Macromolecules最新文献_第5页

Enhancement of Suppressed Segmental Mobility in Thin PS Films Supported on Cyclic PS Brushes by Linear-Cyclic Threading Behavior 通过线性-循环穿线行为增强循环PS刷支撑的PS薄膜中抑制的片段迁移率

IF 5.5 1区化学

Macromolecules Pub Date : 2025-09-22 DOI: 10.1021/acs.macromol.5c01805

Fengliang Wang, Ran Gao, Huifeng Zhu, Xiaozhi Zhan, Zhenwei Jiang, Tao Zhu, Xinping Wang

{"title":"Enhancement of Suppressed Segmental Mobility in Thin PS Films Supported on Cyclic PS Brushes by Linear-Cyclic Threading Behavior","authors":"Fengliang Wang, Ran Gao, Huifeng Zhu, Xiaozhi Zhan, Zhenwei Jiang, Tao Zhu, Xinping Wang","doi":"10.1021/acs.macromol.5c01805","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c01805","url":null,"abstract":"The chain mobility in thin polymer film mediated by interfacial chain conformations has attracted much attention over the past decades, but its mechanism is still unclear. In this paper, we modulated the grafting density (σ) of cyclic (c-) polystyrene (PS) brushes on their substrate to probe their effect on the glass transition temperature (Tg) in overlaying PS thin films. The results show that the segmental mobility of PS films supported on c-PS brushes with σ ≤ 0.22 nm–2 was greatly suppressed compared with that on linear brushes. When σ > 0.31 nm–2, the Tg of the supported PS film decreased with the increase of σ and was lower than that of its bulk Tg. The enhanced suppressed segmental mobility in thin PS films was attributed to the linear-cyclic threading behavior occurring in free chains in the PS film and c-PS brushes at the interface. When σ was relatively low, the PS chains in the film were threaded through cyclic brushes and their mobility was greatly suppressed. However, the PS chains were difficult to thread through the c-PS brushes at relatively high σ and the polymer melts were expelled from the polymer brushes by entropic effects, resulting in a topology of the PS brushes that had no effect on the Tg of the upper PS film. This work demonstrated that the Tg of thin polymers films could be enhanced through the threading behavior of upper free chains with c-polymer brushes anchored on their substrate, providing a novel method to improve the thermal stability of ultrathin polymer films and revealing the mechanism of the effect of adsorbed chains in which the chain mobility in the film should be affected by the threading of the free chains through the “loops” in adsorbed chains on the substrate.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"9 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145103743","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

The Payne Effect in Nanofilled Cross-Linked Polyisoprene 纳米填充交联聚异戊二烯的Payne效应

IF 5.5 1区化学

Macromolecules Pub Date : 2025-09-22 DOI: 10.1021/acs.macromol.5c01384

Deboleena Dhara, Md Anisur Rahman, Eric Ruzicka, Brian Benicewicz, Dimitris Vlassopoulos, Sanat K. Kumar

{"title":"The Payne Effect in Nanofilled Cross-Linked Polyisoprene","authors":"Deboleena Dhara, Md Anisur Rahman, Eric Ruzicka, Brian Benicewicz, Dimitris Vlassopoulos, Sanat K. Kumar","doi":"10.1021/acs.macromol.5c01384","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c01384","url":null,"abstract":"We present a systematic study of the Payne effect, i.e., the difference between the small- and large-amplitude oscillatory shear response of filled elastomers, which is relevant to the performance of tires under dynamic driving conditions. The elastomers consist of 14-nm-diameter spherical silica nanoparticles (NPs) grafted with polyisoprene chains, mixed with polyisoprene matrices, and subsequently cross-linked into the gel state. By changing the grafting density and the ratio of the graft-to-matrix chain length, we vary the NP assembly state and examine its response to large-amplitude oscillations. We find that the Payne effect is present at all filler contents but becomes more pronounced at higher NP loadings and for the connected sheet morphology, with the well-dispersed NP state showing the smallest effect. The key concept that apparently controls the strength of the Payne effect is that the core–core contacts are stronger but more fragile compared to interdigitated grafts. Therefore, to achieve increased modulus but reduced Payne effect, a compromise between enhanced NP core interactions and the interdigitation of grafts with other grafts and with the matrix chains is needed. This compromise is best achieved for a morphology intermediate between these two extremes, i.e., a connected network morphology.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"10 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-09-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145117236","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

