of Tridentate Aminophosphine Ligands. Chem.─Eur. J. 2015, 21, 10851– 10860, DOI: 10.1002/chem.201500907Google Scholar31https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtVegsbjJ&md5=781ca270445f37645aaf0e9d42c8917aOn the Functional Group Tolerance of Ester Hydrogenation and Polyester Depolymerisation Catalysed by Ruthenium Complexes of Tridentate Aminophosphine LigandsFuentes, Jose A.; Smith, Samuel M.; Scharbert, M. Theresa; Carpenter, Ian; Cordes, David B.; Slawin, Alexandra M. Z.; Clarke, Matthew L.Chemistry - A European Journal (2015), 21 (30), 10851-10860CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)The synthesis of a range of phosphine-diamine, phosphine-amino-alc., and phosphine-amino-amide ligands and their ruthenium(II) complexes are reported. Five of these were characterized by X-ray crystallog. The activities of this collection of catalysts were initially compared for the hydrogenation of two model ester hydrogenations. Catalyst turnover frequencies up to 2400 h-1 were obsd. at 85 °C. However, turnover is slow at near ambient temps. By using a phosphine-diamine RuII complex, identified as the most active catalyst, a range of arom. esters were reduced in high yield. The hydrogenation of alkene-, diene-, and alkyne-functionalized esters was also studied. Substrates with a remote, but reactive terminal alkene substituent could be reduced chemoselectively in the presence of 4-dimethylaminopyridine (DMAP) co-catalyst. The chemoselective redn. of the ester function in conjugated dienoate Et sorbate could deliver (2E,4E)-hexa-2,4-dien-1-ol, a precursor to leaf alc. The monounsatd. alc. (E)-hex-4-en-1-ol was produced with reasonable selectivity, but complete chemoselectivity of C=O over the diene is elusive. High chemoselectivity for the redn. of an ester over an alkyne group was obsd. in the hydrogenation of an alkynoate for the first time. The catalysts were also active in the depolymn. redn. of samples of waste poly(ethylene terephthalate) (PET) to produce benzene dimethanol. These depolymns. were found to be poisoned by the ethylene glycol side product, although good yields could still be achieved.
- 32Westhues, S.; Idel, J.; Klankermayer, J. Molecular Catalyst Systems as Key Enablers for Tailored Polyesters and Polycarbonate Recycling Concepts. Sci. Adv. 2018, 4, eaat9669 DOI: 10.1126/sciadv.aat9669Google ScholarThere is no corresponding record for this reference.
- 33Krall, E. M.; Klein, T. W.; Andersen, R. J.; Reader, D. S.; Dauphinais, B. C.; McIlrath, S. P.; Fischer, A. A.; Carney, M. J.; Robertson, N. J. Controlled Hydrogenative Depolymerization of Polyesters and Polycarbonates Catalyzed by Ruthenium(II) PNN Pincer Complexes. Chem. Commun. 2014, 50, 4884– 4887, DOI: 10.1039/C4CC00541DGoogle Scholar33https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXmtlersbY%253D&md5=ecb8abdb75244ee34f593c4cb7e3cb2bControlled hydrogenative depolymerization of polyesters and polycarbonates catalyzed by ruthenium(II) PNN pincer complexesKrall, Eric M.; Klein, Tyler W.; Andersen, Ryan J.; Nett, Alex J.; Glasgow, Ryley W.; Reader, Diana S.; Dauphinais, Brian C.; McIlrath, Sean P.; Fischer, Anne A.; Carney, Michael J.; Hudson, Dylan J.; Robertson, Nicholas J.Chemical Communications (Cambridge, United Kingdom) (2014), 50 (38), 4884-4887CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)Ruthenium(II) PNN complexes depolymerize many polyesters into diols and polycarbonates into glycols plus methanol via hydrogenation. Notably, polyesters with two methylene units between ester linkages depolymerize to carboxylic acids rather than diols. This methodol. represents a new approach for producing useful chems. from waste plastics.
- 34Nunes, B. F. S.; Oliveira, M. C.; Fernandes, A. C. Dioxomolybdenum Complex as an Efficient and Cheap Catalyst for the Reductive Depolymerization of Plastic Waste into Value-Added Compounds and Fuels. Green Chem. 2020, 22, 2419– 2425, DOI: 10.1039/C9GC04206GGoogle Scholar34https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXkt1OqtLo%253D&md5=fcc5be7ccdd534df86227522931773d3Dioxomolybdenum complex as an efficient and cheap catalyst for the reductive depolymerization of plastic waste into value-added compounds and fuelsNunes, Beatriz F. S.; Oliveira, M. Conceicao; Fernandes, Ana C.Green Chemistry (2020), 22 (8), 2419-2425CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)This work describes the efficient and selective reductive depolymn. of PET, PBT, PCL, PLA and PDO plastic waste into value-added compds. and fuels, including 1,6-hexanediol, xylene and propane, catalyzed by the eco-friendly, cheap and air-stable dioxomolybdenum complex MoO2Cl2(H2O)2 using silanes as reducing agents. The catalyst MoO2Cl2(H2O)2 can be used in at least 8 catalytic cycles in the reductive depolymn. of PCL with excellent activity and the catalytic system PMHS/MoO2Cl2(H2O)2 was successfully applied in the prodn. of propane from the reductive depolymn. of PLA on a gram scale. Moreover, this method was also efficiently applied in the selective redn. of a PCL, PLA and PET mixt.
- 35Jehanno, C.; Demarteau, J.; Mantione, D.; Arno, M. C.; Ruipérez, F.; Hedrick, J. L.; Dove, A. P.; Sardon, H. Selective Chemical Upcycling of Mixed Plastics Guided by a Thermally Stable Organocatalyst. Angew. Chem., Int. Ed. 2021, 60, 6710– 6717, DOI: 10.1002/anie.202014860Google Scholar35https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXjvVCktbc%253D&md5=a3497d9b5ad950e1fd66d835c2277648Selective Chemical Upcycling of Mixed Plastics Guided by a Thermally Stable OrganocatalystJehanno, Coralie; Demarteau, Jeremy; Mantione, Daniele; Arno, Maria C.; Ruiperez, Fernando; Hedrick, James L.; Dove, Andrew P.; Sardon, HaritzAngewandte Chemie, International Edition (2021), 60 (12), 6710-6717CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)Chem. recycling of plastic waste represents a greener alternative to landfill and incineration, and potentially offers a soln. to the environmental consequences of increased plastic waste. Most plastics that are widely used today are designed for durability, hence currently available depolymn. methods typically require harsh conditions and when applied to blended and mixed plastic feeds generate a mixt. of products. Herein, we demonstrate that the energetic differences for the glycolysis of BPA-PC and PET in the presence of a protic ionic salt TBD:MSA catalyst enables the selective and sequential depolymn. of these two commonly employed polymers. Employing the same procedure, functionalized cyclic carbonates can be obtained from both mixed plastic wastes and industrial polymer blend. This methodol. demonstrates that the concept of catalytic depolymn. offers great potential for selective polymer recycling and also presents plastic waste as a "greener" alternative feedstock for the synthesis of high added value mols.
- 36Zhang, X.; Chen, Y.; Ye, M.; Wu, J.; Wang, H. Biodegradable Copolyesters with Unexpected Highly Blocky Microstructures and Enhanced Thermal Properties. ACS Sustainable Chem. Eng. 2022, 10, 4438– 4450, DOI: 10.1021/acssuschemeng.1c07993Google Scholar36https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XosFeqtL0%253D&md5=c598bc4d8ddbec9124e9b8aa94e2079cBiodegradable Copolyesters with Unexpected Highly Blocky Microstructures and Enhanced Thermal PropertiesZhang, Xu; Chen, Yong; Ye, Mengting; Wu, Jing; Wang, HuapingACS Sustainable Chemistry & Engineering (2022), 10 (14), 4438-4450CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)To synthesize novel biodegradable polyesters with high heat resistance and good crystn. capability, we designed a series of aliph.-arom. copolyesters, i.e., poly(isoidide-2,5-dimethylene adipate-co-terephthalate)s (PIATs) based on isoidide-2,5-dimethanol (IIDML), a rigid carbohydrate-based building block. The Mn values and intrinsic viscosities of PIAT copolyesters contg. up to 40 mol % arom. moieties are in the range of 6 000-19 000 g·mol-1 and 0.5-0.87 dL·g-1, resp. Interestingly, the products were obtained as blocky copolymers after the one-pot melt polycondensation process because of the thermodn. equil. of IIDML moieties driven by the insufficient thermal stability of the IIDML moieties. In addn., all the copolyesters are semicryst. with crystallinity from 28% to 55% and tunable Tm values ranging from 88°C to a remarkable 189°C. They exhibit better (bio)degradability than the same type of polyesters. This work shows that this green monomer plays a key role in balancing thermal properties (esp. Tg) and (bio)degradability, and these polyesters potentially broaden the application toward, for example, fibers.
- 37Guo, B.; Vanga, S. R.; Lopez-Lorenzo, X.; Saenz-Mendez, P.; Ericsson, S. R.; Fang, Y.; Ye, X.; Schriever, K.; Bäckström, E.; Biundo, A.; Zubarev, R. A.; Furó, I.; Hakkarainen, M.; Syrén, P. O. Conformational Selection in Biocatalytic Plastic Degradation by PETase. ACS Catal. 2022, 12, 3397– 3409, DOI: 10.1021/acscatal.1c05548Google Scholar37https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XltFehs78%253D&md5=0732543ed139b9fd36a771245bfd3db6Conformational Selection in Biocatalytic Plastic Degradation by PETaseGuo, Boyang; Vanga, Sudarsana Reddy; Lopez-Lorenzo, Ximena; Saenz-Mendez, Patricia; Ericsson, Sara Roennblad; Fang, Yuan; Ye, Xinchen; Schriever, Karen; Baeckstroem, Eva; Biundo, Antonino; Zubarev, Roman A.; Furo, Istvan; Hakkarainen, Minna; Syren, Per-OlofACS Catalysis (2022), 12 (6), 3397-3409CODEN: ACCACS; ISSN:2155-5435. (American Chemical Society)Due to the steric effects imposed by bulky polymers, the formation of catalytically competent enzyme and substrate conformations is crit. in the biodegrdn. of plastics. In poly(ethylene terephthalate) (PET), the backbone adopts different conformations, gauche and trans, coexisting to different extents in amorphous and cryst. regions. However, which conformation is susceptible to biodegrdn. and the extent of enzyme and substrate conformational changes required for expedient catalysis remain poorly understood. To overcome this obstacle, we utilized mol. dynamics simulations, docking, and enzyme engineering in concert with high-resoln. microscopy imaging and solid-state NMR to demonstrate the importance of conformational selection in biocatalytic plastic hydrolysis. Our results demonstrate how single-amino acid substitutions in Ideonella sakaiensis PETase can alter its conformational landscape, significantly affecting the relative abundance of productive ground-state structures ready to bind discrete substrate conformers. We exptl. show how an enzyme binds to plastic and provide a model for key residues involved in the recognition of gauche and trans conformations supported by in silico simulations. We demonstrate how enzyme engineering can be used to create a trans-selective variant, resulting in higher activity when combined with an all-trans PET-derived oligomeric substrate, stemming from both increased accessibility and conformational preference. Our work cements the importance of matching enzyme and substrate conformations in plastic hydrolysis, and we show that also the noncanonical trans conformation in PET is conducive for degrdn. Understanding the contribution of enzyme and substrate conformations to biocatalytic plastic degrdn. could facilitate the generation of designer enzymes with increased performance.
- 38Attallah, O. A.; Janssens, A.; Azeem, M.; Fournet, M. B. Fast, High Monomer Yield from Post-Consumer Polyethylene Terephthalate via Combined Microwave and Deep Eutectic Solvent Hydrolytic Depolymerization. ACS Sustainable Chem. Eng. 2021, 9, 17174– 17185, DOI: 10.1021/acssuschemeng.1c07159Google Scholar38https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXis12ksbrK&md5=4a5a53f30db9d86557236cab1d479963Fast, High Monomer Yield from Post-consumer Polyethylene Terephthalate via Combined Microwave and Deep Eutectic Solvent Hydrolytic DepolymerizationAttallah, Olivia A.; Janssens, Arno; Azeem, Muhammad; Fournet, Margaret BrennanACS Sustainable Chemistry & Engineering (2021), 9 (50), 17174-17185CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)Efficient low carbon foot print methods are crit. to achieving circularity for the dominant post-consumer plastic polyethylene terephthalate (PET). In a strong sustainability advancement over previous technologies, depolymn. of waste PET bottles was performed using a dissoln./degrdn. approach optimized in accordance with polymer mech. parameter inter-relationships. A dual functioning deep eutectic solvent (DES), comprising m-cresol and choline chloride, served as both the solubilizing and catalyzing agent for alk. hydrolysis of PET using high energy efficiency microwave (MW) irradn. The PET depolymn. process was optimized using Box-Behnken design while tailoring the DES vol., concn. of the depolymg. agent (sodium hydroxide), and MW irradn. time as independent variables. The percentage PET wt. loss as high as 84% was obtained using 15 mL of DES contg. 10% (w/v) NaOH under 90 s MW irradn. Simple, cost-effective purifn. steps were afforded by the DES's advantageous physicochem. nature and were implemented to provide the terephthalic acid (TPA) monomer with acceptable yield. Validation of the PET depolymn. and identification of obtained monomers were carried out by a range of characterization techniques including FTIR, NMR, DSC, and HPLC. Post-consumer PET bottle depolymn. was evaluated, and a 91.55% TPA monomer yield ready for repolymn. as virgin PET demonstrates the high potential market application of this low energy, low carbon solvent virgin to virgin approach to PET circularity.
- 39Jönsson, C.; Wei, R.; Biundo, A.; Landberg, J.; Schwarz Bour, L.; Pezzotti, F.; Toca, A.; Jacques, L. M.; Syrén, U. T.; Syrén, P. O. Biocatalysis in the Recycling Landscape for Synthetic Polymers and Plastics towards Circular Textiles. ChemSusChem 2021, 14, 4028– 4040, DOI: 10.1002/cssc.202002666Google Scholar39https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BB3srltlGrtA%253D%253D&md5=445f4ced56426741ce19c03f34a5e3e7Biocatalysis in the Recycling Landscape for Synthetic Polymers and Plastics towards Circular TextilesJonsson Christina; Landberg Johan; Schwarz Bour Lisa; Pezzotti Fabio; Wei Ren; Bornscheuer Uwe T; Biundo Antonino; Syren Per-Olof; Biundo Antonino; Syren Per-Olof; Biundo Antonino; Toca Andreea; Toca Andreea; M Jacques Les; Syren Per-OlofChemSusChem (2021), 14 (19), 4028-4040 ISSN:.Although recovery of fibers from used textiles with retained material quality is desired, separation of individual components from polymer blends used in today's complex textile materials is currently not available at viable scale. Biotechnology could provide a solution to this pressing problem by enabling selective depolymerization of recyclable fibers of natural and synthetic origin, to isolate constituents or even recover monomers. We compiled experimental data for biocatalytic polymer degradation with a focus on synthetic polymers with hydrolysable links and calculated conversion rates to explore this path The analysis emphasizes that we urgently need major research efforts: beyond cellulose-based fibers, biotechnological-assisted depolymerization of plastics so far only works for polyethylene terephthalate, with degradation of a few other relevant synthetic polymer chains being reported. In contrast, by analyzing market data and emerging trends for synthetic fibers in the textile industry, in combination with numbers from used garment collection and sorting plants, it was shown that the use of difficult-to-recycle blended materials is rapidly growing. If the lack of recycling technology and production trend for fiber blends remains, a volume of more than 3400 Mt of waste will have been accumulated by 2030. This work highlights the urgent need to transform the textile industry from a biocatalytic perspective.
- 40Burford, T.; Rieg, W.; Madbouly, S. Biodegradable Poly(Butylene Adipate-Co-Terephthalate) (PBAT). Phys. Sci. Rev. 2021, 000010151520200078, DOI: 10.1515/psr-2020-0078Google ScholarThere is no corresponding record for this reference.
- 41Fu, Y.; Wu, G.; Bian, X.; Zeng, J.; Weng, Y. Biodegradation Behavior of Poly(Butylene Adipate-Co-Terephthalate) (PBAT), Poly(Lactic Acid) (PLA), and Their Blend in Freshwater with Sediment. Molecules 2020, 25, 3946, DOI: 10.3390/molecules25173946Google Scholar41https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhvVeju7nE&md5=f3f72e29a53f45b9b6ae158adeca4728Biodegradation Behavior of Poly(Butylene Adipate-Co-Terephthalate) (PBAT), Poly(Lactic Acid)(PLA), and Their Blend in Freshwater with SedimentFu, Ye; Wu, Gang; Bian, Xinchao; Zeng, Jianbing; Weng, YunxuanMolecules (2020), 25 (17), 3946CODEN: MOLEFW; ISSN:1420-3049. (MDPI AG)Poly(butylene adipate-co-terephthalate) (PBAT) and poly(lactic acid) (PLA) are well-known biodegadable polyesters due to their outstanding performance. The biodegrdn. behavior of PLA/PBAT blends in freshwater with sediment is investigated in this study by analyzing the appearance, chem. structure and aggregation structure of their degraded residues via SEM, TG, DSC, gel permeation chromatog. (GPC) and XPS. The effect of aggregation structure, hydrophilia and biodegrdn. mechanisms of PBAT and PLA on the biodegradability of PLA/PBAT blends is illuminated in this work. After biodegrdn., the butylene terephthalate unit in the mol. structure of the components and the mol. wt. of PLA/PBAT blends decreased, while the content of C-O bond in the composites increased, indicating that the samples indeed degraded. After 24 mo of degrdn., the increase in the relative peak area proportion of C-O to C=O in PLA/PBAT-25, PLA/PBAT-50 and PLA/PBAT-75 was 62%, 46% and 68%, resp. The biodegrdn. rates of PBAT and PLA in the PLA/PBAT blend were lower than those for the resp. single polymers.
- 42Ellingford, C.; Samantaray, P. K.; Farris, S.; McNally, T.; Tan, B.; Sun, Z.; Huang, W.; Ji, Y.; Wan, C. Reactive Extrusion of Biodegradable PGA/PBAT Blends to Enhance Flexibility and Gas Barrier Properties. J. Appl. Polym. Sci. 2022, 139, 51617, DOI: 10.1002/app.51617Google Scholar42https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXitVSjsr%252FM&md5=348d7709591da81309f4745fe175646aReactive extrusion of biodegradable PGA / PBAT blends to enhance flexibility and gas barrier propertiesEllingford, Christopher; Samantaray, Paresh Kumar; Farris, Stefano; McNally, Tony; Tan, Bowen; Sun, Zhaoyang; Huang, Weijie; Ji, Yang; Wan, ChaoyingJournal of Applied Polymer Science (2022), 139 (6), 51617CODEN: JAPNAB; ISSN:0021-8995. (John Wiley & Sons, Inc.)Among com. biodegradable polyesters, poly(glycolic acid) (PGA) has been rarely investigated for packaging applications, despite its unique advantages such as 100% compostability, high degree of crystallinity, high thermal stability and high gas barrier properties. The application of PGA has been limited by its mech. brittleness, moisture sensitivity, and high melting temp. (∼240°C), restricting its processing and applications for film packaging. In this study, PGA was modified by blending with poly (butylene adipate-co-terephthalate) (PBAT) via melt-extrusion. A com. terpolymer of ethylene, acrylic ester and glycidyl methacrylate (EMA-GMA) was selected for compatibilization. The phase morphol., rheol., thermal, mech. and gas barrier properties of the blends were investigated. With addn. of 20 wt. % EMA-GMA, the elongation of PGA/PBAT (50/50 wt. %) blends was improved from 10.7% to 145%, the oxygen permeability was reduced from 125 to 103 (cm3 mm)/(m2 24 h atm), and the water vapor barrier performance was improved by ∼47%. The enhancement in ductility, oxygen and water vapor barrier properties of the flexible blends were ascribed to the interfacial bonding between PBAT and PGA enabled by EMA-GMA. The compatibilized PGA/PBAT blends with high thermal stability up to 300°C are preferable for high temp. or hot food packaging.
- 43Sangroniz, A.; Sangroniz, L.; Gonzalez, A.; Santamaria, A.; del Rio, J.; Iriarte, M.; Etxeberria, A. Improving the Barrier Properties of a Biodegradable Polyester for Packaging Applications. Eur. Polym. J. 2019, 115, 76– 85, DOI: 10.1016/j.eurpolymj.2019.03.026Google Scholar43https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXltFCns7s%253D&md5=e8f1521a697cb54d93764ccbe5a6dfeaImproving the barrier properties of a biodegradable polyester for packaging applicationsSangroniz, Ainara; Sangroniz, Leire; Gonzalez, Alba; Santamaria, Antxon; del Rio, Javier; Iriarte, Marian; Etxeberria, AgustinEuropean Polymer Journal (2019), 115 (), 76-85CODEN: EUPJAG; ISSN:0014-3057. (Elsevier Ltd.)Miscible and thermally stable blends of biodegradable poly(butylene adipate-co-terephthalate) (PBAT) with poly(hydroxy ether of bisphenol A) (PH) are investigated to obtain membranes for packaging applications. Previously the miscibility and adequate degradability of these blends was proven, therefore this system is a good candidate for packaging applications. The crystallinity degree and the free vol., both of crucial importance in transport properties, are analyzed as a function of blend compn. The transport properties to different gases and vapors are greatly reduced with the addn. of PH. The blends show high elongational viscosity values, which allows expecting good film processability. Overall, this work sheds light on the factors involved in the redn. of permeability which would allow to broaden this strategy to other promising biodegradable materials.
- 44Williams, C. K. Synthesis of Functionalized Biodegradable Polyesters. Chem. Soc. Rev. 2007, 36, 1573– 1580, DOI: 10.1039/B614342NGoogle Scholar44https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXpsVKitrc%253D&md5=b6ae103b4746f94b18fab4347eeb2db5Synthesis of functionalized biodegradable polyestersWilliams, Charlotte K.Chemical Society Reviews (2007), 36 (10), 1573-1580CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)This tutorial review summarizes recent developments in the syntheses of functionalized aliph. polyesters. These polymers are attracting attention as sustainable alternatives to petrochems. and for applications in medicine. Two main syntheses are described: step polymn. using mild chemo/enzymic catalysis and ring opening polymn., which is usually initiated by metal complexes. The methods are compared and their utility illustrated with ref. to interesting new materials.
- 45Stamm, A.; Öhlin, J.; Mosbech, C.; Olsén, P.; Guo, B.; Söderberg, E.; Biundo, A.; Fogelström, L.; Bhattacharyya, S.; Bornscheuer, U. T.; Malmström, E.; Syrén, P.-O. Pinene-Based Oxidative Synthetic Toolbox for Scalable Polyester Synthesis. JACS Au 2021, 1, 1949– 1960, DOI: 10.1021/jacsau.1c00312Google Scholar45https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXitFymsbrJ&md5=130a0b64c8f6765d93d8811bc53109b1Pinene-based oxidative synthetic toolbox for scalable polyester synthesisStamm, Arne; Oehlin, Johannes; Mosbech, Caroline; Olsen, Peter; Guo, Boyang; Soederberg, Elisabeth; Biundo, Antonino; Fogelstroem, Linda; Bhattacharyya, Shubhankar; Bornscheuer, Uwe T.; Malmstroem, Eva; Syren, Per-OlofJACS Au (2021), 1 (11), 1949-1960CODEN: JAAUCR; ISSN:2691-3704. (American Chemical Society)Generation of renewable polymers is a long-standing goal toward reaching a more sustainable society . Herein we show how conceptually simple oxidative transformations can be used to unlock the inherent reactivity of terpene synthons in generating polyesters by two different mechanisms starting from the same α-pinene substrate. In the first pathway, α-pinene was oxidized into the bicyclic verbanone based lactone (VaL) and subsequently polymd. into star-shaped polymers via ring-opening polymn., resulting in a biobased semicryst. polyester with tunable glass transition and melting temps. In a second pathway, polyesters were synthesized via polycondensation, utilizing the diol (1-(1'-hydroxyethyl)-3-(2'-hydroxyethyl)-2,2-dimethylcyclobutane (HHDC)) synthesized by oxidative cleavage of the double bond of α-pinene, together with unsatd. biobased diesters such as di-Me maleate (DMM) and di-Me itaconate (DMI), resp. The resulting families of terpene-based polyesters were thereafter successfully crosslinked by either transetherification, utilizing the terminal hydroxyl groups of the synthesized verbanone-based materials, or by UV-irradn., utilizing the unsatn. provided by the DMM or DMI moieties within the HHDC-based copolymers. This work highlights the potential to apply an oxidative toolbox to valorize inert terpene metabolites enabling generation of bio sourced polyesters and coatings thereof by complementary mechanisms.
- 46Meereboer, K. W.; Misra, M.; Mohanty, A. K. Review of Recent Advances in the Biodegradability of Polyhydroxyalkanoate (PHA) Bioplastics and Their Composites. Green Chem. 2020, 22, 5519– 5558, DOI: 10.1039/D0GC01647KGoogle Scholar46https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhs1SgsbnK&md5=3f5a40015aba4e142378bb09928d3b33Review of recent advances in the biodegradability of polyhydroxyalkanoate (PHA) bioplastics and their compositesMeereboer, Kjeld W.; Misra, Manjusri; Mohanty, Amar K.Green Chemistry (2020), 22 (17), 5519-5558CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)A review. The detrimental impact of single-use plastics on the environment is daily news across the globe. Single-use plastic packaging materials and other plastic waste originating from petroleum-based sources are continuously building up in landfills and leaching into the environment. Managing plastic waste remains an urgent crisis in the environment and switching to biodegradable plastics can help mitigate some of these issues. This review will summarize recent advances and opportunities to utilize polyhydroxyalkanoates (PHAs) as a biodegradable substitute in some applications where non-biodegradable and petroleum-based plastics are currently used. PHAs are a well-known family of bacteria-based biodegradable plastics and offer an approach to carbon neutrality and support a more sustainable industry. PHAs such as poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) show biodegradable behavior in all aerobic and anaerobic environments defined by ASTM stds., and can be used to make completely compostable, and soil and marine biodegradable products - a strong pos. compared to the negativity assocd. with the landfilling of plastics. However, PHAs are relatively expensive compared to petroleum-based alternatives. To reduce the cost, PHAs can be used in biocomposite materials, where bio-based agro-residues are incorporated, while maintaining the performance in certain applications. Org. fillers and fibers composed of cellulosic material can improve the properties of polymers, however, their effect on the marine biodegradable properties of the composite matrix remains an unexplored area. When used in biocomposites with PHAs, they improve biodegrdn. rates in all environments. In addn. to cellulose, other bio-based fillers such as proteins (i.e. distillers dried grains with solubles) and starch have been reported to significantly improve soil and marine biodegradability rates compared to other fibers and fillers. Other components that affect biodegradability are additives (i.e. chain extenders) and compatibilizers (i.e. maleic anhydride etc.) that are added to optimize the service life properties, but are reported to inhibit the biodegrdn. properties by impacting the hydrophilicity of the polymer and enzyme activity. The multitude of possible combinations of polymers and fillers and fibers, and their effect on the biodegrdn. of PHA-based biocomposites are a largely unexplored frontier. The potential benefits of PHA-based biocomposites make a strong case for further research into this area.
