Macromolecules最新文献_第5页

Relaxation Dynamics of Poly(ethylene oxide)

IF 5.5 1区化学

Macromolecules Pub Date : 2025-03-19 DOI: 10.1021/acs.macromol.5c00265

Peter Lunkenheimer, Alois Loidl

{"title":"Relaxation Dynamics of Poly(ethylene oxide)","authors":"Peter Lunkenheimer, Alois Loidl","doi":"10.1021/acs.macromol.5c00265","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00265","url":null,"abstract":"Poly(ethylene oxide) is an important polymer with many applications, e.g., as solid-state electrolyte in batteries. Its relaxation dynamics, characterizing its molecular and submolecular motions, which is relevant for many of these applications, was investigated numerous times, mostly employing dielectric spectroscopy. However, the various dynamic processes revealed by these studies were interpreted in conflicting ways and even their nomenclature in literature is highly inconsistent. Here we present the results of a detailed investigation of this polymer employing dielectric spectroscopy covering a relatively broad frequency and temperature range. We clearly detect four intrinsic relaxation processes. The slowest one most likely represents a so-called normal mode, reflecting global motions of the polymer chains, an interpretation that was not considered in previous works. The second process can be unequivocally identified with the segmental α relaxation, which governs glassy freezing and the glass transition. The third, only rarely detected process corresponds to the Johari–Goldstein relaxation of poly(ethylene oxide), widely overlooked in previous studies. The fourth and fastest process is unrelated to the supercooled and glassy state of this polymer and probably due to local, intramolecular motions.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"26 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143660663","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

Supramolecular Polymer Brushes Grafted via Atom Transfer Radical Polymerization from Surfaces Presenting Non-covalent, Host–Guest Complex-Based Initiators

IF 5.5 1区化学

Macromolecules Pub Date : 2025-03-19 DOI: 10.1021/acs.macromol.5c00058

Friederike K. Metze, Harm-Anton Klok

{"title":"Supramolecular Polymer Brushes Grafted via Atom Transfer Radical Polymerization from Surfaces Presenting Non-covalent, Host–Guest Complex-Based Initiators","authors":"Friederike K. Metze, Harm-Anton Klok","doi":"10.1021/acs.macromol.5c00058","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00058","url":null,"abstract":"This paper describes the synthesis of supramolecular polymer brushes via surface-initiated polymerization from adamantane-functionalized initiators that are noncovalently bound to β-cyclodextrin- or cucurbit[7]uril-modified substrates. Surface-initiated atom transfer radical polymerization in aqueous media allowed the growth of various hydrophilic polymer brushes with film thicknesses of up to 40 nm from β-cyclodextrin functionalized surfaces. The adamantane moiety not only forms a host–guest complex with β-cyclodextrin, but also with cucurbit[7]uril, which provides opportunities to study the effect of the binding strength of these supramolecular motifs on the film thickness and grafting density of the resulting polymer brushes. Comparison of supramolecular polymer brushes grown from β-cyclodextrin and cucurbit[7]uril-based noncovalent initiators reveals differences in grafting density that are much smaller than expected based on the differences in the solution binding constant of the corresponding host–guest complexes. Both the β-cyclodextrin as well as the cucurbit[7]uril-anchored supramolecular brushes were remarkably robust toward detachment of the polymer grafts. These observations are attributed to the fact that the rates of formation and dissociation of the host–guest complexes are much faster as compared to diffusion of free, detached polymer chains through the polymer brush film. As a result, the surface-grafted polymer brush presents a steric barrier that prevents detachment of individual chains, and also allows surface-initiated polymerization from substrates to which initiators are bound via putatively weak β-cyclodextrin-based host–guest complexes.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"34 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143660662","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

Structures and Segmental Dynamics in Single-Chain Polymer Nanoparticles-Based All-Polymer Nanocomposites