Chain-End Modifications Suppressing Lamellar Thickening of Short Semicrystalline Polymers under Isothermal Annealing: Molecular Dynamics Simulations 等温退火下链端修饰抑制短半晶聚合物片层增厚：分子动力学模拟

IF 5.5 1区化学

Macromolecules Pub Date : 2025-09-21 DOI: 10.1021/acs.macromol.5c01756

Ran Chen, Chuanfu Luo, Shichun Jiang, Xiaoniu Yang

引用次数: 0

Diffusion Properties of PAMAM Dendrimers in Methanol PAMAM树状大分子在甲醇中的扩散特性

IF 5.5 1区化学

Macromolecules Pub Date : 2025-09-20 DOI: 10.1021/acs.macromol.5c01085

Naira R. Gromova, Amina D. Muratova, Andrei V. Komolkin, Denis A. Markelov

引用次数: 0

Correction to “Deep Red Emissive Aliphatic Oligomeric Polyphosphate Esters from the n–π Interaction Enhanced Spatial Electronic Delocalization” 更正“从n -π相互作用增强空间电子离域的深红色发射脂肪低聚聚磷酸酯”

IF 5.5 1区化学

Macromolecules Pub Date : 2025-09-20 DOI: 10.1021/acs.macromol.5c02432

Lihua Bai, Xiaoqian Ge, Shunsheng Zhao, Hui Yang, Juanmin Li, Hongxia Yan, Xiangrong Liu

引用次数: 0

Photodegradable Biobased Polybenzoxazines: Toward Circular Thermosets 光降解的生物基聚苯并恶嗪：朝着圆形热固性发展

IF 5.5 1区化学

Macromolecules Pub Date : 2025-09-19 DOI: 10.1021/acs.macromol.5c01482

Bhavika Bhatia, Prashansa Gupta, Christophe Len, Bimlesh Lochab

{"title":"Photodegradable Biobased Polybenzoxazines: Toward Circular Thermosets","authors":"Bhavika Bhatia, Prashansa Gupta, Christophe Len, Bimlesh Lochab","doi":"10.1021/acs.macromol.5c01482","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c01482","url":null,"abstract":"Biobased polybenzoxazine (PBz) thermosets are emerging as a promising class of high-performance resins due to their exceptional thermal, mechanical, and chemical resistance. While coumarin-based depolymerization strategies have been successfully established in various polymers, their potential in PBz photodegradation remains unexplored. To advance their sustainability, this study introduces a novel strategy for developing chemically deconstructable PBzs that retain the performance of their conventional counterparts. We report the synthesis of a coumarin-functionalized monofunctional benzoxazine monomer (Co-fa), followed by its [2 + 2] photocycloaddition to yield a cyclobutane-bridged bifunctional monomer, (Co-fa)di. This dimeric monomer exhibited significantly enhanced polymerizability compared with both Co-fa and traditional bisphenol A-based benzoxazines. The resulting poly(Co-fa)di thermoset demonstrated superior thermal stability, mechanical strength, and solvent resistance. Crucially, it underwent efficient photodegradation under 254 nm UV irradiation, enabling light-triggered depolymerization into soluble fragments and subsequent recross-linking. This validates its recyclability and reusability, establishing a dynamic and responsive material platform. This work presents a scalable and versatile approach for fabricating melt-processable photodegradable PBz thermosets. The integration of coumarin-based photochemistry not only enables end-of-life management but also paves the way for the development of photopatternable materials suitable for microfabrication, electronics, data encryption, and other advanced applications.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"37 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145083896","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

