Pub Date : 2025-02-10DOI: 10.1021/acs.macromol.4c02670
Zhenjie Yang, Chenyang Hu, Xuan Pang, Liwen Zhang, Ruirui Qiao, Thomas P. Davis, Shunjie Liu, Xianhong Wang, Xuesi Chen
Degradable and self-healing polymers are considered next-generation materials since they can tackle both the end-of-life issues and the long-standing longevity of synthetic materials. Here, we design a series of aliphatic polyester-polycarbonate copolymers combining degradability and self-healability using commodity monomers comprising ε-caprolactone (ε-CL), cyclohexene oxide (CHO), and CO2. These copolymers are synthesized by random copolymerization catalyzed by a dinuclear salen-Mn catalyst under low CO2 pressure, affording randomly distributed carbonate units on a poly(ε-caprolactone) (PCL) chain. High molar mass copolymers with controllable components and microstructures are obtained by regulating the reaction conditions. Different from corresponding triblock copolymers, the random copolymers exhibit autonomous self-healing capability under ambient or even harsh conditions without any external intervention. The outperformance of random copolymers in self-healing is ascribed to the interchain diffusion and reconstruction of nanodomains. This sequence regulation method may serve as a general facile strategy for the design and synthesis of other self-healing copolymers.
{"title":"Sequence Design of Poly(ester-co-carbonate): A Unique Example of Degradable Self-Healing Copolymers","authors":"Zhenjie Yang, Chenyang Hu, Xuan Pang, Liwen Zhang, Ruirui Qiao, Thomas P. Davis, Shunjie Liu, Xianhong Wang, Xuesi Chen","doi":"10.1021/acs.macromol.4c02670","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02670","url":null,"abstract":"Degradable and self-healing polymers are considered next-generation materials since they can tackle both the end-of-life issues and the long-standing longevity of synthetic materials. Here, we design a series of aliphatic polyester-polycarbonate copolymers combining degradability and self-healability using commodity monomers comprising ε-caprolactone (ε-CL), cyclohexene oxide (CHO), and CO<sub>2</sub>. These copolymers are synthesized by random copolymerization catalyzed by a dinuclear salen-Mn catalyst under low CO<sub>2</sub> pressure, affording randomly distributed carbonate units on a poly(ε-caprolactone) (PCL) chain. High molar mass copolymers with controllable components and microstructures are obtained by regulating the reaction conditions. Different from corresponding triblock copolymers, the random copolymers exhibit autonomous self-healing capability under ambient or even harsh conditions without any external intervention. The outperformance of random copolymers in self-healing is ascribed to the interchain diffusion and reconstruction of nanodomains. This sequence regulation method may serve as a general facile strategy for the design and synthesis of other self-healing copolymers.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"25 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143385272","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-10DOI: 10.1021/acs.macromol.4c03244
Xiaohua Wang, Lishuang Ma, Bo Dong, Chunyu Zhang, Xuequan Zhang, Heng Liu
Axial anagostic bond Mt···H–C can occupy the apical site of d8 square planar metal complexes, which is highly desired, yet never explored, for olefin polymerization because of its capability to suppress associative chain transfer to access high molecular weight polyolefin products. In this research, we present a method for how such axial anagostic interaction Ni···H–C can be constructed into α-diimine NiBr2 complexes, and more importantly, demonstrate its pivotal role in improving the overall ethylene polymerization performance, including (i) ultrahigh efficiency in suppressing associative chain transfer to afford UHMWPEs with Mw up to 724.2 × 104 g/mol, (ii) significantly impeded decomposition of the cationic active species that brings in better storage stability, and (iii) higher branched nature of the PE products that guarantee a well-controlled living fashion for the whole polymerization process even when Mw reaches ultrahigh levels. With the aid of DFT calculations, the nature of such an anagostic bond and its influence on each step of the polymerization process are also elucidated.
