Macromolecules最新文献

{"title":"Temperature-Dependent Pre-nucleation Dynamics in Polymer Melts Using Event-Aligned Simulation Analysis","authors":"Elyar Tourani, Brian J. Edwards, Bamin Khomami","doi":"10.1021/acs.macromol.6c00628","DOIUrl":"10.1021/acs.macromol.6c00628","url":null,"abstract":"<p>Polymer nucleation remains difficult to characterize because precursor states are highly localized, transient, and structurally heterogeneous, and these features collectively govern the emergence of the crystalline nucleus. Previous molecular dynamics studies of polyethylene have shown that the organization of pre-nucleation involves local chain alignment, conformational straightening, and densification and that the structural motifs at the growth front vary with the prevailing kinetic regime. Based on these observations, we establish an event-aligned, lead-time-resolved analytical workflow that connects mechanistic descriptors to temperature-dependent precursor dynamics. We first quantify nucleation kinetics across a series of supercooled temperatures to determine how thermal driving forces modulate the onset of ordering. We then evaluate conventional structural parameters by aligning the trajectories to the nucleation event and comparing their precursor signatures. To probe spatially resolved configurational organization, we employ directional entropy band (DEB) features that encode local anisotropic entropy gradients across concentric radial shells. Low-dimensional embeddings of these entropy band features reveal a progressive separation between atoms belonging to the incipient nucleus and those in the surrounding melt well before nucleation occurs. This structural separation systematically intensifies as the nucleation event approaches. Lead-time analysis further shows that the emergence of strong precursor differentiation shifts to earlier times with increasing undercooling, indicating that deeper undercooling enhances the temporal window over which nucleation-relevant ordering can be detected. Finite-time chain-mobility analysis indicates that accelerated melt dynamics contributes to—but does not fully account for—the observed temperature dependence of precursor differentiation, consistent with an additional role for cooperative structural organization in shaping early-stage nucleation pathways. Complementary supervised classification analyses further demonstrate that DEB features retain predictive discriminability at controlled lead times prior to nucleation onset, with the predictive horizon contracting systematically as the temperature increases. Direct comparison with the combined conventional descriptors {<span><span></span><math><msub><mover><mi>S</mi><mo>̅</mo></mover><mi>i</mi></msub></math>⁠</span>, <em>p</em><sub>2</sub>, <em>q</em><sub>6</sub>} reveals the same temperature-dependent reduction of the precursor horizon. However, conditional-association tests and nested-model evaluations show that outer-shell DEB features preserve complementary predictive information beyond these scalar measures, highlighting their ability to capture spatially distributed configurational cues not encoded in traditional order parameters. In general, the event-aligned structural framework introduced here provides a reproducible methodology to quant","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"59 19","pages":"10981–11000"},"PeriodicalIF":5.7,"publicationDate":"2026-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149173151","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":"Ethyl-Branched Polyketones with Tailored Composition and Molecular Weight via Carbonylative Polymerization of Ethylene with 1-Butene","authors":"Shi-Huan Li,&nbsp;Chao-Qun Fang,&nbsp;Shi-Yu Chen,&nbsp;Ye Liu","doi":"10.1021/acs.macromol.6c01890","DOIUrl":"10.1021/acs.macromol.6c01890","url":null,"abstract":"<p>Polyketones are an important class of engineering thermoplastics produced <em>via</em> the carbonylative polymerization of olefins, featuring excellent mechanical strength, chemical resistance, and barrier properties. However, all commercially available polyketones exclusively employ propylene as the comonomer, and the methyl substitution restricts the chain structure and property tunability. Herein, we report an earth-abundant nickel-catalyzed carbonylative polymerization of ethylene and 1-butene, delivering an ethyl-branched polyketone family with tailored composition (1-butene/CO (C4), 1.9–8.8 mol %) and molecular weight (65–500 kg/mol). A C4 incorporation as low as 3.5 mol % suffices to reduce the melting temperature (<em>T</em>_m) to 228 °C, comparable to commercial polyketone grades, while maintaining a productivity of ∼20 kg polyketone (g Ni)^–1. Compared with propylene-derived methyl side groups, the ethyl substituent enables superior toughness, impact resistance, barrier performance, and enhanced hydrophobicity. At a comparable α-olefin/CO incorporation level of ∼5.5 mol %, the representative sample PK_5.5,118 exhibits a tensile toughness of 23.9 MJ m^–3, 27.1% higher than that of the commercial Hyosung M630 grade with comparable yield strength, and a water vapor transmission rate of only 11.4 g m^–2 day^–1, corresponding to a 31.5% reduction relative to the M630 benchmark. This work establishes an industrially viable pathway to 1-butene-based polyketones, with strong potential to expand the polyketone product landscape beyond the current propylene-based portfolio.