Pub Date : 2024-10-30DOI: 10.1021/acs.macromol.4c01618
Felix A. Wenzel, Sebastian Stäter, Padraic O’Reilly, Klaus Kreger, Jürgen Köhler, Richard Hildner, Hans-Werner Schmidt
The preparation of supramolecular mesoscale structures with high intrinsic order and orientation based on π-conjugated systems is of fundamental interest for studying their photophysical characteristics as well as for potential applications in (nano)photonics. However, the preparation, isolation and transfer of individual structures to substrates without compromising their structural integrity is challenging. Here we report on the controlled formation of hierarchical superstructures based on poly(3-hexylthiophene) (P3HT) comprising highly ordered and oriented P3HT nanofibers with lengths of up to 20 μm via a two-step self-assembly process. In the first step, we prepare defined supramolecular ribbons of N,N′-1,4-phenylenebis[4-pyridinecarboxamide]. In the second step, these ribbons act as efficient nucleation sites for the transcrystallization of P3HT into μm-long nanofibers from solution. The resulting shish-kebab-like superstructures can be purified and deposited on substrates without compromising their structural integrity. The densely packed and well-arranged P3HT nanofibers within the isolated superstructures feature a high orientational order parameter close to one up to a distance of 15 μm away from the initial nucleation sites. A systematic variation of photoluminescence spectra along the P3HT nanofibers in isolated superstructures indicates an increasing defect density toward the nanofiber end due to fractionation during growth. We anticipate that these findings can be transferred to designing and realizing superstructures as components for nanophotonic devices or light-harvesting antennae.
{"title":"Isolated Hierarchical Superstructures with Highly Oriented P3HT Nanofibers","authors":"Felix A. Wenzel, Sebastian Stäter, Padraic O’Reilly, Klaus Kreger, Jürgen Köhler, Richard Hildner, Hans-Werner Schmidt","doi":"10.1021/acs.macromol.4c01618","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c01618","url":null,"abstract":"The preparation of supramolecular mesoscale structures with high intrinsic order and orientation based on π-conjugated systems is of fundamental interest for studying their photophysical characteristics as well as for potential applications in (nano)photonics. However, the preparation, isolation and transfer of individual structures to substrates without compromising their structural integrity is challenging. Here we report on the controlled formation of hierarchical superstructures based on poly(3-hexylthiophene) (P3HT) comprising highly ordered and oriented P3HT nanofibers with lengths of up to 20 μm via a two-step self-assembly process. In the first step, we prepare defined supramolecular ribbons of <i>N</i>,<i>N</i>′-1,4-phenylenebis[4-pyridinecarboxamide]. In the second step, these ribbons act as efficient nucleation sites for the transcrystallization of P3HT into μm-long nanofibers from solution. The resulting shish-kebab-like superstructures can be purified and deposited on substrates without compromising their structural integrity. The densely packed and well-arranged P3HT nanofibers within the isolated superstructures feature a high orientational order parameter close to one up to a distance of 15 μm away from the initial nucleation sites. A systematic variation of photoluminescence spectra along the P3HT nanofibers in isolated superstructures indicates an increasing defect density toward the nanofiber end due to fractionation during growth. We anticipate that these findings can be transferred to designing and realizing superstructures as components for nanophotonic devices or light-harvesting antennae.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"10 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142541889","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 : 2024-10-30DOI: 10.1021/acs.macromol.4c01667
Guangzhi Jin, Yuzhen Gong, Jun Wang, Min Wang, Jiadong Wang, Shui Hu, Runguo Wang, Xuan Qin, Yonglai Lu
Studies on structural and performance changes under dynamic loads, such as cyclic tension, are limited. We synthesized a casting polyurethane based on 1,5-naphthalene diisocyanate with exceptional fatigue resistance, capable of withstanding up to 700,000 cycles of flexural fatigue. Tensile fatigue tests were conducted at a stretching strain amplitude of 100%, a frequency of 10 Hz, and cycles ranging from 10,000 to 100,000 to investigate the microstructures and properties. Atomic force microscopy revealed a gradual decrease in the high modulus region content, while the medium modulus region initially increased and then decreased, and the low modulus region showed an increasing trend. Transmission electron microscopy images clearly depicted the destruction process of spherulites: crystal bundles initially separated from the spherulites, and with increasing cycles, these crystal bundles became smaller, eventually evolving into “small black dots” after 100,000 cycles. Wide-angle and small-angle X-ray diffraction analyses indicated that crystallinity, grain size, and long period decreased, while the transition layer thickness increased. We further explored the correlation between structural evolution and performance, elucidating the underlying mechanisms. This study provides crucial insights into the performance of casting polyurethanes under dynamic loading, valuable for designing durable, fatigue-resistant materials.