IF 5.5 1区化学

Macromolecules Pub Date : 2025-03-19 DOI: 10.1021/acs.macromol.5c00570

Peizhi Zhao, Zhiwei Yan, Yuling Liang, Rongchun Zhang

{"title":"Structures and Segmental Dynamics in Single-Chain Polymer Nanoparticles-Based All-Polymer Nanocomposites","authors":"Peizhi Zhao, Zhiwei Yan, Yuling Liang, Rongchun Zhang","doi":"10.1021/acs.macromol.5c00570","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00570","url":null,"abstract":"All-polymer nanocomposites are attracting dramatic attention due to their unique mechanical and viscoelastic properties. In this study, via multiscale solid-state nuclear magnetic resonance (NMR) methods, it is clearly revealed that a polystyrene (PS)-based single-chain polymer nanoparticle (SCNP) is in closer proximity with linear poly(vinyl methyl ether) (PVME) chains compared to linear PS chains, leading to dramatically different phase separation structures as demonstrated by 1H spin diffusion NMR experiments. High-resolution solid-state 1H NMR spectroscopy at ultrafast magic-angle-spinning (MAS) beyond 90 kHz directly reveals the subtle difference in proximity as well as the hydrogen bonding interactions between PVME and PS (or PS-SCNP) at a molecular level. Due to closer proximity between the PS-SCNP and PVME, the segmental dynamics of PVME is also slowed down by its hydrogen bonding interactions with PS-SCNP as revealed by variable-contact-time cross-polarization (CP) experiments. Particularly, 1H fast field cycling NMR experiments at variable temperatures clearly reveal the enhanced glassy and Rouse dynamic heterogeneity of PVME in the PS-SCNP/PVME blend. To the best of our knowledge, this is the first study to apply solid-state NMR spectroscopy to reveal the sophisticated interplay of structures and segmental dynamics in all-polymer nanocomposites at a molecular level, obtaining consistent results with molecular simulations, which could be helpful for the fundamental understanding of the unusual viscoelastic behaviors of all-polymer nanocomposites.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"9 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143660664","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

Comparative Investigation on the Crystallization Behavior of Polypropylene Nucleated by Sorbitol-Based Nucleating Agents with and without Fibrous Network Formation

IF 5.5 1区化学

Macromolecules Pub Date : 2025-03-19 DOI: 10.1021/acs.macromol.4c03187

Xuan Sha, Junjin Duan, Jiachun Feng

{"title":"Comparative Investigation on the Crystallization Behavior of Polypropylene Nucleated by Sorbitol-Based Nucleating Agents with and without Fibrous Network Formation","authors":"Xuan Sha, Junjin Duan, Jiachun Feng","doi":"10.1021/acs.macromol.4c03187","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c03187","url":null,"abstract":"Sorbitol derivatives are effective nucleating agents (NAs) for polypropylene (PP), and their nucleation capacity is generally accepted to associate with fibrous network formation before PP crystallization. However, whether the network must be preformed to promote PP crystallization is overlooked. To address this issue, this work adjusted the network to not form before PP crystallization and compared its effect on PP crystallization to NAs with the networks. Specifically, for PP containing 0.4 wt % Millad NX8000, a sorbitol-based NA, the network is controlled to form by cooling at 2 °C/min and not form by ice-water quenching. Both samples were heated to a temperature sufficient to erase the thermal history of PP while retaining the network of NAs present and absent (NA-p and NA-a), and subsequent PP crystallization was evaluated. Compared to PP/0.4NA-p, the slightly higher nucleation efficiency and density for PP/0.4NA-a indicate that the NA without networks exhibits comparable or even more effective nucleating effects. Additionally, NA-p restricts PP growth in the later crystallization stage and promotes the oriented growth after shear, whereas these phenomena weaken in PP/0.4NA-a. These findings provide new insights into the role of fibrous network formation in the effectiveness of sorbitol-based NAs.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"29 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-03-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143660661","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

Molecular Simulation of Effects of Network Structure on Fracture Behavior of Gels Synthesized by Radical Polymerization

IF 5.5 1区化学

Macromolecules Pub Date : 2025-03-19 DOI: 10.1021/acs.macromol.4c02875

Tsutomu Furuya, Tsuyoshi Koga

引用次数: 0

Analyzing QCM Data Using a New Transfer-Matrix Model: Long-Ranged Asymmetric Gradient in Shear Modulus Identified Across Immiscible Glassy–Rubbery Polymer Interface