</p>","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"59 19","pages":"10825–10832"},"PeriodicalIF":5.7,"publicationDate":"2026-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148974097","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":"Decoupling Mechanical Performance and Macrophase Morphology in Compatibilized Polymer Blends","authors":"Mohammad S. Laeini,&nbsp;Fawaz Motolani,&nbsp;Shubhra Goel,&nbsp;Mykyta Dementyev,&nbsp;Robert J. Hickey,&nbsp;Bryan D. Vogt","doi":"10.1021/acs.macromol.6c00478","DOIUrl":"10.1021/acs.macromol.6c00478","url":null,"abstract":"<p>Recycled plastics suffer from inferior performance due to sorting errors, which limits their commercial adoption. Macromolecular compatibilizers have long been proposed to alleviate embrittlement from imperfect sorting, but compatibilizer cost and varying efficacy limit commercial adoption despite the plethora of compatibilizers reported. In this work, we present a modular C–H activation and click chemistry approach to systematically probe the influence of architectural details of graft copolymers on their efficacy to improve the ductility of polyethylene (HDPE) with dispersed polystyrene (PS) as a model plastic waste. For these compatibilized blends, mechanical performance does not correlate with the size of the dispersed PS phase; moreover, the same compatibilizer can increase or decrease the ductility of identical composition of HDPE/PS blends, where only the molar masses of the matrix and dispersed phase are changed. This sensitivity to ductility is hypothesized to be associated with selection of the dispersed PS and its molar mass dependence of the ductile-to-brittle transition. Increasing the molar mass of the PS grafts of the graft copolymer tends to improve the compatibilization and mechanical performance more effectively than increasing the number of grafts. The sensitivity of compatibilizer performance to the plastic recyclate molar masses demonstrates the value in examining potential compatibilizers against a broad swath of model recyclate to confirm general efficacy.</p>","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"59 19","pages":"10700–10709"},"PeriodicalIF":5.7,"publicationDate":"2026-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149010383","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":"Microscopic Origins of Strength, Damage, and Stretchability in Two-Dimensional Polymer Networks","authors":"Haibo Chen,&nbsp;Jiaqi Li,&nbsp;Dong Yan,&nbsp;Kai Zhang,&nbsp;Xinghua Shi,&nbsp;Jiuling Wang","doi":"10.1021/acs.macromol.6c01335","DOIUrl":"10.1021/acs.macromol.6c01335","url":null,"abstract":"<p>Establishing quantitative links between molecular-scale chain mechanics and the macroscopic response of polymer networks is critical for the design of high-performance soft materials. Here, we combine theoretical analysis with coarse-grained molecular dynamics simulations to investigate the mechanical behavior of two-dimensional (2D) end-linked polymer networks under uniaxial tension and evaluate their ability to capture essential mechanical features of three-dimensional (3D) networks. We first determine the force–extension relation of individual polymer chains and then develop and validate a statistical–mechanical framework that directly relates macroscopic stress to single-chain mechanics and conformational statistics of network strands. We reveal that the inherent strength is approximately two orders of magnitude lower than the ideal strength because of highly heterogeneous load sharing, with only a small fraction of strands sustaining significant energetic tension at failure. Remarkably, damage initiation and progression are controlled by topological shortest paths, on which strand scission preferentially occurs. These features are robust across networks with varying chain lengths, junction functionalities, and fractions of topological defects. The resulting mechanical characteristics are also consistent with those reported for 3D polymer networks, supporting the use of 2D models to capture essential mechanical features of 3D systems. Furthermore, classical constitutive models accurately describe the stress–strain response, although their fitted parameters do not directly correspond to the underlying network structure. Overall, this work provides fundamental insights into the molecular and topological origins of strength, damage, and stretchability in polymer networks and establishes 2D end-linked networks as useful model systems for elucidating these mechanisms.