Macromolecules最新文献

{"title":"Stability of Frank–Kasper Phases in ABn Miktoarm Star Polymers with Dispersity in n: Simulations and Experiments","authors":"Kodai Watanabe, Duyu Chen, Yongsi Zhu, Devon Callan, Glenn H. Fredrickson, Christopher M. Bates","doi":"10.1021/acs.macromol.4c02202","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02202","url":null,"abstract":"Miktoarm star polymers with two or more blocks connected at a common junction are known to stabilize Frank–Kasper phases such as σ and A15 over wide regions of phase space due to arm-number asymmetry. To date, studies on AB_<i>n</i> miktoarm stars in this context have focused on well-defined materials with a precise number of A and B arms. Here, using a combination of self-consistent field theory simulations and experiments, we demonstrate that mixtures of AB_<i>n</i> miktoarm stars with dispersity in the number of B arms per molecule (<i>n</i>) similarly stabilize σ and A15. This insight highlights the utility of a synthetic technique known as μSTAR (miktoarm synthesis by termination after ring-opening metathesis polymerization) that simplifies the synthesis of miktoarm star polymers but inherently produces a mixture of AB_<i>n</i> molecules having a distribution in <i>n</i>.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"7 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142718894","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":"Cyclodextrin-Grafted Poly(vanillin) Antimicrobial Bio-Nanohoops via “Graft From” RAFT and Supramolecular Host–Guest Chemistry","authors":"Jun Li, Yaping Zhang, Feng Zhang, Rongmin Wang, Yufeng He, Pengfei Song","doi":"10.1021/acs.macromol.4c01823","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c01823","url":null,"abstract":"Microbial infections have been recognized as one of the most serious threats to healthcare and agriculture production, and it is still a great challenge to explore antimicrobial biomaterials with supramolecular self-assembling systems. To address this challenge, novel bionanohoops were fabricated via “graft from” reversible addition–fragmentation chain transfer (RAFT) and supramolecular host–guest chemistry. Admittedly, controllable grafting of vanillin-derived homopolymer (PVMA_<i>x</i>) from β-cyclodextrin (β-CD) to synthesize β-cyclodextrin-grafted poly(vanillin methacrylate) (β-CD-<i>g</i>-PVMA_<i>x</i>, <i>x</i> = 5, 35, 103) was calculated from ¹H NMR integral area, and 2D NOESY demonstrated that the primary structured linear homopolymer chains (β-CD-<i>g</i>-PVMA₅) were linked to each other by host–guest interactions. Additionally, GPC results illustrated that the secondary structured nanohoops ([β-CD-<i>g</i>-PVMA₅]_<i>y</i>, <i>y</i> = 38 or 364) were self-assembled in situ from β-CD-<i>g</i>-PVMA₅ through supramolecular host–guest chemistry. Compared with stacking nanorods, nanohoops not only exhibited excellent antibacterial and antifungal activities but also presented good biocompatibility and better paint adhesion. Overall, we provided a valuable strategy that constructs antimicrobial bionanohoops by combining “graft from” RAFT and supramolecular host–guest chemistry for addressing microbial infections.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"71 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142718844","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":"Chemistry Agnostic and Facile Method for Programming the Molecular Weight Distribution of Polymers","authors":"Michael T. Taleff, Antonia Statt, Damien Guironnet","doi":"10.1021/acs.macromol.4c01973","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c01973","url":null,"abstract":"Many of a polymer material’s bulk properties (e.g., tensile strength, viscosity, and self-assembly) are dependent upon its molecular weight distribution. Thus, optimizing the properties of polymers requires systematic tuning of their molecular weight distributions. We developed a simple protocol for the synthesis of polymers with precisely programmed molecular weight distributions, which is applicable across all polymerizations in which molecular weight increases with time. Experimentally, the solution from an active polymerization vessel is transferred to a quenching vessel over time, building a targeted molecular weight distribution. The transfer rate is calculated using a robust and versatile mathematical model. The model includes an interpolation method that predicts the molecular weight distribution at any time during polymerization from a limited set of kinetic data. This interpolation enables the predictive capabilities of our protocol. We demonstrate the method by synthesizing polymers with square or trapezoidal molecular weight distributions using the group transfer polymerization of methyl methacrylate, the ring-opening metathesis polymerization of exo-5-norbornene-2-methylbenzoate, the atom transfer radical polymerization of methyl methacrylate, and the ring-opening polymerization of butylene oxide.