Pub Date : 2025-12-10DOI: 10.1021/acs.macromol.5c02407
Renan Sasaki,Naoko Yoshie,Shintaro Nakagawa
Conventional elastomers tend to have heterogeneous network structures that compromise their mechanical properties. Recently, we reported that star polymer network (SPN) elastomers, which were synthesized by end-cross-linking monodisperse star polymers, exhibited exceptional mechanical performance. In this study, we aimed to elucidate the mechanism underlying the unique properties of SPN elastomers by examining the mechanical properties of samples with varying network strand lengths. The SPN elastomers were obtained by end-cross-linking tetra-arm poly(ether-ester) precursors via highly efficient strain-promoted azide–alkyne cycloaddition in solution, followed by solvent removal. The stress–strain relationship during uniaxial tensile deformation was analyzed using scaling theory. The excellent stretchability with relatively low stress was attributed to the supercoiling phenomenon, wherein the network chains adopt a strongly contracted conformation due to solvent removal during elastomer preparation. Longer network chains contracted more, resulting in a higher fractal dimension of the supercoil and a greater strain requirement to unravel it. The significant strain stiffening was attributed to strain-induced crystallization (SIC), as confirmed by in situ X-ray scattering analyses. SIC was triggered by the uniform stretching of polymer chains under large deformation. These findings highlight the mechanism behind the unique mechanical properties of SPN elastomers and provide quantitative insights into the impact of network strand length as a design parameter to tailor their mechanical performance.
{"title":"Effects of Network Strand Length on the Unique Mechanical Properties of a Homogeneous Star Polymer Network Elastomer","authors":"Renan Sasaki,Naoko Yoshie,Shintaro Nakagawa","doi":"10.1021/acs.macromol.5c02407","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c02407","url":null,"abstract":"Conventional elastomers tend to have heterogeneous network structures that compromise their mechanical properties. Recently, we reported that star polymer network (SPN) elastomers, which were synthesized by end-cross-linking monodisperse star polymers, exhibited exceptional mechanical performance. In this study, we aimed to elucidate the mechanism underlying the unique properties of SPN elastomers by examining the mechanical properties of samples with varying network strand lengths. The SPN elastomers were obtained by end-cross-linking tetra-arm poly(ether-ester) precursors via highly efficient strain-promoted azide–alkyne cycloaddition in solution, followed by solvent removal. The stress–strain relationship during uniaxial tensile deformation was analyzed using scaling theory. The excellent stretchability with relatively low stress was attributed to the supercoiling phenomenon, wherein the network chains adopt a strongly contracted conformation due to solvent removal during elastomer preparation. Longer network chains contracted more, resulting in a higher fractal dimension of the supercoil and a greater strain requirement to unravel it. The significant strain stiffening was attributed to strain-induced crystallization (SIC), as confirmed by in situ X-ray scattering analyses. SIC was triggered by the uniform stretching of polymer chains under large deformation. These findings highlight the mechanism behind the unique mechanical properties of SPN elastomers and provide quantitative insights into the impact of network strand length as a design parameter to tailor their mechanical performance.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"139 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145717303","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}
Soft microgels can deform and adsorb at liquid interfaces, forming monolayers with tunable compressibility and elasticity. Their deformability─or softness─is governed by the internal architecture and inhomogeneity of the polymeric network. However, establishing a direct correlation between single-particle properties and their collective interfacial behaviors─such as self-assembly and mechanical response─remains a fundamental challenge. In this work, we employ core–shell microgels with controllable internal architectures to investigate how single-particle softness influences the elasticity of microgel monolayers at the air/water interface. Flory–Rehner analysis reveals that microgel softness is determined by internal architecture via elastic free energy, with mixing contributions nearly invariant, ultimately governing osmotic deswelling behavior. Application of a generalized Hertzian potential in the semidilute regime further reveals enhanced chain entanglement within the confined interfacial polymer layer. Moreover, by analyzing the relationship between interparticle interactions and nearest neighbor distance in the condensed regime, we quantify the interfacial elasticity of the monolayers. Our findings show that microgels with loosely or homogeneously cross-linked networks─rather than those with dense-core or dense-shell structures─yield higher elasticity. This counterintuitive result suggests that softer microgels can produce stiffer monolayers, which is further examined through the modulation of environmental and solution-related parameters.