- 47Vu, D. H.; Åkesson, D.; Taherzadeh, M. J.; Ferreira, J. A. Recycling Strategies for Polyhydroxyalkanoate-Based Waste Materials: An Overview. Bioresour. Technol. 2020, 298, 122393, DOI: 10.1016/j.biortech.2019.122393Google Scholar47https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXit1GmtLvN&md5=f5826a3b78c2953c571cd7b1e0a1a19fRecycling strategies for polyhydroxyalkanoate-based waste materials: An overviewVu, Danh H.; Aakesson, Dan; Taherzadeh, Mohammad J.; Ferreira, Jorge A.Bioresource Technology (2020), 298 (), 122393CODEN: BIRTEB; ISSN:0960-8524. (Elsevier Ltd.)A review. The plastics market is dominated by fossil-based polymers, but their gradual replacement by bioplastics (e.g., polyhydroxyalkanoates) is occurring. However, recycling strategies need to be developed to truly unveil the impact of bioplastics on waste accumulation. This review provides a state of the art of recycling strategies investigated for polyhydroxyalkanoate-based polymers and proposes future research avenues. Research on mech. and chem. recycling is dominated by the use of extrusion and pyrolysis, resp., while that on biodegrdn. of polyhydroxyalkanoates is related to soil and aquatic samples, and to anaerobic digestion towards biogas prodn. Research gaps exist in the relationships between polymer compn. and ease of use of all recycling strategies investigated. This is of utmost importance since it will influence the need for sepn. at the source. Therefore, research emphasis needs to be given to the area to follow the continuous improvement of the process economics towards widespread com. prodn. of polyhydroxyalkanoates.
- 48Muiruri, J. K.; Yeo, J. C. C.; Zhu, Q.; Ye, E.; Loh, X. J.; Li, Z. Poly(Hydroxyalkanoates): Production, Applications and End-of-Life Strategies-Life Cycle Assessment Nexus. ACS Sustainable Chem. Eng. 2022, 10, 3387– 3406, DOI: 10.1021/acssuschemeng.1c08631Google Scholar48https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XmsFeisb8%253D&md5=dc154188d609c228c5291ed5d5f88d1dPoly(hydroxyalkanoates): Production, Applications and End-of-Life Strategies-Life Cycle Assessment NexusMuiruri, Joseph Kinyanjui; Yeo, Jayven Chee Chuan; Zhu, Qiang; Ye, Enyi; Loh, Xian Jun; Li, ZibiaoACS Sustainable Chemistry & Engineering (2022), 10 (11), 3387-3406CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)A review. The runaway prodn. and consumption of oil-based plastics are key drivers of global warming and the increased carbon footprint. Besides, most of this plastic debris ends up in the oceans and constitutes about 80% of all marine debris. This pollution problem calls for a seismic shift to eco-friendly plastics and marine biodegradable ones. Unlike other biobased polymers, polyhydroxyalkanoates (PHAs) take pride in their degrdn. in soil and marine environments. This intriguing marine biodegrdn. property of PHAs sets it apart as the best choice to curb microplastics, particularly in marine ecosystems. PHAs have also grown in popularity due to other quintessential properties such as biocompatibility, structural variety, and similarity to conventional plastics in terms of phys. properties. PHAs are being widely researched for various applications, including packaging, medical, energy, and agriculture. This review comprehensively focuses on the state-of-art prodn. and applications of PHA plastics, as well as the practical recycling strategies for postconsumer PHAs. The innovative 'next generation industrial biotechnol.' (NGIB) is well covered in this review. Moreover, the nexus between end-of-life strategies and life cycle assessment (LCA) of PHAs waste is elucidated to understand its impact on the environment thoroughly.
- 49Hatti-Kaul, R.; Nilsson, L. J.; Zhang, B.; Rehnberg, N.; Lundmark, S. Designing Biobased Recyclable Polymers for Plastics. Trends Biotechnol. 2020, 38, 50– 67, DOI: 10.1016/j.tibtech.2019.04.011Google Scholar49https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXpsVOrsL0%253D&md5=62433dbccdb763f36a131c834b8ec7d8Designing Biobased Recyclable Polymers for PlasticsHatti-Kaul, Rajni; Nilsson, Lars J.; Zhang, Baozhong; Rehnberg, Nicola; Lundmark, StefanTrends in Biotechnology (2020), 38 (1), 50-67CODEN: TRBIDM; ISSN:0167-7799. (Elsevier Ltd.)Several concurrent developments are shaping the future of plastics. A transition to a sustainable plastics system requires not only a shift to fossil-free feedstock and energy to produce the carbon-neutral building blocks for polymers used in plastics, but also a rational design of the polymers with both desired material properties for functionality and features facilitating their recyclability. Biotechnol. has an important role in producing polymer building blocks from renewable feedstocks, and also shows potential for recycling of polymers. Here, we present strategies for improving the performance and recyclability of the polymers, for enhancing degradability to monomers, and for improving chem. recyclability by designing polymers with different chem. functionalities.
- 50Coates, G. W.; Getzler, Y. D. Y. L. Chemical Recycling to Monomer for an Ideal, Circular Polymer Economy. Nat. Rev. Mater. 2020, 5, 501– 516, DOI: 10.1038/s41578-020-0190-4Google Scholar50https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXntVOmt7Y%253D&md5=ce62cb9ab02615ebcde8b8dd674aa252Chemical recycling to monomer for an ideal, circular polymer economyCoates, Geoffrey W.; Getzler, Yutan D. Y. L.Nature Reviews Materials (2020), 5 (7), 501-516CODEN: NRMADL; ISSN:2058-8437. (Nature Research)Abstr.: The majority of post-consumer plastic waste is not recycled. Impediments to the recycling of commodity polymers include sepn., impurities and degrdn. of the macromol. structures, all of which can neg. affect the properties of recycled materials. An attractive alternative is to transform polymers back into monomers and purify them for repolymn. - a form of chem. recycling we term chem. recycling to monomer (CRM). Material recycled in this way exhibits no loss in properties, creating an ideal, circular polymer economy. This Review presents our vision for realizing a circular polymer economy based on CRM. We examine the energetics of polymn. and other challenges in developing practical and scalable CRM processes. We briefly review attempts to achieve CRM with commodity polymers, including through polyolefin thermolysis and nylon 6 ring-closing depolymn., and closely examine the recent flourishing of CRM with new-to-the-world polymers. The benefits of heterocycle ring-opening polymn. are discussed in terms of synthetic control and kinetically accessible polymer-backbone functionality. Common chem. and structural characteristics of CRM-compatible ring-opening-polymn. monomers are identified, and the properties, benefits and liabilities of these recyclable polymers are discussed. We conclude with our perspective on the ideals and opportunities for the field.
- 51Odegard, I.; Nusselder, S.; Roos Lindgreen, E.; Bergsma, G.; de Graaff, L. Biobased Plastics in a Circular Economy Policy─Policy Suggestions for Biobased and Biobased Biodegradable Plastics. 2017, https://cedelft.eu/publications/biobased-plastics-in-a-circular-economy/ (accessed Jan 11, 2023).Google ScholarThere is no corresponding record for this reference.
- 52Carus, M.; Dammer, L. The “Circular Bioeconomy”-Concepts, Opportunities and Limitations. 2018, https://renewable-carbon.eu/publications/product/nova-paper-9-the-circular-bioeconomy-concepts-opportunities-and-limitations-%e2%88%92-full-version/ (accessed Jan 11, 2023).Google ScholarThere is no corresponding record for this reference.
- 53Shevchenko, T.; Ranjbari, M.; Shams Esfandabadi, Z. S.; Danko, Y.; Bliumska-Danko, K. Promising Developments in Bio-Based Products as Alternatives to Conventional Plastics to Enable Circular Economy in Ukraine. Recycling 2022, 7, 20, DOI: 10.3390/recycling7020020Google ScholarThere is no corresponding record for this reference.
- 54Haider, T. P.; Völker, C.; Kramm, J.; Landfester, K.; Wurm, F. R. Plastics of the Future? The Impact of Biodegradable Polymers on the Environment and on Society. Angew. Chem., Int. Ed. 2019, 58, 50– 62, DOI: 10.1002/anie.201805766Google Scholar54https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXitFGgtL3J&md5=0e9547e37a9ce5cccb5cda51b8485a09Plastics of the Future? The Impact of Biodegradable Polymers on the Environment and on SocietyHaider, Tobias P.; Voelker, Carolin; Kramm, Johanna; Landfester, Katharina; Wurm, Frederik R.Angewandte Chemie, International Edition (2019), 58 (1), 50-62CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)A review is given. In recent years the littering of plastics and the problems related to their persistence in the environment have become a major focus in both research and the news. Biodegradable polymers like poly(lactic acid) are seen as a suitable alternative to commodity plastics. However, poly(lactic acid) is basically non-degradable in seawater. Similarly, the degrdn. rate of other biodegradable polymers also crucially depends on the environments they end up in, such as soil or marine water, or when used in biomedical devices. Here, we show that biodegrdn. tests carried out in artificial environments lack transferability to real conditions and, therefore, highlight the necessity of environmentally authentic and relevant field-testing conditions. We focus on ecotoxicol. implications of biodegradable polymers. We also consider the social aspects and ask how biodegradable polymers influence consumer behavior and municipal waste management. Taken together, this study is intended as a contribution towards evaluating the potential of biodegradable polymers as alternative materials to commodity plastics.
- 55Payne, J.; Jones, M. D. The Chemical Recycling of Polyesters for a Circular Plastics Economy: Challenges and Emerging Opportunities. ChemSusChem 2021, 14, 4041– 4070, DOI: 10.1002/cssc.202100400Google Scholar55https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXptlOhtb8%253D&md5=a6ea2563da9dc271278f870e80718bc7The Chemical Recycling of Polyesters for a Circular Plastics Economy: Challenges and Emerging OpportunitiesPayne, Jack; Jones, Matthew D.ChemSusChem (2021), 14 (19), 4041-4070CODEN: CHEMIZ; ISSN:1864-5631. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. While plastics have played an instrumental role in human development, growing environmental concerns have led to increasing public scrutiny and demands for outright bans. This has stimulated considerable research into renewable alternatives, and more recently, the development of alternative waste management strategies. Herein, the aim was to highlight recent developments in the catalytic chem. recycling of two com. polyesters, namely poly(lactic acid) (PLA) and poly(ethylene terephthalate) (PET). The concept of chem. recycling is first introduced, and assocd. opportunities/challenges are discussed within the context of the governing depolymn. thermodn. Chem. recycling methods for PLA and PET are then discussed, with a particular focus on upcycling and the use of metal-based catalysts. Finally, the attention shifts to the emergence of new materials with the potential to modernise the plastics economy. Emerging opportunities and challenges are discussed within the context of industrial feasibility.
- 56Manzuch, Z.; Akelyte, R.; Camboni, M.; Carlander, D. Chemical Recycling of Polymeric Materials from Waste in the Circular Economy. Final Report for the European Chemical Agency; RPA Europe, August 2021; pp 1– 145.Google ScholarThere is no corresponding record for this reference.
- 57Chanda, M. Chemical Aspects of Polymer Recycling. Adv. Ind. Eng. Polym. Res. 2021, 4, 133– 150, DOI: 10.1016/j.aiepr.2021.06.002Google Scholar57https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhvVGlsbfJ&md5=3cfd3b683a6b48af8e9df2bc1ce381a1Chemical aspects of polymer recyclingChanda, ManasAdvanced Industrial and Engineering Polymer Research (2021), 4 (3), 133-150CODEN: AIEPCN; ISSN:2542-5048. (Elsevier B.V.)Since recycling of polymers is a preferred means of reducing unwanted wastes and land-filling activity, and recovering monomers or other materials of economic value, tertiary methods of recycling (chem. recycling) have been critically reviewed, giving special attention, in each case, to the chem. basis of the particular recycling pathway and its potential applicability. Recycling issues of each of the widely used commodity polymers - polyesters, polyamides, polyurethanes, epoxies, poly(vinyl chloride), polystyrene, and polyolefins - have been discussed individually, giving attention to both conventional and unconventional methods of perceived high potential, such as enzymic degrdn., ionic liqs. mediation, microwave irradn., and treatment in super crit. liqs. as well as super fluids. In addn., novel emerging methods undergoing greater study at present, such as cross-alkane metathesis (CAM), tandem hydrogenolysis/aromatization, vitrimer-based recycling, and dynamic covalent bonding are also highlighted.
- 58Zhang, J.; Jia, W.; Yu, X.; Wang, Q.; Sun, Y.; Yang, S.; Li, Z.; Tang, X.; Zeng, X.; Lin, L. Facile One-Pot Synthesis of Furan Double Schiff Base from 5-Hydroxymethylfurfural via an Amination–Oxidation–Amination Strategy in Water. ACS Sustainable Chem. Eng. 2022, 10, 6835– 6842, DOI: 10.1021/acssuschemeng.2c01576Google Scholar58https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38Xht1GgsrbL&md5=8994cbf76dbca27fda7ebb8316efbd68Facile One-Pot Synthesis of Furan Double Schiff Base from 5-Hydroxymethylfurfural via an Amination-Oxidation-Amination Strategy in WaterZhang, Jie; Jia, Wenlong; Yu, Xin; Wang, Qian; Sun, Yong; Yang, Shuliang; Li, Zheng; Tang, Xing; Zeng, Xianhai; Lin, LuACS Sustainable Chemistry & Engineering (2022), 10 (20), 6835-6842CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)Furan double Schiff base (FDSB), a versatile biomass fine-chem. mol., was efficiently synthesized from 5-hydroxymethylfurfural (HMF) through an amination-oxidn.-amination strategy in water. The activated α-MnO2-S-H+ with a higher sp. surface area, more surface lattice oxygen vacancies, and abundant acid/base sites exhibited a high catalytic efficiency. An FDSB yield of 99.3% with 100% conversion of HMF using air-oxygen as the oxidant was achieved within 20 min in water. The oxidn. of the hydroxyl group in HMF to the carbonyl group underwent a Mars-van Krevelen cycle with the synergy of Mn4+ and lattice oxygen.
- 59Upton, B. M.; Kasko, A. M. Biodegradable Aromatic-Aliphatic Poly(Ester-Amides) from Monolignol-Based Ester Dimers. ACS Sustainable Chem. Eng. 2018, 6, 3659– 3668, DOI: 10.1021/acssuschemeng.7b03784Google Scholar59https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXitFSjsrg%253D&md5=0541ef01ce2bb5b344fc9bda286395aaBiodegradable aromatic-aliphatic poly(ester-amides) from monolignol-based ester dimersUpton, Brianna M.; Kasko, Andrea M.ACS Sustainable Chemistry & Engineering (2018), 6 (3), 3659-3668CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)Biobased polymers with tunable properties have received increased attention in the literature due to a decline in petroleum reserves. Owing to its low cost, abundance, and arom. structure, lignin has great potential as a feedstock for value-added polymeric products. In this work, we condensed carboxylic acid precursors with monolignols to generate reactive dimers for polymer synthesis. Three different arom. ester dimers, each corresponding to a different monolignol, were synthesized and characterized. The dicarboxylic acid dimers were converted to the corresponding diacid chloride in situ with thionyl chloride, and a series of poly(ester-amides) were synthesized via interfacial polymn. of these diacid chlorides with seven different aliph. or arom. diamines. The thermal properties (decompn., glass transition temp., and melting temp.) and hydrolytic stability in acidic and neutral aq. conditions of the resulting polymers were studied.
- 60Liguori, A.; Hakkarainen, M. Designed from Biobased Materials for Recycling: Imine-Based Covalent Adaptable Networks. Macromol. Rapid Commun. 2022, 43, 2100816, DOI: 10.1002/marc.202100816Google Scholar60https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XivV2ntLo%253D&md5=7cbad9701b9026e667185217470e40bdDesigned from Biobased Materials for Recycling: Imine-Based Covalent Adaptable NetworksLiguori, Anna; Hakkarainen, MinnaMacromolecular Rapid Communications (2022), 43 (13), 2100816CODEN: MRCOE3; ISSN:1022-1336. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. Turning thermosets into fully sustainable materials requires utilization of biobased raw materials and design for easy recyclability. Here, dynamic covalent chem. for fabrication of covalent adaptable networks (CANs) could be an enabling tool. CAN thermosets ideally combine the pos. material properties of thermosets with thermal recyclability of linear thermoplastics. Among the dynamic covalent bonds, imine bond, also called Schiff base, can participate in both dissociative and associative pathways. This induces potential for chem. recyclability, thermal reprocessability and self-healing. This review presents an overview of the current research front of biobased thermosets fabricated by Schiff base chem. The discussed materials are categorized on the basis of the employed biobased components. The chem. approaches for the synthesis and curing of the resins, as well as the resulting properties and recyclability of the obtained thermosets are described and discussed. Finally, challenges and future perspectives are briefly summarized.
- 61Xu, Y.; Odelius, K.; Hakkarainen, M. Photocurable, Thermally Reprocessable, and Chemically Recyclable Vanillin-Based Imine Thermosets. ACS Sustainable Chem. Eng. 2020, 8, 17272– 17279, DOI: 10.1021/acssuschemeng.0c06248Google Scholar61https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXit1Ogs73O&md5=93b081daf910874b1d97982d415e871cPhotocurable, thermally reprocessable, and chemically recyclable vanillin-based imine ThermosetsXu, Yunsheng; Odelius, Karin; Hakkarainen, MinnaACS Sustainable Chemistry & Engineering (2020), 8 (46), 17272-17279CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)Two vanillin-based photocurable, thermally reprocessable, and chem. recyclable imine thermosets were successfully designed. The vanillin vitrimer resins were synthesized through a protocol with a two-step reaction: methacrylation and imination with diamine or triamine. The obtained vinyl ester resins with imine bonds and vinyl groups could be photocured into thermosets in 10 min at room temp. The cured thermosets had good solvent resistance against common solvents, good thermal stability up to about 250°C as measured by thermogravimetry, and high storage modulus (1.6-3.4 GPa as detd. by dynamic mech. anal.). Owing to the reversibility of the imine bond, both thermosets exhibited typical vitrimer behavior including stress relaxation and thermal reprocessability, while their activation energy for the imine exchange reaction and recovery ratio of tensile stress after reprocessing varied due to different crosslinking densities. Furthermore, both thermosets could be chem. recycled in hexylamine through an imine exchange reaction. The presented new strategy, thus, paves the way for prodn. of fast-curing, chem. and thermally stable, but still thermally reprocessable and chem. recyclable imine vitrimers from abundant biobased building blocks. Rapidly photocurable vanillin resins with double functionality for chem. and thermally stable, thermally reprocessable, and chem. recyclable imine vitrimers.
- 62Lavilla, C.; de Ilarduya, A. M.; Alla, A.; García-Martín, M. G.; Galbis, J. A.; Muñoz-Guerra, S. Bio-Based Aromatic Polyesters from a Novel Bicyclic Diol Derived from d-Mannitol. Macromolecules 2012, 45, 8257– 8266, DOI: 10.1021/ma3013288Google Scholar62https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhsVyks7bN&md5=9feb9fc6831da32598611bc75f00b7bbBio-Based Aromatic Polyesters from a Novel Bicyclic Diol Derived from D-MannitolLavilla, C.; Martinez de Ilarduya, A.; Alla, A.; Garcia-Martin, M. G.; Galbis, J. A.; Munoz-Guerra, S.Macromolecules (Washington, DC, United States) (2012), 45 (20), 8257-8266CODEN: MAMOBX; ISSN:0024-9297. (American Chemical Society)2,4:3,5-Di-O-methylene-D-mannitol, abbreviated as Manx, is a D-mannitol-derived compd. with the secondary hydroxyl groups acetalized with formaldehyde. The bicyclic structure of Manx consists of two fused 1,3-dioxane rings, with two primary hydroxyl groups standing free for reaction. A homopolyester made of Manx and di-Me terephthalate as well as a set of copolyesters of poly(butylene terephthalate) (PBT) in which 1,4-butanediol was replaced by Manx up to 50% were synthesized and characterized. The polyesters had Mw in the 30 000-52 000 g mol-1 range and a random microstructure and were thermally stable up to nearly 370 °C. They displayed outstanding high Tg with values from 55 to 137 °C which steadily increased with the content in Manx. Copolyesters contg. up to 40% of Manx were semicryst. and adopted the crystal structure of PBT. Their stress-strain parameters were sensitively affected by the presence of carbohydrate-based units with elongation at break decreasing but tensile strength and elastic moduli steadily increasing with the degree of replacement.
- 63Anastas, P. T.; Saltzberg, M.; Subramaniam, B. Plastics Are Not Bad. Bad Plastics Are Bad. ACS Sustainable Chem. Eng. 2021, 9, 9150, DOI: 10.1021/acssuschemeng.1c03046Google Scholar63https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhsFSrtr3J&md5=bf4d751da90d81b240d3d69a61fe261cPlastics Are Not Bad. Bad Plastics Are Bad.Anastas, Paul T.; Saltzberg, Michael; Subramaniam, BalaACS Sustainable Chemistry & Engineering (2021), 9 (28), 9150CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)There is no expanded citation for this reference.
- 64Tachibana, Y.; Hayashi, S.; Kasuya, K. I. Biobased Poly(Schiff-Base) Composed of Bifurfural. ACS Omega 2018, 3, 5336– 5345, DOI: 10.1021/acsomega.8b00466Google Scholar64https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXps1GrsLY%253D&md5=2077dc8d99c998ac8f28a0a85d8ff421Biobased Poly(Schiff-Base) Composed of BifurfuralTachibana, Yuya; Hayashi, Senri; Kasuya, Ken-ichiACS Omega (2018), 3 (5), 5336-5345CODEN: ACSODF; ISSN:2470-1343. (American Chemical Society)In this study, bifurfural, an inedible biobased chem. and a second-generation biomass, was polymd. with several diamines using an environmentally benign process, and the chem. structures of the resulting poly(Schiff base)s were analyzed. Because furan rings, which are only produced from biomass and not from fossil resources, endow polymers with unique properties that include high rigidity and expanded π-conjugation, bifurfural, which contains two furan rings, is of significant interest as a biobased building block. 1H NMR, IR, and matrix assisted laser desorption ionization-time of flight mass spectra of the poly(Schiff base)s reveal that they are composed of mixts. of linear and cyclic structures. The UV-vis spectroscopy and MO theory confirm the extended π-conjugation in the bifurfural/p-phenylenediamine poly(Schiff base) system. Poly(Schiff base)s composed of bifurfural and 1,3-propanediamine, 1,4-butandiamine, 1,5-pentanediamine, and 1,6-hexanediamine were molded at 120 °C into films that exhibited good strengths and were tough to bend. Bifurfural-based poly(Schiff base)s are promising biobased materials.
- 65Li, X.; Wang, X.; Subramaniyan, S.; Liu, Y.; Rao, J.; Zhang, B. Hyperbranched Polyesters Based on Indole- and Lignin-Derived Monomeric Aromatic Aldehydes as Effective Nonionic Antimicrobial Coatings with Excellent Biocompatibility. Biomacromolecules 2022, 23, 150– 162, DOI: 10.1021/acs.biomac.1c01186Google Scholar65https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXislyhtrrK&md5=6f31ca2bebde2b874217dfef3f63a567Hyperbranched Polyesters Based on Indole- and Lignin-Derived Monomeric Aromatic Aldehydes as Effective Nonionic Antimicrobial Coatings with Excellent BiocompatibilityLi, Xiaoya; Wang, Xiao; Subramaniyan, Sathiyaraj; Liu, Yang; Rao, Jingyi; Zhang, BaozhongBiomacromolecules (2022), 23 (1), 150-162CODEN: BOMAF6; ISSN:1525-7797. (American Chemical Society)This research aims to investigate nonionic hyperbranched polyesters (HBPs) derived from indole and lignin resources as new nontoxic antimicrobial coatings. Three nonionic HBPs with zero to two methoxy ether substituents on each benzene ring in the polymer backbones were synthesized by melt-polycondensation of three corresponding AB2 monomers. The mol. structures and thermal properties of the obtained HBPs were characterized by gel permeation chromatog., NMR spectroscopy, Fourier transform IR spectroscopy, thermogravimetric anal., and differential scanning calorimetry analyses. These HBPs were conveniently spin-coated on a silicon substrate, which exhibited significant antibacterial effect against Gram-neg. (Escherichia coli and Pseudomonas aeruginosa) and Gram-pos. bacteria (Staphylococcus aureus and Enterococcus faecalis). The presence of methoxy substituents enhanced the antimicrobial effect, and the resulting polymers showed negligible leakage in water. Finally, the polymers with the methoxy functionality exhibited excellent biocompatibility according to the results of hemolysis and MTT assay, which may facilitate their biomedical applications.
- 66Wang, S.; Ma, S.; Li, Q.; Xu, X.; Wang, B.; Yuan, W.; Zhou, S.; You, S.; Zhu, J. Facile: In Situ Preparation of High-Performance Epoxy Vitrimer from Renewable Resources and Its Application in Nondestructive Recyclable Carbon Fiber Composite. Green Chem. 2019, 21, 1484– 1497, DOI: 10.1039/C8GC03477JGoogle Scholar66https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXislCmtLk%253D&md5=80de6ab5aceffdbad27600458cb59a42Facile in situ preparation of high-performance epoxy vitrimer from renewable resources and its application in nondestructive recyclable carbon fiber compositeWang, Sheng; Ma, Songqi; Li, Qiong; Xu, Xiwei; Wang, Binbo; Yuan, Wangchao; Zhou, Shenghua; You, Shusen; Zhu, JinGreen Chemistry (2019), 21 (6), 1484-1497CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)Epoxy resins have been widely used in several materials including carbon fiber composites; however, they are arduous to recycle. In this study, for the first time, a Schiff base epoxy thermoset combining excellent recyclability and high performance was facilely prepd. from a synthesized formyl group-contg. vanillin-based monoepoxide and a diamine via in situ formation of the Schiff base structure and epoxy network. The chem. structure of the monoepoxide and its crosslinked network were characterized in detail. In addn., the thermal and mech. properties, recyclability of the thermoset and its application in carbon fiber composite were systematically investigated. The results showed that the thermoset possessed a similar glass transition temp. of 172 °C, a tensile strength of 81 MPa and a modulus of 2112 MPa, and higher thermal stability with the degrdn. temp. for 5% wt. loss of 323 °C and elongation at break of 15% in comparison with a bisphenol A epoxy resin. Moreover, it exhibited superior reprocessing recyclability due to the vitrimer or CAN nature of its Schiff base network. Furthermore, it could also be completely degraded under mild acidic conditions, leading to the quick and nondestructive recycling of its carbon fiber composite.