</p>","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"59 19","pages":"11259–11278"},"PeriodicalIF":5.7,"publicationDate":"2026-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149049796","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":"Cooperative Semi-Interpenetrating Polymerization toward Boroxine-Based Dynamic Covalent Networks with Tunable Properties and Chemical Recyclability","authors":"Fan Zhang,Hui Zhou,Tian-Jun Yue,Wei-Min Ren,Xiao-Bing Lu","doi":"10.1021/acs.macromol.6c01784","DOIUrl":"https://doi.org/10.1021/acs.macromol.6c01784","url":null,"abstract":"The dynamic chemistry of covalent boron-oxygen bonds has been extensively leveraged to construct cutting-edge dynamic covalent polymer networks (DCPNs) with self-healing, repairable, and reprocessable properties. However, the inherent poor water resistance of the resulting structural units, such as boronic esters or boroxines, severely limits the widespread application of boron-containing DCPNs. Herein, a novel and effective H2O-induced cooperative semi-interpenetrating polymerization (sIPP) was successfully developed by using diisocyanates (DIC) and linear boronic acid-contained polyesters (P-BA) as starting materials, thus constructing a series of well-mixed and water-resistant dynamic covalent semi-interpenetrating polymer networks (P-sIPNs-DIC) composed of boroxine-based DCPNs and linear polyureas. Additionally, precise control over structural unit composition, sequence distribution, and carbon–carbon double-bond geometry enables tunable mechanical properties of the resultant P-sIPNs-DIC between thermoplastic elastomers and robust plastics. Impressively, P-sIPNs-DIC enable effective acidic depolymerization to selectively recover the pristine P-BA with excellent yield, which can be directly employed to regenerate P-sIPNs-DIC with performance matching the original, thus achieving a closed-loop lifecycle from linear polymers to polymer networks and back to linear polymers.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"27 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149152162","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":"Understanding Relative Reactivity-Governed Kinetics and Network Formation in Thiol-Yne and Other Competitive Consecutive Polymerizations","authors":"Jamison Barcelona,Yunfeng Hu,John F. Rynk,Christopher N. Bowman","doi":"10.1021/acs.macromol.6c02262","DOIUrl":"https://doi.org/10.1021/acs.macromol.6c02262","url":null,"abstract":"Thiol-yne polymerizations couple two sequential additions of thiol: first, to an alkyne and subsequently, to a vinyl sulfide, making the polymerization and the resulting polymer structure dependent on the relative reactivity. Herein, kinetic, analytical, and random-graph frameworks are developed that predict the reaction kinetics and network formation of thiol-yne polymerizations. The kinetic model predicts a chemically driven form of rate acceleration that arises from the interplay between vinyl sulfide generation and consumption and results in the maximum rate being up to 33% faster than the initial rate. Time-independent solutions are found for the conversion trajectories that are then used to derive expressions for gel-point conversion, sol fraction, and elastically active network chain concentrations. The results generalize to other competitive consecutive reactions, such as epoxy-amine reactions. The propagation ratio (γ=kp,enekp,yne) and the stoichiometric ratio of thiol to yne functional groups (χ=[SH0][Y0])are found to govern the relative conversions and network formation, while chain-transfer determines the time scale. In the presence of conversion limitations, the final network develops a kinetic path dependence, transforming the propagation ratio from a transient kinetic property to a governing parameter of the final network structure.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"15 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2026-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149152165","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":"Leveraging Isothermal Crystallization to Actuate the Stress-Free Two-Way Shape Memory Effect within a Narrow and Biocompatible Temperature Window","authors":"Nicoletta Inverardi,&nbsp;Stefano Pandini,&nbsp;Massimo Messori,&nbsp;Maurizio Toselli,&nbsp;Giulia Scalet","doi":"10.1021/acs.macromol.6c00842","DOIUrl":"10.1021/acs.macromol.6c00842","url":null,"abstract":"<p>Two-way shape memory polymers capable of reversible shape changes under a thermal stimulus without applied load remain largely constrained by broad, non-biocompatible actuation windows. In this work, an unconventional strategy is introduced to achieve isothermal, stress-free two-way shape memory actuation in a biocompatible polycaprolactone network without altering its chemistry, after proper programming. This approach exploits isothermal crystallization, the key mechanism underlying the effect, to program reversible deformation. Remarkably, significant elongation is induced by isothermally holding the partially molten network at temperatures well above its peak crystallization temperature. Crystallization kinetics was characterized directly via thermal analysis and indirectly through stress-free two-way shape memory tests. By tuning thermo-mechanical programming conditions while keeping chemistry constant, the actuation window can be confined to a narrow, controlled temperature interval between 37 °C and crystallization temperatures of 10–30 °C. These findings establish a pathway for designing intrinsically reversible polymer networks capable of actuation within tightly defined thermal windows.