IF 5.5 1区化学

Macromolecules Pub Date : 2025-03-18 DOI: 10.1021/acs.macromol.4c02847

Alexander A. Couturier, Justin C. Burton, Connie B. Roth

{"title":"Analyzing QCM Data Using a New Transfer-Matrix Model: Long-Ranged Asymmetric Gradient in Shear Modulus Identified Across Immiscible Glassy–Rubbery Polymer Interface","authors":"Alexander A. Couturier, Justin C. Burton, Connie B. Roth","doi":"10.1021/acs.macromol.4c02847","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02847","url":null,"abstract":"A new approach to analyzing quartz crystal microbalance (QCM) data using an acoustic transfer-matrix model is presented that enables determining a local depth-dependent shear modulus G̃(z) profile. A strong decrease in dissipation upon annealing is observed for immiscible polymer bilayer films of rubbery polybutadiene (PB) atop glassy polystyrene (PS), reflecting large viscoelastic changes in the sample corresponding to the emergence of a broad gradient in modulus G̃(z) when the ≈5 nm compositional interface is formed. Using a new transfer-matrix form of our continuum mechanics model that matches boundary conditions of shear waves between discrete modeled layers, we computationally fit these changes in frequency Δf(n) and dissipation ΔΓ(n) shifts over a range of harmonics n to the evolution of a modulus gradient. The G̃(z) gradient across the PS/PB bilayer, treated as a hyperbolic tangent, is observed to be broad (230 nm) and strongly asymmetric (200 nm) toward the glassy PS side, consistent with the general trends of local glass transition Tg(z) previously reported. Surprisingly, the G̃(z) gradient is found to be symmetric on a log G scale, with the value of G at the interface equivalent to the geometric mean that optimizes acoustic energy transmission.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"25 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143653987","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

Competing Effects of Amorphous and Crystalline Networks on the Mechanical Behavior of Poly(vinyl alcohol) Hydrogel

IF 5.5 1区化学

Macromolecules Pub Date : 2025-03-18 DOI: 10.1021/acs.macromol.4c02149

Kun Song, Ming-Ke Zhang, Jing-Jing Han, Ming-Ming Chen, Jia-Zhuang Xu, Yue Yin, Zhong-Ming Li, Dong Liu

{"title":"Competing Effects of Amorphous and Crystalline Networks on the Mechanical Behavior of Poly(vinyl alcohol) Hydrogel","authors":"Kun Song, Ming-Ke Zhang, Jing-Jing Han, Ming-Ming Chen, Jia-Zhuang Xu, Yue Yin, Zhong-Ming Li, Dong Liu","doi":"10.1021/acs.macromol.4c02149","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02149","url":null,"abstract":"We investigate the effect of amorphous and crystalline networks on the mechanical behavior of poly(vinyl alcohol) physical hydrogels by comparing the rheological properties and flow-induced structural evolution for samples annealed at different temperatures with rheometers and in situ small-angle X-ray and neutron-scattering measurements. Four strain regions, namely, the linear (I), yielding (II), linear (III), and strain-hardening (IV) regions, are revealed in the tensile response. A critical annealing temperature 74 °C is observed, which corresponds to the structural transition from isolated crystal to crystalline network and the mechanical transition from quasi-linear to nonlinear response. For samples annealed below 74 °C, mechanical response depends on the deformation of the soft amorphous network, and the destruction in network connectivity plays a key role in the slight yielding. For samples annealed above 74 °C, the hard crystal network provides high strength and stiffness to the gels, resulting in loss modulus and Young’s modulus an order of magnitude higher than those annealed below 74 °C. In region II, the rupture of crystalline network leads to the more drastic yielding. For all samples, crystal disaggregation along the flow direction is found to be constrained by the secondary nucleus length. Moreover, the flow-induced recrystallization results in the strain-hardening behavior in region IV. These results reveal the role of soft and hard network structures in determining the mechanical performance of physical hydrogels.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"16 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143641040","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

Clustering and Nanoscale Vitrimeric Behavior in Telechelic Polybutadiene Model Vitrimers

IF 5.5 1区化学

Macromolecules Pub Date : 2025-03-18 DOI: 10.1021/acs.macromol.4c03035

Angel Alegría, Arantxa Arbe, Juan Colmenero, Nikolaos Patelis, Saibal Bhaumik, Mingtao Zhou, Nikos Hadjichristidis

{"title":"Clustering and Nanoscale Vitrimeric Behavior in Telechelic Polybutadiene Model Vitrimers","authors":"Angel Alegría, Arantxa Arbe, Juan Colmenero, Nikolaos Patelis, Saibal Bhaumik, Mingtao Zhou, Nikos Hadjichristidis","doi":"10.1021/acs.macromol.4c03035","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c03035","url":null,"abstract":"Despite the promise of vitrimeric materials applications, there are many aspects that remain poorly understood. To advance the fundamental knowledge of these materials, model systems of well-controlled composition are needed. Here we report the synthesis of polybutadiene-based model vitrimers, which are further investigated with respect to their structure and dynamic properties. Four vitrimers with different cross-linking concentrations were obtained by modifying the molecular weight of the precursor functionalized polybutadiene precursors. A tetrafunctional aromatic cross-linker was used in all cases. Due to the nature of the cross-linker, the resulting vitrimers exhibit fluorescence indicative of cross-linker association. The structural investigation by small-angle X-ray diffraction showed that the cross-linkers cluster together to form very stable cylindrical structures linked by polybutadiene chains. The dynamic behavior of the vitrimers, as studied by differential scanning calorimetry and broadband dielectric spectroscopy, can be interpreted by the presence of such a cluster structure, where already a few degrees above the glass transition there are significant fluctuations of the dynamic covalent bonds, which remain essentially limited to the intracluster level─i.e., confined in the interphase between the cross-linkers’ clusters and the polymer. This results in rubber-like vitrimeric materials in which the mechanical stability is maintained by the cluster network as long as it is not perturbed by the application of high mechanical stresses, in stark contrast to recently investigated polyisoprene-based model vitrimers with flexible triamine cross-linkers, which also exhibit cluster structure.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"25 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143653988","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