- 67Austin, H. P.; Allen, M. D.; Donohoe, B. S.; Rorrer, N. A.; Kearns, F. L.; Silveira, R. L.; Pollard, B. C.; Dominick, G.; Duman, R.; El Omari, K. E.; Mykhaylyk, V.; Wagner, A.; Michener, W. E.; Amore, A.; Skaf, M. S.; Crowley, M. F.; Thorne, A. W.; Johnson, C. W.; Woodcock, H.; McGeehan, J. E.; Beckham, G. T. Characterization and Engineering of a Plastic-Degrading Aromatic Polyesterase. Proc. Natl. Acad. Sci. U.S.A. 2018, 115, E4350– E4357, DOI: 10.1073/pnas.1718804115Google Scholar67https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhvVGhtLnF&md5=b8e8d841af1bb06fa2d1fddb6b9d6460Characterization and engineering of a plastic-degrading aromatic polyesteraseAustin, Harry P.; Allen, Mark D.; Donohoe, Bryon S.; Rorrer, Nicholas A.; Kearns, Fiona L.; Silveira, Rodrigo L.; Pollard, Benjamin C.; Dominick, Graham; Duman, Ramona; El Omari, Kamel; Mykhaylyk, Vitaliy; Wagner, Armin; Michener, William E.; Amore, Antonella; Skaf, Munir S.; Crowley, Michael F.; Thorne, Alan W.; Johnson, Christopher W.; Woodcock, H. Lee; McGeehan, John E.; Beckham, Gregg T.Proceedings of the National Academy of Sciences of the United States of America (2018), 115 (19), E4350-E4357CODEN: PNASA6; ISSN:0027-8424. (National Academy of Sciences)Poly(ethylene terephthalate) (PET) is one of the most abundantly produced synthetic polymers and is accumulating in the environment at a staggering rate as discarded packaging and textiles. The properties that make PET so useful also endow it with an alarming resistance to biodegrdn., likely lasting centuries in the environment. Our collective reliance on PET and other plastics means that this buildup will continue unless solns. are found. Recently, a newly discovered bacterium, Ideonella sakaiensis 201-F6, was shown to exhibit the rare ability to grow on PET as a major carbon and energy source. Central to its PET biodegrdn. capability is a secreted PETase (PET-digesting enzyme). Here, we present a 0.92 Å resoln. X-ray crystal structure of PETase, which reveals features common to both cutinases and lipases. PETase retains the ancestral α/β-hydrolase fold but exhibits a more open active-site cleft than homologous cutinases. By narrowing the binding cleft via mutation of two active-site residues to conserved amino acids in cutinases, we surprisingly observe improved PET degrdn., suggesting that PETase is not fully optimized for cryst. PET degrdn., despite presumably evolving in a PET-rich environment. Addnl., we show that PETase degrades another semiarom. polyester, polyethylene-2,5-furandicarboxylate (PEF), which is an emerging, bioderived PET replacement with improved barrier properties. In contrast, PETase does not degrade aliph. polyesters, suggesting that it is generally an arom. polyesterase. These findings suggest that addnl. protein engineering to increase PETase performance is realistic and highlight the need for further developments of structure/activity relationships for biodegrdn. of synthetic polyesters.
- 68Farid, R.; Day, T.; Friesner, R. A.; Pearlstein, R. A. New Insights about HERG Blockade Obtained from Protein Modeling, Potential Energy Mapping, and Docking Studies. Bioorg. Med. Chem. 2006, 14, 3160– 3173, DOI: 10.1016/j.bmc.2005.12.032Google Scholar68https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28Xis1ehs7o%253D&md5=8df638aa78d2d35337bb82d8a94357c4New insights about HERG blockade obtained from protein modeling, potential energy mapping, and docking studiesFarid, Ramy; Day, Tyler; Friesner, Richard A.; Pearlstein, Robert A.Bioorganic & Medicinal Chemistry (2006), 14 (9), 3160-3173CODEN: BMECEP; ISSN:0968-0896. (Elsevier B.V.)We created a homol. model of the homo-tetrameric pore domain of HERG using the crystal structure of the bacterial potassium channel, KvAP, as a template. We docked a set of known blockers with well-characterized effects on channel function into the lumen of the pore between the selectivity filter and extracellular entrance using a novel docking and refinement procedure incorporating Glide and Prime. Key arom. groups of the blockers are predicted to form multiple simultaneous ring stacking and hydrophobic interactions among the eight arom. residues lining the pore. Furthermore, each blocker can achieve these interactions via multiple docking configurations. To further interpret the docking results, we mapped hydrophobic and hydrophilic potentials within the lumen of each refined docked complex. Hydrophilic iso-potential contours define a 'propeller-shaped' vol. at the selectivity filter entrance. Hydrophobic contours define a hollow 'crown-shaped' vol. located above the 'propeller', whose hydrophobic 'rim' extends along the pore axis between Tyr652 and Phe656. Blockers adopt conformations/binding orientations that closely mimic the shapes and properties of these contours. Blocker basic groups are localized in the hydrophilic 'propeller', forming electrostatic interactions with Ser624 rather than a generally accepted π-cation interaction with Tyr652. Terfenadine, cisapride, sertindole, ibutilide, and clofilium adopt similar docked poses, in which their N-substituents bridge radially across the hollow interior of the 'crown' (analogous to the hub and spokes of a wheel), and project arom./hydrophobic portions into the hydrophobic 'rim'. MK-499 docks with its longitudinal axis parallel to the axis of the pore and crown', and its hydrophobic groups buried within the hydrophobic 'rim'.
- 69Sherman, W.; Day, T.; Jacobson, M. P.; Friesner, R. A.; Farid, R. Novel Procedure for Modeling Ligand/Receptor Induced Fit Effects. J. Med. Chem. 2006, 49, 534– 553, DOI: 10.1021/jm050540cGoogle Scholar69https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXhtlCgsr7I&md5=388811ead5cee1fd460951263de486cbNovel Procedure for Modeling Ligand/Receptor Induced Fit EffectsSherman, Woody; Day, Tyler; Jacobson, Matthew P.; Friesner, Richard A.; Farid, RamyJournal of Medicinal Chemistry (2006), 49 (2), 534-553CODEN: JMCMAR; ISSN:0022-2623. (American Chemical Society)We present a novel protein-ligand docking method that accurately accounts for both ligand and receptor flexibility by iteratively combining rigid receptor docking (Glide) with protein structure prediction (Prime) techniques. While traditional rigid-receptor docking methods are useful when the receptor structure does not change substantially upon ligand binding, success is limited when the protein must be "induced" into the correct binding conformation for a given ligand. We provide an in-depth description of our novel methodol. and present results for 21 pharmaceutically relevant examples. Traditional rigid-receptor docking for these 21 cases yields an av. RMSD of 5.5 Å. The av. ligand RMSD for docking to a flexible receptor for the 21 pairs is 1.4 Å; the RMSD is ≤1.8 Å for 18 of the cases. For the three cases with RMSDs greater than 1.8 Å, the core of the ligand is properly docked and all key protein/ligand interactions are captured.
- 70Sherman, W.; Beard, H. S.; Farid, R. Use of an Induced Fit Receptor Structure in Virtual Screening. Chem. Biol. Drug Des. 2006, 67, 83– 84, DOI: 10.1111/j.1747-0285.2005.00327.xGoogle Scholar70https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28XhsVSjtL0%253D&md5=efe9900aacaaea6af805c1cbdb350c73Use of an induced fit receptor structure in virtual screeningSherman, Woody; Beard, Hege S.; Farid, RamyChemical Biology & Drug Design (2006), 67 (1), 83-84CODEN: CBDDAL; ISSN:1747-0277. (Blackwell Publishing Ltd.)A review. The automated induced fit docking protocol was used to generate the DFG-out conformation from a p38 MAP kinase activation loop starting from a DFG-in structure (1a9u) and the ligand from 1kv1 (BMU). In a virtual screening study of 25K decoy ligands and 46 known actives, using an ensemble consisting of the induced fit docking structure (DFG-out) and the 1a9u crystal structure (DFG-in), 14 actives were identified in the top 1% of the database, including BMU and BIRB 796. 3 Actives were identified when 1a9u was used alone.
- 71Madhavi Sastry, G.; Adzhigirey, M.; Day, T.; Annabhimoju, R.; Sherman, W. Protein and Ligand Preparation: Parameters, Protocols, and Influence on Virtual Screening Enrichments. J. Comput.-Aided Mol. Des. 2013, 27, 221– 234, DOI: 10.1007/s10822-013-9644-8Google Scholar71https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXmslalu7c%253D&md5=259a6d547ef3e1310e091fb50fe8de16Protein and ligand preparation: parameters, protocols, and influence on virtual screening enrichmentsMadhavi Sastry, G.; Adzhigirey, Matvey; Day, Tyler; Annabhimoju, Ramakrishna; Sherman, WoodyJournal of Computer-Aided Molecular Design (2013), 27 (3), 221-234CODEN: JCADEQ; ISSN:0920-654X. (Springer)Structure-based virtual screening plays an important role in drug discovery and complements other screening approaches. In general, protein crystal structures are prepd. prior to docking in order to add hydrogen atoms, optimize hydrogen bonds, remove at. clashes, and perform other operations that are not part of the x-ray crystal structure refinement process. In addn., ligands must be prepd. to create 3-dimensional geometries, assign proper bond orders, and generate accessible tautomer and ionization states prior to virtual screening. While the prerequisite for proper system prepn. is generally accepted in the field, an extensive study of the prepn. steps and their effect on virtual screening enrichments has not been performed. In this work, we systematically explore each of the steps involved in prepg. a system for virtual screening. We first explore a large no. of parameters using the Glide validation set of 36 crystal structures and 1,000 decoys. We then apply a subset of protocols to the DUD database. We show that database enrichment is improved with proper prepn. and that neglecting certain steps of the prepn. process produces a systematic degrdn. in enrichments, which can be large for some targets. We provide examples illustrating the structural changes introduced by the prepn. that impact database enrichment. While the work presented here was performed with the Protein Prepn. Wizard and Glide, the insights and guidance are expected to be generalizable to structure-based virtual screening with other docking methods.
- 72Greenwood, J. R.; Calkins, D.; Sullivan, A. P.; Shelley, J. C. Towards the Comprehensive, Rapid, and Accurate Prediction of the Favorable Tautomeric States of Drug-like Molecules in Aqueous Solution. J. Comput.-Aided Mol. Des. 2010, 24, 591– 604, DOI: 10.1007/s10822-010-9349-1Google Scholar72https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXnsFGqtbo%253D&md5=1d7bc0f966ca793d6be80554868367b8Towards the comprehensive, rapid, and accurate prediction of the favorable tautomeric states of drug-like molecules in aqueous solutionGreenwood, Jeremy R.; Calkins, David; Sullivan, Arron P.; Shelley, John C.Journal of Computer-Aided Molecular Design (2010), 24 (6-7), 591-604CODEN: JCADEQ; ISSN:0920-654X. (Springer)A review. Generating the appropriate protonation states of drug-like mols. in soln. is important for success in both ligand- and structure-based virtual screening. Screening collections of millions of compds. requires a method for detg. tautomers and their energies that is sufficiently rapid, accurate, and comprehensive. To maximize enrichment, the lowest energy tautomers must be detd. from heterogeneous input, without over-enumerating unfavorable states. While computationally expensive, the d. functional theory (DFT) method M06-2X/aug-cc-pVTZ(-f) [PB-SCRF] provides accurate energies for enumerated model tautomeric systems. The empirical Hammett-Taft methodol. can very rapidly extrapolate substituent effects from model systems to drug-like mols. via the relationship between pKT and pKa. Combining the 2 complementary approaches transforms the tautomer problem from a scientific challenge to one of engineering scale-up, and avoids issues that arise due to the very limited no. of measured pKT values, esp. for the complicated heterocycles often favored by medicinal chemists for their novelty and versatility. Several hundreds of pre-calcd. tautomer energies and substituent pKa effects are tabulated in databases for use in structural adjustment by the program Epik, which treats tautomers as a subset of the larger problem of the protonation states in aq. ensembles and their energy penalties. Accuracy and coverage is continually improved and expanded by parameterizing new systems of interest using DFT and exptl. data. Recommendations are made for how to best incorporate tautomers in mol. design and virtual screening workflows.
- 73Shelley, J. C.; Cholleti, A.; Frye, L. L.; Greenwood, J. R.; Timlin, M. R.; Uchimaya, M. Epik: A Software Program for PKa Prediction and Protonation State Generation for Drug-like Molecules. J. Comput.-Aided Mol. Des. 2007, 21, 681– 691, DOI: 10.1007/s10822-007-9133-zGoogle Scholar73https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXhsVKrtbzP&md5=f4f429ea3894e1ad2519cdf3333a5645Epik: a software program for pKa prediction and protonation state generation for drug-like moleculesShelley, John C.; Cholleti, Anuradha; Frye, Leah L.; Greenwood, Jeremy R.; Timlin, Mathew R.; Uchimaya, MakotoJournal of Computer-Aided Molecular Design (2007), 21 (12), 681-691CODEN: JCADEQ; ISSN:0920-654X. (Springer)Epik is a computer program for predicting pKa values for drug-like mols. Epik can use this capability in combination with technol. for tautomerization to adjust the protonation state of small drug-like mols. to automatically generate one or more of the most probable forms for use in further mol. modeling studies. Many medicinal chems. can exchange protons with their environment, resulting in various ionization and tautomeric states, collectively known as protonation states. The protonation state of a drug can affect its soly. and membrane permeability. In modeling, the protonation state of a ligand will also affect which conformations are predicted for the mol., as well as predictions for binding modes and ligand affinities based upon protein-ligand interactions. Despite the importance of the protonation state, many databases of candidate mols. used in drug development do not store reliable information on the most probable protonation states. Epik is sufficiently rapid and accurate to process large databases of drug-like mols. to provide this information. Several new technologies are employed. Extensions to the well-established Hammett and Taft approaches are used for pKa prediction, namely, mesomer standardization, charge cancellation, and charge spreading to make the predicted results reflect the nature of the mol. itself rather just for the particular Lewis structure used on input. In addn., a new iterative technol. for generating, ranking and culling the generated protonation states is employed.
- 74Jacobson, M. P.; Pincus, D. L.; Rapp, C. S.; Day, T. J. F.; Honig, B.; Shaw, D. E.; Friesner, R. A. A Hierarchical Approach to All-Atom Protein Loop Prediction. Proteins: Struct., Funct., Bioinf. 2004, 55, 351– 367, DOI: 10.1002/prot.10613Google Scholar74https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXjtFKhsrc%253D&md5=e0eff655eeefb30ea00ae041ea9099c8A hierarchical approach to all-atom protein loop predictionJacobson, Matthew P.; Pincus, David L.; Rapp, Chaya S.; Day, Tyler J. F.; Honig, Barry; Shaw, David E.; Friesner, Richard A.Proteins: Structure, Function, and Bioinformatics (2004), 55 (2), 351-367CODEN: PSFBAF ISSN:. (Wiley-Liss, Inc.)The application of all-atom force fields (and explicit or implicit solvent models) to protein homol.-modeling tasks such as side-chain and loop prediction remains challenging both because of the expense of the individual energy calcns. and because of the difficulty of sampling the rugged all-atom energy surface. Here the authors address this challenge for the problem of loop prediction through the development of numerous new algorithms, with an emphasis on multiscale and hierarchical techniques. As a first step in evaluating the performance of the authors' loop prediction algorithm, the authors have applied it to the problem of reconstructing loops in native structures; the authors also explicitly include crystal packing to provide a fair comparison with crystal structures. In brief, large nos. of loops are generated by using a dihedral angle-based buildup procedure followed by iterative cycles of clustering, side-chain optimization, and complete energy minimization of selected loop structures. The authors evaluate this method by the largest test set yet used for validation of a loop prediction method, with a total of 833 loops ranging from 4 to 12 residues in length. Av./median backbone root-mean-square deviations (RMSDs) to the native structures (superimposing the body of the protein, not the loop itself) are 0.42/0.24 Å for 5 residue loops, 1.00/0.44 Å for 8 residue loops, and 2.47/1.83 Å for 11 residue loops. Median RMSDs are substantially lower than the avs. because of a small no. of outliers; the causes of these failures are examd. in some detail, and many can be attributed to errors in assignment of protonation states of titratable residues, omission of ligands from the simulation, and, in a few cases, probable errors in the exptl. detd. structures. When these obvious problems in the data sets are filtered out, av. RMSDs to the native structures improve to 0.43 Å for 5 residue loops, 0.84 Å for 8 residue loops, and 1.63 Å for 11 residue loops. In the vast majority of cases, the method locates energy min. that are lower than or equal to that of the minimized native loop, thus indicating that sampling rarely limits prediction accuracy. The overall results are, to the authors' knowledge, the best reported to date, and the authors attribute this success to the combination of an accurate all-atom energy function, efficient methods for loop buildup and side-chain optimization, and, esp. for the longer loops, the hierarchical refinement protocol.
- 75Jacobson, M. P.; Friesner, R. A.; Xiang, Z.; Honig, B. On the Role of the Crystal Environment in Determining Protein Side-Chain Conformations. J. Mol. Biol. 2002, 320, 597– 608, DOI: 10.1016/s0022-2836(02)00470-9Google Scholar75https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD38XltVKmu70%253D&md5=006de6bd2d0f233ab32d6798dc1a3fbcOn the Role of the Crystal Environment in Determining Protein Side-chain ConformationsJacobson, Matthew P.; Friesner, Richard A.; Xiang, Zhexin; Honig, BarryJournal of Molecular Biology (2002), 320 (3), 597-608CODEN: JMOBAK; ISSN:0022-2836. (Elsevier Science Ltd.)The role of crystal packing in detg. the obsd. conformations of amino acid side-chains in protein crystals is investigated by (1) anal. of a database of proteins that have been crystd. in different unit cells (space group or unit cell dimensions) and (2) theor. predictions of side-chain conformations with the crystal environment explicitly represented. Both of these approaches indicate that the crystal environment plays an important role in detg. the conformations of polar side-chains on the surfaces of proteins. Inclusion of the crystal environment permits a more sensitive measurement of the achievable accuracy of side-chain prediction programs, when validating against structures obtained by x-ray crystallog. Our side-chain prediction program uses an all-atom force field and a Generalized Born model of solvation and is thus capable of modeling simple packing effects (i.e. van der Waals interactions), electrostatic effects, and desolvation, which are all important mechanisms by which the crystal environment impacts obsd. side-chain conformations. Our results are also relevant to the understanding of changes in side-chain conformation that may result from ligand docking and protein-protein assocn., insofar as the results reveal how side-chain conformations change in response to their local environment.
- 76Lu, C.; Wu, C.; Ghoreishi, D.; Chen, W.; Wang, L.; Damm, W.; Ross, G. A.; Dahlgren, M. K.; Russell, E.; Von Bargen, C. D.; Abel, R.; Friesner, R. A.; Harder, E. D. OPLS4: Improving Force Field Accuracy on Challenging Regimes of Chemical Space. J. Chem. Theory Comput. 2021, 17, 4291– 4300, DOI: 10.1021/acs.jctc.1c00302Google Scholar76https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXht1ejur%252FO&md5=aa4d44468e21abe173534b1323b982d4OPLS4: Improving Force Field Accuracy on Challenging Regimes of Chemical SpaceLu, Chao; Wu, Chuanjie; Ghoreishi, Delaram; Chen, Wei; Wang, Lingle; Damm, Wolfgang; Ross, Gregory A.; Dahlgren, Markus K.; Russell, Ellery; Von Bargen, Christopher D.; Abel, Robert; Friesner, Richard A.; Harder, Edward D.Journal of Chemical Theory and Computation (2021), 17 (7), 4291-4300CODEN: JCTCCE; ISSN:1549-9618. (American Chemical Society)We report on the development and validation of the OPLS4 force field. OPLS4 builds upon our previous work with OPLS3e to improve model accuracy on challenging regimes of drug-like chem. space that includes mol. ions and sulfur contg. moieties. A novel parametrization strategy for charged species, that can be extended to other systems, is introduced. OPLS4 leads to improved accuracy on benchmarks that assess small mol. solvation and protein-ligand binding.
- 77Valsange, N. G.; Garcia Gonzalez, M. N.; Warlin, N.; Mankar, S. V.; Rehnberg, N.; Lundmark, S.; Zhang, B.; Jannasch, P. Biobased Aliphatic Polyesters from a Spirocyclic Dicarboxylate Monomer Derived from Levulinic Acid. Green Chem. 2021, 23, 5706– 5723, DOI: 10.1039/D1GC00724FGoogle Scholar77https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhsVOmu7zE&md5=a880fb8f998158529459d6a76d5f8321Biobased aliphatic polyesters from a spirocyclic dicarboxylate monomer derived from levulinic acidValsange, Nitin G.; Garcia Gonzalez, Maria Nelly; Warlin, Niklas; Mankar, Smita V.; Rehnberg, Nicola; Lundmark, Stefan; Zhang, Baozhong; Jannasch, PatricGreen Chemistry (2021), 23 (15), 5706-5723CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)Levulinic acid derived from lignocellulose is an important biobased building block. Here, we report on the synthesis and polymn. of a rigid spirocyclic diester monomer to produce polyesters and copolyesters. The monomer was prepd. via a one-step acid catalyzed ketalization involving Et levulinate and pentaerythritol by employing a straightforward, solvent-free, and readily scalable method which required no chromatog. purifn. Still, careful removal of traces of water from the spiro-diester prior to polycondensations proved crucial to avoid side reactions. A preliminary life cycle assessment (LCA) in terms of greenhouse gas (GHG) emissions indicated that the corresponding spiro-diacid tended to be environmentally favorable, producing less CO2 emission than e.g., biobased succinic acid and adipic acid. A series of aliph. polyesters with reasonably high mol. wts. was subsequently prepd. in melt and modified melt polycondensations of the spiro-diester with 1,4-butanediol, 1,6-hexanediol, neopentyl glycol and 1,4-cyclohexanedimethanol, resp. The resulting fully amorphous polyesters showed glass transition temps. in the range 12-49°C and thermal stability up to 300°C. Hot-pressed films of the polyesters based on neopentyl glycol and 1,4-cyclohexanedimethanol were transparent and mech. strong, and dynamic melt rheol. showed stable shear moduli over time to indicate good processability. In addn., the spiro-diester monomer was employed in copolycondensations with di-Et adipate and 1,4-butanediol and demonstrated good reactivity and stability. Hence, the results of the present study indicate that the spiro-diester based on levulinic acid is an effective monomer for the prepn. of aliph. polyesters and other condensation polymers.
- 78Fu, T.; Guo, D.-M.; Wu, J.-N.; Wang, X.-L.; Wang, X.-L.; Chen, L.; Wang, Y.-Z. Inherent Flame Retardation of Semi-Aromatic Polyesters via Binding Small-Molecule Free Radicals and Charring. Polym. Chem. 2016, 7, 1584– 1592, DOI: 10.1039/C5PY01938AGoogle Scholar78https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XhtFSgur8%253D&md5=472c6b26d4c5d674d11d0c874ca1da63Inherent flame retardation of semi-aromatic polyesters via binding small-molecule free radicals and charringFu, Teng; Guo, De-Ming; Wu, Jia-Ning; Wang, Xiao-Lin; Wang, Xiu-Li; Chen, Li; Wang, Yu-ZhongPolymer Chemistry (2016), 7 (8), 1584-1592CODEN: PCOHC2; ISSN:1759-9962. (Royal Society of Chemistry)Inherent flame-retardant semi-arom. polyesters, contg. special aryl ether and/or ketone structures ("Ar-CO-Ar", "Ar-O-Ar", "Ar-O-Ar-O-Ar" or "Ar-O-Ar-CO-Ar-O-Ar") were synthesized successfully. Interestingly, these polyesters show different flame retardancy beyond our traditional knowledge that more benzene rings are beneficial to flame retardancy. The polyester contg. "Ar-O-Ar-O-Ar" shows excellent flame retardancy, whose LOI value reaches 34.1% and the UL-94 rating is V-0. Meanwhile, the polyester with the "Ar-O-Ar-CO-Ar-O-Ar" structure does not perform expectedly well (31.6% and V-2 rating resp.). In order to make clear the effect of aryl ether and/or ketone structure units on the flame retardancy, the pyrolysis behaviors and the char residue are investigated by Py-GC/MS, TGA, and SEM. In the TGA test, the char residues of polyesters contg. "Ar-CO-Ar", "Ar-O-Ar", "Ar-O-Ar-O-Ar" or "Ar-O-Ar-CO-Ar-O-Ar" are 31.6%, 22.5%, 30.6% or 38.7%, resp. These values do not match with the calcd. results, which indicate that some special reactions occur during combustion. Furthermore, these polyesters show a common initial pyrolysis pathway and subsequent unique processes in the Py-GC/MS test. Their pyrolysis intermediate products can bind small-mol. free radicals, and eventually form different conjugated arom. structures. And their flame retardant performance has great relationship with the amt. of char formation, microstructure of char, and chem. structure of pyrolysis products.