{"title":"Axial Anagostic Interaction in α-Diimine Nickel Catalysts: An Ultraefficient Occupation Strategy in Suppressing Associative Chain Transfers to Achieve UHMWPEs","authors":"Xiaohua Wang, Lishuang Ma, Bo Dong, Chunyu Zhang, Xuequan Zhang, Heng Liu","doi":"10.1021/acs.macromol.4c03244","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c03244","url":null,"abstract":"Axial anagostic bond Mt···H–C can occupy the apical site of <i>d</i><sup>8</sup> square planar metal complexes, which is highly desired, yet never explored, for olefin polymerization because of its capability to suppress associative chain transfer to access high molecular weight polyolefin products. In this research, we present a method for how such axial anagostic interaction Ni···H–C can be constructed into α-diimine NiBr<sub>2</sub> complexes, and more importantly, demonstrate its pivotal role in improving the overall ethylene polymerization performance, including (i) ultrahigh efficiency in suppressing associative chain transfer to afford UHMWPEs with <i>M</i><sub>w</sub> up to 724.2 × 10<sup>4</sup> g/mol, (ii) significantly impeded decomposition of the cationic active species that brings in better storage stability, and (iii) higher branched nature of the PE products that guarantee a well-controlled living fashion for the whole polymerization process even when <i>M</i><sub>w</sub> reaches ultrahigh levels. With the aid of DFT calculations, the nature of such an anagostic bond and its influence on each step of the polymerization process are also elucidated.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"4 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143375804","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-10DOI: 10.1021/acs.macromol.4c02687
Bocheng Shang, Wei Yu
The transient strain hardening during extension is critical to the industrial processing of polymers. However, the molecular mechanism of strain hardening of linear polymers under fast extension is still controversial. Both extension-enhanced and extension-reduced monomeric frictions have been proposed to explain the experimental observations in different polymers. In this study, we systematically studied the extensional rheology of unentangled azobenzene polymers (Pazo) and their copolymers and revealed the possibility of synergetic contribution of the side-chain self-dilution and π–π stacking to the strain hardening. In the slow flow regime (Rouse Weissenberg number WiR < 0.5), the strain hardening during extension is dominated by extension-enhanced friction due to the side-chain π–π stacking. The importance of side-chain self-dilution grows as WiR increases, and there is a critical side-chain length for the solvation effect to play a role under fast extension (WiR > 0.5). The strain hardening under all extension conditions weakens as the molar fraction of the azobenzene monomer in the copolymer decreases. However, azobenzene content as low as 0.2 in the copolymer is sufficient to generate evident π–π stacking-induced friction enhancement. The in situ wide-angle X-ray scattering (WAXS) experiments reveal a distinct enhancement of π–π stacking in Pazo in the transverse direction of extension due to side-chain flexibility, in contrast to the enhancement in the stretching direction in polymers with short rigid side chains containing benzene rings.
{"title":"Extensional Rheology of Unentangled Azobenzene Polymers: Synergetic Effect of π–π Interactions and Side-Chain Self-Dilution","authors":"Bocheng Shang, Wei Yu","doi":"10.1021/acs.macromol.4c02687","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02687","url":null,"abstract":"The transient strain hardening during extension is critical to the industrial processing of polymers. However, the molecular mechanism of strain hardening of linear polymers under fast extension is still controversial. Both extension-enhanced and extension-reduced monomeric frictions have been proposed to explain the experimental observations in different polymers. In this study, we systematically studied the extensional rheology of unentangled azobenzene polymers (Pazo) and their copolymers and revealed the possibility of synergetic contribution of the side-chain self-dilution and π–π stacking to the strain hardening. In the slow flow regime (Rouse Weissenberg number <i>Wi</i><sub>R</sub> < 0.5), the strain hardening during extension is dominated by extension-enhanced friction due to the side<i>-</i>chain π–π stacking. The importance of side-chain self-dilution grows as <i>Wi</i><sub>R</sub> increases, and there is a critical side-chain length for the solvation effect to play a role under fast extension (<i>Wi</i><sub>R</sub> > 0.5). The strain hardening under all extension conditions weakens as the molar fraction of the azobenzene monomer in the copolymer decreases. However, azobenzene content as low as 0.2 in the copolymer is sufficient to generate evident π–π stacking-induced friction enhancement. The in situ wide-angle X-ray scattering (WAXS) experiments reveal a distinct enhancement of π–π stacking in Pazo in the transverse direction of extension due to side-chain flexibility, in contrast to the enhancement in the stretching direction in polymers with short rigid side chains containing benzene rings.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"62 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143375803","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-09DOI: 10.1021/acs.macromol.4c02829
