Macromolecules最新文献

{"title":"Topology-Dependent Mechanical Failure of Knotted Polymer Chains from Reactive Molecular Dynamics","authors":"Zhirui Xiang,&nbsp;Tianhang Zhou,&nbsp;Francesco Zonta,&nbsp;Zhenghao Wu","doi":"10.1021/acs.macromol.6c01298","DOIUrl":"10.1021/acs.macromol.6c01298","url":null,"abstract":"<p>Long polymer chains are inevitably tangled in knots that compromise their mechanical strength, yet how knot complexity governs the molecular rupture mechanism remains poorly understood. Here, we study the mechanical failure of single polyethylene chains bearing knots of varying complexity (3–7 crossings) using reactive molecular dynamics simulations across multiple pulling rates. We identify a consistent three-stage failure mechanism comprising entropy-driven tightening, enthalpy-driven tightening, and bond rupture. The breaking force follows a stretched exponential decay with knot complexity, while the elastic modulus grows exponentially; topological confinement therefore plays two competing roles. Analysis of bond-breaking locations indicates a gradual crossover in the failure mechanism: knots with lower minimum crossing number (3₁, 4₁) break predominantly at the knot entrance/exit, whereas knots with higher minimum crossing number (7₁) rupture within the densely packed core. Bond angle analysis shows that the geometric distinction between entrance and core regions diminishes with increasing minimum crossing number, providing a structural rationale for the boundary-to-core shift and demonstrating that knot topology offers a tunable handle on both polymer strength and stiffness.</p>","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"59 21","pages":"12138–12146"},"PeriodicalIF":5.7,"publicationDate":"2026-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149251045","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":"Ordering Dynamics of Cylinder-Forming AB Diblock Copolymers under Triangular Confinement","authors":"Lei Huang,&nbsp;Qiancheng Li,&nbsp;Tao Yang,&nbsp;Ruifang Cao,&nbsp;Qingliang Song,&nbsp;Weihua Li","doi":"10.1021/acs.macromol.6c01943","DOIUrl":"10.1021/acs.macromol.6c01943","url":null,"abstract":"<p>Previous studies have shown that the thermodynamic equilibrium structure of cylinder-forming AB diblock copolymer thin films under the lateral confinement of regular triangles with neutral top and bottom surfaces is always perfectly hexagonally arranged perpendicular cylinders. However, for practical applications, a more critical question is whether these perfect hexagonal patterns can be kinetically realized within a reasonably short annealing time. In this work, we employ coarse-grained dissipative particle dynamics simulations to investigate the self-assembly of cylinder-forming diblock copolymers under regular triangular confinement, aiming to determine the size window for achieving perfect hexagonal cylindrical patterns within a given short simulation time. Our results show that when the side length of the triangle, <em>L</em>, is small, with no more than 7 cylinders along each side, perfect hexagonal patterns are always obtained. As <em>L</em> increases such that the number of cylinders per side ranges from 8 to 15, the <em>L</em> window for each hexagonal pattern remains wide, and defects only emerge near the boundaries between two adjacent windows, primarily due to the formation of different numbers of cylinders along different triangular sides. For even larger <em>L</em>, with up to 19 cylinders per side, a notable <em>L</em> window for perfect hexagonal patterns still persists. By mapping the single-chain diffusion time between simulation and experiment, the simulation times chosen in our work are estimated to correspond to very short annealing times in experiments. Our work demonstrates that triangular confinement can rapidly direct cylinder-forming block copolymers to self-assemble into perfectly hexagonally arranged perpendicular cylinders over a wide range of <em>L</em>, providing a simple strategy for the fabrication of large-scale ordered hexagonal patterns.</p>","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"59 21","pages":"12577–12588"},"PeriodicalIF":5.7,"publicationDate":"2026-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149304209","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":"Strain Stiffening Governs the Thermal Memory Window in Swelling-Preset Networks","authors":"Jiageng Pan,Jiayuan Xu,Bo Yan,Hao Ding,Liang Gao,Guowei Yang","doi":"10.1021/acs.macromol.6c02376","DOIUrl":"https://doi.org/10.1021/acs.macromol.6c02376","url":null,"abstract":"Constrained liquid–liquid phase separation in polymer networks is fundamental; however, how nonlinear elasticity modulates the critical threshold remains elusive, particularly in noncovalent lower critical solution temperature hydrogels. To decouple thermodynamics from nonlinear elasticity without altering molecular compatibility, we developed physically crosslinked poly(vinyl butyral) hydrogels. By fixing the degree of acetalization and varying the molecular weight, we utilized chain length to topologically tune the crosslinking density and extensibility. Analysis indicates that thermal memory primarily stems from metastable supersaturation stabilized by elastic constraints. Although the low swelling temperature sets the thermodynamic driving force, the molecular weight determines the strain-stiffening intensity. Crucially, strain stiffening amplifies the elastic penalty of phase separation, establishing a quantitative correlation between critical supersaturation and network elasticity. Consequently, the thermoplastic window is directly driven by the strain-stiffening-modified modulus. Finally, we demonstrated that this hydrogel can serve as an electricity-free time–temperature indicator for cold chains, thereby establishing a mechanothermodynamic framework for the design of topologically smart hydrogels.