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"23 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142718842","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":"Thermo/pH-Responsive Multiamide-Functionalized Y-Junction-Bearing Polyacrylamides with Substituent-Dependent Thermal Reversibility","authors":"Meng Zhang, Qingqing Wang, Xin Zhao, Jinqian Zhang, Youliang Zhao","doi":"10.1021/acs.macromol.4c02080","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02080","url":null,"abstract":"Chain architecture and chemical composition of polymers can play vital roles in regulating thermoresponsive properties. Despite tremendous progress, it remains difficult to achieve LCST/upper critical solution temperature (LCST/UCST) behavior with tunable thermal hysteresis and outstripping. This study affords a promising strategy of an integrated multiamide and specific substituents to address the challenge. The incorporation of two substituents involving isopropyl, 2-diethylaminoethyl, or carbamoylmethyl into each Y junction of multiamide-functionalized Y-junction-bearing polymers (MAYJPs) allows enhancing polymer–polymer interactions. The disruption of intrinsic balances among hydrogen bonding, electrostatic interactions, and hydrophilic-to-hydrophobic ratio renders a multitunable phase transition. The location switching of heterosubstituents can result in either an inverse phase transition or a significantly different phase transition temperature. The thermodynamic or dynamic control over the hydration status of subunits leads to the occurrence of four kinds of thermal reversibility involving slight or significant hysteresis, consecutive outstripping and hysteresis, and pronounced outstripping upon heating–cooling cycles. The solvent isotope effect results in a distinct type or temperature of phase transition, and the pH effect is reflected in the pH-induced increase, decrease, or V-shaped evolution of phase transition temperature. In addition, the phase transition can accompany morphology transformation among spheres, vesicles, nanotubes, and lamellae. These fundamental findings are beneficial for gaining insights into the multiamide-related phase transition and thermal reversibility. Owing to the diversity of substituents, MAYJPs may serve as promising thermoresponsive polymers for multipurpose applications.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"7 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142718441","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":"Time-Scale Bridging in Atomistic Simulations of Epoxy Polymer Mechanics Using Nonaffine Deformation Theory","authors":"Vinay Vaibhav, Timothy W. Sirk, Alessio Zaccone","doi":"10.1021/acs.macromol.4c01360","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c01360","url":null,"abstract":"Developing a deep understanding of macroscopic mechanical properties of amorphous systems, which lack structural periodicity, has posed a key challenge, not only at the level of theory but also in molecular simulations. Despite significant advancements in computational resources, there is a vast time scale disparity, more than 6 orders of magnitude, between mechanical properties probed in simulations compared to experiments. Using the theoretical framework of nonaffine lattice dynamics (NALD), based on the instantaneous normal modes analysis determined through the dynamical matrix of the system, we study the viscoelastic response of a cross-linked epoxy system of diglycidyl ether of bisphenol A (DGEBA) and poly(oxypropylene) diamine, over many orders of magnitude in deformation frequency, below the glass transition temperature. Predictions of the elastic modulus are satisfactorily validated against the nonequilibrium molecular dynamics simulations in the high-frequency regime and against experimental data from dynamic mechanical analysis at frequencies ∼1 Hz, hence successfully bridging the time scale gap. The comparison shows that nonaffine displacements at the atomic level account for nearly 2 orders of magnitude reduction in the low-frequency elastic modulus of the polymer glass, compared to affine elasticity estimates. The analysis also reveals the role of internal stresses (as reflected in the instantaneous normal modes), which act to strengthen the mechanical response.