Macromolecules最新文献

Evolution of Crystalline Morphology in Ultrathin Films of Copolyesters with Controlled Rigid Dihydric Alcohol Contents 控制刚性二水醇含量的共聚酯超薄膜的结晶形态演变

IF 5.5 1区化学

Macromolecules Pub Date : 2025-05-28 DOI: 10.1021/acs.macromol.5c00799

Decai Lin, Cuiyun Zhang, Miao Zhou, Shicun Jiang, Xinping Wang

{"title":"Evolution of Crystalline Morphology in Ultrathin Films of Copolyesters with Controlled Rigid Dihydric Alcohol Contents","authors":"Decai Lin, Cuiyun Zhang, Miao Zhou, Shicun Jiang, Xinping Wang","doi":"10.1021/acs.macromol.5c00799","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00799","url":null,"abstract":"The isothermal crystalline morphology of random copolyesters, PTTxGy, prepared by polycondensation of terephthalic acid with mixtures of 1,3-propylene glycol (1,3-PDO, T) and 1,4-cyclohexanedimethanol (1,4-CHDM, G) in different molar ratios, was studied by atomic force microscopy (AFM). The results show that with an increasing molar ratio of the rigid component (G) in the dihydric alcohol, the size of the lamellar crystals in ultrathin films initially increased, followed by the formation of stacked lamellae, where the number of stacking layers progressively increased. The lamellar thickness also increased from 5.6 nm in PTT (0% G) to 12.2 nm in PTT85G15 (15% G) after crystallization at 195 °C. These phenomena are attributed to the inhibition of nucleation in the film with the increase of the G component. Consequently, the crystal size increased, while the crystal density decreased. This further makes the lamellar crystals to nucleate and grow on top of a basal lamellar crystal, forming correlated lamellar crystals. Exclusion of the G component from the crystal results in more tails and loops on the lamellar surface and forms thicker amorphous layers on two sides of the crystal; therefore, the lamellar thickness measured by AFM was increased. The effect of the number of nuclei on the formation of correlated lamellar crystals was further demonstrated through a two-step crystallization procedure. As the number of crystal nuclei increased, the degree of stacking and crystal size decreased until a monolayer of lamellae formed after crystallization at 195 °C. This paper highlights the role of the polymer chemical structure in the resulting crystalline morphology of ultrathin films.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"3 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144153422","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}

引用次数: 0

Critical Role of the Steric Factor in the Viscoelasticity of Vitrimers 位阻因子在玻璃体粘弹性中的关键作用

IF 5.5 1区化学

Macromolecules Pub Date : 2025-05-28 DOI: 10.1021/acs.macromol.5c00552

Gregory P. Carden, Murillo L. Martins, Gaukhar Toleutay, Shinian Cheng, Bryson Blad, Jeff Foster, Catalin Gainaru, Alexei P. Sokolov

{"title":"Critical Role of the Steric Factor in the Viscoelasticity of Vitrimers","authors":"Gregory P. Carden, Murillo L. Martins, Gaukhar Toleutay, Shinian Cheng, Bryson Blad, Jeff Foster, Catalin Gainaru, Alexei P. Sokolov","doi":"10.1021/acs.macromol.5c00552","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00552","url":null,"abstract":"Dynamic covalent networks (DCNs) are a promising solution to mitigate plastic-waste-related issues through improved recyclability enabled by dynamic bonds. However, our understanding of the mechanisms controlling their viscoelasticity, especially in vitrimers where bond exchange relies on associative reactions, remains limited. Here, we investigate the dynamics in model DCNs with boric ester functionalities, and the analysis of the temperature dependence of their terminal relaxation times revealed a puzzling result: extremely large Arrhenius prefactors associated with their dynamic bond rearrangement times. We ascribe this observation to the often-overlooked chemical steric factor that slows down chemical reactions, therefore decreasing the vitrimers’ bond exchange rate by many orders. The estimated steric factor of the bond exchange in our model DCNs is comparable to those observed in boronic ester exchange reactions between small molecules. Additional analysis of literature data revealed an overall low steric factor also for imine bond exchange, thus highlighting the role of this parameter in tremendously slowing down bond exchange in DCNs despite low activation energy barriers. We propose a general approach for designing vitrimers with desired viscoelastic and creep properties considering the critical role of the steric factor in bond rearrangement mechanisms, in addition to the traditionally considered activation energy and matrix properties.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"25 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144153420","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}

引用次数: 0

Crystallization Rate Minima of Aliphatic Polyesters Type PE-X,Y in a Wide Range of Undercooling: Role of CH2 Sequence Length and Layered Crystallites 大范围过冷条件下PE-X，Y型脂肪族聚酯的最小结晶速率：CH2序列长度和层状结晶的作用