- 79Cyriac, A.; Lee, S. H.; Varghese, J. K.; Park, J. H.; Jeon, J. Y.; Kim, S. J.; Lee, B. Y. Preparation of Flame-Retarding Poly(Propylene Carbonate). Green Chem. 2011, 13, 3469– 3475, DOI: 10.1039/C1GC15722AGoogle Scholar79https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhsFantLjO&md5=a2e1dbbc07603475f8d05e59c34c2486Preparation of flame-retarding poly(propylene carbonate)Cyriac, Anish; Lee, Sang Hwan; Varghese, Jobi Kodiyan; Park, Ji Hae; Jeon, Jong Yeob; Kim, Seung Jin; Lee, Bun YeoulGreen Chemistry (2011), 13 (12), 3469-3475CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)A preparative method for a flame-retarding poly(propylene carbonate) (PPC) was demonstrated by employing diphenylphosphinic acid (Ph2P(O)(OH)), phenylphosphonic acid (PhP(O)(OH)2), or phosphoric acid (P(O)(OH)3) as a chain transfer agent in the immortal CO2/propylene oxide copolymn. catalyzed by a highly active catalyst, a cobalt(III) complex of a Salen-type ligand tethered by four quaternary ammonium salts (1). High turnover frequencies of 10, 000-20, 000 h-1 (700-1300 g-polymer per g-cat·h) were maintained even in the presence of a large amt. of the protic chain transfer agent ([-OH]/[1], 1600-200). Directly after the copolymn. using PhP(O)(OH)2 as a chain transfer agent, thermoplastic polyurethane (TPU) was formed by adding a stoichiometric amt. of toluene-2,4-diisocyanate. The TPU also was not inflammable. Cone calorimeter studies showed that PPC itself and TPU prepd. using PPC-diol emitted significantly less smoke while burning than common plastics, such as polystyrene.
- 80Kasmi, N.; Papadopoulos, L.; Chebbi, Y.; Papageorgiou, G. Z.; Bikiaris, D. N. Effective and Facile Solvent-Free Synthesis Route to Novel Biobased Monomers from Vanillic Acid: Structure–Thermal Property Relationships of Sustainable Polyesters. Polym. Degrad. Stab. 2020, 181, 109315, DOI: 10.1016/j.polymdegradstab.2020.109315Google Scholar80https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhsF2iu73L&md5=a6fec56327c7e6d75ffd39230a55e5daEffective and facile solvent-free synthesis route to novel biobased monomers from vanillic acid: Structure-thermal property relationships of sustainable polyestersKasmi, Nejib; Papadopoulos, Lazaros; Chebbi, Yosra; Papageorgiou, George Z.; Bikiaris, Dimitrios N.Polymer Degradation and Stability (2020), 181 (), 109315CODEN: PDSTDW; ISSN:0141-3910. (Elsevier Ltd.)Solvent-free synthesis of monomers is one among the most promising ways to develop greener polymers that are both environmentally and economically acceptable, but it was described as one of the "grand challenges" facing chemists. As a contribution towards sustainable bioplastics development which has attracted great attention in materials science research, a truly efficient, practical, and more environmentally friendly solvent-free synthetic route was successfully applied herein to prep. three new fully biobased diol monomers derived from vanillic acid and aliph. diols (ethylene glycol, 1,3-propanediol and 1,4-butanediol). Their chem. structures were confirmed in detail by 1H, 13C NMR and FTIR spectroscopies while their thermal properties were investigated by DSC and TGA. Results showed high m.ps. in the 121.8-142.3°C range and no significant wt. loss (Td, 5%) up to 243, 312 and 284°C resp. for diols with 2, 3, and 4 methylene units. To prove their suitability in polymn., melt polycondensation of prepd. diols with three diacyl chlorides and also with di-Me 2,5-furandicarboxylate were successfully carried out under catalyst-free conditions and using tetra-Bu titanate (TBT), resp. The chem. structures of the novel series of polyesters were confirmed in detail by NMR and FTIR spectroscopies. The latter showed satisfactory intrinsic viscosity values in the 0.25-0.30 dL/g range and a wholly amorphous nature. All materials revealed high thermal stability with onset degrdn. temps. Td, 5% ranging from 314 to 373°C and a wide glass transition temp. (Tg) range oscillating from -2.8 to 69.5°C. The innovative approach proposed herein for the first time, which involves the synthesis of sustainable monomers under solvent-free conditions, is fully aligned with one of the main principles of green chem.
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Abstract
Figure 1
Figure 1. 1H NMR (400.13 MHz, DMSO-d6) spectra of (A) monomer SBM2 (4) and (B,C) its corresponding polymers SBP4a–b, received after reaction with DMS and DMT, respectively.
Figure 2
Figure 2. 13C NMR (100.61 MHz, DMSO-d6) spectra of (A) monomer SBM2 (4) and (B,C) its corresponding polymers SBP4a–b formed after reaction with DMS and DMT, respectively.
Scheme 1
Scheme 1. General Reaction Scheme for the Synthesis of Schiff Base PolymersaaFirst, the synthesis of SB diol monomers SBM1–SBM3 (3–5) starting by reaction between modified vanillin [4-(2-hydroxyethoxy)-2-methoxybenzaldehyde] and EDA (2a), BDA (2b) or m-xylylenediamine (XylDA, 2c), respectively, followed by polymerizations of the diol monomers with aliphatic or aromatic diester, DMS (6a) and DMT (6b), respectively, yielding polyesters (SBP3a–b and SBP5a–b) with different aliphatic/aromatic contents.
Figure 3
Figure 3. TGA curves showing the weight loss (A,C,E) and first derivative weight loss curves (B,D,F) of monomers SBM1 (3), SBM2 (4), and SBM3 (5) and polyesters SBP3a–b, SBP4a–b, and SBP5a–b.
Figure 4
Figure 4. DSC thermograms from the second heating of polyesters SBP3a–b, SBP4a–b, and SBP5a–b.
Figure 5
Figure 5. 1H (400.13 MHz, DMSO-d6) and 13C NMR (100.61 MHz, DMSO-d6) spectra of the recycled products RP1 (A,C) and RP2 (B,D) respectively.
Figure 6
Figure 6. Real-time 1H NMR spectra of (A) original SBP4a and (B) SBP4a after 30 min in acidic solution. (C) SBP4a after 24 h in acidic solution illustrating the chemical recycling of polyester SBP4a in 0.1 M HCl solution (methanol-d4 and water = 8:2 ratio v/v) at room temperature during 24 h. Reference spectra for (D) BDA and (E) recycled dialdehyde product (RP1).
Figure 7
Figure 7. (A) Chemical structures and molecular weights of the expected aldehydes formed from SBP3a, SBP4a, and SBP5b by opening of the imine bonds and hydrolysis of ester bonds. The degradation products DP1 and DP2 formed by opening of the imine bond have same chemical structure than the recycled products RP1 and RP2. Comparative analysis of (B) degradation product DP3 released from all three polymers and (C) degradation product DP4 released from SBP3a and SBP4a and DP5 released from SBP5b after 1 and 24 h with or without (control) enzymes.
Figure 8
Figure 8. Binding mode of the degradation products, DP1 (panel A; green) and DP4 (panel B; blue), are shown. Key residues are represented in cyan color lines.
Figure 9
Figure 9. Binding mode of polymers SBP3a (panel A,D; magenta), SBP4a (panel B,E; yellow), and SBP5b (panel C,F; orange) obtained in the induced-fit docking calculations of PETase (PDB ID: 6EQE) in poses A and B, respectively. Key residues are represented in cyan color lines.
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- 2Lange, J. P. Managing Plastic Waste-Sorting, Recycling, Disposal, and Product Redesign. ACS Sustainable Chem. Eng. 2021, 9, 15722– 15738, DOI: 10.1021/acssuschemeng.1c050132https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXisVGrsrnJ&md5=be962b076476e32830ca7d179a7e3bcaManaging Plastic Waste-Sorting, Recycling, Disposal, and Product RedesignLange, Jean-PaulACS Sustainable Chemistry & Engineering (2021), 9 (47), 15722-15738CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)A review. Over the years, the petrochem. industry has developed a plethora of polymers that are contributing to the well-being of humanity. Irresponsible disposal of used plastics has, however, led to the buildup of litter, which is fouling the environment, harming wildlife, and wasting valuable resources. This paper critically reviews the challenge and opportunities in converting plastic waste into a feedstock for the industry. It discusses (a) the amt., quality, and sorting of plastic waste; (b) mech. recycling and extn. or dissoln./pptn.; (c) chem. recycling to monomers and to feedstock and other chems.; and (d) waste disposal by incineration, biodegrdn., landfill, and microplastics. It will, finally, broaden the circularity discussion with life-cycle analyses (LCA), design for recycling, and the future role of renewable carbon as a feedstock.
- 3Hong, M.; Chen, E. Y. X. Chemically Recyclable Polymers: A Circular Economy Approach to Sustainability. Green Chem. 2017, 19, 3692– 3706, DOI: 10.1039/C7GC01496A3https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtVChtbjJ&md5=c7d6c91c0f58b2899be23facc1f3d0e3Chemically recyclable polymers: a circular economy approach to sustainabilityHong, Miao; Chen, Eugene Y.-X.Green Chemistry (2017), 19 (16), 3692-3706CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)A crit. review presenting selected highlights of the emerging area of recyclable green polymers focusing on major progress made and tech. and environmental benefits obtained in development of re-purposing and depolymn. processes for chem. recycling of polymers at the end of their useful life, is given. Topics discussed include: introduction; re-purposing processes (engineering plastics into new value-added materials [one-step conversion of polycarbonate into poly(aryl ether sulfone), aminolysis and glycolysis of poly(ethylene terephthalate)], commodity polyolefins re-purposing into equal- or higher-value materials [polyethylene degrdn. into liq. fuels and waxes, recycling polyethylene/isotactic polypropylene blends by adding polyethylene/isotactic polypropylene block copolymers]); depolymn. processes (chem. recycling of high performance thermosets at controlled pH, chem. or mech. triggered depolymn. of poly(o-phthalaldehyde), thermal and chem. recycling of polyurethanes, cross-linked polycarbonates and polyester elastomers, thermal and chem. recycling of poly(L-lactide), thermal and chem. recycling of nylon-6, complete thermal or chem. recyclability of poly(γ-butyrolactone), chem. recyclable polyester based on α-methylene-γ-butyrolactone, polymn./depolymn. cycle for an arom. polyester and CO2/epoxide copolymer or polycarbonate); and conclusions and outlook.
- 4Welsby, D.; Price, J.; Pye, S.; Ekins, P. Unextractable Fossil Fuels in a 1.5 °C World. Nature 2021, 597, 230– 234, DOI: 10.1038/s41586-021-03821-84https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhvFyntrzI&md5=d0514d16c17af6f4fe9e0a792d08c559Unextractable fossil fuels in a 1.5°C worldWelsby, Dan; Price, James; Pye, Steve; Ekins, PaulNature (London, United Kingdom) (2021), 597 (7875), 230-234CODEN: NATUAS; ISSN:0028-0836. (Nature Portfolio)Parties to the 2015 Paris Agreement pledged to limit global warming to well below 2° and to pursue efforts to limit the temp. increase to 1.5° relative to pre-industrial times. However, fossil fuels continue to dominate the global energy system and a sharp decline in their use must be realized to keep the temp. increase below 1.5°. Here we use a global energy systems model to assess the amt. of fossil fuels that would need to be left in the ground, regionally and globally, to allow for a 50 per cent probability of limiting warming to 1.5°. By 2050, we find that nearly 60 per cent of oil and fossil methane gas, and 90 per cent of coal must remain unextd. to keep within a 1.5° carbon budget. This is a large increase in the unextractable ests. for a 2° carbon budget, particularly for oil, for which an addnl. 25 per cent of reserves must remain unextd. Furthermore, we est. that oil and gas prodn. must decline globally by 3 per cent each year until 2050. This implies that most regions must reach peak prodn. now or during the next decade, rendering many operational and planned fossil fuel projects unviable. We probably present an underestimate of the prodn. changes required, because a greater than 50 per cent probability of limiting warming to 1.5° requires more carbon to stay in the ground and because of uncertainties around the timely deployment of neg. emission technologies at scale.
- 5Xu, G.; Wang, Q. Chemically Recyclable Polymer Materials: Polymerization and Depolymerization Cycles. Green Chem. 2022, 24, 2321– 2346, DOI: 10.1039/D1GC03901F5https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XmtVKgu7k%253D&md5=3918654e2c1f81fc90bfd0cd6da4b58aChemically recyclable polymer materials: polymerization and depolymerization cyclesXu, Guangqiang; Wang, QinggangGreen Chemistry (2022), 24 (6), 2321-2346CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)A review. The design and synthesis of chem. recyclable polymers, which can be reutilized as their starting monomers or new value-added chems., has provided a practical approach to address the end-of-use problem of polymer materials and a possible closed-loop method for polymer material usage. More and more attention has been paid to chem. recyclable polymers, which exhibit an increasing and prominent role in sustainable development. Nowadays, chem. recyclable polymers including polyesters, polythioesters, polycarbonates, polyacetals, polyamides, and so on have made significant achievements. Consequently, this minireview summarizes the examples for achieving the polymn.-depolymn. cycle to access chem. recyclable polymers, which are categorized into seven parts based on monomers.
- 6Zhu, Y.; Romain, C.; Williams, C. K. Sustainable Polymers from Renewable Resources. Nature 2016, 540, 354– 362, DOI: 10.1038/nature210016https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XitVyru7%252FP&md5=1a3419dd9b1a7e1643b4671cdf42553fSustainable polymers from renewable resourcesZhu, Yunqing; Romain, Charles; Williams, Charlotte K.Nature (London, United Kingdom) (2016), 540 (7633), 354-362CODEN: NATUAS; ISSN:0028-0836. (Nature Publishing Group)Renewable resources are used increasingly in the prodn. of polymers. In particular, monomers such as carbon dioxide, terpenes, vegetable oils and carbohydrates can be used as feedstocks for the manuf. of a variety of sustainable materials and products, including elastomers, plastics, hydrogels, flexible electronics, resins, engineering polymers and composites. Efficient catalysis is required to produce monomers, to facilitate selective polymns. and to enable recycling or upcycling of waste materials. There are opportunities to use such sustainable polymers in both high-value areas and in basic applications such as packaging. Life-cycle assessment can be used to quantify the environmental benefits of sustainable polymers.
- 7Gregory, G. L.; Williams, C. K. Exploiting Sodium Coordination in Alternating Monomer Sequences to Toughen Degradable Block Polyester Thermoplastic Elastomers. Macromolecules 2022, 55, 2290– 2299, DOI: 10.1021/acs.macromol.2c000687https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XlsVKrt78%253D&md5=6e9185e9e7b97342b86aae50a7465aafExploiting Sodium Coordination in Alternating Monomer Sequences to Toughen Degradable Block Polyester Thermoplastic ElastomersGregory, Georgina L.; Williams, Charlotte K.Macromolecules (Washington, DC, United States) (2022), 55 (6), 2290-2299CODEN: MAMOBX; ISSN:0024-9297. (American Chemical Society)Thermoplastic elastomers (TPEs) that are closed-loop recyclable are needed in a circular material economy, but many current materials degrade during recycling, and almost all are pervasive hydrocarbons. Here, well-controlled block polyester TPEs featuring regularly placed sodium/lithium carboxylate side chains are described. They show significantly higher tensile strengths than unfunctionalized analogs, with high elasticity and elastic recovery. The materials are prepd. using controlled polymns., exploiting a single catalyst that switches between different polymn. cycles. ABA block polyesters of high molar mass (60-100 kg mol-1; 21 wt. % A-block) are constructed using the ring-opening polymn. of ε-decalactone (derived from castor oil; B-block), followed by the alternating ring-opening copolymn. of phthalic anhydride with 4-vinyl-cyclohexene oxide (A-blocks). The polyesters undergo efficient functionalization to install regularly placed carboxylic acids onto the A blocks. Reacting the polymers with sodium or lithium hydroxide controls the extent of ionization (0-100%); ionized polymers show a higher tensile strength (20 MPa), elasticity (>2000%), and elastic recovery (>80%). In one case, sodium functionalization results in 35x higher stress at break than the carboxylic acid polymer; in all cases, changing the quantity of sodium tunes the properties. A leading sample, 2-COONa75 (Mn 100 kg mol-1, 75% sodium), shows a wide operating temp. range (-52 to 129°C) and is recycled (x3) by hot-pressing at 200°C, without the loss of mech. properties. Both the efficient synthesis of ABA block polymers and precision ionization in perfectly alternating monomer sequences are concepts that can be generalized to many other monomers, functional groups, and metals. These materials are partly bioderived and have degradable ester backbone chemistries, deliver useful properties, and allow for thermal reprocessing; these features are attractive as future sustainable TPEs.
- 8Tu, Y. M.; Wang, X. M.; Yang, X.; Fan, H. Z.; Gong, F. L.; Cai, Z.; Zhu, J. B. Biobased High-Performance Aromatic-Aliphatic Polyesters with Complete Recyclability. J. Am. Chem. Soc. 2021, 143, 20591– 20597, DOI: 10.1021/jacs.1c101628https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXis1Wns7rJ&md5=16e514059bbbbf791092cb5d52d86ff2Biobased High-Performance Aromatic-Aliphatic Polyesters with Complete RecyclabilityTu, Yi-Min; Wang, Xue-Mei; Yang, Xing; Fan, Hua-Zhong; Gong, Fu-Long; Cai, Zhongzheng; Zhu, Jian-BoJournal of the American Chemical Society (2021), 143 (49), 20591-20597CODEN: JACSAT; ISSN:0002-7863. (American Chemical Society)The development of high-performance recyclable polymers represents a circular plastics economy to address the urgent issues of plastic sustainability. Herein, we design a series of biobased seven-membered-ring esters contg. arom. and aliph. moieties. Ring-opening polymn. studies showed that they readily polymerize with excellent activity (TOF up to 2.1 × 105 h-1) at room temp. and produce polymers with high mol. wt. (Mn up to 438 kg/mol). The variety of functionalities allows us to investigate the substitution effect on polymerizability/recyclability of monomers and properties of polymers (such as Tgs from -1 to 79°C). Remarkably, a stereocomplexed P(M2) exhibited significantly increased Tm and crystn. rate. More importantly, product P(M)s were capable of depolymg. into their monomers in soln. or bulk with high efficiency, thus establishing their circular life cycle.
- 9Vilela, C.; Sousa, A. F.; Fonseca, A. C.; Serra, A. C.; Coelho, J. F. J.; Freire, C. S. R.; Silvestre, A. N. D. The Quest for Sustainable Polyesters-Insights into the Future. Polym. Chem. 2014, 5, 3119– 3141, DOI: 10.1039/C3PY01213A9https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXlt1Siur4%253D&md5=1bf365b5d2bfe29b6080f6f5b421b30eThe quest for sustainable polyesters - insights into the futureVilela, Carla; Sousa, Andreia F.; Fonseca, Ana C.; Serra, Armenio C.; Coelho, Jorge F. J.; Freire, Carmen S. R.; Silvestre, Armando J. D.Polymer Chemistry (2014), 5 (9), 3119-3141CODEN: PCOHC2; ISSN:1759-9962. (Royal Society of Chemistry)A review. Polyesters from renewable resources are an expanding area with a burgeoning scientific activity, nevertheless little has been reviewed about this particular class of polymers. The present appraisal intends to contribute to fill this literature gap by reviewing recent aspects related to the most promising renewable-based polyesters. Emphasis will be placed on bio-based polyesters that, given their comparable properties, may replace polymers derived from fossil fuel feedstock, and on bio-based polyesters with completely innovative properties for novel applications. Furthermore, the sources of renewable monomers will also be reviewed, together with the most relevant eco-friendly synthetic approaches used in polycondensation reactions leading to polyesters.
- 10Boyer, C.; Liu, J.; Wong, J.; Tippett, M.; Bulmus, V.; Davis, T. P. Stability and Utility of Pyridyl Disulfide Functionality in RAFT and Conventional Radical Polymerizations. J. Polym. Sci., Part A: Polym. Chem. 2008, 46, 7207– 7224, DOI: 10.1002/pola.2302810https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD1cXhsVSnur%252FE&md5=80410dd2e4377c98e90a92ad07cfeec0Stability and utility of pyridyl disulfide functionality in RAFT and conventional radical polymerizationsBoyer, Cyrille; Liu, Jingquan; Wong, Lingjiun; Tippett, Michael; Bulmus, Volga; Davis, Thomas P.Journal of Polymer Science, Part A: Polymer Chemistry (2008), 46 (21), 7207-7224CODEN: JPACEC; ISSN:0887-624X. (John Wiley & Sons, Inc.)Two RAFT (reversible addn. fragmentation chain transfer) agents, suitable for inducing living radical polymn. in water, have been synthesized. Both RAFT agents were shown to be effective over the temp. range 25°-70°. One RAFT agent was functionalized with a pyridyl disulfide group. RAFT efficacy was demonstrated for the polymns. of N-iso-Pr acrylamide (NIPAAM) and poly(ethylene oxide)-acrylate (PEG-A) in both water and acetonitrile. The kinetic data indicates that the pyridyl disulfide functionality is largely benign in free radical polymns., remaining intact for subsequent reaction with thiol groups. This result was confirmed by studying conventional radical polymns. in the presence of hydroxyethyl pyridyl disulfide. The utility of the pyridyl disulfide functionality at the terminus of the polymers was demonstrated by synthesizing polymer-BSA (bovine serum albumin) conjugates.
- 11Vecchiato, S.; Ahrens, J.; Pellis, A.; Scaini, D.; Mueller, B.; Herrero Acero, E.; Guebitz, G. M. Enzymatic Functionalization of HMLS-Polyethylene Terephthalate Fabrics Improves the Adhesion to Rubber. ACS Sustainable Chem. Eng. 2017, 5, 6456– 6465, DOI: 10.1021/acssuschemeng.7b0047511https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2sXhtVCktr7J&md5=cd51f0455e009600c70a03fc6ff1f859Enzymatic Functionalization of HMLS-Polyethylene Terephthalate Fabrics Improves the Adhesion to RubberVecchiato, Sara; Ahrens, Jennifer; Pellis, Alessandro; Scaini, Denis; Mueller, Bernhard; Herrero Acero, Enrique; Guebitz, Georg M.ACS Sustainable Chemistry & Engineering (2017), 5 (8), 6456-6465CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)Among synthetic thermoplastic fiber materials for reinforcement, high modulus and low shrinkage poly(ethylene terephthalate) (HMLS-PET) became the major carcass material for the low to medium-end tire segment. Usually cords are coated with a resorcinol-formaldehyde latex (RFL) dip to achieve acceptable power transmission. However, the low concn. of polar groups on the PET's surface requires an addnl. activation with costly and potentially toxic chems. to create addnl. nucleophilic groups prior to RFL dipping. Here, a green enzyme based alternative to chem. HMLS-PET activation was investigated. Four different cutinase variants from Thermobifida cellulosilytica were shown to hydrolyze HMLS-PET-cords creating new carboxylic and hydroxyl groups with distinct exoendo wise selectivity. The highest degree of enzymic functionalization reached a concn. of 0.51 nmol mm-2 of COOH with a release of 1.35 mM of sol. products after 72 h. The chem. treatment with 1 M NaOH released more sol. products leading up to a 10% decrease of the tensile strength while the functionalization degree achieved was only 0.21 nmol mm-2. This clearly indicates a more endowise mode of hydrolysis for the enzymic treatment when compared to chem. hydrolysis. SEM of the fibers confirmed the aggressiveness of the chem. treatment, whereas the enzymic approach only led to 0.7% solubilization of the polymer with no loss of mech. properties and crystallinity changes. The newly created groups were chem. accessible and reactive in the dipping step and lead after the vulcanization to a significant improvement of the adhesion between the polymer and a representative carcass rubber-compd. according to the peel tests.
- 12Brown, A. E.; Reinhart, A. K. Polyester Fiber : From Its Invention to Its Present Position. Science 1971, 173, 287– 293, DOI: 10.1126/science.173.3994.28712https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADyaE3MXlsFakurk%253D&md5=cc942112d6a5a938003d28a772bd0e65Polyester fiber. From its invention to its present positionBrown, Alfred E.; Reinhart, Kenneth A.Science (Washington, DC, United States) (1971), 173 (3994), 287-93CODEN: SCIEAS; ISSN:0036-8075.Developments in polyester fibers since their invention 30 years ago were reviewed with 27 refs. emphasising the polymer chemistry, mol. structure, properties, and end uses.
- 13Mashiur, R. Degradation of Polyester in Medical Applications. In Polyester; Saleh, H. M., Ed.; IntechOpen, 2012; Chapter 5, pp 1– 35.There is no corresponding record for this reference.
- 14Oblak, P.; Gonzalez-Gutierrez, J.; Zupančič, B.; Aulova, A.; Emri, I. Processability and Mechanical Properties of Extensively Recycled High Density Polyethylene. Polym. Degrad. Stab. 2015, 114, 133– 145, DOI: 10.1016/j.polymdegradstab.2015.01.01214https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhvFCht7k%253D&md5=eb74f4072d3d06f8c8bfe5e5eb59c24fProcessability and mechanical properties of extensively recycled high density polyethyleneOblak, Pavel; Gonzalez-Gutierrez, Joamin; Zupancic, Barbara; Aulova, Alexandra; Emri, IgorPolymer Degradation and Stability (2015), 114 (), 133-145CODEN: PDSTDW; ISSN:0141-3910. (Elsevier Ltd.)In plastics industry it is a common practice to mech. recycle waste material arising from prodn. However, while plastics are mech. recycled, their mech. properties change. These changes may affect material processing conditions and quality of the end products; therefore they need to be quantified. In this study, mech. recycling of high d. polyethylene (HDPE) was simulated by one-hundred (100) consecutive extrusions cycles. During extrusion, processability of virgin HDPE and its recyclates was studied by recording the processing conditions, i.e. melt pressure and extrusion torque, while after prepn. of the recyclates, melt flow index measurements (MFI), small amplitude oscillatory shear tests (rheol. properties), and differential scanning calorimetry measurements (DSC) of thermal properties were performed. Also, mech. properties in solid state were characterized in terms of hardness and modulus measured by nanoindentation, and finally, shear creep compliance was measured to characterize the materials' time-dependent mech. properties and its durability in solid state. In addn., gel permeation chromatog. (GPC) and soly. tests were implemented to study changes in the material structure. The results on rheol. and MFI measurements indicate significant structural changes in the material that occurred during the first 30 extrusion cycles. Those changes affect material processability which is as well supported by the recorded processing pressure and torque. On the other hand, processing did not significantly affect material thermal properties. Results on hardness and modulus show deterioration of the material mech. properties after 10th reprocessing cycle. Similarly, shear creep compliance measurements showed an unfavorable effect of mech. recycling on the time-dependent mech. properties, particularly after the 30th extrusion cycle. In addn., results suggested chain branching as a dominating mechanism through first 30 extrusion cycles, domination of chain scission afterwards and also presence of crosslinking after 60th extrusion cycle.