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"119 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142718841","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":"Charge Density Can Enhance Both Transport and Ion Exclusion in Simulated Polystyrenesulfonated Membranes","authors":"Ritwick Kali, Scott T. Milner","doi":"10.1021/acs.macromol.4c01565","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c01565","url":null,"abstract":"Bound charge density is a critical design parameter for tuning water and ion diffusivity in polyelectrolyte membranes. Higher charge density results in increased water uptake and improved diffusivity (transport). However, the impact of bound charge density and consequent water uptake on ion exclusion is crucial for designing membranes with uncompromised selectivity. In this molecular simulation study, we investigate sulfonated polystyrene–polymethylbutylene (PSS–PMB) membranes at different sulfonation levels to explore the effects of bound charge density on water and ion transport and salt exclusion. Remarkably, the equilibrium water uptake per sulfonate group and pore size remain constant irrespective of sulfonation, while the pore morphology transforms significantly. At lower sulfonation levels, the tortuous pores are locally one-dimensional, while higher sulfonation results in locally two-dimensional pores and consequently a 2-fold increase in molecular diffusivity. This morphological change also increases ion concentration at the pore centers, resulting in improvement in salt exclusion of up to 50%.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"12 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142712825","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":"Role of Dynamic Covalent Bond Density on the Structure and Properties of Vitrimers","authors":"Hengheng Zhao, Zhenyuan Li, Siqi Zhan, Tongkui Yue, Jiajun Qu, Haoxiang Li, Liqun Zhang, Venkat Ganesan, Jun Liu","doi":"10.1021/acs.macromol.4c02473","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02473","url":null,"abstract":"Vitrimers, as a novel class of dynamic polymers, require precise regulation of their dynamic and mechanical properties to achieve optimal, comprehensive performance. This study utilizes a coarse-grained vitrimer elastomer model, composed of simple linear polymer chains by varying dynamic cross-link densities (ρ), to systematically investigate the structural, dynamic, and mechanical properties of vitrimers. The results demonstrate that the system number density decreases with increasing ρ due to the repulsion between reactive sites. The characteristic glass transition temperature (<i>T</i>_g) increases linearly with cross-link densities such as <i>T</i>_g ∼ ρ, while the characteristic topological transition temperature <i>T</i>_v exhibits nonmonotonic changes versus ρ. Interestingly, the bond exchange autocorrelation function indicates that the bond exchange rate reaches the maximum at intermediate cross-link densities attributed to the competition between the number and the mobility of the reactive sites. Mean square displacement analysis reveals that the mobility of beads and polymer chains decreased with ρ, and the logarithm of the diffusion coefficients linearly decreases with ρ, ln <i>D</i> ∼ −ρ. The chain segment relaxation times with different cross-link densities can be described with an exponential equation τ_α ∼ exp(ρ/<i>C</i>), while the whole chain relaxation times are more sensitive to the cross-link density. The linear viscoelasticity via equilibrium molecular dynamics simulations indicate that higher cross-link densities lead to greater elasticity and higher energy dissipation capabilities, as indicated by the storage and loss moduli, and the derived viscosity versus the cross-link density for various energy barriers (Δ<i>E</i>_sw) exhibits the universal following relation ln η⁰ ∼ ρ. Uniaxial and triaxial tensile tests both show that high ρ and high Δ<i>E</i>_sw systems exhibit higher tensile strength at low strains due to the tight and stable network structure, whereas at high strains, the voids occur due to the stress concentration and the breakage of the dynamic covalent bonds, which reduces the maximum tensile strength, toughness, and elongation at break, as compared to the lower ρ and lower Δ<i>E</i>_sw systems. Therefore, the optimal tailoring of the cross-link density and the exchange barrier show the capability to achieve the most excellent comprehensive performance of the vitrimer. These findings provide crucial theoretical guidelines for the design and optimization of high performance vitrimers.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"3 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142712828","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":"Prediction and Explanation of Properties in Multicomponent Polyurethane Elastomers: Integrating Molecular Dynamics and Machine Learning","authors":"Yujiang Meng, Yaling Lin, Anqiang Zhang","doi":"10.1021/acs.macromol.4c02559","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02559","url":null,"abstract":"Establishing quantitative connections among the chemical composition, molecular structure, and macroscopic properties of multicomponent polyurethane elastomers remains a challenging task. Molecular dynamics (MD) has been extensively utilized in the study of various materials and serves as a crucial tool for exploring the relationship between structure and properties. However, the intricate modeling process and lengthy computation times associated with the MD method complicate