Bailee N. Barrett, Pedram AziziHariri, Vijay T. John, Donghui Zhang
The micellar aggregation of singly charged sequence-defined ionic peptoid block copolymers can be finely tuned by adjusting the position of the ionizable monomer along the chain and varying the solution pH. The pH-induced structural reorganization of these micelles was found to depend on the position of the ionizable monomer along the chain, influencing the balance of the hydrophobic interactions, excluded volume effect, and electrostatic forces (i.e., charge repulsion, solvation of the ionic monomers, counterion association) that govern the micellar structure. As the solution pH increases, positioning the ionizable monomer closer to the junction of the hydrophobic and hydrophilic blocks causes a larger reduction in the micellar size and aggregation number across two distinct regimes. In contrast, placing the ionizable monomer at the terminus of the hydrophilic block results in a smaller reduction in the micellar size and aggregation number over three regimes. This study provides new insights into leveraging the strategic positioning of ionizable monomers to design stimuli-responsive nanoassemblies capable of programmable structural reorganization.
{"title":"Modulating the Aqueous Micellar Reorganization of Sequence-Defined Ionic Peptoid Block Copolymers by Ionizable Monomer Position and Solution pH","authors":"Bailee N. Barrett, Pedram AziziHariri, Vijay T. John, Donghui Zhang","doi":"10.1021/acs.macromol.4c02829","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02829","url":null,"abstract":"The micellar aggregation of singly charged sequence-defined ionic peptoid block copolymers can be finely tuned by adjusting the position of the ionizable monomer along the chain and varying the solution pH. The pH-induced structural reorganization of these micelles was found to depend on the position of the ionizable monomer along the chain, influencing the balance of the hydrophobic interactions, excluded volume effect, and electrostatic forces (i.e., charge repulsion, solvation of the ionic monomers, counterion association) that govern the micellar structure. As the solution pH increases, positioning the ionizable monomer closer to the junction of the hydrophobic and hydrophilic blocks causes a larger reduction in the micellar size and aggregation number across two distinct regimes. In contrast, placing the ionizable monomer at the terminus of the hydrophilic block results in a smaller reduction in the micellar size and aggregation number over three regimes. This study provides new insights into leveraging the strategic positioning of ionizable monomers to design stimuli-responsive nanoassemblies capable of programmable structural reorganization.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"41 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143375805","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-09DOI: 10.1021/acs.macromol.4c02992
Luis L. Jessen, Tanner L. Grover, Nicholas V. Oberbroeckling, Robin Willemse, C. Allan Guymon
Photoiniferter RAFT polymerization was utilized to synthesize and functionalize small-molecular-weight hyperbranched prepolymers (HBPs). HBPs were incorporated in densely cross-linking photocurable systems to investigate the impact of their size and structure on resin and material properties. The incorporation of HBPs induced a significant reduction in viscosity, enhanced network homogeneity, and increased material toughness compared to linear prepolymer counterparts. When shrinkage stress was normalized using the Young’s modulus of the final network, lower shrinkage stresses were observed for HBP-modified systems, especially when functionalized with pendant acrylate groups. In comparison to commercial linear urethane diacrylate cross-linkers, the HBP-modified network showed significantly enhanced network homogeneity and mechanical toughness. This study demonstrates that HBPs enable access to reduced resin viscosity and shrinkage stress as well as enhanced network homogeneity compared to conventional linear oligomer additives in densely cross-linked photocurable systems.