Small-angle Neutron Scattering Combined with Spin Polarization Contrast Variation Elucidates Structural Details of Multinetwork Elastomer 小角中子散射结合自旋极化对比变化揭示了多网络弹性体的结构细节

IF 5.5 1区化学

Macromolecules Pub Date : 2025-09-19 DOI: 10.1021/acs.macromol.5c00572

Keitaro Iwasaki, Keisuke Chino, Yohei Noda, Satoshi Koizumi

{"title":"Small-angle Neutron Scattering Combined with Spin Polarization Contrast Variation Elucidates Structural Details of Multinetwork Elastomer","authors":"Keitaro Iwasaki, Keisuke Chino, Yohei Noda, Satoshi Koizumi","doi":"10.1021/acs.macromol.5c00572","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00572","url":null,"abstract":"To elucidate the complexity of cross-linking in multinetwork elastomers (MNEs), we employed small-angle neutron scattering combined with dynamic nuclear polarization (DNP-SANS). MNEs were designed as thermoplastic elastomers with three kinds of cross-linking consisting of hydrogen, covalent, and clay plane bonds. DNP-SANS profiles were obtained with continuously changing scattering contrasts for MNEs with different cross-link densities. We clearly recognize the three matching points in scattering intensity, originating from pairs of cross-linking groups, clay, or main chains. DNP-SANS profiles were decomposed into three partial scattering functions for self-terms of cross-linking groups clay and their cross-terms. The self-term exhibits a scattering maximum due to the interplane distance of clay, which changes with the cross-link density. The cross-term between clay and cross-link was obtained as negative, indicating that the cross-linking domains are tightly correlated, localizing on the clay surface. The results indicate that DNP-SANS is a crucial technique for obtaining structural details of MNE cross-linking without chemical deuteration.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"177 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145084083","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

Structure and Dynamics of Polymer Segments in Polymer-Grafted Nanoparticle Melts 聚合物接枝纳米颗粒熔体中聚合物段的结构和动力学

IF 5.5 1区化学

Macromolecules Pub Date : 2025-09-19 DOI: 10.1021/acs.macromol.5c02155

Jiarul Midya, Arash Nikoubashman

{"title":"Structure and Dynamics of Polymer Segments in Polymer-Grafted Nanoparticle Melts","authors":"Jiarul Midya, Arash Nikoubashman","doi":"10.1021/acs.macromol.5c02155","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c02155","url":null,"abstract":"We present an extensive coarse-grained molecular dynamics study of polymer-grafted nanoparticle (GNP) melts, focusing on the structure and dynamics of the grafted polymers by systematically varying grafting density and chain length. Consistent with theoretical predictions from the recently established two-layer GNP model, we observed the formation of a self-monomer-rich dry layer near the nanoparticle (NP) surface that limits interchain mixing from neighboring GNPs. Beyond this region, an interpenetration layer forms with significant chain mixing. At fixed chain length, the degree of interchain mixing decreases with increasing grafting density, leading to a more extended dry layer at the expense of the interpenetration layer. Segmental analysis shows pronounced chain stretching within the dry layer, while segments adopt coil-like conformations within the interpenetration layer. At high grafting densities, the relative stretching of chain segments becomes nonmonotonic, with a maximum near the center of the interpenetration layer. The bond vector autocorrelation function, which probes segmental dynamics, exhibits a saturation plateau for bonds near the NP surface, reflecting persistent confinement and restricted mobility due to the dense grafting environment. This plateau gradually disappears with an increasing distance of the bonds from the NP surface, and the bond dynamics instead exhibits a power-law decay characteristic of Rouse dynamics in bulk polymer melts. These findings highlight the spatially heterogeneous nature of chain conformations and mobility within the grafted corona.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"38 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145089171","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 a Tough Elastomer by the Introduction of Multiple Flexible Hydrogen Bonds via Simple Modification 通过简单改性引入多个柔性氢键制备韧性弹性体