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"15 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149374845","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":"Investigation of the Nanomechanical Behaviors of Polymer Single Crystals by Atomic Force Microscopy Nanoindentation","authors":"Yongkang Deng,&nbsp;Peng Yang,&nbsp;Xiaoye Zhang,&nbsp;Ziwen Ma,&nbsp;Yu Song,&nbsp;Wenke Zhang","doi":"10.1021/acs.macromol.6c02126","DOIUrl":"10.1021/acs.macromol.6c02126","url":null,"abstract":"<p>Understanding the nanomechanical behavior of crystalline domains is crucial for establishing structure–property relationships in semicrystalline polymers. In this study, atomic force microscopy (AFM) nanoindentation on compliant polydimethylsiloxane (PDMS) substrates was used to quantify the Young’s modulus, fracture force, and deformation mechanisms of ultrathin polymer single crystals, including polyethylene (PE), poly(ethylene oxide) (PEO), poly(<span>l</span>-lactic acid) (PLLA), poly(ε-caprolactone) (PCL), and polyamide 66 (PA 66). Although several crystals showed comparable Young’s moduli, their fracture behaviors differed markedly. PE and PEO exhibited ductile deformation with permanent imprints and material pile-up, whereas PLLA, PCL, and PA 66 underwent brittle fragmentation. Cyclic loading–unloading further revealed pronounced crystal slip in PEO and hidden slip in thickness-stepped PE, while the other crystals remained mainly elastic before failure. These findings highlight force-activated chain dynamics as a key factor governing crystalline stem slip and the resulting brittle-to-ductile transition in polymer crystals.</p>","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"59 21","pages":"12241–12249"},"PeriodicalIF":5.7,"publicationDate":"2026-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149221631","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":"Solution Behavior of Semiflexible Polyelectrolyte Carboxymethylcellulose with Anisotropic Counterions That Have Spatially Separated Charges","authors":"Can Hou,&nbsp;Max Hohenschutz,&nbsp;Takaichi Watanabe,&nbsp;Walter Richtering,&nbsp;Carlos G. Lopez","doi":"10.1021/acs.macromol.6c01930","DOIUrl":"10.1021/acs.macromol.6c01930","url":null,"abstract":"<p>The properties of polyelectrolytes depend on the counterions that neutralize their backbone. Although the effects of counterion valence and size have been studied, the influence of charge topology, i.e., the spatial distribution of charge within a multivalent counterion, has not been investigated experimentally. We address this question by comparing aqueous solutions of carboxymethyl cellulose (CMC) containing conventional divalent metal ions with solutions containing the organic ditopic counterions hexamethonium and suxamethonium. Conductivity measurements indicate comparable counterion dissociation at low polymer concentrations but substantially greater dissociation of the ditopic ions at higher concentrations. SAXS measurements reveal corresponding structural differences: CMC with ditopic counterions exhibits correlation peaks and smaller stretching parameters, consistent with a larger effective polymer charge and reduced local chain folding, whereas CMC with monotopic divalent metal counterions displays broad correlation shoulders, consistent with weaker electrostatic correlations. Partially “dangling” condensed ditopic ions provide a possible explanation for the observation that the monotopic and ditopic counterions show similar fractions of free counterions from conductivity at low concentrations, while the SAXS profiles indicate a higher effective charge for the ditopic salts. However, this mechanism cannot be established unambiguously from the present conductivity and scattering measurements. Overall, the results demonstrate that counterion charge topology provides a tuneable parameter for controlling polyelectrolyte conformation and charge transport.