- 15Rosenboom, J. G.; Langer, R.; Traverso, G. Bioplastics for a Circular Economy. Nat. Rev. Mater. 2022, 7, 117– 137, DOI: 10.1038/s41578-021-00407-815https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BB2M7islGhtg%253D%253D&md5=7fa8c602781b3396112169c4bc4ca9a2Bioplastics for a circular economyRosenboom Jan-Georg; Langer Robert; Rosenboom Jan-Georg; Langer Robert; Traverso Giovanni; Rosenboom Jan-Georg; Traverso Giovanni; Traverso GiovanniNature reviews. Materials (2022), 7 (2), 117-137 ISSN:2058-8437.Bioplastics - typically plastics manufactured from bio-based polymers - stand to contribute to more sustainable commercial plastic life cycles as part of a circular economy, in which virgin polymers are made from renewable or recycled raw materials. Carbon-neutral energy is used for production and products are reused or recycled at their end of life (EOL). In this Review, we assess the advantages and challenges of bioplastics in transitioning towards a circular economy. Compared with fossil-based plastics, bio-based plastics can have a lower carbon footprint and exhibit advantageous materials properties; moreover, they can be compatible with existing recycling streams and some offer biodegradation as an EOL scenario if performed in controlled or predictable environments. However, these benefits can have trade-offs, including negative agricultural impacts, competition with food production, unclear EOL management and higher costs. Emerging chemical and biological methods can enable the 'upcycling' of increasing volumes of heterogeneous plastic and bioplastic waste into higher-quality materials. To guide converters and consumers in their purchasing choices, existing (bio)plastic identification standards and life cycle assessment guidelines need revision and homogenization. Furthermore, clear regulation and financial incentives remain essential to scale from niche polymers to large-scale bioplastic market applications with truly sustainable impact.
- 16Geyer, R.; Jambeck, J. R.; Law, K. L. Production , Use , and Fate of All Plastics Ever Made. Science 2017, 3, 25– 29, DOI: 10.1126/sciadv.1700782There is no corresponding record for this reference.
- 17Chinthapalli, R.; Skoczinski, P.; Carus, M.; Baltus, W.; de Guzman, D. D.; Käb, H.; Raschka, A.; Ravenstijn, J. Bio-Based Building Blocks and Polymers─Global Capacities and Trends, 2018–2023. Ind. Biotechnol. 2019, 15, 237– 241, DOI: 10.1089/ind.2019.29179.rchThere is no corresponding record for this reference.
- 18Kratish, Y.; Marks, T. J. Efficient Polyester Hydrogenolytic Deconstruction via Tandem Catalysis. Angew. Chem., Int. Ed. 2022, 61, e202112576 DOI: 10.1002/anie.20211257618https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXislOns7nL&md5=ca486a806d432b38b18f84aaa628a3baEfficient Polyester Hydrogenolytic Deconstruction via Tandem CatalysisKratish, Yosi; Marks, Tobin J.Angewandte Chemie, International Edition (2022), 61 (9), e202112576CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)Using a mechanism-based solvent-free tandem catalytic approach, commodity polyester plastics such as polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene naphthalate (PEN) are rapidly and selectively deconstructed by combining the two air- and moisture-stable catalysts, Hf(OTf)4 and Pd/C, under 1 atm H2, affording terephthalic acid (or naphthalene dicarboxylic acid for PEN) and ethane (or butane for PBT) in essentially quant. yield. This process is effective for both lab. grade and waste plastics, and comingled polypropylene remains unchanged. Combined exptl. and DFT mechanistic analyses indicate that Hf(OTf)4 catalyzes a mildly exergonic retro-hydroalkoxylation reaction in which an alkoxy C-O bond is first cleaved, yielding a carboxylic acid and alkene, and this process is closely coupled to an exergonic olefin hydrogenation step, driving the overall reaction forward.
- 19Lange, J. P. Towards Circular Carbo-Chemicals-the Metamorphosis of Petrochemicals. Energy Environ. Sci. 2021, 14, 4358– 4376, DOI: 10.1039/D1EE00532D19https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXht1Citb7J&md5=1c7a8c0444c4b95d5b25017ea54d46baTowards circular carbo-chemicals - the metamorphosis of petrochemicalsLange, J.-P.Energy & Environmental Science (2021), 14 (8), 4358-4376CODEN: EESNBY; ISSN:1754-5706. (Royal Society of Chemistry)A review. The petrochem. industry grew to become one of the world's largest industries during the 20th century. It is expected that it will continue to grow, as the world's population gets wealthier, social dynamics change and people demand more affordable and useful materials. The industry recognizes that the Earth's carrying capacity is limited. It is adapting to seek to become a truly sustainable 'carbo'-chem. industry. This paper will address the three main challenges of this transition: shifting hydrocarbon stock, climate change and circular economy. As the energy sector transitions from oil, coal and eventually natural gas, it is expected that the chem. industry will have access to abundant hydrocarbon stocks for which it can find valuable uses. But rising CO2 prices and increasing upgrading costs will likely encourage greater use of alternative, low-carbon feedstocks. In particular, there may be a development of biomass for manufg. oxygenated chem. intermediates and bio-based materials. To help tackle climate change, the industry will need to reduce the CO2 emissions of its processes and utilities (energy sources). Ways to achieve this will include efficiency improvements, electrification of utilities and processes and switching to renewable H2; upgrading byproducts to chems.; and CO2 capture and storage or utilization (CCS/CCU). The issue of plastic waste pollution is combining with the challenges discussed above to push society and governments towards a more circular economy. Customer demand for sustainable products is growing. New regulations (and technologies) are being rolled out for waste collection, sorting and recycling. In addn., the industry is making pledges to produce and use more sustainably. However, it is expected that fresh carbon will still have to enter the material cycle. It will be needed to feed the growth of the chem. industry and to compensate for inevitable recycling losses. For a truly circular industry, this fresh carbon would come from a renewable source, i.e. from atm. CO2, initially via biomass and later possibly from direct CO2 capture and utilization (CCU).
- 20Geyer, R.; Jambeck, J. R.; Law, K. L. Production, Use, and Fate of All Plastics Ever Made. Sci. Adv. 2017, 3, 25– 29, DOI: 10.1126/sciadv.1700782There is no corresponding record for this reference.
- 21Monsigny, L.; Berthet, J. C.; Cantat, T. Depolymerization of Waste Plastics to Monomers and Chemicals Using a Hydrosilylation Strategy Facilitated by Brookhart’s Iridium(III) Catalyst. ACS Sustainable Chem. Eng. 2018, 6, 10481– 10488, DOI: 10.1021/acssuschemeng.8b0184221https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXht1ejsrvO&md5=83de2d7600445886a6fed591619c08c5Depolymerization of Waste Plastics to Monomers and Chemicals Using a Hydrosilylation Strategy Facilitated by Brookhart's Iridium(III) CatalystMonsigny, Louis; Berthet, Jean-Claude; Cantat, ThibaultACS Sustainable Chemistry & Engineering (2018), 6 (8), 10481-10488CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)Plastic waste management is a major concern. While the societal demand for sustainability is growing, landfilling and incineration of waste plastics remain the norm and methods able to efficiently recycle these materials are desirable. Herein, we report the depolymn., under mild conditions, of oxygenated plastics in the presence of hydrosilanes with the cationic pincer complex [Ir(PCP)H(THF)][B(C6F5)4] (PCP=1,3-(tBu2P)2C6H3) as catalyst. The iridium catalyst, with a low loading (0.3-1 mol%), proves selective toward the formation of silyl ethers or the corresponding alkanes depending only on the reaction temp. The depolymn. of real household waste plastics such as PET (from plastic bottles) and polylactic acid (PLA) from 3D printer filaments is not altered by the presence of dye or other plastic's additives.
- 22Kim, D. H.; Han, D. O.; In Shim, K.; Kim, J. K.; Pelton, J. G.; Ryu, M. H.; Joo, J. C.; Han, J. W.; Kim, H. T.; Kim, K. H. One-Pot Chemo-Bioprocess of PET Depolymerization and Recycling Enabled by a Biocompatible Catalyst, Betaine. ACS Catal. 2021, 11, 3996– 4008, DOI: 10.1021/acscatal.0c0401422https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXmvV2nsL8%253D&md5=b655049ecbf843cdfa9eb03790065e19One-Pot Chemo-bioprocess of PET Depolymerization and Recycling Enabled by a Biocompatible Catalyst, BetaineKim, Dong Hyun; Han, Dong Oh; In Shim, Kyu; Kim, Jae Kyun; Pelton, Jeffrey G.; Ryu, Mi Hee; Joo, Jeong Chan; Han, Jeong Woo; Kim, Hee Taek; Kim, Kyoung HeonACS Catalysis (2021), 11 (7), 3996-4008CODEN: ACCACS; ISSN:2155-5435. (American Chemical Society)Poly(ethylene terephthalate) (PET) has been widely used in various industries due to its unique phys. properties. However, PET causes major environmental problems globally due to its low degradability and recycling rate. Since it is nearly impossible to replace PET with other materials, an efficient approach for PET recycling is necessary for a circular economy. Herein, for a paradigm shift toward the approach for resource recovery of PET components, we developed an integrated process for depolymg. PET and converting PET monomers to high-value products in a one-pot process. The key of our approach is the use of the biocompatible catalyst betaine in a glycolysis process that enables whole PET glycolysis slurry as a substrate to be directly applied to further bioprocesses. Based on the d. functional theory (DFT) anal., betaine effectively catalyzed PET depolymn. by two strong hydrogen interactions between betaine, EG, and PET as well as a synergetic effect by the anion and cation groups of betaine. Through the glycolysis of PET with betaine and the optimized enzymic hydrolytic process for the PET glycolysis slurry, PET was depolymd. to terephthalate (TPA, 31.0 g/L, 62.8%, mol./mol) and ethylene glycol (EG, 11.7 g/L, 63.3%, mol./mol) at a high titer value and high yield. This process was further applied to the bioconversion of TPA and EG present in the PET hydrolyzate to protocatechuic acid (PCA) and glycolic acid (GLA), resp. This one-pot chemo-bioprocess integrating chem. glycolysis, enzymic hydrolysis, and bioconversion for PET depolymn. and recycling was suggested to be highly applicable to the upcycling of waste PET.
- 23Han, X.; Liu, W.; Huang, J. W.; Ma, J.; Zheng, Y.; Ko, T. P.; Xu, L.; Cheng, Y. S.; Chen, C. C.; Guo, R. T. Structural Insight into Catalytic Mechanism of PET Hydrolase. Nat. Commun. 2017, 8, 2106, DOI: 10.1038/s41467-017-02255-z23https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BC1MzgvFKltw%253D%253D&md5=97def04a6e570a4a7a37cb1941246d73Structural insight into catalytic mechanism of PET hydrolaseHan Xu; Liu Weidong; Ma Jiantao; Zheng Yingying; Chen Chun-Chi; Guo Rey-Ting; Huang Jian-Wen; Xu Limin; Cheng Ya-Shan; Ma Jiantao; Ko Tzu-PingNature communications (2017), 8 (1), 2106 ISSN:.PET hydrolase (PETase), which hydrolyzes polyethylene terephthalate (PET) into soluble building blocks, provides an attractive avenue for the bioconversion of plastics. Here we present the structures of a novel PETase from the PET-consuming microbe Ideonella sakaiensis in complex with substrate and product analogs. Through structural analyses, mutagenesis, and activity measurements, a substrate-binding mode is proposed, and several features critical for catalysis are elucidated.
- 24Wang, Z.; Jin, Y.; Wang, Y.; Tang, Z.; Wang, S.; Xiao, G.; Su, H. Cyanamide as a Highly Efficient Organocatalyst for the Glycolysis Recycling of PET. ACS Sustainable Chem. Eng. 2022, 10, 7965– 7973, DOI: 10.1021/acssuschemeng.2c0123524https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XhsVKgtbjJ&md5=9be27323d8a965d9b676a276119b008dCyanamide as a Highly Efficient Organocatalyst for the Glycolysis Recycling of PETWang, Zishuai; Jin, Yu; Wang, Yaoqiang; Tang, Zequn; Wang, Shaojie; Xiao, Gang; Su, HaijiaACS Sustainable Chemistry & Engineering (2022), 10 (24), 7965-7973CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)Due to the antibiodegradable properties, numerous plastics have been accumulated in the ecosystem and aggravate ecol. pollution. Poly (ethylene terephthalate) (PET) is among the most used plastics. Glycolysis of PET is a useful approach to solve the waste PET pollution and obtain bis(2-hydroxyethyl) terephthalate (BHET). In this paper, waste PET was efficiently depolymd. through glycolysis catalyzed by cyanamide. In particular, compared with the previously reported catalyst, cyanamide is more readily available and can be used directly in catalysis without a complex prepn. process. Under optimal conditions, PET was completely depolymd. with up to nearly 100% BHET yield. Even at a temp. as low as 150°C, a good BHET yield can be obtained. The application potential of this glycolysis procedure was demonstrated by its excellent performance in the glycolysis of various real PET wastes like transparent and opaque PET samples and polyester foam and by the high quality of the obtained BHET products. The mechanism was studied by 1H NMR anal., and DFT calcns. showed that the higher activity of cyanamide than its trimer, melamine, is due to the stronger hydrogen bonds formed between cyanamide and PET or ethylene glycol.
- 25Wei, R.; Tiso, T.; Bertling, J.; O’Connor, K.; Blank, L. M.; Bornscheuer, U. T. Possibilities and Limitations of Biotechnological Plastic Degradation and Recycling. Nat. Catal. 2020, 3, 867– 871, DOI: 10.1038/s41929-020-00521-w25https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXit1OrtLzF&md5=20e6b8a93db4a95f037d7318f2aed801Possibilities and limitations of biotechnological plastic degradation and recyclingWei, Ren; Tiso, Till; Bertling, Juergen; O'Connor, Kevin; Blank, Lars M.; Bornscheuer, Uwe T.Nature Catalysis (2020), 3 (11), 867-871CODEN: NCAACP; ISSN:2520-1158. (Nature Research)Considerable research achievements were made to address the plastic crisis using biotechnol., but this is still limited to polyesters. This Comment aims to clarify important aspects related to myths and realities about plastic biodegrdn. and suggests distinct strategies for a bio-based circular plastic economy in the future.
- 26Fernandes, A. C. Reductive Depolymerization of Plastic Waste Catalyzed by Zn(OAc)2 · 2H2O. ChemSusChem 2021, 14, 4228– 4233, DOI: 10.1002/cssc.20210013026https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXmt1eltbg%253D&md5=5835ec60b0d05383ba51b1db20870716Reductive Depolymerization of Plastic Waste Catalyzed by Zn(OAc)2 · 2H2OFernandes, Ana C.ChemSusChem (2021), 14 (19), 4228-4233CODEN: CHEMIZ; ISSN:1864-5631. (Wiley-VCH Verlag GmbH & Co. KGaA)Plastic pollution is one of the biggest problems all over the world. Beyond change/awareness of consumer behavior, there is an urgent need to search for efficient, economical and environmentally friendly catalysts for the valorization of plastic waste to value-added compds. This work describes the reductive depolymn. of several types of plastic waste into value-added compds., including 1,6-hexanediol, 1,2-propanediol, p-xylene and THF, in good yields using the eco-friendly, air-stable, com. available and very cheap catalyst Zn(OAc)2 · 2H2O. This is the first example of the reductive depolymn. of polyester waste catalyzed by a zinc catalyst. Moreover, the catalytic system silane/Zn(OAc)2 · 2H2O was successfully applied to the redn. of polycaprolactone (PCL) on the gram scale with good yield and also to the selective reductive depolymn. of plastic mixts. Finally, this work demonstrated that the catalyst Zn(OAc)2 · 2H2O can be used in at least 7 cycles with good yields.
- 27López-Fonseca, R.; Duque-Ingunza, I.; de Rivas, B. D.; Arnaiz, S.; Gutiérrez-Ortiz, J. I. Chemical Recycling of Post-Consumer PET Wastes by Glycolysis in the Presence of Metal Salts. Polym. Degrad. Stab. 2010, 95, 1022– 1028, DOI: 10.1016/j.polymdegradstab.2010.03.00727https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXlsFCrurg%253D&md5=98706e0420cdf812405847975213be15Chemical recycling of post-consumer PET wastes by glycolysis in the presence of metal saltsLopez-Fonseca, R.; Duque-Ingunza, I.; de Rivas, B.; Arnaiz, S.; Gutierrez-Ortiz, J. I.Polymer Degradation and Stability (2010), 95 (6), 1022-1028CODEN: PDSTDW; ISSN:0141-3910. (Elsevier Ltd.)Chem. recycling of poly(ethylene terephthalate) (PET) has been the subject of increased interest as a valuable feedstock for different chem. processes. In this work, glycolysis of PET waste granules was carried out using excess ethylene glycol in the presence of different simple chems. acting as catalysts, namely zinc acetate, sodium carbonate, sodium bicarbonate, sodium sulfate and potassium sulfate. Comparable high yields (≈70%) of the monomer bis(2-hydroxyethyl terephthalate) were obtained with zinc acetate and sodium carbonate as depolymn. catalysts at 196 °C with a PET:catalyst molar ratio of 100:1 in the presence of a large excess of glycol. The purified monomer was characterized by elemental anal., differential scanning calorimetry, IR spectroscopy, and NMR. The purified monomer was characterized by elemental anal., differential scanning calorimetry, IR spectroscopy, and NMR. Also an exploratory study on the application of this catalytic recycling technol. for complex PET wastes, namely highly colored and multi-layered PET, was performed.
- 28Pham, D. D.; Cho, J. Low-Energy Catalytic Methanolysis of Poly(Ethyleneterephthalate). Green Chem. 2021, 23, 511– 525, DOI: 10.1039/D0GC03536J28https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXisFWrt73I&md5=54474c6ca08c40c435cd6ec1474ceadfLow-energy catalytic methanolysis of poly(ethyleneterephthalate)Pham, Duong Dinh; Cho, JoungmoGreen Chemistry (2021), 23 (1), 511-525CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)Methanolysis is a chem. pathway for depolymg. post-consumer PET plastic waste into monomeric feedstock, which can be utilized as a starting component to produce polymer materials with the same quality as the original polymer or other valuable products. In general, conventional methanolysis is carried out at a high reaction temp. under high pressure, demanding high capital and operating costs and in turn leading to an adverse effect on the environment from CO2 emissions. In this study, we developed a low-energy catalytic route for methanolysis to convert PET resin to di-Me terephthalate (DMT). Potassium carbonate (K2CO3), which is an inexpensive and nontoxic salt, was used as a catalyst, and the effects of cosolvents on the catalytic performance were investigated to develop a new decompn. pathway towards DMT at ambient temp. Compared to existing methanolysis processes, the overall reaction rate of the proposed system was relatively slow and steady, but the PET resins were completely decompd. into monomers within 24 h. Intriguingly, a high selectivity of DMT was obtained at a mild temp. range of 20-35°C. The yield of DMT, obtained by methanolysis at 25°C, was 93.1% as the molar ratios of methanol, dichloromethane and K2CO3 to PET repeating units were 50, 50, and 0.2, resp. In this exptl. setup, the initial molar ratio of moisture to PET repeating units was adjusted to be 0.4. 2-Hydroxyethyl Me terephthalate and monomethyl terephthalate were the major byproducts created during the process. It was demonstrated that the ideal conversion of PET into DMT could be achieved by controlling the moisture level. In addn. to several anal. methods for product characterization, we performed a parametric study to probe the most likely reaction steps and to observe the reaction behavior of PET methanolysis. Based on the proposed mechanism, a kinetic model was developed and compared with the exptl. data to est. kinetic parameters. In the reaction system, PET depolymn. apparently proceeded through two series of reaction steps, and the degrdn. of PET had a relatively low activation energy of 66.5 kJ mol-1, which was accountable for catalytic methanolysis of PET at ambient conditions.
- 29Bäckström, E.; Odelius, K.; Hakkarainen, M. Ultrafast Microwave Assisted Recycling of PET to a Family of Functional Precursors and Materials. Eur. Polym. J. 2021, 151, 110441, DOI: 10.1016/j.eurpolymj.2021.110441There is no corresponding record for this reference.
- 30Fukushima, K.; Lecuyer, J. M.; Wei, D. S.; Horn, H. W.; Jones, G. O.; Al-Megren, H. A.; Alabdulrahman, A. M.; Alsewailem, F. D.; McNeil, M. A.; Rice, J. E.; Hedrick, J. L. Advanced Chemical Recycling of Poly(Ethylene Terephthalate) through Organocatalytic Aminolysis. Polym. Chem. 2013, 4, 1610– 1616, DOI: 10.1039/C2PY20793A30https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXit1Wju7o%253D&md5=7fadbc098571fe3762b730a509b07522Advanced chemical recycling of poly(ethylene terephthalate) through organocatalytic aminolysisFukushima, Kazuki; Lecuyer, Julien M.; Wei, Di S.; Horn, Hans W.; Jones, Gavin O.; Al-Megren, Hamid A.; Alabdulrahman, Abdullah M.; Alsewailem, Fares D.; McNeil, Melanie A.; Rice, Julia E.; Hedrick, James L.Polymer Chemistry (2013), 4 (5), 1610-1616CODEN: PCOHC2; ISSN:1759-9962. (Royal Society of Chemistry)We report the effective organocatalysis of the aminolytic depolymn. of waste poly(ethylene terephthalate) (PET) using 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) producing a broad range of cryst. terephthalamides. This diverse set of monomers possesses great potential as building blocks for high performance materials with desirable thermal and mech. properties deriving from the terephthalic moiety and amide hydrogen bonding. Further, a computational study established mechanistic insight into self-catalyzed and organocatalyzed aminolysis of terephthalic esters, suggesting that the bifunctionality of TBD particularly concerning activation of the carbonyl group differentiates TBD from other org. bases.
- 31Fuentes, J. A.; Smith, S. M.; Scharbert, M. T.; Carpenter, I.; Cordes, D. B.; Slawin, A. M. Z.; Clarke, M. L. On the Functional Group Tolerance of Ester Hydrogenation and Polyester Depolymerisation Catalysed by Ruthenium Complexes of Tridentate Aminophosphine Ligands. Chem.─Eur. J. 2015, 21, 10851– 10860, DOI: 10.1002/chem.20150090731https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2MXhtVegsbjJ&md5=781ca270445f37645aaf0e9d42c8917aOn the Functional Group Tolerance of Ester Hydrogenation and Polyester Depolymerisation Catalysed by Ruthenium Complexes of Tridentate Aminophosphine LigandsFuentes, Jose A.; Smith, Samuel M.; Scharbert, M. Theresa; Carpenter, Ian; Cordes, David B.; Slawin, Alexandra M. Z.; Clarke, Matthew L.Chemistry - A European Journal (2015), 21 (30), 10851-10860CODEN: CEUJED; ISSN:0947-6539. (Wiley-VCH Verlag GmbH & Co. KGaA)The synthesis of a range of phosphine-diamine, phosphine-amino-alc., and phosphine-amino-amide ligands and their ruthenium(II) complexes are reported. Five of these were characterized by X-ray crystallog. The activities of this collection of catalysts were initially compared for the hydrogenation of two model ester hydrogenations. Catalyst turnover frequencies up to 2400 h-1 were obsd. at 85 °C. However, turnover is slow at near ambient temps. By using a phosphine-diamine RuII complex, identified as the most active catalyst, a range of arom. esters were reduced in high yield. The hydrogenation of alkene-, diene-, and alkyne-functionalized esters was also studied. Substrates with a remote, but reactive terminal alkene substituent could be reduced chemoselectively in the presence of 4-dimethylaminopyridine (DMAP) co-catalyst. The chemoselective redn. of the ester function in conjugated dienoate Et sorbate could deliver (2E,4E)-hexa-2,4-dien-1-ol, a precursor to leaf alc. The monounsatd. alc. (E)-hex-4-en-1-ol was produced with reasonable selectivity, but complete chemoselectivity of C=O over the diene is elusive. High chemoselectivity for the redn. of an ester over an alkyne group was obsd. in the hydrogenation of an alkynoate for the first time. The catalysts were also active in the depolymn. redn. of samples of waste poly(ethylene terephthalate) (PET) to produce benzene dimethanol. These depolymns. were found to be poisoned by the ethylene glycol side product, although good yields could still be achieved.
- 32Westhues, S.; Idel, J.; Klankermayer, J. Molecular Catalyst Systems as Key Enablers for Tailored Polyesters and Polycarbonate Recycling Concepts. Sci. Adv. 2018, 4, eaat9669 DOI: 10.1126/sciadv.aat9669There is no corresponding record for this reference.
- 33Krall, E. M.; Klein, T. W.; Andersen, R. J.; Reader, D. S.; Dauphinais, B. C.; McIlrath, S. P.; Fischer, A. A.; Carney, M. J.; Robertson, N. J. Controlled Hydrogenative Depolymerization of Polyesters and Polycarbonates Catalyzed by Ruthenium(II) PNN Pincer Complexes. Chem. Commun. 2014, 50, 4884– 4887, DOI: 10.1039/C4CC00541D33https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC2cXmtlersbY%253D&md5=ecb8abdb75244ee34f593c4cb7e3cb2bControlled hydrogenative depolymerization of polyesters and polycarbonates catalyzed by ruthenium(II) PNN pincer complexesKrall, Eric M.; Klein, Tyler W.; Andersen, Ryan J.; Nett, Alex J.; Glasgow, Ryley W.; Reader, Diana S.; Dauphinais, Brian C.; McIlrath, Sean P.; Fischer, Anne A.; Carney, Michael J.; Hudson, Dylan J.; Robertson, Nicholas J.Chemical Communications (Cambridge, United Kingdom) (2014), 50 (38), 4884-4887CODEN: CHCOFS; ISSN:1359-7345. (Royal Society of Chemistry)Ruthenium(II) PNN complexes depolymerize many polyesters into diols and polycarbonates into glycols plus methanol via hydrogenation. Notably, polyesters with two methylene units between ester linkages depolymerize to carboxylic acids rather than diols. This methodol. represents a new approach for producing useful chems. from waste plastics.