{"title":"Enhancing the Thermomechanical Properties of Photopolymer Networks Using Small-Molecular-Weight Hyperbranched Prepolymer Additives","authors":"Luis L. Jessen, Tanner L. Grover, Nicholas V. Oberbroeckling, Robin Willemse, C. Allan Guymon","doi":"10.1021/acs.macromol.4c02992","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02992","url":null,"abstract":"Photoiniferter RAFT polymerization was utilized to synthesize and functionalize small-molecular-weight hyperbranched prepolymers (HBPs). HBPs were incorporated in densely cross-linking photocurable systems to investigate the impact of their size and structure on resin and material properties. The incorporation of HBPs induced a significant reduction in viscosity, enhanced network homogeneity, and increased material toughness compared to linear prepolymer counterparts. When shrinkage stress was normalized using the Young’s modulus of the final network, lower shrinkage stresses were observed for HBP-modified systems, especially when functionalized with pendant acrylate groups. In comparison to commercial linear urethane diacrylate cross-linkers, the HBP-modified network showed significantly enhanced network homogeneity and mechanical toughness. This study demonstrates that HBPs enable access to reduced resin viscosity and shrinkage stress as well as enhanced network homogeneity compared to conventional linear oligomer additives in densely cross-linked photocurable systems.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"26 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143375820","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-07DOI: 10.1021/acs.macromol.4c02390
Mahuya Kar, Tarun K. Mandal
The development of stimuli-responsive azocopolymer amphiphiles, especially those responsive to pH, light, thermal, and enzyme stimuli, as well as their micellization/demicellization, remains a challenging endeavor for their application in drug delivery. In this work, first, a tailor-made p-aminobenzoic acid end-capped poly(2-ethyl-2-oxazoline) (PABA–PEtOx) is synthesized by a one-pot technique involving cationic ring-opening polymerization (CROP) followed by chain-termination. It is then allowed for diazotization to PEtOx–PABA–N2+Cl– for coupling with electron-rich phenolic polymers, such as poly(l-tyrosine) or poly(4-vinylphenol) to produce azo-bridged water-soluble PTyr–N2–PEtOx or PVPh–N2–PEtOx graft copolymers. The grafted PEtOx segments introduce tunable lower critical solution temperature (LCST)-type phase behavior into copolymers in response to the pH and polymer concentration. The absorbance of trans- and cis-azobenzene peaks in copolymers varies with pH and the irradiation time of light. Amphiphilicity drives the self-assembly of copolymers into spherical micelles, with hydrophobic azo-bridged PTyr/PVPh segments in the core exhibiting unusual emission in water as well as in DCM. Intriguingly, the temperature above which a significant jump in emission intensity is observed, due to copolymer’s micellar agglomeration, can be correlated with the cloud point. The micellar size increases with increasing pH and shape deforms upon light irradiation. The acidic treatment of PVPh-N2–PEtOx produces poly(4-vinylphenol)-N2–poly(ethylene imine) (91% hydrolyzed) copolymer with no LCST in water. The copolymer micelles with low cytotoxicity disintegrate with azoreductase treatment, which triggers the release of Nile red (NR) dye from the NR-loaded micelles. The synthetic approach is simple, yet versatile and can be extended for preparing thermoresponsive azo-bridged bioconjugate by coupling PEtOx–PABA-N2+Cl– with BSA protein.