</p>","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"59 19","pages":"11016–11032"},"PeriodicalIF":5.7,"publicationDate":"2026-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148933577","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":"Influence of Crosslinking and Deformation on Polymer Crystallization and Melting: A Molecular Dynamics Study","authors":"Atmika Bhardwaj,&nbsp;Huzaifa Shabbir,&nbsp;Jens-Uwe Sommer,&nbsp;Marco Werner","doi":"10.1021/acs.macromol.6c00181","DOIUrl":"10.1021/acs.macromol.6c00181","url":null,"abstract":"<p>We investigate the crystallization of crosslinked and entangled polymers under external deformation using a coarse-grained poly(vinyl alcohol) (CG-PVA) model and molecular dynamics simulations. Following uniaxial deformation, the systems are cooled at a constant rate to form semicrystalline states and subsequently heated at a constant rate to induce melting. For unstretched systems, network junctions do not significantly affect the nucleation temperature but increase the amorphous fraction and reduce the melting temperature. Uniaxial deformation accelerates nucleation and markedly increases the crystallization temperature, with more strongly crosslinked polymers exhibiting larger shifts that correlate with an enhanced orientation order parameter. We further compare cooling and heating cycles under constant strain and constant stress conditions. Under constant stress, crystallization induces additional elongation beyond the initial pre-stretch and leads to pronounced mechanical hysteresis upon heating, a behavior characteristic of reversible shape-memory materials.</p>","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"59 19","pages":"10966–10980"},"PeriodicalIF":5.7,"publicationDate":"2026-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148974103","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":"One Core, Many Cures: Quantitative Design Rules for Ionic Liquid Epoxy Curing Agents","authors":"Andrea Szpecht,&nbsp;Dawid Zielinski,&nbsp;Kamil Ochota,&nbsp;Ákos Pomázi,&nbsp;Andrea Toldy","doi":"10.1021/acs.macromol.6c01435","DOIUrl":"10.1021/acs.macromol.6c01435","url":null,"abstract":"<p>Epoxy formulations containing a 20-member library of 1-methylimidazolium dicyanamide ionic liquids showed systematic <em>N</em>-substituent-dependent differences in thermal curing behavior. The library comprised alkyl, unsaturated, polar-functionalized, ether/silyl-containing, and aromatic/bulky substituents. Principal component analysis combined five cation descriptors- topological polar surface area, molar refractivity, fraction of sp³-hybridized carbon atoms, number of rotatable bonds, and cLogP - with four differential scanning calorimetry (DSC) parameters (<em>T</em>_p, Δ<em>H</em>_c, <em>T</em>_g, Δ<em>T</em>_g). Across the library, <em>T</em>_p ranged 120.8–172.5 °C, <em>T</em>_g 46.0–98.6 °C, and Δ<em>H</em>_c 141–620 J g^–1. PC1 (43.04%) described a polarity–flexibility dimension associated with temperature-related parameters, whereas PC2 (21.85%) was associated primarily with curing enthalpy. PC1 decreased approximately linearly across the C2-C16 alkyl series. Three low-enthalpy systems occupied distinct multivariate regions consistent with possible steric limitation, amide-mediated self-association, or trimethoxysilyl-group reactions. The resulting map provides quantitative within-library design rules under the investigated formulation, fixed molar ionic-pair content, and DSC conditions.</p>","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"59 19","pages":"10736–10747"},"PeriodicalIF":5.7,"publicationDate":"2026-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148974104","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":"Polyacrylamide Network Permeation in Hyaluronic Acid and Poly-l-lysine Complex Coacervates","authors":"Kai R. Yamagami,&nbsp;Ping-Huan Tsai,&nbsp;Charles E. Sing,&nbsp;Svetlana Morozova","doi":"10.1021/acs.macromol.6c00699","DOIUrl":"10.1021/acs.macromol.6c00699","url":null,"abstract":"<p>For many biomolecular condensates, complex coacervation occurs in a viscoelastic medium, which can permeate the droplets and regulate phase separation. Here, we study the permeation of complex coacervate droplets composed of hyaluronic acid (HA) and poly-<span>l</span>-lysine (PLL) inside synthetic polyacrylamide (PAM) hydrogels (160–2200 Pa). From the confocal images of fluorescently conjugated complex coacervate phases in the background of a separately labeled gel, we measure the intensity-derived normalized gel concentration λ_g. λ_g rose from ∼0.4 in the soft gels to ∼0.6 in the stiffest gels, showing that the extent of permeation is dependent on elasticity. By varying the solvent ionic strength (10–280 mM) and loading polyelectrolyte concentration (2–40 g L^–1), we find that λ_g is maximized near the critical ionic strength and at the lowest polyelectrolyte loading concentration. Straightforward theory is used to explain the overall physical trends, showing that coacervation in a crosslinked network is governed by a competition between network elasticity and excluded volume interactions.</p>","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"59 19","pages":"10710–10722"},"PeriodicalIF":5.7,"publicationDate":"2026-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"149049756","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}