- 34Nunes, B. F. S.; Oliveira, M. C.; Fernandes, A. C. Dioxomolybdenum Complex as an Efficient and Cheap Catalyst for the Reductive Depolymerization of Plastic Waste into Value-Added Compounds and Fuels. Green Chem. 2020, 22, 2419– 2425, DOI: 10.1039/C9GC04206G34https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXkt1OqtLo%253D&md5=fcc5be7ccdd534df86227522931773d3Dioxomolybdenum complex as an efficient and cheap catalyst for the reductive depolymerization of plastic waste into value-added compounds and fuelsNunes, Beatriz F. S.; Oliveira, M. Conceicao; Fernandes, Ana C.Green Chemistry (2020), 22 (8), 2419-2425CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)This work describes the efficient and selective reductive depolymn. of PET, PBT, PCL, PLA and PDO plastic waste into value-added compds. and fuels, including 1,6-hexanediol, xylene and propane, catalyzed by the eco-friendly, cheap and air-stable dioxomolybdenum complex MoO2Cl2(H2O)2 using silanes as reducing agents. The catalyst MoO2Cl2(H2O)2 can be used in at least 8 catalytic cycles in the reductive depolymn. of PCL with excellent activity and the catalytic system PMHS/MoO2Cl2(H2O)2 was successfully applied in the prodn. of propane from the reductive depolymn. of PLA on a gram scale. Moreover, this method was also efficiently applied in the selective redn. of a PCL, PLA and PET mixt.
- 35Jehanno, C.; Demarteau, J.; Mantione, D.; Arno, M. C.; Ruipérez, F.; Hedrick, J. L.; Dove, A. P.; Sardon, H. Selective Chemical Upcycling of Mixed Plastics Guided by a Thermally Stable Organocatalyst. Angew. Chem., Int. Ed. 2021, 60, 6710– 6717, DOI: 10.1002/anie.20201486035https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXjvVCktbc%253D&md5=a3497d9b5ad950e1fd66d835c2277648Selective Chemical Upcycling of Mixed Plastics Guided by a Thermally Stable OrganocatalystJehanno, Coralie; Demarteau, Jeremy; Mantione, Daniele; Arno, Maria C.; Ruiperez, Fernando; Hedrick, James L.; Dove, Andrew P.; Sardon, HaritzAngewandte Chemie, International Edition (2021), 60 (12), 6710-6717CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)Chem. recycling of plastic waste represents a greener alternative to landfill and incineration, and potentially offers a soln. to the environmental consequences of increased plastic waste. Most plastics that are widely used today are designed for durability, hence currently available depolymn. methods typically require harsh conditions and when applied to blended and mixed plastic feeds generate a mixt. of products. Herein, we demonstrate that the energetic differences for the glycolysis of BPA-PC and PET in the presence of a protic ionic salt TBD:MSA catalyst enables the selective and sequential depolymn. of these two commonly employed polymers. Employing the same procedure, functionalized cyclic carbonates can be obtained from both mixed plastic wastes and industrial polymer blend. This methodol. demonstrates that the concept of catalytic depolymn. offers great potential for selective polymer recycling and also presents plastic waste as a "greener" alternative feedstock for the synthesis of high added value mols.
- 36Zhang, X.; Chen, Y.; Ye, M.; Wu, J.; Wang, H. Biodegradable Copolyesters with Unexpected Highly Blocky Microstructures and Enhanced Thermal Properties. ACS Sustainable Chem. Eng. 2022, 10, 4438– 4450, DOI: 10.1021/acssuschemeng.1c0799336https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XosFeqtL0%253D&md5=c598bc4d8ddbec9124e9b8aa94e2079cBiodegradable Copolyesters with Unexpected Highly Blocky Microstructures and Enhanced Thermal PropertiesZhang, Xu; Chen, Yong; Ye, Mengting; Wu, Jing; Wang, HuapingACS Sustainable Chemistry & Engineering (2022), 10 (14), 4438-4450CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)To synthesize novel biodegradable polyesters with high heat resistance and good crystn. capability, we designed a series of aliph.-arom. copolyesters, i.e., poly(isoidide-2,5-dimethylene adipate-co-terephthalate)s (PIATs) based on isoidide-2,5-dimethanol (IIDML), a rigid carbohydrate-based building block. The Mn values and intrinsic viscosities of PIAT copolyesters contg. up to 40 mol % arom. moieties are in the range of 6 000-19 000 g·mol-1 and 0.5-0.87 dL·g-1, resp. Interestingly, the products were obtained as blocky copolymers after the one-pot melt polycondensation process because of the thermodn. equil. of IIDML moieties driven by the insufficient thermal stability of the IIDML moieties. In addn., all the copolyesters are semicryst. with crystallinity from 28% to 55% and tunable Tm values ranging from 88°C to a remarkable 189°C. They exhibit better (bio)degradability than the same type of polyesters. This work shows that this green monomer plays a key role in balancing thermal properties (esp. Tg) and (bio)degradability, and these polyesters potentially broaden the application toward, for example, fibers.
- 37Guo, B.; Vanga, S. R.; Lopez-Lorenzo, X.; Saenz-Mendez, P.; Ericsson, S. R.; Fang, Y.; Ye, X.; Schriever, K.; Bäckström, E.; Biundo, A.; Zubarev, R. A.; Furó, I.; Hakkarainen, M.; Syrén, P. O. Conformational Selection in Biocatalytic Plastic Degradation by PETase. ACS Catal. 2022, 12, 3397– 3409, DOI: 10.1021/acscatal.1c0554837https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XltFehs78%253D&md5=0732543ed139b9fd36a771245bfd3db6Conformational Selection in Biocatalytic Plastic Degradation by PETaseGuo, Boyang; Vanga, Sudarsana Reddy; Lopez-Lorenzo, Ximena; Saenz-Mendez, Patricia; Ericsson, Sara Roennblad; Fang, Yuan; Ye, Xinchen; Schriever, Karen; Baeckstroem, Eva; Biundo, Antonino; Zubarev, Roman A.; Furo, Istvan; Hakkarainen, Minna; Syren, Per-OlofACS Catalysis (2022), 12 (6), 3397-3409CODEN: ACCACS; ISSN:2155-5435. (American Chemical Society)Due to the steric effects imposed by bulky polymers, the formation of catalytically competent enzyme and substrate conformations is crit. in the biodegrdn. of plastics. In poly(ethylene terephthalate) (PET), the backbone adopts different conformations, gauche and trans, coexisting to different extents in amorphous and cryst. regions. However, which conformation is susceptible to biodegrdn. and the extent of enzyme and substrate conformational changes required for expedient catalysis remain poorly understood. To overcome this obstacle, we utilized mol. dynamics simulations, docking, and enzyme engineering in concert with high-resoln. microscopy imaging and solid-state NMR to demonstrate the importance of conformational selection in biocatalytic plastic hydrolysis. Our results demonstrate how single-amino acid substitutions in Ideonella sakaiensis PETase can alter its conformational landscape, significantly affecting the relative abundance of productive ground-state structures ready to bind discrete substrate conformers. We exptl. show how an enzyme binds to plastic and provide a model for key residues involved in the recognition of gauche and trans conformations supported by in silico simulations. We demonstrate how enzyme engineering can be used to create a trans-selective variant, resulting in higher activity when combined with an all-trans PET-derived oligomeric substrate, stemming from both increased accessibility and conformational preference. Our work cements the importance of matching enzyme and substrate conformations in plastic hydrolysis, and we show that also the noncanonical trans conformation in PET is conducive for degrdn. Understanding the contribution of enzyme and substrate conformations to biocatalytic plastic degrdn. could facilitate the generation of designer enzymes with increased performance.
- 38Attallah, O. A.; Janssens, A.; Azeem, M.; Fournet, M. B. Fast, High Monomer Yield from Post-Consumer Polyethylene Terephthalate via Combined Microwave and Deep Eutectic Solvent Hydrolytic Depolymerization. ACS Sustainable Chem. Eng. 2021, 9, 17174– 17185, DOI: 10.1021/acssuschemeng.1c0715938https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXis12ksbrK&md5=4a5a53f30db9d86557236cab1d479963Fast, High Monomer Yield from Post-consumer Polyethylene Terephthalate via Combined Microwave and Deep Eutectic Solvent Hydrolytic DepolymerizationAttallah, Olivia A.; Janssens, Arno; Azeem, Muhammad; Fournet, Margaret BrennanACS Sustainable Chemistry & Engineering (2021), 9 (50), 17174-17185CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)Efficient low carbon foot print methods are crit. to achieving circularity for the dominant post-consumer plastic polyethylene terephthalate (PET). In a strong sustainability advancement over previous technologies, depolymn. of waste PET bottles was performed using a dissoln./degrdn. approach optimized in accordance with polymer mech. parameter inter-relationships. A dual functioning deep eutectic solvent (DES), comprising m-cresol and choline chloride, served as both the solubilizing and catalyzing agent for alk. hydrolysis of PET using high energy efficiency microwave (MW) irradn. The PET depolymn. process was optimized using Box-Behnken design while tailoring the DES vol., concn. of the depolymg. agent (sodium hydroxide), and MW irradn. time as independent variables. The percentage PET wt. loss as high as 84% was obtained using 15 mL of DES contg. 10% (w/v) NaOH under 90 s MW irradn. Simple, cost-effective purifn. steps were afforded by the DES's advantageous physicochem. nature and were implemented to provide the terephthalic acid (TPA) monomer with acceptable yield. Validation of the PET depolymn. and identification of obtained monomers were carried out by a range of characterization techniques including FTIR, NMR, DSC, and HPLC. Post-consumer PET bottle depolymn. was evaluated, and a 91.55% TPA monomer yield ready for repolymn. as virgin PET demonstrates the high potential market application of this low energy, low carbon solvent virgin to virgin approach to PET circularity.
- 39Jönsson, C.; Wei, R.; Biundo, A.; Landberg, J.; Schwarz Bour, L.; Pezzotti, F.; Toca, A.; Jacques, L. M.; Syrén, U. T.; Syrén, P. O. Biocatalysis in the Recycling Landscape for Synthetic Polymers and Plastics towards Circular Textiles. ChemSusChem 2021, 14, 4028– 4040, DOI: 10.1002/cssc.20200266639https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A280%3ADC%252BB3srltlGrtA%253D%253D&md5=445f4ced56426741ce19c03f34a5e3e7Biocatalysis in the Recycling Landscape for Synthetic Polymers and Plastics towards Circular TextilesJonsson Christina; Landberg Johan; Schwarz Bour Lisa; Pezzotti Fabio; Wei Ren; Bornscheuer Uwe T; Biundo Antonino; Syren Per-Olof; Biundo Antonino; Syren Per-Olof; Biundo Antonino; Toca Andreea; Toca Andreea; M Jacques Les; Syren Per-OlofChemSusChem (2021), 14 (19), 4028-4040 ISSN:.Although recovery of fibers from used textiles with retained material quality is desired, separation of individual components from polymer blends used in today's complex textile materials is currently not available at viable scale. Biotechnology could provide a solution to this pressing problem by enabling selective depolymerization of recyclable fibers of natural and synthetic origin, to isolate constituents or even recover monomers. We compiled experimental data for biocatalytic polymer degradation with a focus on synthetic polymers with hydrolysable links and calculated conversion rates to explore this path The analysis emphasizes that we urgently need major research efforts: beyond cellulose-based fibers, biotechnological-assisted depolymerization of plastics so far only works for polyethylene terephthalate, with degradation of a few other relevant synthetic polymer chains being reported. In contrast, by analyzing market data and emerging trends for synthetic fibers in the textile industry, in combination with numbers from used garment collection and sorting plants, it was shown that the use of difficult-to-recycle blended materials is rapidly growing. If the lack of recycling technology and production trend for fiber blends remains, a volume of more than 3400 Mt of waste will have been accumulated by 2030. This work highlights the urgent need to transform the textile industry from a biocatalytic perspective.
- 40Burford, T.; Rieg, W.; Madbouly, S. Biodegradable Poly(Butylene Adipate-Co-Terephthalate) (PBAT). Phys. Sci. Rev. 2021, 000010151520200078, DOI: 10.1515/psr-2020-0078There is no corresponding record for this reference.
- 41Fu, Y.; Wu, G.; Bian, X.; Zeng, J.; Weng, Y. Biodegradation Behavior of Poly(Butylene Adipate-Co-Terephthalate) (PBAT), Poly(Lactic Acid) (PLA), and Their Blend in Freshwater with Sediment. Molecules 2020, 25, 3946, DOI: 10.3390/molecules2517394641https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhvVeju7nE&md5=f3f72e29a53f45b9b6ae158adeca4728Biodegradation Behavior of Poly(Butylene Adipate-Co-Terephthalate) (PBAT), Poly(Lactic Acid)(PLA), and Their Blend in Freshwater with SedimentFu, Ye; Wu, Gang; Bian, Xinchao; Zeng, Jianbing; Weng, YunxuanMolecules (2020), 25 (17), 3946CODEN: MOLEFW; ISSN:1420-3049. (MDPI AG)Poly(butylene adipate-co-terephthalate) (PBAT) and poly(lactic acid) (PLA) are well-known biodegadable polyesters due to their outstanding performance. The biodegrdn. behavior of PLA/PBAT blends in freshwater with sediment is investigated in this study by analyzing the appearance, chem. structure and aggregation structure of their degraded residues via SEM, TG, DSC, gel permeation chromatog. (GPC) and XPS. The effect of aggregation structure, hydrophilia and biodegrdn. mechanisms of PBAT and PLA on the biodegradability of PLA/PBAT blends is illuminated in this work. After biodegrdn., the butylene terephthalate unit in the mol. structure of the components and the mol. wt. of PLA/PBAT blends decreased, while the content of C-O bond in the composites increased, indicating that the samples indeed degraded. After 24 mo of degrdn., the increase in the relative peak area proportion of C-O to C=O in PLA/PBAT-25, PLA/PBAT-50 and PLA/PBAT-75 was 62%, 46% and 68%, resp. The biodegrdn. rates of PBAT and PLA in the PLA/PBAT blend were lower than those for the resp. single polymers.
- 42Ellingford, C.; Samantaray, P. K.; Farris, S.; McNally, T.; Tan, B.; Sun, Z.; Huang, W.; Ji, Y.; Wan, C. Reactive Extrusion of Biodegradable PGA/PBAT Blends to Enhance Flexibility and Gas Barrier Properties. J. Appl. Polym. Sci. 2022, 139, 51617, DOI: 10.1002/app.5161742https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXitVSjsr%252FM&md5=348d7709591da81309f4745fe175646aReactive extrusion of biodegradable PGA / PBAT blends to enhance flexibility and gas barrier propertiesEllingford, Christopher; Samantaray, Paresh Kumar; Farris, Stefano; McNally, Tony; Tan, Bowen; Sun, Zhaoyang; Huang, Weijie; Ji, Yang; Wan, ChaoyingJournal of Applied Polymer Science (2022), 139 (6), 51617CODEN: JAPNAB; ISSN:0021-8995. (John Wiley & Sons, Inc.)Among com. biodegradable polyesters, poly(glycolic acid) (PGA) has been rarely investigated for packaging applications, despite its unique advantages such as 100% compostability, high degree of crystallinity, high thermal stability and high gas barrier properties. The application of PGA has been limited by its mech. brittleness, moisture sensitivity, and high melting temp. (∼240°C), restricting its processing and applications for film packaging. In this study, PGA was modified by blending with poly (butylene adipate-co-terephthalate) (PBAT) via melt-extrusion. A com. terpolymer of ethylene, acrylic ester and glycidyl methacrylate (EMA-GMA) was selected for compatibilization. The phase morphol., rheol., thermal, mech. and gas barrier properties of the blends were investigated. With addn. of 20 wt. % EMA-GMA, the elongation of PGA/PBAT (50/50 wt. %) blends was improved from 10.7% to 145%, the oxygen permeability was reduced from 125 to 103 (cm3 mm)/(m2 24 h atm), and the water vapor barrier performance was improved by ∼47%. The enhancement in ductility, oxygen and water vapor barrier properties of the flexible blends were ascribed to the interfacial bonding between PBAT and PGA enabled by EMA-GMA. The compatibilized PGA/PBAT blends with high thermal stability up to 300°C are preferable for high temp. or hot food packaging.
- 43Sangroniz, A.; Sangroniz, L.; Gonzalez, A.; Santamaria, A.; del Rio, J.; Iriarte, M.; Etxeberria, A. Improving the Barrier Properties of a Biodegradable Polyester for Packaging Applications. Eur. Polym. J. 2019, 115, 76– 85, DOI: 10.1016/j.eurpolymj.2019.03.02643https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXltFCns7s%253D&md5=e8f1521a697cb54d93764ccbe5a6dfeaImproving the barrier properties of a biodegradable polyester for packaging applicationsSangroniz, Ainara; Sangroniz, Leire; Gonzalez, Alba; Santamaria, Antxon; del Rio, Javier; Iriarte, Marian; Etxeberria, AgustinEuropean Polymer Journal (2019), 115 (), 76-85CODEN: EUPJAG; ISSN:0014-3057. (Elsevier Ltd.)Miscible and thermally stable blends of biodegradable poly(butylene adipate-co-terephthalate) (PBAT) with poly(hydroxy ether of bisphenol A) (PH) are investigated to obtain membranes for packaging applications. Previously the miscibility and adequate degradability of these blends was proven, therefore this system is a good candidate for packaging applications. The crystallinity degree and the free vol., both of crucial importance in transport properties, are analyzed as a function of blend compn. The transport properties to different gases and vapors are greatly reduced with the addn. of PH. The blends show high elongational viscosity values, which allows expecting good film processability. Overall, this work sheds light on the factors involved in the redn. of permeability which would allow to broaden this strategy to other promising biodegradable materials.
- 44Williams, C. K. Synthesis of Functionalized Biodegradable Polyesters. Chem. Soc. Rev. 2007, 36, 1573– 1580, DOI: 10.1039/B614342N44https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXpsVKitrc%253D&md5=b6ae103b4746f94b18fab4347eeb2db5Synthesis of functionalized biodegradable polyestersWilliams, Charlotte K.Chemical Society Reviews (2007), 36 (10), 1573-1580CODEN: CSRVBR; ISSN:0306-0012. (Royal Society of Chemistry)This tutorial review summarizes recent developments in the syntheses of functionalized aliph. polyesters. These polymers are attracting attention as sustainable alternatives to petrochems. and for applications in medicine. Two main syntheses are described: step polymn. using mild chemo/enzymic catalysis and ring opening polymn., which is usually initiated by metal complexes. The methods are compared and their utility illustrated with ref. to interesting new materials.
- 45Stamm, A.; Öhlin, J.; Mosbech, C.; Olsén, P.; Guo, B.; Söderberg, E.; Biundo, A.; Fogelström, L.; Bhattacharyya, S.; Bornscheuer, U. T.; Malmström, E.; Syrén, P.-O. Pinene-Based Oxidative Synthetic Toolbox for Scalable Polyester Synthesis. JACS Au 2021, 1, 1949– 1960, DOI: 10.1021/jacsau.1c0031245https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXitFymsbrJ&md5=130a0b64c8f6765d93d8811bc53109b1Pinene-based oxidative synthetic toolbox for scalable polyester synthesisStamm, Arne; Oehlin, Johannes; Mosbech, Caroline; Olsen, Peter; Guo, Boyang; Soederberg, Elisabeth; Biundo, Antonino; Fogelstroem, Linda; Bhattacharyya, Shubhankar; Bornscheuer, Uwe T.; Malmstroem, Eva; Syren, Per-OlofJACS Au (2021), 1 (11), 1949-1960CODEN: JAAUCR; ISSN:2691-3704. (American Chemical Society)Generation of renewable polymers is a long-standing goal toward reaching a more sustainable society . Herein we show how conceptually simple oxidative transformations can be used to unlock the inherent reactivity of terpene synthons in generating polyesters by two different mechanisms starting from the same α-pinene substrate. In the first pathway, α-pinene was oxidized into the bicyclic verbanone based lactone (VaL) and subsequently polymd. into star-shaped polymers via ring-opening polymn., resulting in a biobased semicryst. polyester with tunable glass transition and melting temps. In a second pathway, polyesters were synthesized via polycondensation, utilizing the diol (1-(1'-hydroxyethyl)-3-(2'-hydroxyethyl)-2,2-dimethylcyclobutane (HHDC)) synthesized by oxidative cleavage of the double bond of α-pinene, together with unsatd. biobased diesters such as di-Me maleate (DMM) and di-Me itaconate (DMI), resp. The resulting families of terpene-based polyesters were thereafter successfully crosslinked by either transetherification, utilizing the terminal hydroxyl groups of the synthesized verbanone-based materials, or by UV-irradn., utilizing the unsatn. provided by the DMM or DMI moieties within the HHDC-based copolymers. This work highlights the potential to apply an oxidative toolbox to valorize inert terpene metabolites enabling generation of bio sourced polyesters and coatings thereof by complementary mechanisms.
- 46Meereboer, K. W.; Misra, M.; Mohanty, A. K. Review of Recent Advances in the Biodegradability of Polyhydroxyalkanoate (PHA) Bioplastics and Their Composites. Green Chem. 2020, 22, 5519– 5558, DOI: 10.1039/D0GC01647K46https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhs1SgsbnK&md5=3f5a40015aba4e142378bb09928d3b33Review of recent advances in the biodegradability of polyhydroxyalkanoate (PHA) bioplastics and their compositesMeereboer, Kjeld W.; Misra, Manjusri; Mohanty, Amar K.Green Chemistry (2020), 22 (17), 5519-5558CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)A review. The detrimental impact of single-use plastics on the environment is daily news across the globe. Single-use plastic packaging materials and other plastic waste originating from petroleum-based sources are continuously building up in landfills and leaching into the environment. Managing plastic waste remains an urgent crisis in the environment and switching to biodegradable plastics can help mitigate some of these issues. This review will summarize recent advances and opportunities to utilize polyhydroxyalkanoates (PHAs) as a biodegradable substitute in some applications where non-biodegradable and petroleum-based plastics are currently used. PHAs are a well-known family of bacteria-based biodegradable plastics and offer an approach to carbon neutrality and support a more sustainable industry. PHAs such as poly(3-hydroxybutyrate) (PHB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) show biodegradable behavior in all aerobic and anaerobic environments defined by ASTM stds., and can be used to make completely compostable, and soil and marine biodegradable products - a strong pos. compared to the negativity assocd. with the landfilling of plastics. However, PHAs are relatively expensive compared to petroleum-based alternatives. To reduce the cost, PHAs can be used in biocomposite materials, where bio-based agro-residues are incorporated, while maintaining the performance in certain applications. Org. fillers and fibers composed of cellulosic material can improve the properties of polymers, however, their effect on the marine biodegradable properties of the composite matrix remains an unexplored area. When used in biocomposites with PHAs, they improve biodegrdn. rates in all environments. In addn. to cellulose, other bio-based fillers such as proteins (i.e. distillers dried grains with solubles) and starch have been reported to significantly improve soil and marine biodegradability rates compared to other fibers and fillers. Other components that affect biodegradability are additives (i.e. chain extenders) and compatibilizers (i.e. maleic anhydride etc.) that are added to optimize the service life properties, but are reported to inhibit the biodegrdn. properties by impacting the hydrophilicity of the polymer and enzyme activity. The multitude of possible combinations of polymers and fillers and fibers, and their effect on the biodegrdn. of PHA-based biocomposites are a largely unexplored frontier. The potential benefits of PHA-based biocomposites make a strong case for further research into this area.
- 47Vu, D. H.; Åkesson, D.; Taherzadeh, M. J.; Ferreira, J. A. Recycling Strategies for Polyhydroxyalkanoate-Based Waste Materials: An Overview. Bioresour. Technol. 2020, 298, 122393, DOI: 10.1016/j.biortech.2019.12239347https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXit1GmtLvN&md5=f5826a3b78c2953c571cd7b1e0a1a19fRecycling strategies for polyhydroxyalkanoate-based waste materials: An overviewVu, Danh H.; Aakesson, Dan; Taherzadeh, Mohammad J.; Ferreira, Jorge A.Bioresource Technology (2020), 298 (), 122393CODEN: BIRTEB; ISSN:0960-8524. (Elsevier Ltd.)A review. The plastics market is dominated by fossil-based polymers, but their gradual replacement by bioplastics (e.g., polyhydroxyalkanoates) is occurring. However, recycling strategies need to be developed to truly unveil the impact of bioplastics on waste accumulation. This review provides a state of the art of recycling strategies investigated for polyhydroxyalkanoate-based polymers and proposes future research avenues. Research on mech. and chem. recycling is dominated by the use of extrusion and pyrolysis, resp., while that on biodegrdn. of polyhydroxyalkanoates is related to soil and aquatic samples, and to anaerobic digestion towards biogas prodn. Research gaps exist in the relationships between polymer compn. and ease of use of all recycling strategies investigated. This is of utmost importance since it will influence the need for sepn. at the source. Therefore, research emphasis needs to be given to the area to follow the continuous improvement of the process economics towards widespread com. prodn. of polyhydroxyalkanoates.
- 48Muiruri, J. K.; Yeo, J. C. C.; Zhu, Q.; Ye, E.; Loh, X. J.; Li, Z. Poly(Hydroxyalkanoates): Production, Applications and End-of-Life Strategies-Life Cycle Assessment Nexus. ACS Sustainable Chem. Eng. 2022, 10, 3387– 3406, DOI: 10.1021/acssuschemeng.1c0863148https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XmsFeisb8%253D&md5=dc154188d609c228c5291ed5d5f88d1dPoly(hydroxyalkanoates): Production, Applications and End-of-Life Strategies-Life Cycle Assessment NexusMuiruri, Joseph Kinyanjui; Yeo, Jayven Chee Chuan; Zhu, Qiang; Ye, Enyi; Loh, Xian Jun; Li, ZibiaoACS Sustainable Chemistry & Engineering (2022), 10 (11), 3387-3406CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)A review. The runaway prodn. and consumption of oil-based plastics are key drivers of global warming and the increased carbon footprint. Besides, most of this plastic debris ends up in the oceans and constitutes about 80% of all marine debris. This pollution problem calls for a seismic shift to eco-friendly plastics and marine biodegradable ones. Unlike other biobased polymers, polyhydroxyalkanoates (PHAs) take pride in their degrdn. in soil and marine environments. This intriguing marine biodegrdn. property of PHAs sets it apart as the best choice to curb microplastics, particularly in marine ecosystems. PHAs have also grown in popularity due to other quintessential properties such as biocompatibility, structural variety, and similarity to conventional plastics in terms of phys. properties. PHAs are being widely researched for various applications, including packaging, medical, energy, and agriculture. This review comprehensively focuses on the state-of-art prodn. and applications of PHA plastics, as well as the practical recycling strategies for postconsumer PHAs. The innovative 'next generation industrial biotechnol.' (NGIB) is well covered in this review. Moreover, the nexus between end-of-life strategies and life cycle assessment (LCA) of PHAs waste is elucidated to understand its impact on the environment thoroughly.