{"title":"Versatile Azo-Coupling Route to Amphiphilic Poly(2-Oxazoline) Graft Copolymers for Multi-Responsive Micelles and Enzymatic Demicellization","authors":"Mahuya Kar, Tarun K. Mandal","doi":"10.1021/acs.macromol.4c02390","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02390","url":null,"abstract":"The development of stimuli-responsive azocopolymer amphiphiles, especially those responsive to pH, light, thermal, and enzyme stimuli, as well as their micellization/demicellization, remains a challenging endeavor for their application in drug delivery. In this work, first, a tailor-made <i>p-</i>aminobenzoic acid end-capped poly(2-ethyl-2-oxazoline) (PABA–PEtOx) is synthesized by a one-pot technique involving cationic ring-opening polymerization (CROP) followed by chain-termination. It is then allowed for diazotization to PEtOx–PABA–N<sub>2</sub><sup>+</sup>Cl<sup>–</sup> for coupling with electron-rich phenolic polymers, such as poly(<span>l</span>-tyrosine) or poly(4-vinylphenol) to produce azo-bridged water-soluble PTyr–N<sub>2</sub>–PEtOx or PVPh–N<sub>2</sub>–PEtOx graft copolymers. The grafted PEtOx segments introduce tunable lower critical solution temperature (LCST)-type phase behavior into copolymers in response to the pH and polymer concentration. The absorbance of <i>trans</i>- and <i>cis</i>-azobenzene peaks in copolymers varies with pH and the irradiation time of light. Amphiphilicity drives the self-assembly of copolymers into spherical micelles, with hydrophobic azo-bridged PTyr/PVPh segments in the core exhibiting unusual emission in water as well as in DCM. Intriguingly, the temperature above which a significant jump in emission intensity is observed, due to copolymer’s micellar agglomeration, can be correlated with the cloud point. The micellar size increases with increasing pH and shape deforms upon light irradiation. The acidic treatment of PVPh-N<sub>2</sub>–PEtOx produces poly(4-vinylphenol)-N<sub>2</sub>–poly(ethylene imine) (91% hydrolyzed) copolymer with no LCST in water. The copolymer micelles with low cytotoxicity disintegrate with azoreductase treatment, which triggers the release of Nile red (NR) dye from the NR-loaded micelles. The synthetic approach is simple, yet versatile and can be extended for preparing thermoresponsive azo-bridged bioconjugate by coupling PEtOx–PABA-N<sub>2</sub><sup>+</sup>Cl<sup>–</sup> with BSA protein.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"1 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143258417","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-07DOI: 10.1021/acs.macromol.4c02838
Mengtao Wang, Luxin Sun, Chen Luo, Jiachen Chu, Congcong Wu, Kunying Li, Xuepeng Li, Kai Song, Jianxin Li, Xiaohua Ma
Formation of porous organic polymer (POP) membranes is a great challenge due to their highly cross-linked nature that prevents film formability. Here, we reported a series of mechanically strong POP membranes derived from a cross-linked Tröger’s base using 3,3′-dimethylbiphenyl-4,4′-diamine as a linear monomer and 1,3,5-tris(4-aminophenyl)benzene (TPB) as a cross-linking node. As the TPB content increased from 0% (TPB-0) to 75% (TPB-75), these POP membranes show a continuously decreased chain spacing from 7.96 to 6.22 Å, increased Brunauer–Emmet–Teller surface areas from 250 to 531 m2 g–1, and enhanced ultramicropore volumes from 0.046 to 0.143 cm3. Thereby, a huge increase in permeability without sacrificing selectivity was observed for these TPB-based POP membranes. For example, TPB-75 exhibited not only over 19 times larger O2 permeability (790 vs 50.3 Barrer) but also slightly higher O2/N2 selectivity (4.8 vs 4.5) than the linear TPB-0. The overall separation performances quickly improved from below the 2008 trade-off curves for TPB-0 to near the latest 2015 curves for O2/N2, H2/N2, and H2/CH4 as the TPB content increased. These results are attributed to the significantly improved ultramicroporosity that enhanced the molecular sieving effect by the POP structure induced by in situ cross-linking. This design protocol and the POP membranes provide a novel direction for advanced gas separation membranes.