{"title":"Dynamic Load Response of 1,5-Naphthalene Diisocyanate (NDI) Based Casting Polyurethane: A Study of Microstructural and Mechanical Evolution","authors":"Guangzhi Jin, Yuzhen Gong, Jun Wang, Min Wang, Jiadong Wang, Shui Hu, Runguo Wang, Xuan Qin, Yonglai Lu","doi":"10.1021/acs.macromol.4c01667","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c01667","url":null,"abstract":"Studies on structural and performance changes under dynamic loads, such as cyclic tension, are limited. We synthesized a casting polyurethane based on 1,5-naphthalene diisocyanate with exceptional fatigue resistance, capable of withstanding up to 700,000 cycles of flexural fatigue. Tensile fatigue tests were conducted at a stretching strain amplitude of 100%, a frequency of 10 Hz, and cycles ranging from 10,000 to 100,000 to investigate the microstructures and properties. Atomic force microscopy revealed a gradual decrease in the high modulus region content, while the medium modulus region initially increased and then decreased, and the low modulus region showed an increasing trend. Transmission electron microscopy images clearly depicted the destruction process of spherulites: crystal bundles initially separated from the spherulites, and with increasing cycles, these crystal bundles became smaller, eventually evolving into “small black dots” after 100,000 cycles. Wide-angle and small-angle X-ray diffraction analyses indicated that crystallinity, grain size, and long period decreased, while the transition layer thickness increased. We further explored the correlation between structural evolution and performance, elucidating the underlying mechanisms. This study provides crucial insights into the performance of casting polyurethanes under dynamic loading, valuable for designing durable, fatigue-resistant materials.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"66 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142542084","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 : 2024-10-30DOI: 10.1021/acs.macromol.4c01640
De-Long Li, Chun-Yan Liu, Yue Li, Ling Xu, Jun Lei, Gan-Ji Zhong, Hua-Dong Huang, Zhong-Ming Li
High-performance dielectric capacitors are essential for advanced electronics and electrical power systems. Nonetheless, the enhanced discharged energy density (Ud) of polymer-based dielectric films is frequently accompanied by increased conduction and polarization losses as well as reduced charge–discharge efficiency (η). In this study, a scalable “melting extrusion–hot stretching–solid-state stretching” technique was proposed to fabricate high-performance polypropylene (PP)/poly(ethylene terephthalate) (PET) all-organic dielectric films. During hot stretching, PET microdroplets deformed into microfibrils in situ, establishing massive parallel interfaces. The subsequent solid-state stretching induced a mesophase-to-α-crystal transition, forming a mother–daughter crystalline structure. The synergistic effect of well-aligned microfibrillar interfaces and the dense mother–daughter crystalline structure could significantly enhance the breakdown strength and capacitive storage capability by suppressing carrier transport. As a result, the as-prepared PP/PET dielectric films demonstrated an exceptional breakdown strength of 672.2 MV m–1 and a maximum Ud of 4.11 J cm–3 with an η of as high as 92.8%. The proposed technique is demonstrated to be highly effective for structuring in situ well-aligned microfibrils and mother–daughter crystalline structures, thus promoting the development of next-generation, high-performance PP-based film capacitors.