- 49Hatti-Kaul, R.; Nilsson, L. J.; Zhang, B.; Rehnberg, N.; Lundmark, S. Designing Biobased Recyclable Polymers for Plastics. Trends Biotechnol. 2020, 38, 50– 67, DOI: 10.1016/j.tibtech.2019.04.01149https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXpsVOrsL0%253D&md5=62433dbccdb763f36a131c834b8ec7d8Designing Biobased Recyclable Polymers for PlasticsHatti-Kaul, Rajni; Nilsson, Lars J.; Zhang, Baozhong; Rehnberg, Nicola; Lundmark, StefanTrends in Biotechnology (2020), 38 (1), 50-67CODEN: TRBIDM; ISSN:0167-7799. (Elsevier Ltd.)Several concurrent developments are shaping the future of plastics. A transition to a sustainable plastics system requires not only a shift to fossil-free feedstock and energy to produce the carbon-neutral building blocks for polymers used in plastics, but also a rational design of the polymers with both desired material properties for functionality and features facilitating their recyclability. Biotechnol. has an important role in producing polymer building blocks from renewable feedstocks, and also shows potential for recycling of polymers. Here, we present strategies for improving the performance and recyclability of the polymers, for enhancing degradability to monomers, and for improving chem. recyclability by designing polymers with different chem. functionalities.
- 50Coates, G. W.; Getzler, Y. D. Y. L. Chemical Recycling to Monomer for an Ideal, Circular Polymer Economy. Nat. Rev. Mater. 2020, 5, 501– 516, DOI: 10.1038/s41578-020-0190-450https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXntVOmt7Y%253D&md5=ce62cb9ab02615ebcde8b8dd674aa252Chemical recycling to monomer for an ideal, circular polymer economyCoates, Geoffrey W.; Getzler, Yutan D. Y. L.Nature Reviews Materials (2020), 5 (7), 501-516CODEN: NRMADL; ISSN:2058-8437. (Nature Research)Abstr.: The majority of post-consumer plastic waste is not recycled. Impediments to the recycling of commodity polymers include sepn., impurities and degrdn. of the macromol. structures, all of which can neg. affect the properties of recycled materials. An attractive alternative is to transform polymers back into monomers and purify them for repolymn. - a form of chem. recycling we term chem. recycling to monomer (CRM). Material recycled in this way exhibits no loss in properties, creating an ideal, circular polymer economy. This Review presents our vision for realizing a circular polymer economy based on CRM. We examine the energetics of polymn. and other challenges in developing practical and scalable CRM processes. We briefly review attempts to achieve CRM with commodity polymers, including through polyolefin thermolysis and nylon 6 ring-closing depolymn., and closely examine the recent flourishing of CRM with new-to-the-world polymers. The benefits of heterocycle ring-opening polymn. are discussed in terms of synthetic control and kinetically accessible polymer-backbone functionality. Common chem. and structural characteristics of CRM-compatible ring-opening-polymn. monomers are identified, and the properties, benefits and liabilities of these recyclable polymers are discussed. We conclude with our perspective on the ideals and opportunities for the field.
- 51Odegard, I.; Nusselder, S.; Roos Lindgreen, E.; Bergsma, G.; de Graaff, L. Biobased Plastics in a Circular Economy Policy─Policy Suggestions for Biobased and Biobased Biodegradable Plastics. 2017, https://cedelft.eu/publications/biobased-plastics-in-a-circular-economy/ (accessed Jan 11, 2023).There is no corresponding record for this reference.
- 52Carus, M.; Dammer, L. The “Circular Bioeconomy”-Concepts, Opportunities and Limitations. 2018, https://renewable-carbon.eu/publications/product/nova-paper-9-the-circular-bioeconomy-concepts-opportunities-and-limitations-%e2%88%92-full-version/ (accessed Jan 11, 2023).There is no corresponding record for this reference.
- 53Shevchenko, T.; Ranjbari, M.; Shams Esfandabadi, Z. S.; Danko, Y.; Bliumska-Danko, K. Promising Developments in Bio-Based Products as Alternatives to Conventional Plastics to Enable Circular Economy in Ukraine. Recycling 2022, 7, 20, DOI: 10.3390/recycling7020020There is no corresponding record for this reference.
- 54Haider, T. P.; Völker, C.; Kramm, J.; Landfester, K.; Wurm, F. R. Plastics of the Future? The Impact of Biodegradable Polymers on the Environment and on Society. Angew. Chem., Int. Ed. 2019, 58, 50– 62, DOI: 10.1002/anie.20180576654https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXitFGgtL3J&md5=0e9547e37a9ce5cccb5cda51b8485a09Plastics of the Future? The Impact of Biodegradable Polymers on the Environment and on SocietyHaider, Tobias P.; Voelker, Carolin; Kramm, Johanna; Landfester, Katharina; Wurm, Frederik R.Angewandte Chemie, International Edition (2019), 58 (1), 50-62CODEN: ACIEF5; ISSN:1433-7851. (Wiley-VCH Verlag GmbH & Co. KGaA)A review is given. In recent years the littering of plastics and the problems related to their persistence in the environment have become a major focus in both research and the news. Biodegradable polymers like poly(lactic acid) are seen as a suitable alternative to commodity plastics. However, poly(lactic acid) is basically non-degradable in seawater. Similarly, the degrdn. rate of other biodegradable polymers also crucially depends on the environments they end up in, such as soil or marine water, or when used in biomedical devices. Here, we show that biodegrdn. tests carried out in artificial environments lack transferability to real conditions and, therefore, highlight the necessity of environmentally authentic and relevant field-testing conditions. We focus on ecotoxicol. implications of biodegradable polymers. We also consider the social aspects and ask how biodegradable polymers influence consumer behavior and municipal waste management. Taken together, this study is intended as a contribution towards evaluating the potential of biodegradable polymers as alternative materials to commodity plastics.
- 55Payne, J.; Jones, M. D. The Chemical Recycling of Polyesters for a Circular Plastics Economy: Challenges and Emerging Opportunities. ChemSusChem 2021, 14, 4041– 4070, DOI: 10.1002/cssc.20210040055https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXptlOhtb8%253D&md5=a6ea2563da9dc271278f870e80718bc7The Chemical Recycling of Polyesters for a Circular Plastics Economy: Challenges and Emerging OpportunitiesPayne, Jack; Jones, Matthew D.ChemSusChem (2021), 14 (19), 4041-4070CODEN: CHEMIZ; ISSN:1864-5631. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. While plastics have played an instrumental role in human development, growing environmental concerns have led to increasing public scrutiny and demands for outright bans. This has stimulated considerable research into renewable alternatives, and more recently, the development of alternative waste management strategies. Herein, the aim was to highlight recent developments in the catalytic chem. recycling of two com. polyesters, namely poly(lactic acid) (PLA) and poly(ethylene terephthalate) (PET). The concept of chem. recycling is first introduced, and assocd. opportunities/challenges are discussed within the context of the governing depolymn. thermodn. Chem. recycling methods for PLA and PET are then discussed, with a particular focus on upcycling and the use of metal-based catalysts. Finally, the attention shifts to the emergence of new materials with the potential to modernise the plastics economy. Emerging opportunities and challenges are discussed within the context of industrial feasibility.
- 56Manzuch, Z.; Akelyte, R.; Camboni, M.; Carlander, D. Chemical Recycling of Polymeric Materials from Waste in the Circular Economy. Final Report for the European Chemical Agency; RPA Europe, August 2021; pp 1– 145.There is no corresponding record for this reference.
- 57Chanda, M. Chemical Aspects of Polymer Recycling. Adv. Ind. Eng. Polym. Res. 2021, 4, 133– 150, DOI: 10.1016/j.aiepr.2021.06.00257https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhvVGlsbfJ&md5=3cfd3b683a6b48af8e9df2bc1ce381a1Chemical aspects of polymer recyclingChanda, ManasAdvanced Industrial and Engineering Polymer Research (2021), 4 (3), 133-150CODEN: AIEPCN; ISSN:2542-5048. (Elsevier B.V.)Since recycling of polymers is a preferred means of reducing unwanted wastes and land-filling activity, and recovering monomers or other materials of economic value, tertiary methods of recycling (chem. recycling) have been critically reviewed, giving special attention, in each case, to the chem. basis of the particular recycling pathway and its potential applicability. Recycling issues of each of the widely used commodity polymers - polyesters, polyamides, polyurethanes, epoxies, poly(vinyl chloride), polystyrene, and polyolefins - have been discussed individually, giving attention to both conventional and unconventional methods of perceived high potential, such as enzymic degrdn., ionic liqs. mediation, microwave irradn., and treatment in super crit. liqs. as well as super fluids. In addn., novel emerging methods undergoing greater study at present, such as cross-alkane metathesis (CAM), tandem hydrogenolysis/aromatization, vitrimer-based recycling, and dynamic covalent bonding are also highlighted.
- 58Zhang, J.; Jia, W.; Yu, X.; Wang, Q.; Sun, Y.; Yang, S.; Li, Z.; Tang, X.; Zeng, X.; Lin, L. Facile One-Pot Synthesis of Furan Double Schiff Base from 5-Hydroxymethylfurfural via an Amination–Oxidation–Amination Strategy in Water. ACS Sustainable Chem. Eng. 2022, 10, 6835– 6842, DOI: 10.1021/acssuschemeng.2c0157658https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38Xht1GgsrbL&md5=8994cbf76dbca27fda7ebb8316efbd68Facile One-Pot Synthesis of Furan Double Schiff Base from 5-Hydroxymethylfurfural via an Amination-Oxidation-Amination Strategy in WaterZhang, Jie; Jia, Wenlong; Yu, Xin; Wang, Qian; Sun, Yong; Yang, Shuliang; Li, Zheng; Tang, Xing; Zeng, Xianhai; Lin, LuACS Sustainable Chemistry & Engineering (2022), 10 (20), 6835-6842CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)Furan double Schiff base (FDSB), a versatile biomass fine-chem. mol., was efficiently synthesized from 5-hydroxymethylfurfural (HMF) through an amination-oxidn.-amination strategy in water. The activated α-MnO2-S-H+ with a higher sp. surface area, more surface lattice oxygen vacancies, and abundant acid/base sites exhibited a high catalytic efficiency. An FDSB yield of 99.3% with 100% conversion of HMF using air-oxygen as the oxidant was achieved within 20 min in water. The oxidn. of the hydroxyl group in HMF to the carbonyl group underwent a Mars-van Krevelen cycle with the synergy of Mn4+ and lattice oxygen.
- 59Upton, B. M.; Kasko, A. M. Biodegradable Aromatic-Aliphatic Poly(Ester-Amides) from Monolignol-Based Ester Dimers. ACS Sustainable Chem. Eng. 2018, 6, 3659– 3668, DOI: 10.1021/acssuschemeng.7b0378459https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXitFSjsrg%253D&md5=0541ef01ce2bb5b344fc9bda286395aaBiodegradable aromatic-aliphatic poly(ester-amides) from monolignol-based ester dimersUpton, Brianna M.; Kasko, Andrea M.ACS Sustainable Chemistry & Engineering (2018), 6 (3), 3659-3668CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)Biobased polymers with tunable properties have received increased attention in the literature due to a decline in petroleum reserves. Owing to its low cost, abundance, and arom. structure, lignin has great potential as a feedstock for value-added polymeric products. In this work, we condensed carboxylic acid precursors with monolignols to generate reactive dimers for polymer synthesis. Three different arom. ester dimers, each corresponding to a different monolignol, were synthesized and characterized. The dicarboxylic acid dimers were converted to the corresponding diacid chloride in situ with thionyl chloride, and a series of poly(ester-amides) were synthesized via interfacial polymn. of these diacid chlorides with seven different aliph. or arom. diamines. The thermal properties (decompn., glass transition temp., and melting temp.) and hydrolytic stability in acidic and neutral aq. conditions of the resulting polymers were studied.
- 60Liguori, A.; Hakkarainen, M. Designed from Biobased Materials for Recycling: Imine-Based Covalent Adaptable Networks. Macromol. Rapid Commun. 2022, 43, 2100816, DOI: 10.1002/marc.20210081660https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB38XivV2ntLo%253D&md5=7cbad9701b9026e667185217470e40bdDesigned from Biobased Materials for Recycling: Imine-Based Covalent Adaptable NetworksLiguori, Anna; Hakkarainen, MinnaMacromolecular Rapid Communications (2022), 43 (13), 2100816CODEN: MRCOE3; ISSN:1022-1336. (Wiley-VCH Verlag GmbH & Co. KGaA)A review. Turning thermosets into fully sustainable materials requires utilization of biobased raw materials and design for easy recyclability. Here, dynamic covalent chem. for fabrication of covalent adaptable networks (CANs) could be an enabling tool. CAN thermosets ideally combine the pos. material properties of thermosets with thermal recyclability of linear thermoplastics. Among the dynamic covalent bonds, imine bond, also called Schiff base, can participate in both dissociative and associative pathways. This induces potential for chem. recyclability, thermal reprocessability and self-healing. This review presents an overview of the current research front of biobased thermosets fabricated by Schiff base chem. The discussed materials are categorized on the basis of the employed biobased components. The chem. approaches for the synthesis and curing of the resins, as well as the resulting properties and recyclability of the obtained thermosets are described and discussed. Finally, challenges and future perspectives are briefly summarized.
- 61Xu, Y.; Odelius, K.; Hakkarainen, M. Photocurable, Thermally Reprocessable, and Chemically Recyclable Vanillin-Based Imine Thermosets. ACS Sustainable Chem. Eng. 2020, 8, 17272– 17279, DOI: 10.1021/acssuschemeng.0c0624861https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXit1Ogs73O&md5=93b081daf910874b1d97982d415e871cPhotocurable, thermally reprocessable, and chemically recyclable vanillin-based imine ThermosetsXu, Yunsheng; Odelius, Karin; Hakkarainen, MinnaACS Sustainable Chemistry & Engineering (2020), 8 (46), 17272-17279CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)Two vanillin-based photocurable, thermally reprocessable, and chem. recyclable imine thermosets were successfully designed. The vanillin vitrimer resins were synthesized through a protocol with a two-step reaction: methacrylation and imination with diamine or triamine. The obtained vinyl ester resins with imine bonds and vinyl groups could be photocured into thermosets in 10 min at room temp. The cured thermosets had good solvent resistance against common solvents, good thermal stability up to about 250°C as measured by thermogravimetry, and high storage modulus (1.6-3.4 GPa as detd. by dynamic mech. anal.). Owing to the reversibility of the imine bond, both thermosets exhibited typical vitrimer behavior including stress relaxation and thermal reprocessability, while their activation energy for the imine exchange reaction and recovery ratio of tensile stress after reprocessing varied due to different crosslinking densities. Furthermore, both thermosets could be chem. recycled in hexylamine through an imine exchange reaction. The presented new strategy, thus, paves the way for prodn. of fast-curing, chem. and thermally stable, but still thermally reprocessable and chem. recyclable imine vitrimers from abundant biobased building blocks. Rapidly photocurable vanillin resins with double functionality for chem. and thermally stable, thermally reprocessable, and chem. recyclable imine vitrimers.
- 62Lavilla, C.; de Ilarduya, A. M.; Alla, A.; García-Martín, M. G.; Galbis, J. A.; Muñoz-Guerra, S. Bio-Based Aromatic Polyesters from a Novel Bicyclic Diol Derived from d-Mannitol. Macromolecules 2012, 45, 8257– 8266, DOI: 10.1021/ma301328862https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC38XhsVyks7bN&md5=9feb9fc6831da32598611bc75f00b7bbBio-Based Aromatic Polyesters from a Novel Bicyclic Diol Derived from D-MannitolLavilla, C.; Martinez de Ilarduya, A.; Alla, A.; Garcia-Martin, M. G.; Galbis, J. A.; Munoz-Guerra, S.Macromolecules (Washington, DC, United States) (2012), 45 (20), 8257-8266CODEN: MAMOBX; ISSN:0024-9297. (American Chemical Society)2,4:3,5-Di-O-methylene-D-mannitol, abbreviated as Manx, is a D-mannitol-derived compd. with the secondary hydroxyl groups acetalized with formaldehyde. The bicyclic structure of Manx consists of two fused 1,3-dioxane rings, with two primary hydroxyl groups standing free for reaction. A homopolyester made of Manx and di-Me terephthalate as well as a set of copolyesters of poly(butylene terephthalate) (PBT) in which 1,4-butanediol was replaced by Manx up to 50% were synthesized and characterized. The polyesters had Mw in the 30 000-52 000 g mol-1 range and a random microstructure and were thermally stable up to nearly 370 °C. They displayed outstanding high Tg with values from 55 to 137 °C which steadily increased with the content in Manx. Copolyesters contg. up to 40% of Manx were semicryst. and adopted the crystal structure of PBT. Their stress-strain parameters were sensitively affected by the presence of carbohydrate-based units with elongation at break decreasing but tensile strength and elastic moduli steadily increasing with the degree of replacement.
- 63Anastas, P. T.; Saltzberg, M.; Subramaniam, B. Plastics Are Not Bad. Bad Plastics Are Bad. ACS Sustainable Chem. Eng. 2021, 9, 9150, DOI: 10.1021/acssuschemeng.1c0304663https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhsFSrtr3J&md5=bf4d751da90d81b240d3d69a61fe261cPlastics Are Not Bad. Bad Plastics Are Bad.Anastas, Paul T.; Saltzberg, Michael; Subramaniam, BalaACS Sustainable Chemistry & Engineering (2021), 9 (28), 9150CODEN: ASCECG; ISSN:2168-0485. (American Chemical Society)There is no expanded citation for this reference.
- 64Tachibana, Y.; Hayashi, S.; Kasuya, K. I. Biobased Poly(Schiff-Base) Composed of Bifurfural. ACS Omega 2018, 3, 5336– 5345, DOI: 10.1021/acsomega.8b0046664https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXps1GrsLY%253D&md5=2077dc8d99c998ac8f28a0a85d8ff421Biobased Poly(Schiff-Base) Composed of BifurfuralTachibana, Yuya; Hayashi, Senri; Kasuya, Ken-ichiACS Omega (2018), 3 (5), 5336-5345CODEN: ACSODF; ISSN:2470-1343. (American Chemical Society)In this study, bifurfural, an inedible biobased chem. and a second-generation biomass, was polymd. with several diamines using an environmentally benign process, and the chem. structures of the resulting poly(Schiff base)s were analyzed. Because furan rings, which are only produced from biomass and not from fossil resources, endow polymers with unique properties that include high rigidity and expanded π-conjugation, bifurfural, which contains two furan rings, is of significant interest as a biobased building block. 1H NMR, IR, and matrix assisted laser desorption ionization-time of flight mass spectra of the poly(Schiff base)s reveal that they are composed of mixts. of linear and cyclic structures. The UV-vis spectroscopy and MO theory confirm the extended π-conjugation in the bifurfural/p-phenylenediamine poly(Schiff base) system. Poly(Schiff base)s composed of bifurfural and 1,3-propanediamine, 1,4-butandiamine, 1,5-pentanediamine, and 1,6-hexanediamine were molded at 120 °C into films that exhibited good strengths and were tough to bend. Bifurfural-based poly(Schiff base)s are promising biobased materials.
- 65Li, X.; Wang, X.; Subramaniyan, S.; Liu, Y.; Rao, J.; Zhang, B. Hyperbranched Polyesters Based on Indole- and Lignin-Derived Monomeric Aromatic Aldehydes as Effective Nonionic Antimicrobial Coatings with Excellent Biocompatibility. Biomacromolecules 2022, 23, 150– 162, DOI: 10.1021/acs.biomac.1c0118665https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXislyhtrrK&md5=6f31ca2bebde2b874217dfef3f63a567Hyperbranched Polyesters Based on Indole- and Lignin-Derived Monomeric Aromatic Aldehydes as Effective Nonionic Antimicrobial Coatings with Excellent BiocompatibilityLi, Xiaoya; Wang, Xiao; Subramaniyan, Sathiyaraj; Liu, Yang; Rao, Jingyi; Zhang, BaozhongBiomacromolecules (2022), 23 (1), 150-162CODEN: BOMAF6; ISSN:1525-7797. (American Chemical Society)This research aims to investigate nonionic hyperbranched polyesters (HBPs) derived from indole and lignin resources as new nontoxic antimicrobial coatings. Three nonionic HBPs with zero to two methoxy ether substituents on each benzene ring in the polymer backbones were synthesized by melt-polycondensation of three corresponding AB2 monomers. The mol. structures and thermal properties of the obtained HBPs were characterized by gel permeation chromatog., NMR spectroscopy, Fourier transform IR spectroscopy, thermogravimetric anal., and differential scanning calorimetry analyses. These HBPs were conveniently spin-coated on a silicon substrate, which exhibited significant antibacterial effect against Gram-neg. (Escherichia coli and Pseudomonas aeruginosa) and Gram-pos. bacteria (Staphylococcus aureus and Enterococcus faecalis). The presence of methoxy substituents enhanced the antimicrobial effect, and the resulting polymers showed negligible leakage in water. Finally, the polymers with the methoxy functionality exhibited excellent biocompatibility according to the results of hemolysis and MTT assay, which may facilitate their biomedical applications.
- 66Wang, S.; Ma, S.; Li, Q.; Xu, X.; Wang, B.; Yuan, W.; Zhou, S.; You, S.; Zhu, J. Facile: In Situ Preparation of High-Performance Epoxy Vitrimer from Renewable Resources and Its Application in Nondestructive Recyclable Carbon Fiber Composite. Green Chem. 2019, 21, 1484– 1497, DOI: 10.1039/C8GC03477J66https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1MXislCmtLk%253D&md5=80de6ab5aceffdbad27600458cb59a42Facile in situ preparation of high-performance epoxy vitrimer from renewable resources and its application in nondestructive recyclable carbon fiber compositeWang, Sheng; Ma, Songqi; Li, Qiong; Xu, Xiwei; Wang, Binbo; Yuan, Wangchao; Zhou, Shenghua; You, Shusen; Zhu, JinGreen Chemistry (2019), 21 (6), 1484-1497CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)Epoxy resins have been widely used in several materials including carbon fiber composites; however, they are arduous to recycle. In this study, for the first time, a Schiff base epoxy thermoset combining excellent recyclability and high performance was facilely prepd. from a synthesized formyl group-contg. vanillin-based monoepoxide and a diamine via in situ formation of the Schiff base structure and epoxy network. The chem. structure of the monoepoxide and its crosslinked network were characterized in detail. In addn., the thermal and mech. properties, recyclability of the thermoset and its application in carbon fiber composite were systematically investigated. The results showed that the thermoset possessed a similar glass transition temp. of 172 °C, a tensile strength of 81 MPa and a modulus of 2112 MPa, and higher thermal stability with the degrdn. temp. for 5% wt. loss of 323 °C and elongation at break of 15% in comparison with a bisphenol A epoxy resin. Moreover, it exhibited superior reprocessing recyclability due to the vitrimer or CAN nature of its Schiff base network. Furthermore, it could also be completely degraded under mild acidic conditions, leading to the quick and nondestructive recycling of its carbon fiber composite.
- 67Austin, H. P.; Allen, M. D.; Donohoe, B. S.; Rorrer, N. A.; Kearns, F. L.; Silveira, R. L.; Pollard, B. C.; Dominick, G.; Duman, R.; El Omari, K. E.; Mykhaylyk, V.; Wagner, A.; Michener, W. E.; Amore, A.; Skaf, M. S.; Crowley, M. F.; Thorne, A. W.; Johnson, C. W.; Woodcock, H.; McGeehan, J. E.; Beckham, G. T. Characterization and Engineering of a Plastic-Degrading Aromatic Polyesterase. Proc. Natl. Acad. Sci. U.S.A. 2018, 115, E4350– E4357, DOI: 10.1073/pnas.171880411567https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC1cXhvVGhtLnF&md5=b8e8d841af1bb06fa2d1fddb6b9d6460Characterization and engineering of a plastic-degrading aromatic polyesteraseAustin, Harry P.; Allen, Mark D.; Donohoe, Bryon S.; Rorrer, Nicholas A.; Kearns, Fiona L.; Silveira, Rodrigo L.; Pollard, Benjamin C.; Dominick, Graham; Duman, Ramona; El Omari, Kamel; Mykhaylyk, Vitaliy; Wagner, Armin; Michener, William E.; Amore, Antonella; Skaf, Munir S.; Crowley, Michael F.; Thorne, Alan W.; Johnson, Christopher W.; Woodcock, H. Lee; McGeehan, John E.; Beckham, Gregg T.Proceedings of the National Academy of Sciences of the United States of America (2018), 115 (19), E4350-E4357CODEN: PNASA6; ISSN:0027-8424. (National Academy of Sciences)Poly(ethylene terephthalate) (PET) is one of the most abundantly produced synthetic polymers and is accumulating in the environment at a staggering rate as discarded packaging and textiles. The properties that make PET so useful also endow it with an alarming resistance to biodegrdn., likely lasting centuries in the environment. Our collective reliance on PET and other plastics means that this buildup will continue unless solns. are found. Recently, a newly discovered bacterium, Ideonella sakaiensis 201-F6, was shown to exhibit the rare ability to grow on PET as a major carbon and energy source. Central to its PET biodegrdn. capability is a secreted PETase (PET-digesting enzyme). Here, we present a 0.92 Å resoln. X-ray crystal structure of PETase, which reveals features common to both cutinases and lipases. PETase retains the ancestral α/β-hydrolase fold but exhibits a more open active-site cleft than homologous cutinases. By narrowing the binding cleft via mutation of two active-site residues to conserved amino acids in cutinases, we surprisingly observe improved PET degrdn., suggesting that PETase is not fully optimized for cryst. PET degrdn., despite presumably evolving in a PET-rich environment. Addnl., we show that PETase degrades another semiarom. polyester, polyethylene-2,5-furandicarboxylate (PEF), which is an emerging, bioderived PET replacement with improved barrier properties. In contrast, PETase does not degrade aliph. polyesters, suggesting that it is generally an arom. polyesterase. These findings suggest that addnl. protein engineering to increase PETase performance is realistic and highlight the need for further developments of structure/activity relationships for biodegrdn. of synthetic polyesters.