{"title":"In Situ Formation of Tröger’s Base-Derived Porous Organic Polymer Membranes with Greatly Enhanced Ultramicroporosity and Gas Separation Property","authors":"Mengtao Wang, Luxin Sun, Chen Luo, Jiachen Chu, Congcong Wu, Kunying Li, Xuepeng Li, Kai Song, Jianxin Li, Xiaohua Ma","doi":"10.1021/acs.macromol.4c02838","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02838","url":null,"abstract":"Formation of porous organic polymer (POP) membranes is a great challenge due to their highly cross-linked nature that prevents film formability. Here, we reported a series of mechanically strong POP membranes derived from a cross-linked Tröger’s base using 3,3′-dimethylbiphenyl-4,4′-diamine as a linear monomer and 1,3,5-tris(4-aminophenyl)benzene (TPB) as a cross-linking node. As the TPB content increased from 0% (TPB-0) to 75% (TPB-75), these POP membranes show a continuously decreased chain spacing from 7.96 to 6.22 Å, increased Brunauer–Emmet–Teller surface areas from 250 to 531 m<sup>2</sup> g<sup>–1</sup>, and enhanced ultramicropore volumes from 0.046 to 0.143 cm<sup>3</sup>. Thereby, a huge increase in permeability without sacrificing selectivity was observed for these TPB-based POP membranes. For example, TPB-75 exhibited not only over 19 times larger O<sub>2</sub> permeability (790 vs 50.3 Barrer) but also slightly higher O<sub>2</sub>/N<sub>2</sub> selectivity (4.8 vs 4.5) than the linear TPB-0. The overall separation performances quickly improved from below the 2008 trade-off curves for TPB-0 to near the latest 2015 curves for O<sub>2</sub>/N<sub>2</sub>, H<sub>2</sub>/N<sub>2</sub>, and H<sub>2</sub>/CH<sub>4</sub> as the TPB content increased. These results are attributed to the significantly improved ultramicroporosity that enhanced the molecular sieving effect by the POP structure induced by in situ cross-linking. This design protocol and the POP membranes provide a novel direction for advanced gas separation membranes.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"15 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143258418","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-07DOI: 10.1021/acs.macromol.4c02130
Daria Lazarenko, Graham P. Schmidt, Michael F. Crowley, Gregg T. Beckham, Brandon C. Knott
Waste polyesters are a potential feedstock for recycled and upcycled products. These polymers are generally semicrystalline, which presents a challenge for chemical and biological recycling to monomers, and thus the thermodynamic work associated with polyester decrystallization is an important consideration in some depolymerization strategies. Here, we use molecular dynamics simulations to calculate the free energy required to decrystallize a single chain from the crystal surface of five commercially and scientifically important, semiaromatic polyesters (PET, PTT, PBT, PEN, and PEF) in water. Our results indicate the decrystallization work ranges from approximately 15 kcal/mol (PEN) to 8 kcal/mol (PEF) per repeat unit for chains in the middle of a crystal surface. The insight gained into the molecular interactions that form the structural basis of semicrystalline synthetic polyesters can guide the pursuit of more efficient plastic processing, which could include catalyst development, optimizing recycling conditions including pretreatment, enzyme and solvent selections, and design of new materials.
{"title":"Molecular Details of Polyester Decrystallization via Molecular Simulation","authors":"Daria Lazarenko, Graham P. Schmidt, Michael F. Crowley, Gregg T. Beckham, Brandon C. Knott","doi":"10.1021/acs.macromol.4c02130","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02130","url":null,"abstract":"Waste polyesters are a potential feedstock for recycled and upcycled products. These polymers are generally semicrystalline, which presents a challenge for chemical and biological recycling to monomers, and thus the thermodynamic work associated with polyester decrystallization is an important consideration in some depolymerization strategies. Here, we use molecular dynamics simulations to calculate the free energy required to decrystallize a single chain from the crystal surface of five commercially and scientifically important, semiaromatic polyesters (PET, PTT, PBT, PEN, and PEF) in water. Our results indicate the decrystallization work ranges from approximately 15 kcal/mol (PEN) to 8 kcal/mol (PEF) per repeat unit for chains in the middle of a crystal surface. The insight gained into the molecular interactions that form the structural basis of semicrystalline synthetic polyesters can guide the pursuit of more efficient plastic processing, which could include catalyst development, optimizing recycling conditions including pretreatment, enzyme and solvent selections, and design of new materials.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"85 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143367254","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-07DOI: 10.1021/acs.macromol.4c02693
Margaret A. Hall, Broderick Lewis, Kenneth R. Shull
Covalent adaptable networks are frequently studied as alternatives to conventional thermosetting polymers because they can be recycled and reprocessed; however, the inclusion of dynamic covalent bonds within high-temperature (or high-performance) engineering thermoplastics remains largely unexplored. In this work, dynamic disulfide-containing thermoplastic polyimides were synthesized and compared to nondynamic thermoplastic polyimides. The thermomechanical properties of these polymers were examined by utilizing several techniques, including thermogravimetric analysis, differential scanning calorimetry, along with the use of the rheometric quartz crystal microbalance, and traditional dynamic mechanical analysis. The resulting experimental data suggest that the thermal stability of the dynamic compositions was slightly reduced in comparison to the nondynamic analogs, but the dynamic compositions exhibit a similar mechanical response under service conditions. The dynamic compositions also demonstrated significantly easier reprocessability via compression molding than their nondynamic counterparts.
