Macromolecules最新文献

{"title":"Tracking the Evolution of Heterogeneous Crystallization Driven by Complex Deformation Scenarios in Natural Rubber","authors":"Daichi Nozaki, Thanh-Tam Mai, Katsuhiko Tsunoda, Kenji Urayama","doi":"10.1021/acs.macromol.5c00160","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00160","url":null,"abstract":"Natural rubber (NR) has regained attention due to its sustainability and exceptional mechanical properties driven by strain-induced crystallization (SIC)─a unique self-reinforcing mechanism. Despite extensive research, the SIC behavior under complex deformation conditions, frequently encountered in NR products, remains insufficiently understood. This study investigates the evolution of nonuniform SIC in unfilled NR under heterogeneous deformation using a specially designed geometry where diverse local deformation modes are achieved within a single tensile test. By integrating digital image correlation and high-speed infrared thermography, we map the spatial distributions of strain and the associated crystallinity evolution across the specimen. The findings reveal that local SIC initiates at nearly the same critical longitudinal strain, regardless of local strain biaxiality characterized by the lateral-to-longitudinal true strain ratio (μ₁₂ = −ε₂/ε₁). However, the subsequent evolution of SIC is strongly influenced by local deformation characteristics. At a constant μ₁₂, local crystallinity (χ) increases with ε₁. Conversely, at a constant ε₁, χ increases with μ₁₂, indicating that uniaxial stretching promotes higher crystallization than other deformation modes. An empirical relation describing the strain–crystallinity relationship, using ε₁ and μ₁₂ as variables, enables comprehensive tracking of crystallinity evolution under nonuniform deformation. These insights deepen the understanding of SIC mechanisms, and guide the design of high-performance, sustainable rubber materials.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"18 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143766859","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":"Architecture-Dependent Thin Film Self-Assembly of Star Polystyrene-poly(2-vinylpyridine) Block Copolymers","authors":"Xuchen Gan, Zhan Chen, Christian Steinmetz, Mingqiu Hu, Zachary Fink, Xuefei Wu, William T. Heller, E. Bryan Coughlin, Thomas P. Russell","doi":"10.1021/acs.macromol.4c03005","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c03005","url":null,"abstract":"Controlling the orientation of nanostructured block copolymer (BCP) thin films is essential for their use in templating, transport, and pattern transfer. Conventional efforts mainly focus on adjusting enthalpic interactions between the blocks and interfaces, while entropic contributions are often overlooked. Here, we show that the morphology of BCP thin films can be precisely tuned by the architectural design of star BCPs. Specifically, we synthesized multiarm star BCPs with a polystyrene (PS) core and poly(2-vinylpyridine) (P2VP) corona, which exhibits a lamellar microdomain morphology. The entropic penalty associated with a parallel orientation of the microdomains to the substrate is controlled by varying the number of arms comprising the star BCPs, from 2-arms (triblock) to 3-arms and 4-arms. We systematically investigated the thin film morphology at different depths using grazing incidence small-angle X-ray and neutron scattering (GISAXS and GISANS), atomic force microscopy (AFM), water contact angle (WCA), and interference microscopy. The results show that 2-arm star BCPs show a parallel orientation, the 3-arm star BCPs form a uniform PS film at the air surface with a vertical orientation of the microdomains underneath, and the 4-arm star BCPs exhibit a parallel microdomain orientation at the air surface with mixed parallel and perpendicular microdomain orientation in the bulk. Additionally, we found that the inclination angle of microdomains at the edges of islands and holes, resulting from the incommensurability between film thickness and the characteristic period of the microdomain morphology, increases with a higher number of arms. This suggests a greater grain boundary tilt angle in the microdomains of star-shaped block copolymers (BCPs). When silicon substrates were modified with PS homopolymer, the selective interaction between substrate and core blocks promotes a parallel orientation for the 4-arm star BCPs. This work shows that control of arm number in star BCPs affords diverse BCP thin film morphologies, offering insights into the star BCP conformations in thin films across different depths.