</p>","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"59 21","pages":"12025–12034"},"PeriodicalIF":5.7,"publicationDate":"2026-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149241807","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":"Precision Synthesis of Living Anionic Polymer Cross-Linked Nanorods in Concentrated Solutions","authors":"Anqi Gu,&nbsp;Zhenzhong Yang","doi":"10.1021/acs.macromol.6c02135","DOIUrl":"10.1021/acs.macromol.6c02135","url":null,"abstract":"<p>One-dimensional polymeric nanostructures provide a versatile platform to construct multifunctional materials. The conventional grafting-from approach toward bottlebrushes and derivative nanorods is compromised by inefficient initiation, heterogeneous propagation, incomplete conversion, and uncontrolled intermolecular cross-linking. Herein, we propose a difunctional asymmetric monomer assisted orthogonal living anionic grafting-from method to precisely synthesize polymer bottlebrushes and nanorods in concentrated solutions. The polymer backbone is achieved by selective anionic polymerization of methacrylate group at the 1,1-diphenylethylene (DPE)-methacrylate monomer, while the pendant DPE groups could be further initiated quantitatively to grow side chains <em>via</em> living anionic copolymerization of methacrylates and the vinylphenyl-methacrylate asymmetric monomer (StMA). The pendant vinylphenyl groups could be initiated for polymerization of styrenic monomers, which could be selectively terminated with alkyl chlorides. Under the inherent electrostatic mediation from the anionic methacrylate enolates at the growth frontier, the cross-linking within the layer <em>via</em> copolymerization of cross-linker contained styrenic monomers is allowed to achieve living cross-linked nanorod in concentrated solutions. The orthogonal living anionic grafting-from method could be iterative in one pot to achieve multilayered bottlebrushes or nanorods. Similarly, the Janus nanorods bearing distinct groups at the opposite blocks are derived from the triblock terpolymers. Various components and functions are distinctly compartmentalized within desired regions.</p>","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"59 21","pages":"12333–12341"},"PeriodicalIF":5.7,"publicationDate":"2026-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149241810","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":"A Proximity-Driven Neighbor Effect in the Degradation of PLA/PLGA Bottlebrush Copolymers","authors":"Yisheng Sun,&nbsp;Basma Elshazly,&nbsp;Tara Y. Meyer","doi":"10.1021/acs.macromol.6c01637","DOIUrl":"10.1021/acs.macromol.6c01637","url":null,"abstract":"<p>Tuning the degradation profile of resorbable polymers is a longstanding goal in materials design. Bottlebrush copolymers (BBCs) offer an additional handle, relative to linear polymers, which is the spatial arrangement of chemically distinct sidechains along a common backbone. We report that backbone sequence modulates the sidechain degradation rate in BBCs bearing poly(lactic acid) (PLA) and/or poly(lactic<em>-co-</em>glycolic acid) (PLGA, 50/50 L:G) sidechains. Using a grafting-through strategy with vinyl-terminated PLA and PLGA macromonomers, we prepared BBCs of matched overall composition but distinct sidechain distributions: random, alternating, gradient, and diblock. Hydrolytic degradation was tracked by ¹H NMR spectroscopy, size-exclusion chromatography, and multi-angle light scattering. The architectures exhibit sequence-dependent PLA degradation rates in the order diblock &lt; gradient &lt; (random ≈ alternating), with random and alternating profiles indistinguishable within experimental error. This ordering is consistent with a neighboring effect wherein greater PLGA-PLA proximity accelerates PLA degradation. The finding that the random and alternating BBCs share a degradation profile despite different local adjacencies indicates that the effect is regional, set by the fraction of nearby fast-cleaving PLGA rather than by direct neighbor identity. Sidechain arrangement along the backbone is therefore a distinct handle for tuning hydrolytic degradation, alongside composition, molecular weight, stereochemistry, and microstructure.</p>","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"59 21","pages":"12250–12259"},"PeriodicalIF":5.7,"publicationDate":"2026-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149304189","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":"Core-Functionalized 1,4-Naphthoquinone-Based Polymer Donors for Efficient and Stable Quasi-Planar Heterojunction Organic Solar Cells","authors":"Sichang Chen,&nbsp;Ying Qian,&nbsp;Xuechun Yang,&nbsp;Yunpeng Wang,&nbsp;Junyin Dong,&nbsp;Jiaying Wu,&nbsp;Feng He","doi":"10.1021/acs.macromol.6c01860","DOIUrl":"10.1021/acs.macromol.6c01860","url":null,"abstract":"<p>Although organic solar cells (OSCs) have achieved major breakthroughs in device efficiency, the development of high-performance polymer donors still lags behind that of acceptors. Herein, we engineered a novel 1,4-naphthoquinone-based building block, naphtho[2,1-b:3,4-b′]dithiophene-4,7-dione (NDTD), by embedding a 1,4-naphthoquinone skeleton into a rigid fused-ring architecture. Based on this scaffold, a series of polymer donors with methyl, hydrogen, and fluorine substituents were synthesized to systematically regulate their optoelectronic properties and photovoltaic potential. When paired with L8-BO in quasi-planar heterojunction (Q-PHJ) devices, the NDTD-Me-based OSCs achieved a champion efficiency of 16.21% and exceptional operational stability, exhibiting T₈₀ lifetimes exceeding 1800 h under storage and continuous illumination, and nearly 1730 h under thermal stress at 65 °C, outperforming both the H- and F-substituted counterparts. Mechanistic investigations further revealed that the superior molecular packing and optimized active-layer miscibility of NDTD-Me/L8-BO contributed to enhanced exciton dissociation, suppressed charge recombination, balanced carrier transport, and reduced energy loss. These findings validate NDTD as a robust electron-deficient platform and highlight rational quinone functionalization as a powerful strategy for concurrently achieving high efficiency and stability in OSCs.