{"title":"Effect of Internal Architecture on the Elasticity of Microgel Monolayers at the Air/Water Interface","authors":"Wei Liu,Li Zhang,Zehua Han,He Cheng,Hailin Li,Xiangjun Gong,Hang Jiang,Yuwei Zhu,To Ngai","doi":"10.1021/acs.macromol.5c02434","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c02434","url":null,"abstract":"Soft microgels can deform and adsorb at liquid interfaces, forming monolayers with tunable compressibility and elasticity. Their deformability─or softness─is governed by the internal architecture and inhomogeneity of the polymeric network. However, establishing a direct correlation between single-particle properties and their collective interfacial behaviors─such as self-assembly and mechanical response─remains a fundamental challenge. In this work, we employ core–shell microgels with controllable internal architectures to investigate how single-particle softness influences the elasticity of microgel monolayers at the air/water interface. Flory–Rehner analysis reveals that microgel softness is determined by internal architecture via elastic free energy, with mixing contributions nearly invariant, ultimately governing osmotic deswelling behavior. Application of a generalized Hertzian potential in the semidilute regime further reveals enhanced chain entanglement within the confined interfacial polymer layer. Moreover, by analyzing the relationship between interparticle interactions and nearest neighbor distance in the condensed regime, we quantify the interfacial elasticity of the monolayers. Our findings show that microgels with loosely or homogeneously cross-linked networks─rather than those with dense-core or dense-shell structures─yield higher elasticity. This counterintuitive result suggests that softer microgels can produce stiffer monolayers, which is further examined through the modulation of environmental and solution-related parameters.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"4 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145717304","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}
Pub Date : 2025-12-10DOI: 10.1021/acs.macromol.5c03014
Minyeong Cho,Songsu Kang,Yeram Kim,Christopher W. Bielawski
We report the design, synthesis, and study of poly(methylene)s with benzoxazine groups attached to every repeat unit of the main polymer chain. Diazoacetate monomers functionalized with pendant benzoxazine groups were first prepared and characterized. The length of the spacer between the diazoacetate and the pendant benzoxazine proved to be a critical design factor. When the spacer was relatively short (i.e., one methylene unit), the corresponding polymer underwent premature decomposition by emitting gaseous carbon dioxide at elevated temperatures. The use of longer (i.e., ethylene) spacers effectively circumvented premature decomposition. Each monomer was transformed into its respective poly(methylene) using a C1 polymerization methodology that employed a Pd-based catalyst. A poly(vinylene) analogue, which features benzoxazine groups attached to every other carbon unit of the main chain, and a bis(benzoxazine) that is commonly used to prepare thermosets were also prepared as controls. The structures of the monomers and polymers were elucidated using NMR and Fourier transform infrared (FT-IR) spectroscopy, and the molecular weights of the polymers were determined using size exclusion chromatography (SEC). Exposure of the benzoxazine-functionalized polymers or the bis(benzoxazine) to elevated temperatures, typically >200 °C, afforded mechanically robust, cross-linked resins. Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA) were used to characterize the thermal and physical properties of the cured materials. The thermally cured poly(methylene)s exhibited higher cross-link densities (25,937 mol m–3) than those derived from the poly(vinylene) analogue (12,904 mol m–3) or the bis(benzoxazine) (3513 mol m–3). The cured poly(methylene)s also exhibited a higher storage modulus (329.8 MPa) than the controls (145.8 and 44.6 MPa, respectively). Although the control thermosets were stiffer at room temperature (5.4–5.5 GPa vs 4.4 GPa), the higher cross-link density of the cured C1 polymers provides superior high-temperature performance and thermal stability. These findings demonstrate how incorporating benzoxazines into every repeat unit of a polymer backbone effectively increases cross-link density and enables the development of robust, high-performance thermosets with potential utility in advanced structural and electronic applications.
{"title":"Poly(methylene)s Bearing Pendant Benzoxazines via C1 Polymerization: Maximizing Functional Group Density for Enhanced Cross-Linking","authors":"Minyeong Cho,Songsu Kang,Yeram Kim,Christopher W. Bielawski","doi":"10.1021/acs.macromol.5c03014","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c03014","url":null,"abstract":"We report the design, synthesis, and study of poly(methylene)s with benzoxazine groups attached to every repeat unit of the main polymer chain. Diazoacetate monomers functionalized with pendant benzoxazine groups were first prepared and characterized. The length of the spacer between the diazoacetate and the pendant benzoxazine proved to be a critical design factor. When the spacer was relatively short (i.e., one methylene unit), the corresponding polymer underwent premature decomposition by emitting gaseous carbon dioxide at elevated temperatures. The use of longer (i.e., ethylene) spacers effectively circumvented premature decomposition. Each monomer was transformed into its respective poly(methylene) using a C1 polymerization methodology that employed a Pd-based catalyst. A poly(vinylene) analogue, which features benzoxazine groups attached to every other carbon unit of the main chain, and a bis(benzoxazine) that is commonly used to prepare thermosets were also prepared as controls. The structures of the monomers and polymers were elucidated using NMR and Fourier transform infrared (FT-IR) spectroscopy, and the molecular weights of the polymers were determined using size exclusion chromatography (SEC). Exposure of the benzoxazine-functionalized polymers or the bis(benzoxazine) to elevated temperatures, typically >200 °C, afforded mechanically robust, cross-linked resins. Thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA) were used to characterize the thermal and physical properties of the cured materials. The thermally cured poly(methylene)s exhibited higher cross-link densities (25,937 mol m–3) than those derived from the poly(vinylene) analogue (12,904 mol m–3) or the bis(benzoxazine) (3513 mol m–3). The cured poly(methylene)s also exhibited a higher storage modulus (329.8 MPa) than the controls (145.8 and 44.6 MPa, respectively). Although the control thermosets were stiffer at room temperature (5.4–5.5 GPa vs 4.4 GPa), the higher cross-link density of the cured C1 polymers provides superior high-temperature performance and thermal stability. These findings demonstrate how incorporating benzoxazines into every repeat unit of a polymer backbone effectively increases cross-link density and enables the development of robust, high-performance thermosets with potential utility in advanced structural and electronic applications.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"7 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145717412","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}