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"106 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143758222","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":"Molecular Structure of Foldable Bottlebrush Polymers in Melts","authors":"Li-Heng Cai","doi":"10.1021/acs.macromol.4c02981","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02981","url":null,"abstract":"A bottlebrush polymer consists of a long linear backbone densely grafted with many relatively short side chains. A widely accepted view is that strong steric repulsion among the highly overlapped side chains prestrains the bottlebrush backbone, resulting in low polymer extensibility. However, we recently discovered that in the melt of bottlebrush polymers with highly incompatible side chains and backbone, the backbone collapses to reduce interfacial free energy, regardless of the strong steric repulsion among side chains. Despite this discovery, the molecular structure of these so-called “foldable” bottlebrush polymers and their assemblies remains poorly understood. Here, we present the deterministic relationships among molecular architecture, mesoscopic conformation, and macroscopic properties of foldable bottlebrush polymers. A combination of scaling theory and experiments reveals that as the side chain grafting density decreases, the bottlebrush diameter increases, whereas the bottlebrush end-to-end distance decreases. These behaviors contradict the existing understanding of bottlebrush polymers, which assumes that the backbone and side chains are compatible. Since foldable bottlebrush polymers store lengths that can be released upon large deformations, they offer a way to decouple the intrinsic stiffness-extensibility trade-off in single-network elastomers. These findings provide foundational insights into using foldable bottlebrush polymers as building blocks for designing soft (bio)materials.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"23 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143758216","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":"Radiative Cooling Hierarchically Porous Fluoropolymer Film by Ambient Humidity-Induced Phase Separation","authors":"Yiting Zhang, Jiahui Sun, Yufeng Wang, Yunchen Wu, Chun Huang, Xu Zhang, Chao Zhang, Tianxi Liu","doi":"10.1021/acs.macromol.5c00395","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00395","url":null,"abstract":"Daytime passive radiative cooling is a highly desirable technology for cooling objects exposed to direct sunlight, offering a sustainable and energy-efficient solution without the need for electricity. However, widespread implementation of this cooling method is hindered by the complex preparation process and limited cooling power of existing radiative cooling materials. Herein, a simple and sustainable ambient humidity-induced phase separation approach was proposed for the fabrication of porous fluoropolymer films with unique hierarchical structures. This method is based on the exchange from DMSO (good solvent) to H₂O (poor solvent), where interactions within and between the poly(vinylidene fluoride) (PVDF) and poly(vinyl alcohol) (PVA) are first inhibited and then restored, leading to polymer dissolution and cross-linking. The PVA-coated granular PVDF was phase-separated from the solution by controlling the rate of solvent exchange, resulting in the formation of film with graded micro- and nanoporosity upon freeze-drying. The porous fluoropolymer film exhibits an exceptional spectral performance with an infrared emissivity exceeding 97.6% within the atmospheric window and a high sunlight scattering capability of 95.3%. When subjected to direct sunlight, the porous fluoropolymer film is capable of achieving an average net radiative cooling power of 76.09 W m^–2, rendering it to cool objects by 7.5 °C. Moreover, the film demonstrates mechanical flexibility and environmental stability, enabling its application on irregularly shaped cooling surfaces. This study therefore introduces a promising avenue for the cost-effective and large-scale production of radiative cooling porous materials.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"3 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143758220","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":"Investigating Elastic Modulus and Glass Transition of Gelatin Methacryloyl under Ambient Humidity Using Dynamic Mechanical Analysis and Wrinkling Metrology","authors":"Jiajin Tang, Zhuxiong Zuo, Qingsong Cao, Yanbo Yao, Tao Liu","doi":"10.1021/acs.macromol.4c02647","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c02647","url":null,"abstract":"The excellent biocompatibility, formability, and moisture-responsive behavior of GelMA (gelatin methacryloyl) films make it an attractive sensing and intelligent material. To better understand the mechanical properties and glass transition behavior of GelMA with a lower water content beyond the range often utilized for biomedical applications, herein, we employed the conventional dynamic mechanical analysis (DMA) in combination with the emerging technique of wrinkling metrology to investigate the mechanical properties and glass transition behavior of thick and thin GelMA films under a moisture-controlled environment. We found that the degree of methacrylation or substitution has a profound effect on the glassy modulus of GelMA films, in particular, for thin film samples. In contrast, the photo-cross-linking leads to only a modest increase in the glassy modulus for both thick and thin GelMA films. Additionally, by utilizing the Gordon–Taylor equation and the Flory–Huggins model, a universal relationship is established for correlating the results of glass transition temperature and the glass transition relative humidity for GelMA and gelatin prepared at different conditions, which provides a convenient tool for predicting the glass transition temperature of GelMA or gelatin when the sample being exposed to relative humidity is known or vice versa.