IF 5.5 1区化学

Macromolecules Pub Date : 2025-05-28 DOI: 10.1021/acs.macromol.5c00614

Hamed Janani, Clay W. Kramer, Nickolas R. Boyd, Marcel Eck, Stefan Mecking, Rufina G. Alamo

{"title":"Crystallization Rate Minima of Aliphatic Polyesters Type PE-X,Y in a Wide Range of Undercooling: Role of CH2 Sequence Length and Layered Crystallites","authors":"Hamed Janani, Clay W. Kramer, Nickolas R. Boyd, Marcel Eck, Stefan Mecking, Rufina G. Alamo","doi":"10.1021/acs.macromol.5c00614","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00614","url":null,"abstract":"Herein, we use three series of aliphatic polyesters, designated as PE-X,Y─where X and Y denote the number of carbon atoms in the diol and diacid, respectively─as model systems to ascertain the molecular and structural factors that govern the manifestation of minima in the temperature dependence of the isothermal crystallization rate. We demonstrate that a required structural factor to observe rate minima is the formation of layered crystallites (lamellar crystals with ester-layered crystalline regions). Up to X ≅ Y/2, polyesters of series PE-X,18 develop layered crystals, and many display up to three rate minima. Unlayered polyesters such as PE-10,18 do not show rate minima. Such correspondence supports the notion of frustration or “self-poisoning” to explain the retardation of the rate observed in a narrow range of temperatures at the transition between quantized crystal thicknesses, thus indicating that the layer is a marker to detect rate anomalies that may point out specifics of polymer crystal growth. The aliphatic CH2 length between esters is an additional factor limiting the manifestation of rate minima. Despite forming layered crystals with quantized crystal thicknesses, as documented by X-ray measurements, the lack of rate minima in the even-spaced polyesters PE-X,12 is explained as a fast thickening at the transition between quantized crystal thicknesses. Furthermore, we also point out that the rate minima observed at temperatures close to the glass transition occur at the convergence of bimodal crystallization kinetics that differs between heterogeneous (high temperature) and homogeneous (low temperature) nucleation modes. Polymorphism, which is observed in some polyesters with a short odd-spaced diol, is uncorrelated with the observed rate minima.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"17 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144153421","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}

引用次数: 0

Hydrophobic Collapse of a Poly(ethylene Oxide)–Poly(propylene Oxide) Alternating Multiblock Copolymer in Water 聚环氧乙烷-聚环氧丙烷交联多嵌段共聚物在水中的疏水崩塌

IF 5.5 1区化学

Macromolecules Pub Date : 2025-05-28 DOI: 10.1021/acs.macromol.4c02433

Kenji Sakanaya, Yusuke Sanada, Keisuke Watanabe, Yuichi Harano, Yukiteru Katsumoto

{"title":"Hydrophobic Collapse of a Poly(ethylene Oxide)–Poly(propylene Oxide) Alternating Multiblock Copolymer in Water","authors":"Kenji Sakanaya, Yusuke Sanada, Keisuke Watanabe, Yuichi Harano, Yukiteru Katsumoto","doi":"10.1021/acs.macromol.4c02433","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02433","url":null,"abstract":"The morphology of single chains and micelles formed by a poly(ethylene oxide) (PEO)–poly(propylene oxide) (PPO) alternating multiblock (AMB) copolymer in water was investigated using scattering techniques. Two series of PEO–PPO AMB copolymers, (EO220PO33)n and (EO68PO33)n─where EO and PO represent ethylene oxide and propylene oxide units, respectively, and n denotes the number of repeating PEO–PPO units─were synthesized with varying overall chain lengths while maintaining a 1:1 block ratio of PEO to PPO. Small-angle X-ray scattering (SAXS) and dynamic light scattering revealed that both (EO220PO33)n and (EO68PO33)n adopt a collapsed conformation in water at ambient temperature. Interestingly, the morphology of the AMB copolymers changes with n: in both series, the polymers exhibit increased shrinkage in water as n increases. AMB copolymers possessing longer PEO chains undergo a more pronounced shrinkage. This aligns with the theoretical prediction for the hydrophobic collapse in protein folding [Y. Harano and M. Kinoshita, Biophys. J. 2005, 89, 2701]. As the temperature increases, AMB copolymers associate to form micelles. The SAXS profiles for (EO220PO33)n are independent of n, indicating that the size and morphologies of micelles remain consistent. A similar trend is observed for (EO68PO33)n. These results suggest that the entropy gain of the surrounding water─resulting from the association of a specific number of PPO blocks─compensates for the entropy loss associated with micelle formation.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"151 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144153419","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}

引用次数: 0

De Novo Design of Polymers with Specified Properties Using Reinforcement Learning 用强化学习重新设计具有特定性质的聚合物