</p>","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"59 21","pages":"12364–12373"},"PeriodicalIF":5.7,"publicationDate":"2026-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149226218","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":"Anisotropic Thermal Conductivity of Poly(lactic acid) Polymers Subjected to Uniaxial Elongation","authors":"Oscar Sanchez Pinosa,&nbsp;David C. Venerus","doi":"10.1021/acs.macromol.6c02061","DOIUrl":"10.1021/acs.macromol.6c02061","url":null,"abstract":"<p>The processing and application of polymeric materials involves thermal transport. In many cases, the thermal conductivity is anisotropic due to flow-induced anisotropy of the polymer microstructure. The relationship between the microstructure and thermal conductivity is, however, poorly understood. A major reason for this is the scarcity of reliable thermal conductivity data, particularly for anisotropic systems. Here, we use a robust optical technique to measure the components of the thermal diffusivity tensor for several grades of poly(lactic acid) polymers that have been subjected to uniaxial elongation in the molten state. These data are complemented with tensile stress measurements, and with thermodynamic property measurements that include density, heat capacity, and crystalline fraction. With these data, we examine for amorphous and semi-crystalline polymers the validity of the stress-thermal rule, which gives a linear relation between the thermal conductivity and stress tensors.</p>","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"59 21","pages":"12120–12127"},"PeriodicalIF":5.7,"publicationDate":"2026-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149152063","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":"Hierarchical Dynamics and Phase Transitions in Wedge-Shaped Side-Chain Liquid Crystalline Polymers with Varying Spacer Lengths","authors":"Minghe Sun,&nbsp;Yining Fan,&nbsp;Pingchuan Sun,&nbsp;Shuang Yang,&nbsp;Er-Qiang Chen","doi":"10.1021/acs.macromol.6c01947","DOIUrl":"10.1021/acs.macromol.6c01947","url":null,"abstract":"<p>As an important class of graft polymers, side-chain liquid crystalline polymers (SCLCPs) containing anisotropic mesogenic groups exhibit complex molecular dynamics that are closely coupled with hierarchical structural evolution. In this study, using various characterization techniques, we investigate the phase structures and viscoelastic behavior of a series of wedge-shaped SCLCPs, denoted as <strong>C<em>x</em>BP</strong> (<em>x</em> = 1, 3, 7), where <em>x</em> is the number of methylene units in the spacer linking the wedge-shaped mesogenic side group to the polynorbornene backbone. <strong>C<em>x</em>BP</strong>s form a hexagonal columnar phase (Col_H), with multichain supramolecular columns serving as the basic building block arising from microphase separation of the main and side chains. Upon cooling from the isotropic state, <strong>C<em>x</em>BP</strong>s show unique multistep increases in modulus through four distinct stages (I–IV) with shear moduli of 10⁴, 10⁵, 10⁷, and 10⁸ Pa, respectively, separated by three relaxation/transition processes (α, β, γ). When approaching to –100 °C, a δ-relaxation further raises the modulus to ∼10⁹ Pa. The α- and γ-processes correspond to first-order transitions: the isotropic-to-Col_H transition at ∼90 °C and partial ordering of the side-chain alkyl tails at ∼0 °C, respectively. Notably, the β-process is a predominantly noncooperative relaxation following Arrhenius behavior with an activation energy of ∼300 kJ/mol, attributed to the motion of mesogens on the side chains. Freezing of this motion transforms the Col_H from a “mobile” to a “mesogen-arrested” state, increasing the shear modulus by 2 orders of magnitude from stage II to stage III. We find that a longer spacer lowers the β-relaxation temperature. With a single methylene unit as the spacer, <strong>C<em>1</em>BP</strong> shows β-relaxation partially overlapping with the α-process. Extending the spacer length to three or more methylene units (<strong>C<em>3</em>BP</strong>, <strong>C<em>7</em>BP</strong>) enables sufficient dynamic decoupling of the main and side chains, yielding a wider stage II with a shear modulus of 10⁵ Pa.</p>","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"59 21","pages":"11959–11969"},"PeriodicalIF":5.7,"publicationDate":"2026-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149218895","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}