- 68Farid, R.; Day, T.; Friesner, R. A.; Pearlstein, R. A. New Insights about HERG Blockade Obtained from Protein Modeling, Potential Energy Mapping, and Docking Studies. Bioorg. Med. Chem. 2006, 14, 3160– 3173, DOI: 10.1016/j.bmc.2005.12.03268https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28Xis1ehs7o%253D&md5=8df638aa78d2d35337bb82d8a94357c4New insights about HERG blockade obtained from protein modeling, potential energy mapping, and docking studiesFarid, Ramy; Day, Tyler; Friesner, Richard A.; Pearlstein, Robert A.Bioorganic & Medicinal Chemistry (2006), 14 (9), 3160-3173CODEN: BMECEP; ISSN:0968-0896. (Elsevier B.V.)We created a homol. model of the homo-tetrameric pore domain of HERG using the crystal structure of the bacterial potassium channel, KvAP, as a template. We docked a set of known blockers with well-characterized effects on channel function into the lumen of the pore between the selectivity filter and extracellular entrance using a novel docking and refinement procedure incorporating Glide and Prime. Key arom. groups of the blockers are predicted to form multiple simultaneous ring stacking and hydrophobic interactions among the eight arom. residues lining the pore. Furthermore, each blocker can achieve these interactions via multiple docking configurations. To further interpret the docking results, we mapped hydrophobic and hydrophilic potentials within the lumen of each refined docked complex. Hydrophilic iso-potential contours define a 'propeller-shaped' vol. at the selectivity filter entrance. Hydrophobic contours define a hollow 'crown-shaped' vol. located above the 'propeller', whose hydrophobic 'rim' extends along the pore axis between Tyr652 and Phe656. Blockers adopt conformations/binding orientations that closely mimic the shapes and properties of these contours. Blocker basic groups are localized in the hydrophilic 'propeller', forming electrostatic interactions with Ser624 rather than a generally accepted π-cation interaction with Tyr652. Terfenadine, cisapride, sertindole, ibutilide, and clofilium adopt similar docked poses, in which their N-substituents bridge radially across the hollow interior of the 'crown' (analogous to the hub and spokes of a wheel), and project arom./hydrophobic portions into the hydrophobic 'rim'. MK-499 docks with its longitudinal axis parallel to the axis of the pore and crown', and its hydrophobic groups buried within the hydrophobic 'rim'.
- 69Sherman, W.; Day, T.; Jacobson, M. P.; Friesner, R. A.; Farid, R. Novel Procedure for Modeling Ligand/Receptor Induced Fit Effects. J. Med. Chem. 2006, 49, 534– 553, DOI: 10.1021/jm050540c69https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2MXhtlCgsr7I&md5=388811ead5cee1fd460951263de486cbNovel Procedure for Modeling Ligand/Receptor Induced Fit EffectsSherman, Woody; Day, Tyler; Jacobson, Matthew P.; Friesner, Richard A.; Farid, RamyJournal of Medicinal Chemistry (2006), 49 (2), 534-553CODEN: JMCMAR; ISSN:0022-2623. (American Chemical Society)We present a novel protein-ligand docking method that accurately accounts for both ligand and receptor flexibility by iteratively combining rigid receptor docking (Glide) with protein structure prediction (Prime) techniques. While traditional rigid-receptor docking methods are useful when the receptor structure does not change substantially upon ligand binding, success is limited when the protein must be "induced" into the correct binding conformation for a given ligand. We provide an in-depth description of our novel methodol. and present results for 21 pharmaceutically relevant examples. Traditional rigid-receptor docking for these 21 cases yields an av. RMSD of 5.5 Å. The av. ligand RMSD for docking to a flexible receptor for the 21 pairs is 1.4 Å; the RMSD is ≤1.8 Å for 18 of the cases. For the three cases with RMSDs greater than 1.8 Å, the core of the ligand is properly docked and all key protein/ligand interactions are captured.
- 70Sherman, W.; Beard, H. S.; Farid, R. Use of an Induced Fit Receptor Structure in Virtual Screening. Chem. Biol. Drug Des. 2006, 67, 83– 84, DOI: 10.1111/j.1747-0285.2005.00327.x70https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD28XhsVSjtL0%253D&md5=efe9900aacaaea6af805c1cbdb350c73Use of an induced fit receptor structure in virtual screeningSherman, Woody; Beard, Hege S.; Farid, RamyChemical Biology & Drug Design (2006), 67 (1), 83-84CODEN: CBDDAL; ISSN:1747-0277. (Blackwell Publishing Ltd.)A review. The automated induced fit docking protocol was used to generate the DFG-out conformation from a p38 MAP kinase activation loop starting from a DFG-in structure (1a9u) and the ligand from 1kv1 (BMU). In a virtual screening study of 25K decoy ligands and 46 known actives, using an ensemble consisting of the induced fit docking structure (DFG-out) and the 1a9u crystal structure (DFG-in), 14 actives were identified in the top 1% of the database, including BMU and BIRB 796. 3 Actives were identified when 1a9u was used alone.
- 71Madhavi Sastry, G.; Adzhigirey, M.; Day, T.; Annabhimoju, R.; Sherman, W. Protein and Ligand Preparation: Parameters, Protocols, and Influence on Virtual Screening Enrichments. J. Comput.-Aided Mol. Des. 2013, 27, 221– 234, DOI: 10.1007/s10822-013-9644-871https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3sXmslalu7c%253D&md5=259a6d547ef3e1310e091fb50fe8de16Protein and ligand preparation: parameters, protocols, and influence on virtual screening enrichmentsMadhavi Sastry, G.; Adzhigirey, Matvey; Day, Tyler; Annabhimoju, Ramakrishna; Sherman, WoodyJournal of Computer-Aided Molecular Design (2013), 27 (3), 221-234CODEN: JCADEQ; ISSN:0920-654X. (Springer)Structure-based virtual screening plays an important role in drug discovery and complements other screening approaches. In general, protein crystal structures are prepd. prior to docking in order to add hydrogen atoms, optimize hydrogen bonds, remove at. clashes, and perform other operations that are not part of the x-ray crystal structure refinement process. In addn., ligands must be prepd. to create 3-dimensional geometries, assign proper bond orders, and generate accessible tautomer and ionization states prior to virtual screening. While the prerequisite for proper system prepn. is generally accepted in the field, an extensive study of the prepn. steps and their effect on virtual screening enrichments has not been performed. In this work, we systematically explore each of the steps involved in prepg. a system for virtual screening. We first explore a large no. of parameters using the Glide validation set of 36 crystal structures and 1,000 decoys. We then apply a subset of protocols to the DUD database. We show that database enrichment is improved with proper prepn. and that neglecting certain steps of the prepn. process produces a systematic degrdn. in enrichments, which can be large for some targets. We provide examples illustrating the structural changes introduced by the prepn. that impact database enrichment. While the work presented here was performed with the Protein Prepn. Wizard and Glide, the insights and guidance are expected to be generalizable to structure-based virtual screening with other docking methods.
- 72Greenwood, J. R.; Calkins, D.; Sullivan, A. P.; Shelley, J. C. Towards the Comprehensive, Rapid, and Accurate Prediction of the Favorable Tautomeric States of Drug-like Molecules in Aqueous Solution. J. Comput.-Aided Mol. Des. 2010, 24, 591– 604, DOI: 10.1007/s10822-010-9349-172https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3cXnsFGqtbo%253D&md5=1d7bc0f966ca793d6be80554868367b8Towards the comprehensive, rapid, and accurate prediction of the favorable tautomeric states of drug-like molecules in aqueous solutionGreenwood, Jeremy R.; Calkins, David; Sullivan, Arron P.; Shelley, John C.Journal of Computer-Aided Molecular Design (2010), 24 (6-7), 591-604CODEN: JCADEQ; ISSN:0920-654X. (Springer)A review. Generating the appropriate protonation states of drug-like mols. in soln. is important for success in both ligand- and structure-based virtual screening. Screening collections of millions of compds. requires a method for detg. tautomers and their energies that is sufficiently rapid, accurate, and comprehensive. To maximize enrichment, the lowest energy tautomers must be detd. from heterogeneous input, without over-enumerating unfavorable states. While computationally expensive, the d. functional theory (DFT) method M06-2X/aug-cc-pVTZ(-f) [PB-SCRF] provides accurate energies for enumerated model tautomeric systems. The empirical Hammett-Taft methodol. can very rapidly extrapolate substituent effects from model systems to drug-like mols. via the relationship between pKT and pKa. Combining the 2 complementary approaches transforms the tautomer problem from a scientific challenge to one of engineering scale-up, and avoids issues that arise due to the very limited no. of measured pKT values, esp. for the complicated heterocycles often favored by medicinal chemists for their novelty and versatility. Several hundreds of pre-calcd. tautomer energies and substituent pKa effects are tabulated in databases for use in structural adjustment by the program Epik, which treats tautomers as a subset of the larger problem of the protonation states in aq. ensembles and their energy penalties. Accuracy and coverage is continually improved and expanded by parameterizing new systems of interest using DFT and exptl. data. Recommendations are made for how to best incorporate tautomers in mol. design and virtual screening workflows.
- 73Shelley, J. C.; Cholleti, A.; Frye, L. L.; Greenwood, J. R.; Timlin, M. R.; Uchimaya, M. Epik: A Software Program for PKa Prediction and Protonation State Generation for Drug-like Molecules. J. Comput.-Aided Mol. Des. 2007, 21, 681– 691, DOI: 10.1007/s10822-007-9133-z73https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2sXhsVKrtbzP&md5=f4f429ea3894e1ad2519cdf3333a5645Epik: a software program for pKa prediction and protonation state generation for drug-like moleculesShelley, John C.; Cholleti, Anuradha; Frye, Leah L.; Greenwood, Jeremy R.; Timlin, Mathew R.; Uchimaya, MakotoJournal of Computer-Aided Molecular Design (2007), 21 (12), 681-691CODEN: JCADEQ; ISSN:0920-654X. (Springer)Epik is a computer program for predicting pKa values for drug-like mols. Epik can use this capability in combination with technol. for tautomerization to adjust the protonation state of small drug-like mols. to automatically generate one or more of the most probable forms for use in further mol. modeling studies. Many medicinal chems. can exchange protons with their environment, resulting in various ionization and tautomeric states, collectively known as protonation states. The protonation state of a drug can affect its soly. and membrane permeability. In modeling, the protonation state of a ligand will also affect which conformations are predicted for the mol., as well as predictions for binding modes and ligand affinities based upon protein-ligand interactions. Despite the importance of the protonation state, many databases of candidate mols. used in drug development do not store reliable information on the most probable protonation states. Epik is sufficiently rapid and accurate to process large databases of drug-like mols. to provide this information. Several new technologies are employed. Extensions to the well-established Hammett and Taft approaches are used for pKa prediction, namely, mesomer standardization, charge cancellation, and charge spreading to make the predicted results reflect the nature of the mol. itself rather just for the particular Lewis structure used on input. In addn., a new iterative technol. for generating, ranking and culling the generated protonation states is employed.
- 74Jacobson, M. P.; Pincus, D. L.; Rapp, C. S.; Day, T. J. F.; Honig, B.; Shaw, D. E.; Friesner, R. A. A Hierarchical Approach to All-Atom Protein Loop Prediction. Proteins: Struct., Funct., Bioinf. 2004, 55, 351– 367, DOI: 10.1002/prot.1061374https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD2cXjtFKhsrc%253D&md5=e0eff655eeefb30ea00ae041ea9099c8A hierarchical approach to all-atom protein loop predictionJacobson, Matthew P.; Pincus, David L.; Rapp, Chaya S.; Day, Tyler J. F.; Honig, Barry; Shaw, David E.; Friesner, Richard A.Proteins: Structure, Function, and Bioinformatics (2004), 55 (2), 351-367CODEN: PSFBAF ISSN:. (Wiley-Liss, Inc.)The application of all-atom force fields (and explicit or implicit solvent models) to protein homol.-modeling tasks such as side-chain and loop prediction remains challenging both because of the expense of the individual energy calcns. and because of the difficulty of sampling the rugged all-atom energy surface. Here the authors address this challenge for the problem of loop prediction through the development of numerous new algorithms, with an emphasis on multiscale and hierarchical techniques. As a first step in evaluating the performance of the authors' loop prediction algorithm, the authors have applied it to the problem of reconstructing loops in native structures; the authors also explicitly include crystal packing to provide a fair comparison with crystal structures. In brief, large nos. of loops are generated by using a dihedral angle-based buildup procedure followed by iterative cycles of clustering, side-chain optimization, and complete energy minimization of selected loop structures. The authors evaluate this method by the largest test set yet used for validation of a loop prediction method, with a total of 833 loops ranging from 4 to 12 residues in length. Av./median backbone root-mean-square deviations (RMSDs) to the native structures (superimposing the body of the protein, not the loop itself) are 0.42/0.24 Å for 5 residue loops, 1.00/0.44 Å for 8 residue loops, and 2.47/1.83 Å for 11 residue loops. Median RMSDs are substantially lower than the avs. because of a small no. of outliers; the causes of these failures are examd. in some detail, and many can be attributed to errors in assignment of protonation states of titratable residues, omission of ligands from the simulation, and, in a few cases, probable errors in the exptl. detd. structures. When these obvious problems in the data sets are filtered out, av. RMSDs to the native structures improve to 0.43 Å for 5 residue loops, 0.84 Å for 8 residue loops, and 1.63 Å for 11 residue loops. In the vast majority of cases, the method locates energy min. that are lower than or equal to that of the minimized native loop, thus indicating that sampling rarely limits prediction accuracy. The overall results are, to the authors' knowledge, the best reported to date, and the authors attribute this success to the combination of an accurate all-atom energy function, efficient methods for loop buildup and side-chain optimization, and, esp. for the longer loops, the hierarchical refinement protocol.
- 75Jacobson, M. P.; Friesner, R. A.; Xiang, Z.; Honig, B. On the Role of the Crystal Environment in Determining Protein Side-Chain Conformations. J. Mol. Biol. 2002, 320, 597– 608, DOI: 10.1016/s0022-2836(02)00470-975https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BD38XltVKmu70%253D&md5=006de6bd2d0f233ab32d6798dc1a3fbcOn the Role of the Crystal Environment in Determining Protein Side-chain ConformationsJacobson, Matthew P.; Friesner, Richard A.; Xiang, Zhexin; Honig, BarryJournal of Molecular Biology (2002), 320 (3), 597-608CODEN: JMOBAK; ISSN:0022-2836. (Elsevier Science Ltd.)The role of crystal packing in detg. the obsd. conformations of amino acid side-chains in protein crystals is investigated by (1) anal. of a database of proteins that have been crystd. in different unit cells (space group or unit cell dimensions) and (2) theor. predictions of side-chain conformations with the crystal environment explicitly represented. Both of these approaches indicate that the crystal environment plays an important role in detg. the conformations of polar side-chains on the surfaces of proteins. Inclusion of the crystal environment permits a more sensitive measurement of the achievable accuracy of side-chain prediction programs, when validating against structures obtained by x-ray crystallog. Our side-chain prediction program uses an all-atom force field and a Generalized Born model of solvation and is thus capable of modeling simple packing effects (i.e. van der Waals interactions), electrostatic effects, and desolvation, which are all important mechanisms by which the crystal environment impacts obsd. side-chain conformations. Our results are also relevant to the understanding of changes in side-chain conformation that may result from ligand docking and protein-protein assocn., insofar as the results reveal how side-chain conformations change in response to their local environment.
- 76Lu, C.; Wu, C.; Ghoreishi, D.; Chen, W.; Wang, L.; Damm, W.; Ross, G. A.; Dahlgren, M. K.; Russell, E.; Von Bargen, C. D.; Abel, R.; Friesner, R. A.; Harder, E. D. OPLS4: Improving Force Field Accuracy on Challenging Regimes of Chemical Space. J. Chem. Theory Comput. 2021, 17, 4291– 4300, DOI: 10.1021/acs.jctc.1c0030276https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXht1ejur%252FO&md5=aa4d44468e21abe173534b1323b982d4OPLS4: Improving Force Field Accuracy on Challenging Regimes of Chemical SpaceLu, Chao; Wu, Chuanjie; Ghoreishi, Delaram; Chen, Wei; Wang, Lingle; Damm, Wolfgang; Ross, Gregory A.; Dahlgren, Markus K.; Russell, Ellery; Von Bargen, Christopher D.; Abel, Robert; Friesner, Richard A.; Harder, Edward D.Journal of Chemical Theory and Computation (2021), 17 (7), 4291-4300CODEN: JCTCCE; ISSN:1549-9618. (American Chemical Society)We report on the development and validation of the OPLS4 force field. OPLS4 builds upon our previous work with OPLS3e to improve model accuracy on challenging regimes of drug-like chem. space that includes mol. ions and sulfur contg. moieties. A novel parametrization strategy for charged species, that can be extended to other systems, is introduced. OPLS4 leads to improved accuracy on benchmarks that assess small mol. solvation and protein-ligand binding.
- 77Valsange, N. G.; Garcia Gonzalez, M. N.; Warlin, N.; Mankar, S. V.; Rehnberg, N.; Lundmark, S.; Zhang, B.; Jannasch, P. Biobased Aliphatic Polyesters from a Spirocyclic Dicarboxylate Monomer Derived from Levulinic Acid. Green Chem. 2021, 23, 5706– 5723, DOI: 10.1039/D1GC00724F77https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3MXhsVOmu7zE&md5=a880fb8f998158529459d6a76d5f8321Biobased aliphatic polyesters from a spirocyclic dicarboxylate monomer derived from levulinic acidValsange, Nitin G.; Garcia Gonzalez, Maria Nelly; Warlin, Niklas; Mankar, Smita V.; Rehnberg, Nicola; Lundmark, Stefan; Zhang, Baozhong; Jannasch, PatricGreen Chemistry (2021), 23 (15), 5706-5723CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)Levulinic acid derived from lignocellulose is an important biobased building block. Here, we report on the synthesis and polymn. of a rigid spirocyclic diester monomer to produce polyesters and copolyesters. The monomer was prepd. via a one-step acid catalyzed ketalization involving Et levulinate and pentaerythritol by employing a straightforward, solvent-free, and readily scalable method which required no chromatog. purifn. Still, careful removal of traces of water from the spiro-diester prior to polycondensations proved crucial to avoid side reactions. A preliminary life cycle assessment (LCA) in terms of greenhouse gas (GHG) emissions indicated that the corresponding spiro-diacid tended to be environmentally favorable, producing less CO2 emission than e.g., biobased succinic acid and adipic acid. A series of aliph. polyesters with reasonably high mol. wts. was subsequently prepd. in melt and modified melt polycondensations of the spiro-diester with 1,4-butanediol, 1,6-hexanediol, neopentyl glycol and 1,4-cyclohexanedimethanol, resp. The resulting fully amorphous polyesters showed glass transition temps. in the range 12-49°C and thermal stability up to 300°C. Hot-pressed films of the polyesters based on neopentyl glycol and 1,4-cyclohexanedimethanol were transparent and mech. strong, and dynamic melt rheol. showed stable shear moduli over time to indicate good processability. In addn., the spiro-diester monomer was employed in copolycondensations with di-Et adipate and 1,4-butanediol and demonstrated good reactivity and stability. Hence, the results of the present study indicate that the spiro-diester based on levulinic acid is an effective monomer for the prepn. of aliph. polyesters and other condensation polymers.
- 78Fu, T.; Guo, D.-M.; Wu, J.-N.; Wang, X.-L.; Wang, X.-L.; Chen, L.; Wang, Y.-Z. Inherent Flame Retardation of Semi-Aromatic Polyesters via Binding Small-Molecule Free Radicals and Charring. Polym. Chem. 2016, 7, 1584– 1592, DOI: 10.1039/C5PY01938A78https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC28XhtFSgur8%253D&md5=472c6b26d4c5d674d11d0c874ca1da63Inherent flame retardation of semi-aromatic polyesters via binding small-molecule free radicals and charringFu, Teng; Guo, De-Ming; Wu, Jia-Ning; Wang, Xiao-Lin; Wang, Xiu-Li; Chen, Li; Wang, Yu-ZhongPolymer Chemistry (2016), 7 (8), 1584-1592CODEN: PCOHC2; ISSN:1759-9962. (Royal Society of Chemistry)Inherent flame-retardant semi-arom. polyesters, contg. special aryl ether and/or ketone structures ("Ar-CO-Ar", "Ar-O-Ar", "Ar-O-Ar-O-Ar" or "Ar-O-Ar-CO-Ar-O-Ar") were synthesized successfully. Interestingly, these polyesters show different flame retardancy beyond our traditional knowledge that more benzene rings are beneficial to flame retardancy. The polyester contg. "Ar-O-Ar-O-Ar" shows excellent flame retardancy, whose LOI value reaches 34.1% and the UL-94 rating is V-0. Meanwhile, the polyester with the "Ar-O-Ar-CO-Ar-O-Ar" structure does not perform expectedly well (31.6% and V-2 rating resp.). In order to make clear the effect of aryl ether and/or ketone structure units on the flame retardancy, the pyrolysis behaviors and the char residue are investigated by Py-GC/MS, TGA, and SEM. In the TGA test, the char residues of polyesters contg. "Ar-CO-Ar", "Ar-O-Ar", "Ar-O-Ar-O-Ar" or "Ar-O-Ar-CO-Ar-O-Ar" are 31.6%, 22.5%, 30.6% or 38.7%, resp. These values do not match with the calcd. results, which indicate that some special reactions occur during combustion. Furthermore, these polyesters show a common initial pyrolysis pathway and subsequent unique processes in the Py-GC/MS test. Their pyrolysis intermediate products can bind small-mol. free radicals, and eventually form different conjugated arom. structures. And their flame retardant performance has great relationship with the amt. of char formation, microstructure of char, and chem. structure of pyrolysis products.
- 79Cyriac, A.; Lee, S. H.; Varghese, J. K.; Park, J. H.; Jeon, J. Y.; Kim, S. J.; Lee, B. Y. Preparation of Flame-Retarding Poly(Propylene Carbonate). Green Chem. 2011, 13, 3469– 3475, DOI: 10.1039/C1GC15722A79https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BC3MXhsFantLjO&md5=a2e1dbbc07603475f8d05e59c34c2486Preparation of flame-retarding poly(propylene carbonate)Cyriac, Anish; Lee, Sang Hwan; Varghese, Jobi Kodiyan; Park, Ji Hae; Jeon, Jong Yeob; Kim, Seung Jin; Lee, Bun YeoulGreen Chemistry (2011), 13 (12), 3469-3475CODEN: GRCHFJ; ISSN:1463-9262. (Royal Society of Chemistry)A preparative method for a flame-retarding poly(propylene carbonate) (PPC) was demonstrated by employing diphenylphosphinic acid (Ph2P(O)(OH)), phenylphosphonic acid (PhP(O)(OH)2), or phosphoric acid (P(O)(OH)3) as a chain transfer agent in the immortal CO2/propylene oxide copolymn. catalyzed by a highly active catalyst, a cobalt(III) complex of a Salen-type ligand tethered by four quaternary ammonium salts (1). High turnover frequencies of 10, 000-20, 000 h-1 (700-1300 g-polymer per g-cat·h) were maintained even in the presence of a large amt. of the protic chain transfer agent ([-OH]/[1], 1600-200). Directly after the copolymn. using PhP(O)(OH)2 as a chain transfer agent, thermoplastic polyurethane (TPU) was formed by adding a stoichiometric amt. of toluene-2,4-diisocyanate. The TPU also was not inflammable. Cone calorimeter studies showed that PPC itself and TPU prepd. using PPC-diol emitted significantly less smoke while burning than common plastics, such as polystyrene.
- 80Kasmi, N.; Papadopoulos, L.; Chebbi, Y.; Papageorgiou, G. Z.; Bikiaris, D. N. Effective and Facile Solvent-Free Synthesis Route to Novel Biobased Monomers from Vanillic Acid: Structure–Thermal Property Relationships of Sustainable Polyesters. Polym. Degrad. Stab. 2020, 181, 109315, DOI: 10.1016/j.polymdegradstab.2020.10931580https://chemport.cas.org/services/resolver?origin=ACS&resolution=options&coi=1%3ACAS%3A528%3ADC%252BB3cXhsF2iu73L&md5=a6fec56327c7e6d75ffd39230a55e5daEffective and facile solvent-free synthesis route to novel biobased monomers from vanillic acid: Structure-thermal property relationships of sustainable polyestersKasmi, Nejib; Papadopoulos, Lazaros; Chebbi, Yosra; Papageorgiou, George Z.; Bikiaris, Dimitrios N.Polymer Degradation and Stability (2020), 181 (), 109315CODEN: PDSTDW; ISSN:0141-3910. (Elsevier Ltd.)Solvent-free synthesis of monomers is one among the most promising ways to develop greener polymers that are both environmentally and economically acceptable, but it was described as one of the "grand challenges" facing chemists. As a contribution towards sustainable bioplastics development which has attracted great attention in materials science research, a truly efficient, practical, and more environmentally friendly solvent-free synthetic route was successfully applied herein to prep. three new fully biobased diol monomers derived from vanillic acid and aliph. diols (ethylene glycol, 1,3-propanediol and 1,4-butanediol). Their chem. structures were confirmed in detail by 1H, 13C NMR and FTIR spectroscopies while their thermal properties were investigated by DSC and TGA. Results showed high m.ps. in the 121.8-142.3°C range and no significant wt. loss (Td, 5%) up to 243, 312 and 284°C resp. for diols with 2, 3, and 4 methylene units. To prove their suitability in polymn., melt polycondensation of prepd. diols with three diacyl chlorides and also with di-Me 2,5-furandicarboxylate were successfully carried out under catalyst-free conditions and using tetra-Bu titanate (TBT), resp. The chem. structures of the novel series of polyesters were confirmed in detail by NMR and FTIR spectroscopies. The latter showed satisfactory intrinsic viscosity values in the 0.25-0.30 dL/g range and a wholly amorphous nature. All materials revealed high thermal stability with onset degrdn. temps. Td, 5% ranging from 314 to 373°C and a wide glass transition temp. (Tg) range oscillating from -2.8 to 69.5°C. The innovative approach proposed herein for the first time, which involves the synthesis of sustainable monomers under solvent-free conditions, is fully aligned with one of the main principles of green chem.
Supporting Information
Supporting Information
The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acssuschemeng.2c06935.
1D and 2D NMR and FT-IR spectra of monomers [SBM1 (3), SBM2 (4), and SBM3 (5)] and their corresponding polymers (SBP3a–b and SBP5a–b), the recycled products (RP1 and RP2), real-time 1H NMR spectra of SBP4a, SBP4b and SBP5b, SDS-PAGE of purified PETase after expression in E. coli, LC–MS calibration curve of DP3, and a table presenting the total number of binding poses obtained in each category (PDF)
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