IF 5.5 1区化学

Macromolecules Pub Date : 2025-05-27 DOI: 10.1021/acs.macromol.5c00427

Haifan Zhou, Yue Fang, Linyan Li, Pingwei Liu, Hanyu Gao

{"title":"De Novo Design of Polymers with Specified Properties Using Reinforcement Learning","authors":"Haifan Zhou, Yue Fang, Linyan Li, Pingwei Liu, Hanyu Gao","doi":"10.1021/acs.macromol.5c00427","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00427","url":null,"abstract":"Designing polymers with specified properties is crucial for industries such as aerospace, automotive, and construction, where high yield strength is necessary for stability and performance. Traditionally, the design of polymers has relied on decades of trial-and-error experiments that are time-consuming and inefficient. While recent advancements in computational methods have emerged as promising tools for polymer design, they predominantly focus on property prediction or unbiased polymer generation and do not fully progress toward the tailored design of novel polymer structures that meet specific performance criteria. To accelerate the exploration of new high-performance polymers, we proposed Reinforcement Learning for Polymer Generation (RLPolyG), an integrated goal-oriented exploration workflow for de novo polymer design with specified properties. This framework employs a forward model for predicting polymer properties and an inverse model optimized via reinforcement learning to generate polymers with specific yield strength. Our forward model achieved an R2 of 0.84 in predicting yield strength, enabling the inverse model to generate 4991 novel polymer candidates, resulting in a significant 45.20% improvement in average yield strength. We further screened these candidates based on synthetic accessibility (SA) scores and degradability, identifying 3099 polymers with excellent feasibility for synthesis and degradation performance. Finally, we validated the nine top-performing polymers through molecular dynamics (MD) simulations, which showed an average related error of 14.64% between the predicted and MD-validated values. This work demonstrates the potential of using reinforcement learning to transform polymer design, providing a systematic and efficient pathway to explore the vast polymer space and accelerate the discovery of materials tailored to meet specific industrial needs.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"2020 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144153495","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}

引用次数: 0

Preparation of Polyethoxysiloxanes as a Solid (“a Solid Sol”) by Acid-Catalyzed Sol–Gel Reaction of Tetraethoxysilane 四乙氧基硅烷酸催化溶胶-凝胶反应制备固体聚氧基硅氧烷(固体溶胶

IF 5.5 1区化学

Macromolecules Pub Date : 2025-05-27 DOI: 10.1021/acs.macromol.5c00390

Yohei Sato, Ryo Iida, Ryohei Hayami, Yoshimoto Abe, Takahiro Gunji

引用次数: 0

Branching-Density Dependent Chain Relaxation and Orientated Crystallization Behavior of the Stretched Polylactic Acid Melt 拉伸聚乳酸熔体支链-密度依赖性链弛豫和取向结晶行为

IF 5.5 1区化学

Macromolecules Pub Date : 2025-05-27 DOI: 10.1021/acs.macromol.5c00347

Ye Ma, Deyu Niu, Jiale Liu, Bo Liu, Pengwu Xu, Xingchen Jiao, Weijun Yang, Tianxi Liu, Piming Ma

{"title":"Branching-Density Dependent Chain Relaxation and Orientated Crystallization Behavior of the Stretched Polylactic Acid Melt","authors":"Ye Ma, Deyu Niu, Jiale Liu, Bo Liu, Pengwu Xu, Xingchen Jiao, Weijun Yang, Tianxi Liu, Piming Ma","doi":"10.1021/acs.macromol.5c00347","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00347","url":null,"abstract":"The branching density of long-chain branched polymers is crucial for polymer crystallization and orientation during melt processing, but there are few reports on related quantitative research. In this work, poly(lactic acid) (PLA) was used as an example, and long-chain branched PLA (LCB-PLA) with different branching densities (φ) was constructed by melt blending with epoxy copolymers. The influence of branching density on the chain relaxation, orientation, and crystallization of stretched PLA melt was quantitatively studied. The long-chain branched structure effectively inhibited the chain relaxation of PLA melt, promoting the orientation and crystallization of PLA. The orientated crystallization behavior of LCB-PLA is closely related to the branching density, and there are two critical branching densities. When φ ≤ 2.57 mol/104 mol C, an effective strong molecular chain network that inhibits the chain relaxation of PLA has not yet been formed, and the orientation and crystal structure are hardly formed. When φ is in the intermediate stage (2.57 mol/104 mol C < φ < 6.47 mol/104 mol C), a local strong chain network is formed, which is able to inhibit the relaxation of the oriented chains to some extent. At a higher φ (≥6.47 mol/104 mol C), chain slip and chain mobility are enormously reduced due to the complex topological constraints of adjacent chains, forming a strong global chain network that effectively restricted the relaxation of oriented chains during melt stretching (increasing relaxation time by 3 orders of magnitude), As a result, the orientation degree and crystallinity of stretched LCB-PLA increased to 56% and 36%, respectively. This work provides valuable insights into the structural evolution and performance improvement of long-chain branched polymers during melt processing.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"26 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144153423","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}