IF 5.5 1区化学

Macromolecules Pub Date : 2025-09-19 DOI: 10.1021/acs.macromol.5c01964

Dian Zhang, Shintaro Nakagawa, Hirohiko Houjou, Naoko Yoshie

{"title":"Preparation of a Tough Elastomer by the Introduction of Multiple Flexible Hydrogen Bonds via Simple Modification","authors":"Dian Zhang, Shintaro Nakagawa, Hirohiko Houjou, Naoko Yoshie","doi":"10.1021/acs.macromol.5c01964","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c01964","url":null,"abstract":"The introduction of multiple hydrogen bonds (H-bonds) into polymers as dynamic cross-links can increase toughness and enable dynamic functions. In this work, we report a simple and versatile method to introduce a novel flexible H-bond group, namely, vicinal amino alcohol (VAA), into commercially available diene-based polymers. We found that structurally simple and flexible H-bonding groups can act as effective dynamic cross-links, conferring mechanical robustness without sacrificing dynamic properties. These VAA-modified polybutadiene (PB) were synthesized by the epoxidation of PB followed by a ring-opening reaction with various amines. PB modified with vicinal (ethylamino)alcohol presented approximately a 90-fold increase in stress at break and approximately a 75-fold increase in toughness. The VAA modification endowed PB with mechanical strength comparable to that of covalently cross-linked elastomers while maintaining dynamic properties such as self-recoverability. Quantum chemical calculations revealed that VAA adopted a wide variety of stable H-bonded dimer structures, which stabilized the dimer both enthalpically and entropically. Moreover, this method is applicable to other diene polymers, such as polystyrene-block-polybutadiene-block-polystyrene. This study paves the way to transform various diene-based polymers into robust yet dynamic high-performance materials by utilizing the unique features of flexible H-bonds.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"3 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145089169","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

Exploring Long-Range Surface-Induced Mobility Enhancement in Poly(methyl methacrylate) 远距离表面诱导的聚甲基丙烯酸甲酯迁移率增强研究

IF 5.5 1区化学

Macromolecules Pub Date : 2025-09-18 DOI: 10.1021/acs.macromol.5c01939

Haoran Nie, Xiwen Chen, Zongyi Ma, Rui Zhang, Ophelia K. C. Tsui

{"title":"Exploring Long-Range Surface-Induced Mobility Enhancement in Poly(methyl methacrylate)","authors":"Haoran Nie, Xiwen Chen, Zongyi Ma, Rui Zhang, Ophelia K. C. Tsui","doi":"10.1021/acs.macromol.5c01939","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c01939","url":null,"abstract":"The mechanical relaxation behavior of freestanding poly(methyl methacrylate) (PMMA) films and freestanding PMMA supported by a polydimethylsiloxane micrometer film was investigated by using dynamic mechanical analysis (DMA). Results reveal two tiers of enhanced molecular mobility near the surface: a significant enhancement in the nanoscale outer region and a lesser enhancement in a thicker region (thickness, ht ∼ 140 nm) underneath, consistent with observations made in polystyrene (PS) films, where ht ∼ 1000 nm, however. Coarse-grained molecular dynamics simulations of PMMA and PS suggest that fast-moving molecules in the nanoscale surface region activate adjacent molecules, facilitating collective motion in both polymers. For PMMA, this enhancement terminates at a distance consistent with the experimental observation. In contrast, for PS, this dynamic enhancement persists up to the simulated thickness of 250 nm, showing no sign of termination. These findings support the role of near-surface collective motions in driving long-range mobility enhancement, with greater enhancement observed in PS compared to PMMA, accounting for the different ht values.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"1 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145078449","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