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"75 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143758443","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":"l-lysine Efficiently Polymerizes with CO2 under Mild Conditions for Biocompatible Fluorescent Polyurea","authors":"Shangzhong Zhang, Yixuan Xu, Panpan Li, Minghui Fan, Dejia Chen, Chengming Wang, Lifeng Yan","doi":"10.1021/acs.macromol.4c03112","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c03112","url":null,"abstract":"Polymerization of CO₂ into polyurea under mild pressure and temperature is still a challenge, especially when using diamine from natural feedstocks. Herein, <span>l</span>-lysine is directly used as a diamine without derivatization and protection for capture and copolymerization of CO₂ under mild temperatures and pressures (0.1–0.5 MPa, 60–90 °C) with the assistance of superbase 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU). Water-soluble lysine-polyurea (L-PU) has been synthesized. The weight-average molecular weight of L-PU reaches 3 × 10⁴ g/mol, indicating the efficient reaction of lysine and CO₂. In addition, NMR studies confirmed that the unprotected carboxyl acid group (−COOH) in L-PU remains more than 80%, and the polymer may be a candidate to replace nonbiodegradable polyacrylate acid (PAA). The free carboxyl acid group also provides a change to further derivatives of the L-PU. Interestingly, the water-soluble L-PU showed efficient fluorescence performance with quantum yield (QY) up to 20%, which may be attributed to the nonconventional intrinsic fluorescence of nonconjugated aliphatic polyureas containing heteroatoms. It allows the L-PU to be used for cell bioimaging, and in vitro studies reveal that the L-PU is biocompatible and can be efficiently endocytosed by cells with bioimaging ability, indicating that it may be a potential drug delivery system for imaging-guided treatment for cancer tissue.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"40 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143736983","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":"Solid–Solid Phase Change Composites Templated from Thermoreversible Octadecane Gel-in-Water Emulsions","authors":"Yuan Yuan, Yu Jiang, Zhihao Huang, Zhiguang Xu, Tao Zhang, Yan Zhao","doi":"10.1021/acs.macromol.5c00122","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00122","url":null,"abstract":"Phase change material (PCM)-microencapsulated monolithic composites hold considerable promise in applications for latent heat storage and release, but they face the issue that the microencapsulated PCMs, when in the liquid state, might leak via an open pathway. Herein, we report the synthesis of solid–solid phase change composites from thermoreversible octadecane (OD) gel-in-water emulsions through in situ closed-cell polyHIPE generation and encapsulation. The thermoreversible OD gels, formed simply by heating OD and a low-molecular-weight gelator together, exhibit a reversible crystal-gel phase transition and a gel–liquid phase transition. Through light-driven interface-initiated radical polymerization, solid–solid phase change composites have been fabricated from Pickering emulsions containing the thermoreversible OD gel as the dispersed phase via in situ closed-cell polyHIPE generation and encapsulation. The resulting composites show predesignable external shapes, negligible leakage even for fractured samples after 10 heating–cooling cycles, high flexibility, and robust compression. The composites possess extremely high heats of melting and crystallization (up to 197.5 J/g) and good reusability. The advantageous properties enable the solid–solid composites to be excellent candidates for efficient latent heat storage and temperature management.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"1 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-03-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143745508","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":"Effect of Thermal Annealing on the Bound Layer in Polymer Thin Films: Insights from Swelling Kinetics and Guiselin’s Approach","authors":"Sonam Zangpo Bhutia, Sivasurender Chandran, Sathish K. Sukumaran, Dillip K. Satapathy","doi":"10.1021/acs.macromol.5c00410","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c00410","url":null,"abstract":"In supported polymer thin films, dependent on the polymer–substrate interactions, a distinct polymer layer forms next to the polymer–substrate interface. This distinct, buried layer is typically investigated using “Guiselin’s approach” which involves washing the thin film in a good solvent. Recently, we introduced a novel approach wherein the thickness of the distinct layer was obtained using only the swelling kinetics of the thin films. However, the relationship between the characteristics of the distinct layer as determined by the two approaches remains unclear. To address this, we have used spectroscopic ellipsometry and X-ray reflectivity measurements of spin-coated PVA thin films to systematically compare the characteristics of the “bound layer”, determined using an analysis of the time-dependent swelling, and the “adsorbed layer”, obtained using Guiselin’s