{"title":"In Situ Well-Aligned Microfibrils and Mother–Daughter Crystals as Promising Blocks to Suppress Carrier Transport in Polypropylene Dielectric Films","authors":"De-Long Li, Chun-Yan Liu, Yue Li, Ling Xu, Jun Lei, Gan-Ji Zhong, Hua-Dong Huang, Zhong-Ming Li","doi":"10.1021/acs.macromol.4c01640","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c01640","url":null,"abstract":"High-performance dielectric capacitors are essential for advanced electronics and electrical power systems. Nonetheless, the enhanced discharged energy density (<i>U</i><sub>d</sub>) of polymer-based dielectric films is frequently accompanied by increased conduction and polarization losses as well as reduced charge–discharge efficiency (η). In this study, a scalable “melting extrusion–hot stretching–solid-state stretching” technique was proposed to fabricate high-performance polypropylene (PP)/poly(ethylene terephthalate) (PET) all-organic dielectric films. During hot stretching, PET microdroplets deformed into microfibrils in situ, establishing massive parallel interfaces. The subsequent solid-state stretching induced a mesophase-to-α-crystal transition, forming a mother–daughter crystalline structure. The synergistic effect of well-aligned microfibrillar interfaces and the dense mother–daughter crystalline structure could significantly enhance the breakdown strength and capacitive storage capability by suppressing carrier transport. As a result, the as-prepared PP/PET dielectric films demonstrated an exceptional breakdown strength of 672.2 MV m<sup>–1</sup> and a maximum <i>U</i><sub>d</sub> of 4.11 J cm<sup>–3</sup> with an η of as high as 92.8%. The proposed technique is demonstrated to be highly effective for structuring in situ well-aligned microfibrils and mother–daughter crystalline structures, thus promoting the development of next-generation, high-performance PP-based film capacitors.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"16 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142541778","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 : 2024-10-30DOI: 10.1021/acs.macromol.4c02086
Ziyue Deng, Dan Yuan, Yingming Yao
Poly(cyclopentenyl carbonate) (PCPC) is a recyclable polymer with great potential applications. However, the selective preparation of PCPC from cyclopentene oxide (CPO) and CO2 copolymerization and the chemical recycling of PCPC back to the original monomer CPO are of great challenge. In this work, it was found that the heterometallic rare-earth metal(III)/Zn(II) complexes (RE(III)-Zn(II) complexes) supported by phenylenediamine-bridged triphenols could serve as highly active catalysts for the copolymerization of CPO and CO2 to give pure PCPC. Remarkably, the same complexes alone could also promote the selective depolymerization of PCPC to CPO only by simply raising the reaction temperature up to ca. 160 °C. The copolymerization and depolymerization mechanisms were also proposed.
{"title":"Efficient Polymerization and Selective Depolymerization of Poly(cyclopentene carbonate) Mediated Solely by Heterometallic Rare-Earth(III)/Zinc(II) Complexes","authors":"Ziyue Deng, Dan Yuan, Yingming Yao","doi":"10.1021/acs.macromol.4c02086","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02086","url":null,"abstract":"Poly(cyclopentenyl carbonate) (PCPC) is a recyclable polymer with great potential applications. However, the selective preparation of PCPC from cyclopentene oxide (CPO) and CO<sub>2</sub> copolymerization and the chemical recycling of PCPC back to the original monomer CPO are of great challenge. In this work, it was found that the heterometallic rare-earth metal(III)/Zn(II) complexes (RE(III)-Zn(II) complexes) supported by phenylenediamine-bridged triphenols could serve as highly active catalysts for the copolymerization of CPO and CO<sub>2</sub> to give pure PCPC. Remarkably, the same complexes alone could also promote the selective depolymerization of PCPC to CPO only by simply raising the reaction temperature up to ca. 160 °C. The copolymerization and depolymerization mechanisms were also proposed.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"66 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142541780","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 : 2024-10-30DOI: 10.1021/acs.macromol.4c02051
Minghui Wu, Qian Ren, Xueyun Li, Peng Gao, Long Wang, Wenge Zheng, Ping Cui, Xiaosu Yi, Wei Yang
The mechanical properties of polymeric foams are strongly associated with their cellular structure. However, the relationship between the cellular structure and the mechanical behavior of polymeric foams is complicated by the interdependence of cell size and expansion ratio. Herein, we explored the relationship between cell size and impact strength in poly(lactic acid) (PLA)/rubber blend foams by controlling the cell size while maintaining a constant expansion ratio. Surprisingly, a cell size-induced brittle-to-tough transition was observed at a critical cell size. Foams exhibited brittleness when the cell size exceeded this critical threshold, whereas smaller cell sizes led to improved toughness. The increased toughness was attributed to the robust interaction of stress fields generated by adjacent cells and rubber particles, which could hinder the progression of cell-induced crazes into cracks, resulting in greater energy absorption. This study provides a universal strategy for enhancing the resilience of polymer/rubber blend foams.
