Macromolecules最新文献

{"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 &lt; φ &lt; 6.47 mol<i>/</i>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}

{"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}

{"title":"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","authors":"Shota Usukawa, Akikazu Matsumoto, Yasuhito Suzuki","doi":"10.1021/acs.macromol.5c00937","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00937","url":null,"abstract":"One of the important parameters characterizing semicrystalline polymers is the melting temperature, which is linked to the lamellar thickness. However, within reasonable experimental time scales, the range of achievable lamellar thicknesses is limited, which makes the validation of theory difficult. Herein, we prepared polymer crystals of polymuconate with fully extended chains via topochemical polymerization. The melting temperature of the as-prepared polymer was found to be 217 °C. In contrast, the same polymer exhibited melting temperatures ranging from 148 to 156 °C after crystallization from the melt at various crystallization temperatures within the accessible experimental range. This extremely large difference in melting temperature cannot be explained by linear extrapolation of the Hoffmann–Weeks plot. We show that the experimental data can be described by the nonlinear Hoffmann–Weeks approach and discuss the applicability of the nonlinear Hoffmann–Weeks approach.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"35 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144153498","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}

{"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}

{"title":"Reversible Deactivation Radical Polymerization in Heterogeneous Systems: Enhancing Access to High Molecular Weight Polymers","authors":"Shuangqi Lian, Ruoyu Li, Yidan Chen, Zesheng An","doi":"10.1021/acs.macromol.5c00820","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00820","url":null,"abstract":"High molecular weight (HMW) polymers (<i>M</i>_n &gt; 500 kg mol^–1) are indispensable in advanced applications owing to their superior physical properties and performance characteristics. While homogeneous reversible deactivation radical polymerization (RDRP) systems struggle with viscosity-driven limitations at high conversions, heterogeneous RDRP techniques (emulsion, miniemulsion, dispersion) offer compelling environmental, kinetic, and processing advantages. This Perspective examines the synthesis of HMW polymers in these heterogeneous systems, highlighting their unique mechanistic features, rapid kinetics, and scalability. We also outline the challenges and opportunities in system engineering, polymer chain engineering, polymerization techniques, and circularity. By bridging fundamental insights with industrial scalability, heterogeneous RDRP systems stand at the forefront of macromolecular innovation for next-generation materials that harmonize performance with sustainability.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"8 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144136970","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}

{"title":"Reconfigurable Shape Memory Polythiourethane with Covalent Adaptable Networks","authors":"Juan Tan, Jian Chen, Ya Wen, Xinchun Wang, Hongmei Chen, Hailiang Ni, Wenhao Yu, Yuefeng Bai, Ping Hu, Xiuchen Li","doi":"10.1021/acs.macromol.5c00566","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00566","url":null,"abstract":"Introducing dynamic covalent bonds into polymer networks to construct thermoadaptive networks enables materials to exhibit plasticity and facilitates the reconstruction of permanent shapes. This study implements dynamic thiol-based carbamate bonds as cross-linking points within shape memory polyurethane networks, connecting segments of crystalline polycaprolactone (PCL) and amorphous hydroxyl-terminated polybutadiene (HTPB) to form a cross-linked structure. The one-pot synthesis method facilitates the facile adjustment of the ratio between PCL and HTPB, and the mechanical properties and shape memory capabilities of the material can be tailored. Small-molecule simulation experiments confirm the dynamic nature of the thiol-based carbamate bonds; due to the exchange properties of the dynamic bonds at lower temperatures, the cross-linked network is prone to rearrangement, enabling the shape memory material to easily achieve permanent shape reconfiguration and facilitating the recycling and reprocessing of the material. The topology freezing transition temperature (<i>T</i>_v) and the operational temperature can be determined by identifying the abrupt plateau in the Tan Delta curve. This design merges plasticity with reprocessability within a shape memory network, offering greater possibilities for the deformation performance of shape memory materials.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"41 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144153499","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}

{"title":"Interfacial Polarization and Electrorheology of Suspensions Containing Monodispersed Ellipsoidal Poly(ionic liquid) Particles","authors":"Yudong Wang, Xiaoyang Zhao, Jingyi Li, Haoming Pang, Xiaopeng Zhao, Jianbo Yin","doi":"10.1021/acs.macromol.5c00175","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00175","url":null,"abstract":"The shape parameters of dispersed phase particles, such as the aspect ratio, have a significant influence on the performance of composite and suspension materials. However, due to the difficulty in preparing uniform dielectric particles having the same individual particle volume and chemical structure but different aspect ratios, the influence of the aspect ratio on the electrorheological (ER) effect of particle suspensions remains controversial. In this article, we prepared uniform ellipsoidal poly(ionic liquid) (PIL) particles with different aspect ratios via a thermal stretching method and investigated the influence of aspect ratio on the ER effect of suspensions containing ellipsoidal PIL particles. Because the ellipsoidal PIL particles are obtained by uniaxially stretching the identical uniform PIL microspheres, they are prolate ellipsoids of revolution (spheroids) having the same individual particle volume, density, and chemical structure and uniform size distribution and shape. In particular, the PIL particles are not hydrophilic because they have polyatomic fluorine-containing counterions. Thus, we remove the influences of volume, density, chemical structure, size and shape distribution of particles, and external water on the ER effect, leaving the aspect ratio as the sole factor to affect the ER effect. Under electric fields, we found that, unlike the early conclusion, the ER effect of PIL particle suspensions first decreases and then increases with the increase in aspect ratio. Dielectric spectroscopy analysis and microscopic ER structure observation showed that the difference in the dielectric intensity and the relaxation time of the two interfacial polarizations along the long axis and short axis of low-aspect-ratio ellipsoidal PIL particles is not significant, which leads low-aspect-ratio ellipsoidal particles to orientate randomly along the direction of the electric field and form short and thin chain-like ER structures, and this is the reason why their ER effect is lower compared to their spherical counterparts. However, high-aspect-ratio ellipsoidal PIL particles exhibit significantly increased polarization intensity along the long axis, which leads them to orient with their long axis along the direction of the electric field and form a thick, network-like ER structure at even low particle volume fraction, and this is why their ER effect significantly increases. Additionally, we found that the settling velocity of the low-aspect-ratio ellipsoidal PIL particle suspension with a moderate volume fraction is even faster than that of the spherical counterpart, while that of high-aspect-ratio particle suspensions is significantly reduced. The results of this paper give clear clarification about the influence of aspect ratio on the ER effect of particle suspensions.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"12 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-05-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144136923","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}