引用次数: 0

Highly Loaded Actuation Achieved by Shape Memory Block Copolyimide Aerogels with Tunable Distribution of Stationary and Reversible Phases 固定相和可逆相可调分布的形状记忆嵌段共聚物气凝胶实现了高负载驱动

IF 5.5 1区化学

Macromolecules Pub Date : 2025-05-27 DOI: 10.1021/acs.macromol.5c00483

Shiyang Wang, Dingzheng Zhou, Zhaoyang Tang, Yan Xia, Yan Lv, Zicheng Wang, Bomou Ma, Xu Zhang, Wei Fan, Tianxi Liu

{"title":"Highly Loaded Actuation Achieved by Shape Memory Block Copolyimide Aerogels with Tunable Distribution of Stationary and Reversible Phases","authors":"Shiyang Wang, Dingzheng Zhou, Zhaoyang Tang, Yan Xia, Yan Lv, Zicheng Wang, Bomou Ma, Xu Zhang, Wei Fan, Tianxi Liu","doi":"10.1021/acs.macromol.5c00483","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00483","url":null,"abstract":"The need for a new generation of smart materials in aerospace engineering has spurred substantial research into shape memory materials. As one of the newest types, the shape memory polyimide aerogels have shown great potential due to the lightness, high transition temperature, and stability in an extreme environment. Herein, two kinds of amines with different stiffnesses were screened to prepare a series of shape memory block copolyimide aerogels, which demonstrate the amazing shape memory properties. Over five shape memory cycles, the shape fixation and recovery ratio both surpassed 99%; other than that, the as-prepared block copolyimide aerogels showed the swift (less than 4 s) and complete (over 99%) recovery in the furnace and could lift 250 times their own weight during the recovery process. The distribution of stationary and reversible phases was regulated by controlling the length ratio of the rigid and flexible segments. The AFM results showed that the distribution of the high- and low-modulus areas was successfully controlled, indicating the precise manipulation of stationary and reversible phases. In this process, for the very first time, the relationship between the shape memory properties and the distribution of stationary and reversible phases were managed to uncover. Furthermore, pioneering studies on energy absorption and release in shape memory cycles were conducted. This study may provide significant guidelines for future work on shape memory block copolymer aerogels.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"36 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144153497","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}

引用次数: 0

Exceptionally High Melting Temperature of Polymer Crystal with Fully Extended Chains Prepared via Topochemical Polymerization and Its Analysis Based on Nonlinear Modified Hoffman–Weeks Approach 拓扑化学聚合法制备全延伸链聚合物晶体的超高熔融温度及其基于非线性修正Hoffman-Weeks法的分析

IF 5.5 1区化学

Macromolecules Pub Date : 2025-05-27 DOI: 10.1021/acs.macromol.5c00937

Shota Usukawa, Akikazu Matsumoto, Yasuhito Suzuki

引用次数: 0

Comprehensive Study of the Synergistic Effect in Photocyclic Three-Component Initiating System for Radical Polymerization 光环三组分自由基聚合引发体系协同效应的综合研究

IF 5.5 1区化学

Macromolecules Pub Date : 2025-05-27 DOI: 10.1021/acs.macromol.5c00392

Julien Christmann, Christian Ley, Xavier Allonas

{"title":"Comprehensive Study of the Synergistic Effect in Photocyclic Three-Component Initiating System for Radical Polymerization","authors":"Julien Christmann, Christian Ley, Xavier Allonas","doi":"10.1021/acs.macromol.5c00392","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00392","url":null,"abstract":"In radical photopolymerization, synergistic three-component initiating systems lead to far better radical polymerization performances compared with the corresponding two-component systems. The third component is able to produce additional initiating radicals, regenerate the photoinitiator, thus forming a photocyclic initiating system, and consume terminating photoproducts that occur in two-component photoinitiators. However, the respective roles of these reactions are not well-defined. Kinetic modeling is applied to a synergistic photocyclic initiating system to provide insights into the synergistic effects observed in a system based on an organic dye (Rose Bengal), a triazine derivative, and a tertiary amine as the third component. From kinetic modeling, the low polymerization performances of the dye-triazine system are attributed to back electron transfer but mainly to termination reactions by the oxidized dye photoproduct. Introduction of the amine greatly improves the polymerization performances. From time-resolved experiments, this is explained by its reaction with oxidized Rose Bengal to regenerate the dye and produce additional initiating radicals. It is also shown that the combination of these three components leads to dual photocyclic behavior. Kinetic modeling of the three-component system shows good agreement with the experimental data. Finally, a theoretical study using the kinetic model developed here highlights that the consumption of the oxidized dye terminating agent by the tertiary amine is the main reason for the improved polymerization kinetics.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"58 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144153494","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}

引用次数: 0