{"title":"Supertough Polylactide Blend Foams with Controlled Cell Size","authors":"Minghui Wu, Qian Ren, Xueyun Li, Peng Gao, Long Wang, Wenge Zheng, Ping Cui, Xiaosu Yi, Wei Yang","doi":"10.1021/acs.macromol.4c02051","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02051","url":null,"abstract":"The mechanical properties of polymeric foams are strongly associated with their cellular structure. However, the relationship between the cellular structure and the mechanical behavior of polymeric foams is complicated by the interdependence of cell size and expansion ratio. Herein, we explored the relationship between cell size and impact strength in poly(lactic acid) (PLA)/rubber blend foams by controlling the cell size while maintaining a constant expansion ratio. Surprisingly, a cell size-induced brittle-to-tough transition was observed at a critical cell size. Foams exhibited brittleness when the cell size exceeded this critical threshold, whereas smaller cell sizes led to improved toughness. The increased toughness was attributed to the robust interaction of stress fields generated by adjacent cells and rubber particles, which could hinder the progression of cell-induced crazes into cracks, resulting in greater energy absorption. This study provides a universal strategy for enhancing the resilience of polymer/rubber blend foams.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"23 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142541779","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 : 2024-10-29DOI: 10.1021/acs.macromol.4c01819
Oleksandr Dolynchuk, Robert T. Kahl, Florian Meichsner, Alexander J. Much, Andrii Pechevystyi, Anna Averkova, Andreas Erhardt, Mukundan Thelakkat, Thomas Thurn-Albrecht
It has been a long-term goal to understand the molecular orientation in films of conjugated polymers, which is crucial to their efficient exploitation. Here, we show that the surface energies determine the crystal orientation in films of model conjugated polymers, substituted polythiophenes crystallized on substrates. We systematically increase the surface energy of edge-on crystals formed at the vacuum interface by attaching polar groups to the ends of the polymer side chains. This suppresses crystallization at the vacuum interface, resulting in a uniform face-on crystal orientation induced by the graphene substrate in polythiophene films as thick as 200 nm, which is relevant for devices. Surprisingly, face-on crystal orientation is attained in the modified polythiophenes crystallized even on amorphous surfaces. Furthermore, for the samples with still competing interfacial interactions, the crystal orientation can be switched in the same sample, depending on the crystallization conditions. Thus, we report a fundamental understanding and control of the equilibrium crystal orientation in films of conjugated polymers.
{"title":"Controlling Crystal Orientation in Films of Conjugated Polymers by Tuning the Surface Energy","authors":"Oleksandr Dolynchuk, Robert T. Kahl, Florian Meichsner, Alexander J. Much, Andrii Pechevystyi, Anna Averkova, Andreas Erhardt, Mukundan Thelakkat, Thomas Thurn-Albrecht","doi":"10.1021/acs.macromol.4c01819","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c01819","url":null,"abstract":"It has been a long-term goal to understand the molecular orientation in films of conjugated polymers, which is crucial to their efficient exploitation. Here, we show that the surface energies determine the crystal orientation in films of model conjugated polymers, substituted polythiophenes crystallized on substrates. We systematically increase the surface energy of edge-on crystals formed at the vacuum interface by attaching polar groups to the ends of the polymer side chains. This suppresses crystallization at the vacuum interface, resulting in a uniform face-on crystal orientation induced by the graphene substrate in polythiophene films as thick as 200 nm, which is relevant for devices. Surprisingly, face-on crystal orientation is attained in the modified polythiophenes crystallized even on amorphous surfaces. Furthermore, for the samples with still competing interfacial interactions, the crystal orientation can be switched in the same sample, depending on the crystallization conditions. Thus, we report a fundamental understanding and control of the equilibrium crystal orientation in films of conjugated polymers.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"16 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142536668","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 : 2024-10-29DOI: 10.1021/acs.macromol.4c01588
Natsumi Kyoda, Tatsuya Ishiyama
All-atom molecular dynamics (MD) simulations at the air/polyethylene (PE) melt interface are performed to investigate the entanglement of polymer chains specific to the interfacial region. Before analyzing the entanglement, certain properties of the PE melt such as density, melting point, and glass transition temperature are examined, and the present model accurately reproduces these properties. The MD simulations reveal an enhancement of kink (entanglement) density in the subsurface region of the PE melt. Additionally, it is observed that the enhanced entanglement density exhibits temperature dependence, decreasing as the temperature increases. The influence of the enhanced entanglement density on the diffusion dynamics (mean square displacement) of the polymer chains is examined in the time scale of several tens of nanoseconds. The results confirm that the chain dynamics at the interfacial region are affected by the interface-specific entanglement in the time scale of a reptation-like regime.