approach. In particular, we investigated the effect of annealing above <i>T</i>_g for varying time durations, <i>t</i>_ann. The thickness of the bound layer, <i>d</i>_s, and that of the adsorbed layer, <i>d</i>_ads, were found to be nearly independent of the initial (dry) thickness of the thin film, <i>d</i>(0). For <i>t</i>_ann = 0, <i>d</i>_s ≈ 5 <i>d</i>_ads, suggesting that the bound layer included a significant fraction of chains that were weakly adsorbed. With increasing <i>t</i>_ann, <i>d</i>_s exhibited a monotonic decrease from ≈15 nm to a plateau value of ≈7 nm, while <i>d</i>_ads exhibited a rapid monotonic increase from ≈3 nm and approached a plateau value of ≈11 nm. Irrespective of <i>t</i>_ann and <i>d</i>_ads(0), the adsorbed layers exhibited a maximum increase in thickness of ≈2.7–4.5 nm when exposed to H₂O vapor. Interestingly, upon increasing <i>t</i>_ann, while the short-time diffusion coefficient of H₂O into the polymer thin film was found to decrease by approximately an order of magnitude, the corresponding effect on the adsorbed layer appeared to be significantly weaker.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"60 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-03-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143736487","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":"Visualization and Characterization of Stress–Strain Behavior in Resin-Based Mechanoresponsive Sensors 3D-Printed Using Mechanochromic Cross-Linkers","authors":"Wichean Khawdas, Ramu Iijima, Ko Onuma, Hideyuki Otsuka, Hiroshi Ito","doi":"10.1021/acs.macromol.4c03179","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c03179","url":null,"abstract":"This study explores the use of difluorenylsuccinonitrile-containing methacrylate (DFMA) as a mechanochromic cross-linker in a polymer system (<i>N</i>,<i>N</i>-dimethyl acrylamide, DMAA) for resin-based three-dimensional (3D) printing applications. The effect of the DFMA content on the mechanical properties and color response under mechanical stimulation was evaluated using tensile tests and color analysis. With the increase in the DFMA content, particularly when it reached 1.0 mol %, the tensile strength and mechanochromic intensity increase. DFMA incorporation also enabled the detection of localized polymer chain scission. Rheological analysis demonstrated that the DFMA–DMAA mixture exhibited a favorable photocuring behavior, making it suitable for liquid crystal display 3D printing. Moreover, the optimal 3D printing conditions were determined to minimize the dimension distortion of the printed specimens. A correlation between the red–green–blue (RGB) values and the stress–strain behavior was established based on the color analysis, providing a comprehensive understanding of the mechanochromic response of the material. These findings highlight the potential of P(DFMA–DMAA) for creating customizable, mechanochromic 3D-printed sensors with improved mechanical properties for various applications.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"183 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143734479","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":"Quantifying Hydrophilicity in Polyelectrolytes and Polyzwitterions","authors":"Nagham Abou Hamad, John Akintola, Joseph B. Schlenoff","doi":"10.1021/acs.macromol.4c03126","DOIUrl":"https://doi.org/10.1021/acs.macromol.4c03126","url":null,"abstract":"The affinity of charged polymers for water is of central interest in polyelectrolyte science. Hydration controls the solution properties of polyelectrolytes as well as their performance in materials having a balance of positive and negative repeat units, such as polyelectrolyte complexes, PECs, and polyzwitterions, PZs. As with neutral polymers, a ranking of water affinity, loosely termed hydrophilicity, is often sought. Apart from the solubility in water, there are few methods for determining relative hydrophilicity. The scaling exponent of size with molecular weight provides, for polymers in general, a classical measure of solvent quality. In this work, using aqueous size exclusion chromatography coupled with static light scattering, the radius of gyration scaling with molecular weight was determined for a range of cationic and anionic polyelectrolytes and for some polyzwitterions. For a more definitive comparison of hydrophilicity, solution calorimetry was used to measure the enthalpy of solution, Δ<i>H</i>_sol, when rigorously dried samples of these polymers were dissolved in aqueous 0.1 M NaCl. All polymers yielded strongly exothermic Δ<i>H</i>_sol, which provided a ranking of hydrophilicity. The first four molecules of water appear to generate almost all of the heat. Methacryl versions of polymers were more hydrophilic, as Δ<i>H</i>_sol was 3–5 kJ mol^–1 more exothermic than the nonmethacryl polymer. Polyzwitterions were shown to be strongly hydrated, consistent with the proposed mechanisms for their antifouling properties, although water is not necessarily more strongly held for PZs compared to PEs.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"31 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-03-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143734478","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}