Versatile Anisotropic Coarse-Grained Models for the Structure and Dynamics of Unentangled Poly(tetrafluoroethylene) Melt

IF 5.5 1区化学

Macromolecules Pub Date : 2025-03-18 DOI: 10.1021/acs.macromol.4c02413

Yen-Ting Hsu, Hsiu-Yu Yu

{"title":"Versatile Anisotropic Coarse-Grained Models for the Structure and Dynamics of Unentangled Poly(tetrafluoroethylene) Melt","authors":"Yen-Ting Hsu, Hsiu-Yu Yu","doi":"10.1021/acs.macromol.4c02413","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02413","url":null,"abstract":"We develop anisotropic coarse-grained (CG) models for unentangled poly(tetrafluoroethylene) (PTFE) melts to investigate their structural and dynamical properties at two CG levels, corresponding to six and eight CF2 groups per bead. Higher CG levels improve computational efficiency but face challenges, such as unphysical chain crossing due to reduced steric hindrance and weaker interactions. Additionally, the inherent chain stiffness of PTFE chains is evident. Analyses of the gyration tensor and asphericity indicate that structural anisotropy increases with CG levels. Therefore, we pursue a structure-based, bottom-up coarse-graining approach based on accurate all-atom (AA) simulations. Systematic probing of intermolecular interactions, internal conformations, and global chain dimensions reveals that our models effectively capture structural characteristics. Chain stiffness, such as the Kuhn length, agrees reasonably with AA simulations and experimental data. Furthermore, with appropriate scaling factors introduced, these CG models closely align with the atomistic counterpart in dynamics, including self-diffusivity and zero-shear viscosity. Assessments across molecular weights (48–192 carbons per chain) and temperatures (500 to 650 K) confirm the adaptability of these models. Utilizing the devised CG models, the computational efficiency is approximately accelerated by a factor of N2, where N is the number of CF2 groups per CG bead.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"7 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143653986","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

Designing Highly Entangled, Homogeneous, and Low-Defect Networks for High-Performance Rubbers

IF 5.5 1区化学

Macromolecules Pub Date : 2025-03-17 DOI: 10.1021/acs.macromol.4c03133

Lingmin Kong, Junqi Zhang, Shaoqi Huang, Rongchun Zhang, Jiaming Li, Zhengtian Xie, Jinrong Wu

{"title":"Designing Highly Entangled, Homogeneous, and Low-Defect Networks for High-Performance Rubbers","authors":"Lingmin Kong, Junqi Zhang, Shaoqi Huang, Rongchun Zhang, Jiaming Li, Zhengtian Xie, Jinrong Wu","doi":"10.1021/acs.macromol.4c03133","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c03133","url":null,"abstract":"Rubbers are critical in a wide range of engineering applications; however, conventional processing methods often disrupt the entanglements and introduce defects that compromise their mechanical performance. In this study, we introduce a nondestructive, latex-based processing method for the fabrication of high-performance rubbers with highly entangled, homogeneous, and low-defect networks. As a proof of concept, natural rubber (NR) materials prepared using this novel approach retain their intrinsic entanglements while exhibiting a more homogeneous network structure with fewer defects. This optimized NR network enhances strain-induced crystallization (SIC), achieving a crystallinity of up to 38% and larger crystal sizes. These improvements lead to superior mechanical properties, including a tensile strength of 37.3 MPa, a toughness of 77.3 MJ/m3, a modulus of 2.37 MPa, and a fatigue threshold of 258 J/m2, outperforming conventional NR materials. Furthermore, this method is versatile and can be applied to other rubbers, demonstrating its broad potential for producing high-performance rubber materials.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"75 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143635395","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