{"title":"Enhanced Entanglement Density and Its Implication on Chain Diffusion Dynamics at the Air/Polyethylene Melt Interface","authors":"Natsumi Kyoda, Tatsuya Ishiyama","doi":"10.1021/acs.macromol.4c01588","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c01588","url":null,"abstract":"All-atom molecular dynamics (MD) simulations at the air/polyethylene (PE) melt interface are performed to investigate the entanglement of polymer chains specific to the interfacial region. Before analyzing the entanglement, certain properties of the PE melt such as density, melting point, and glass transition temperature are examined, and the present model accurately reproduces these properties. The MD simulations reveal an enhancement of kink (entanglement) density in the subsurface region of the PE melt. Additionally, it is observed that the enhanced entanglement density exhibits temperature dependence, decreasing as the temperature increases. The influence of the enhanced entanglement density on the diffusion dynamics (mean square displacement) of the polymer chains is examined in the time scale of several tens of nanoseconds. The results confirm that the chain dynamics at the interfacial region are affected by the interface-specific entanglement in the time scale of a reptation-like regime.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"104 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142536667","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 : 2024-10-29DOI: 10.1021/acs.macromol.4c02156
Somin Cha, Jeung Gon Kim, Gregory I. Peterson
Polymers can undergo mechanochemical chain scission during ball-mill grinding (BMG). Various milling and polymer parameters were known to influence chain scission, but the influence of crystallinity was not fully explored. In this report, using ring-opening polymerization, we prepared a library of poly(lactide)s (PLAs) with varying molecular weight and varying crystallinity by changing the stereochemistry of monomers. Semicrystalline PLLA and PDLA (from l- and d-lactide, respectively), amorphous PLDLA (from a copolymerization of l- and d-lactide), and a stereocomplex between PLLA and PDLA were subjected to degradation experiments to assess their degradation kinetics. We found degradation rate constant trends that suggested that the crystallinity had a negligible influence on degradation rates. We attributed this behavior to the fast amorphization of the semicrystalline PLAs. This work provides important insight into how other polymer transformations that occur during ball milling can influence chain scission.