{"title":"Thermomechanical Characterization of High Tg Disulfide-Containing Thermoplastic Polyimides","authors":"Margaret A. Hall, Broderick Lewis, Kenneth R. Shull","doi":"10.1021/acs.macromol.4c02693","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02693","url":null,"abstract":"Covalent adaptable networks are frequently studied as alternatives to conventional thermosetting polymers because they can be recycled and reprocessed; however, the inclusion of dynamic covalent bonds within high-temperature (or high-performance) engineering thermoplastics remains largely unexplored. In this work, dynamic disulfide-containing thermoplastic polyimides were synthesized and compared to nondynamic thermoplastic polyimides. The thermomechanical properties of these polymers were examined by utilizing several techniques, including thermogravimetric analysis, differential scanning calorimetry, along with the use of the rheometric quartz crystal microbalance, and traditional dynamic mechanical analysis. The resulting experimental data suggest that the thermal stability of the dynamic compositions was slightly reduced in comparison to the nondynamic analogs, but the dynamic compositions exhibit a similar mechanical response under service conditions. The dynamic compositions also demonstrated significantly easier reprocessability via compression molding than their nondynamic counterparts.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"78 1 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-02-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143367257","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-06DOI: 10.1021/acs.macromol.4c02349
Xiang Cui, Yulin Luo, Yuliang Yang, Ping Tang
The distinctive rheological behavior of associative polymers (APs) is commonly attributed to the supramolecular interactions between stickers, where transient bonds are continually forming and breaking. This ongoing disruption and reconstruction significantly extend the terminal relaxation time, endowing APs with properties similar to those of entangled polymers. Based on the fundamental sticky Rouse model (SRM), the terminal relaxation of APs can be understood as a result of a combination of strand motion and associative interactions. However, this explanation may be overly simplistic. The presence of multiple relaxation modes arising from a broader range of molecular processes introduces complexity, and their individual contributions to the terminal relaxation time remain uncertain. In this work, we focus on decoupling these multiple relaxation modes. Our findings reveal that, beyond strand motion and associative interactions, the terminal relaxation time is also influenced by factors such as the loss of cross-links, reassociation dynamics, and small molecule reactants. Furthermore, the difference between the activation energy required for strand motion and the magnitude of reaction kinetic activation energy between stickers plays a crucial role in determining the distribution of the terminal relaxation time. We believe that this work offers significant insights into the linear viscoelasticity (LVE) of APs.
{"title":"Decoupling Multiple Relaxation Modes: Composition and Distribution of Terminal Relaxation Time in Associative Polymers","authors":"Xiang Cui, Yulin Luo, Yuliang Yang, Ping Tang","doi":"10.1021/acs.macromol.4c02349","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02349","url":null,"abstract":"The distinctive rheological behavior of associative polymers (APs) is commonly attributed to the supramolecular interactions between stickers, where transient bonds are continually forming and breaking. This ongoing disruption and reconstruction significantly extend the terminal relaxation time, endowing APs with properties similar to those of entangled polymers. Based on the fundamental sticky Rouse model (SRM), the terminal relaxation of APs can be understood as a result of a combination of strand motion and associative interactions. However, this explanation may be overly simplistic. The presence of multiple relaxation modes arising from a broader range of molecular processes introduces complexity, and their individual contributions to the terminal relaxation time remain uncertain. In this work, we focus on decoupling these multiple relaxation modes. Our findings reveal that, beyond strand motion and associative interactions, the terminal relaxation time is also influenced by factors such as the loss of cross-links, reassociation dynamics, and small molecule reactants. Furthermore, the difference between the activation energy required for strand motion and the magnitude of reaction kinetic activation energy between stickers plays a crucial role in determining the distribution of the terminal relaxation time. We believe that this work offers significant insights into the linear viscoelasticity (LVE) of APs.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"67 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143258419","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}