{"title":"Coarse-Grained Parameters for Simulations of Methyl-Methacrylate-Based Polymer Brushes That Reproduce Experimental Swelling Coefficients","authors":"Vinicius Firmino dos Santos, Eduardo R. Almeida, Lucas Miguel Pereira Souza, André Silva Pimentel, Madeleine Ramstedt, Thereza A. Soares","doi":"10.1021/acs.macromol.5c00273","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00273","url":null,"abstract":"Polymer brushes exhibit unique structural and dynamic properties compared to free polymers due to their confined and tethered nature. While coarse-grained (CG) models for free polymers are well-established in the literature, their direct application to polymer brushes is limited. This is because brushes demonstrate distinct conformational behaviors, scaling laws, and responses to environmental stimuli that may not be accurately captured by models developed for free polymers. We have systematically evaluated chemically specific CG parameters within the MARTINI v3 force field for methyl-methacrylate-based polymer brushes. We have found that the most CG parameter assignments led to an excessive coiling of the brush chains and a strong dependence of the calculated swelling coefficient <i>S</i>_C with the water model used (RW, SW, and TW). We traced these issues to an imbalance between polymer–polymer and polymer–water interactions. The revised parameter set accurately reproduced experimental swelling coefficients for methyl-methacrylate-based brushes with varying grafting densities, pH responsiveness, charge, and hydrophilicity, namely, poly(dimethylaminoethyl methacrylate) (pDMAEMA), poly((2-methacryloyloxy)-ethyl trimethylammonium chloride) (pMETAC), poly[2-(methacryloyloxy)ethyl dimethyl-(3-sulfopropyl)] ammonium hydroxide (pMEDSAH), and poly(3-sulfopropyl methacrylate) (pSPMA). Furthermore, these parameters mitigated brush chain hypercoiling and dependence on the water model, ensuring better reproducibility of experimental data and alignment with theoretical brush models.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"34 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144133534","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}

{"title":"Height-Switching of Active Polymers in Binary Polymer Brushes","authors":"Yi-Fan Shen, Meng-Bo Luo","doi":"10.1021/acs.macromol.5c00035","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00035","url":null,"abstract":"Modifying surface properties by polymer brushes is very important in polymer science. The surface properties of binary polymer brushes can be changed by switching the height of one of the two polymers. In this study, the height-switching of the active polymer in a binary polymer brush composed of active and passive polymers was investigated through Langevin dynamics simulations. The active polymer was modeled as a copolymer consisting of an active head possessing a self-propelled force with magnitude <i>F</i>_s and a subsequent passive block. Both the active polymer and passive polymers were end-grafted onto a surface that exhibits an attraction to the active polymer but pure repulsion to the passive polymers. The active polymer is adsorbed on the surface at low <i>F</i>_s while it is desorbed at large <i>F</i>_s. The alteration of the state of the active polymer leads to the reversible height-switching of the active polymer, specifically, the switch between the immersed state of the active polymer beneath the polymer brush at small <i>F</i>_s and the exposed state of the active polymer protruding out of the polymer brush at large <i>F</i>_s. The dependence of the critical self-propelled force <i>F</i>_s^* for this height-switching on the length of the active polymer and the grafting density of the polymer brush was investigated. The results show that active polymers have significant potential as candidates for smart polymer brushes.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"41 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144130288","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}

{"title":"Effect of Molecular Structures on Entanglements and Mechanics of Zwitterionic Hydrogels","authors":"Mengjie Si, Yan-Jie Wang, Yueman Tang, Wei Jian, Ji Lin, Si Yu Zheng, Jintao Yang","doi":"10.1021/acs.macromol.5c00812","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00812","url":null,"abstract":"Zwitterionic hydrogels have great potential as implant materials due to their excellent resistance to protein adsorption. However, it remains a great challenge to toughen these gels owing to the ultrastrong hydration capability of polyzwitterions, which leads to weak associations between hydrated chains. Herein, a zwitterionic hydrogel with integration of toughness and protein resistance was developed by programming the benzene–methylene–imidazolium motif into the zwitterionic moiety and regulating its association behavior. It was found that the benzene and imidazolium did not interfere with the hydration of the anionic group, yet they changed the water coordination shell around the cationic group to allow the formation of compact zwitterion pairs. Taking advantage of ¹H NMR technology and MD simulation, all of the benzene, imidazolium, and methylene between them were revealed as key moieties that facilitate the associations, especially at high monomer concentrations. Among them, the imidazolium was proven to be the predominant factor. Then, the densely associated monomers were conducive to polymerizing into a highly entangled network, contributing to simultaneous improvements in Young’s modulus, toughness, and resilience. Meanwhile, the typical characteristics of a zwitterionic gel were not sacrificed, showing high resistance to protein adsorption. This work provides new insights into the chemical and mechanical design of the zwitterionic gels.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"31 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-05-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144122707","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}