{"title":"Influence of Crystallinity on the Mechanochemical Degradation of Poly(lactide) with Ball-Mill Grinding","authors":"Somin Cha, Jeung Gon Kim, Gregory I. Peterson","doi":"10.1021/acs.macromol.4c02156","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02156","url":null,"abstract":"Polymers can undergo mechanochemical chain scission during ball-mill grinding (BMG). Various milling and polymer parameters were known to influence chain scission, but the influence of crystallinity was not fully explored. In this report, using ring-opening polymerization, we prepared a library of poly(lactide)s (PLAs) with varying molecular weight and varying crystallinity by changing the stereochemistry of monomers. Semicrystalline PLLA and PDLA (from <span>l</span>- and <span>d</span>-lactide, respectively), amorphous PLDLA (from a copolymerization of <span>l</span>- and <span>d</span>-lactide), and a stereocomplex between PLLA and PDLA were subjected to degradation experiments to assess their degradation kinetics. We found degradation rate constant trends that suggested that the crystallinity had a negligible influence on degradation rates. We attributed this behavior to the fast amorphization of the semicrystalline PLAs. This work provides important insight into how other polymer transformations that occur during ball milling can influence chain scission.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"45 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142536669","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 : 2024-10-29DOI: 10.1021/acs.macromol.4c01764
Bei Liu, Zhinan Xia, Wanchao Hu, Shiyi Li, Changli Lü
All-inorganic lead-free halide perovskite Cs3Bi2I9 was encapsulated in a zirconium-porphyrin metal–organic framework (MOF-545) to create a S-scheme heterojunction photocatalyst Cs3Bi2I9@MOF-545 for efficient copper-mediated photoinduced atom transfer radical polymerization (photo-ATRP). The close interfacial contact and the disparity in the work function between MOF-545 and Cs3Bi2I9 has been demonstrated to facilitate photoinduced charge transfer at the interface and boost the efficiency of photogenerated charge separation and utilization. The distinctive advantage of S-scheme charge transfer enabled the optimized Cs3Bi2I9@MOF-545 to effectively regulate the Cu-mediated photo-ATRP of diverse monomers under 850 nm near-infrared (NIR) light with good terminal fidelity, even achieving high monomer conversion on the barriers of 5 mm PP board and 4 mm pigskin. In a large reaction volume (250 mL), the monomer conversion reached approximately 99% with a first-order kinetic behavior under 850 nm NIR light, demonstrating potential for industrial applications. High photocatalytic activity was maintained after 10 cycles of use in organic solvent (DMSO) or 6 days of water immersion. Furthermore, it is unveiled that the limited oxygen can enhance trithanolamine (TEOA) oxidation to accelerate Cu-mediated photo-ATRP in heterojunction photocatalysts for the first time. This study offers insights into designing MOF-based photocatalysts to augment Cu-mediated photo-ATRP performance under NIR-light.
{"title":"Efficient Oxygen-Accelerated Near-Infrared Photoinduced Atom Transfer Radical Polymerization Mediated with S-Scheme Heterojunction Photocatalyst Composed of Lead-Free Halide Perovskite Encapsulated into Metal–Organic Framework","authors":"Bei Liu, Zhinan Xia, Wanchao Hu, Shiyi Li, Changli Lü","doi":"10.1021/acs.macromol.4c01764","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c01764","url":null,"abstract":"All-inorganic lead-free halide perovskite Cs<sub>3</sub>Bi<sub>2</sub>I<sub>9</sub> was encapsulated in a zirconium-porphyrin metal–organic framework (MOF-545) to create a S-scheme heterojunction photocatalyst Cs<sub>3</sub>Bi<sub>2</sub>I<sub>9</sub>@MOF-545 for efficient copper-mediated photoinduced atom transfer radical polymerization (photo-ATRP). The close interfacial contact and the disparity in the work function between MOF-545 and Cs<sub>3</sub>Bi<sub>2</sub>I<sub>9</sub> has been demonstrated to facilitate photoinduced charge transfer at the interface and boost the efficiency of photogenerated charge separation and utilization. The distinctive advantage of S-scheme charge transfer enabled the optimized Cs<sub>3</sub>Bi<sub>2</sub>I<sub>9</sub>@MOF-545 to effectively regulate the Cu-mediated photo-ATRP of diverse monomers under 850 nm near-infrared (NIR) light with good terminal fidelity, even achieving high monomer conversion on the barriers of 5 mm PP board and 4 mm pigskin. In a large reaction volume (250 mL), the monomer conversion reached approximately 99% with a first-order kinetic behavior under 850 nm NIR light, demonstrating potential for industrial applications. High photocatalytic activity was maintained after 10 cycles of use in organic solvent (DMSO) or 6 days of water immersion. Furthermore, it is unveiled that the limited oxygen can enhance trithanolamine (TEOA) oxidation to accelerate Cu-mediated photo-ATRP in heterojunction photocatalysts for the first time. This study offers insights into designing MOF-based photocatalysts to augment Cu-mediated photo-ATRP performance under NIR-light.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"6 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142541783","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}
Enantiomeric blends of L- and D-type chiral polymers usually show distinct crystallization behavior and physical properties from the corresponding enantiopure polymers. However, the crystallization kinetics and crystalline structure of the enantiomeric blends of L- and D-polymers are not yet well understood, particularly concerning the chiral polymers with low chiral moiety densities. Herein, we synthesized a series of long-spaced chiral polyesters with a relatively low chiral moiety content and investigated the effects of enantiomeric blending on the crystallization kinetics and crystal polymorphism of chiral polyesters. Different from the other chiral polyesters with high chiral moiety content, the enantiomeric blends of long-spaced chiral polyesters do not crystallize into the new stereocomplex crystals but have a faster crystallization rate than the corresponding enantiopure polyesters. Compared to the enantiopure polyesters, the enantiomeric blends show the preferred formation of thermally stable form-I crystals in the cooling process and the broader temperature range for generating the form-I crystals in isothermal crystallization. The effects of enantiomeric blending on crystallization become less obvious with decreasing the chiral moiety content or increasing the methylene spacer length. We infer that the accelerated crystallization and facilitated formation of form-I crystals in enantiomeric blends are correlated with the interchain interactions between L- and D-polyesters. This study provides new insights into the crystallization of long-spaced chiral polyesters.