the attainment of complex combinatorial results for the various components of polyurethane elastomers. Machine learning (ML) offers a solution by integrating and analyzing existing data, along with the capability to predict new outcomes. Consequently, we combine MD and ML methods to conduct a comprehensive investigation of multicomponent polyurethane elastomers. MD simulations indicate the presence of various types of hydrogen bonds within the elastic matrix of polyurethane, and the strong hydrogen bonds formed in the hard segments significantly affect the tensile properties of material. While the incorporation of long molecular chains in the soft segments enhances the material’s flexibility, it simultaneously diminishes its tensile strength. Feature engineering techniques, including parametric representation and feature screening of the MD model, were employed to create a data set suitable for ML applications. The application of the interpretable ML method has demonstrated that the number of hydrogen bonds in the hard segment is regulated by the hydrogen bond donor and acceptor, while the rotatable bonds in the soft segment are the primary characteristics contributing to the material’s flexibility and are also key factors that regulate the number of free hydrogen bonds. This integration of MD and ML methods not only enhances predictive capabilities for novel polyurethane elastomers but also facilitates quantitative analysis of how microstructural characteristics affect macroscopic properties.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"3 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142712831","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":"Fatigue Behaviors of Anisotropic Hydrogels with a Macroscopic Lamellar Bilayer Structure and Swelling Effects","authors":"Most Laboni Begum, Milena Lama, Wenqi Yang, Xiang Li, Md. Anamul Haque, Xueyu Li, Jian Ping Gong","doi":"10.1021/acs.macromol.4c01698","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c01698","url":null,"abstract":"The application of soft materials for long-term use requires a profound understanding of their fatigue mechanisms and structural evolution under cyclic loading conditions. In this work, we studied the fatigue resistance behaviors of an anisotropic hydrogel composite consisting of periodically stacked, polymerized bilayers embedded in an elastic hydrogel matrix. The hydrogel composite exhibits high toughness and self-resilience under monotonic loading due to efficient energy dissipation from the lamellar bilayers, which act as reversible sacrificial bonds. We found that at a loading rate similar to the monotonic loading test, bilayers only modestly enhance the fatigue threshold itself but significantly suppress the fatigue crack extension rate above the fatigue threshold. Specifically, the fatigue crack extension length per cycle is only 1/10,000 that of the pristine elastic hydrogel. This enhancement in fatigue fracture resistance is only modestly reduced in the fully swollen sample.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"28 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142712826","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":"Anomalous Structural Changes and Gas Transport Properties in Ultrathin Films of Polymers of Intrinsic Microporosity","authors":"Tae Hoon Lee, Jun Kyu Jang, Byung Kwan Lee, Wan-Ni Wu, Zachary P. Smith, Ho Bum Park","doi":"10.1021/acs.macromol.4c01712","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c01712","url":null,"abstract":"Solution-processable polymers of intrinsic microporosity (PIMs) have been explored as a next-generation material for the synthesis of CO₂ capture membranes. Herein, we highlight the critical need for understanding the transition from bulk PIM materials (50–150 μm) to their thin films (&lt;3 μm). 6FDA-DAM and PIM-1 were chosen as archetypal PIMs, and their thin-film composite (TFC) membranes were prepared via a spin-coating method. Interestingly, the PIM-based TFC membranes always exhibited lower gas permeabilities compared to the model predictions based on their bulk films. Moreover, such deviations became more pronounced by reducing the selective layer thickness to several tens of nanometers. Two-dimensional grazing-incidence wide-angle X-ray scattering (2D GIWAXS) analyses reveal that the PIM thin films significantly differ from those of bulk films by showing thickness-dependent anisotropic microstructures potentially due to fast solvent evaporation and confinement effects during film preparation. Also, physical aging significantly affects the microstructures and the CO₂ capture performance of the aged PIM films, which should be decoupled from the effects of film thickness.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"8 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2024-11-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142718519","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}