L 型和 D 型手性聚合物的对映体混合物通常表现出与相应的对映体纯聚合物截然不同的结晶行为和物理性质。然而，人们对 L 型和 D 型聚合物对映体混合物的结晶动力学和结晶结构还不甚了解，尤其是对低手性分子密度的手性聚合物。在此，我们合成了一系列手性分子含量相对较低的长间距手性聚酯，并研究了对映体共混对手性聚酯结晶动力学和晶体多态性的影响。与其他手性分子含量较高的手性聚酯不同，长间距手性聚酯的对映体混合物不会结晶成新的立体复合物晶体，但其结晶速度比相应的对映体纯聚酯快。与对映体纯聚酯相比，对映体混合物在冷却过程中更容易形成热稳定的 I 型晶体，在等温结晶过程中生成 I 型晶体的温度范围更广。随着手性分子含量的减少或亚甲基间隔长度的增加，对映体共混物对结晶的影响变得不那么明显。我们推断，在对映体共混物中加速结晶和促进形成 I 型晶体与 L 型和 D 型聚酯之间的链间相互作用有关。这项研究为了解长间隔手性聚酯的结晶提供了新的视角。
{"title":"Accelerated Crystallization and Preferred Formation of a Thermally Stable Crystal Phase in Enantiomeric Blends of Long-Spaced Chiral Polyesters","authors":"Chenxuan Sun, Xuekuan Ma, Mengru Ding, Chengtao Yu, Junfeng Liu, Guorong Shan, Yongzhong Bao, Ying Zheng, Pengju Pan","doi":"10.1021/acs.macromol.4c01881","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c01881","url":null,"abstract":"Enantiomeric blends of L- and D-type chiral polymers usually show distinct crystallization behavior and physical properties from the corresponding enantiopure polymers. However, the crystallization kinetics and crystalline structure of the enantiomeric blends of L- and D-polymers are not yet well understood, particularly concerning the chiral polymers with low chiral moiety densities. Herein, we synthesized a series of long-spaced chiral polyesters with a relatively low chiral moiety content and investigated the effects of enantiomeric blending on the crystallization kinetics and crystal polymorphism of chiral polyesters. Different from the other chiral polyesters with high chiral moiety content, the enantiomeric blends of long-spaced chiral polyesters do not crystallize into the new stereocomplex crystals but have a faster crystallization rate than the corresponding enantiopure polyesters. Compared to the enantiopure polyesters, the enantiomeric blends show the preferred formation of thermally stable form-I crystals in the cooling process and the broader temperature range for generating the form-I crystals in isothermal crystallization. The effects of enantiomeric blending on crystallization become less obvious with decreasing the chiral moiety content or increasing the methylene spacer length. We infer that the accelerated crystallization and facilitated formation of form-I crystals in enantiomeric blends are correlated with the interchain interactions between L- and D-polyesters. This study provides new insights into the crystallization of long-spaced chiral polyesters.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"10 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142519947","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}
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