Pub Date : 2025-12-10DOI: 10.1021/acs.macromol.5c02567
Keerthi Radhakrishnan,Christian Holm
The like-charge attraction of proteins to polyelectrolyte brushes beyond their isoelectric point has been extensively studied yet the complex nature of this phenomenon continues to prompt investigation. Two popular lines of argument have been proposed: the “charge regulation” (CR) effect, involving reionization and charge reversal, and the “charge patch” (CP) effect, arising from the anisotropic distribution of protein charges. In this work, we employ “explicit-ion based” coarse-grained simulations to investigate the competing roles of CR and CP interactions in the adsorption of inhomogeneously charged patchy nanoparticles (NPs) as model proteins onto polyelectrolyte brushes. Previous studies have largely reported their contributions as additive, with both independently influencing adsorption behavior. In contrast, our study reveals that these two effects are coupled and interdependent, exerting a synergistic influence on adsorption. High local charge densities (patches) induce strong monopolar charge regulation in a NP, favoring higher charge reversibility near the isoelectric point (pI). Additionally, these patches undergo direct complexation with stretched polymer strands via a latching mechanism, accompanied by strong charge regulation and the emergence of higher charge moments, collectively enhancing adsorption in patchy NPs, in cases where a homogeneous NP exhibits negligible adsorption, defying ideal expectations. These strong local electrostatic couplings transcend mean-field descriptions, particularly in patchy NPs. We also observe intriguing asymmetry effects: for patchy NPs, the sign of ΔpKa = pKaacid – pKabase (ΔpKa ≪ 0 or ΔpKa ≫ 0) leads to contrasting uptake behaviors. This asymmetry arises from patch-induced cooperative charge regulation effects, which adds up differently in the two cases, causing huge nonidealities. While previous models of patchy proteins attributed binding affinities to multipolar effects or opposite patch-association and counterion release, our study uncovers an additional layer of complexity in the interplay between charge patchiness and charge regulation, which dominates over the others.
{"title":"How Patch-Induced Charge Regulation Drives Adsorption of Proteins into Polyelectrolyte Brushes","authors":"Keerthi Radhakrishnan,Christian Holm","doi":"10.1021/acs.macromol.5c02567","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c02567","url":null,"abstract":"The like-charge attraction of proteins to polyelectrolyte brushes beyond their isoelectric point has been extensively studied yet the complex nature of this phenomenon continues to prompt investigation. Two popular lines of argument have been proposed: the “charge regulation” (CR) effect, involving reionization and charge reversal, and the “charge patch” (CP) effect, arising from the anisotropic distribution of protein charges. In this work, we employ “explicit-ion based” coarse-grained simulations to investigate the competing roles of CR and CP interactions in the adsorption of inhomogeneously charged patchy nanoparticles (NPs) as model proteins onto polyelectrolyte brushes. Previous studies have largely reported their contributions as additive, with both independently influencing adsorption behavior. In contrast, our study reveals that these two effects are coupled and interdependent, exerting a synergistic influence on adsorption. High local charge densities (patches) induce strong monopolar charge regulation in a NP, favoring higher charge reversibility near the isoelectric point (pI). Additionally, these patches undergo direct complexation with stretched polymer strands via a latching mechanism, accompanied by strong charge regulation and the emergence of higher charge moments, collectively enhancing adsorption in patchy NPs, in cases where a homogeneous NP exhibits negligible adsorption, defying ideal expectations. These strong local electrostatic couplings transcend mean-field descriptions, particularly in patchy NPs. We also observe intriguing asymmetry effects: for patchy NPs, the sign of ΔpKa = pKaacid – pKabase (ΔpKa ≪ 0 or ΔpKa ≫ 0) leads to contrasting uptake behaviors. This asymmetry arises from patch-induced cooperative charge regulation effects, which adds up differently in the two cases, causing huge nonidealities. While previous models of patchy proteins attributed binding affinities to multipolar effects or opposite patch-association and counterion release, our study uncovers an additional layer of complexity in the interplay between charge patchiness and charge regulation, which dominates over the others.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"31 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145717306","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}
Pub Date : 2025-12-10DOI: 10.1021/acs.macromol.5c02734
Shiwei Han,Kenny Lee,Parker T. Morris,Maxime Michelas,Graeme Moad,Christopher M. Bates,Craig J. Hawker,Cyrille Boyer
Radical ring-opening copolymerization of lipoic acid derivatives with vinyl monomers (VMs) is a versatile route to create degradable copolymers and enables tuning of vinyl polymer properties. Although thermally initiated systems with acrylates, styrene, and acrylamide are well established, photoinduced polymerization remains comparatively underexplored. In this work, we investigate the photopolymerization of ethyl lipoate (ELp) with diverse VMs, including butyl acrylate (BA), N,N-dimethylacrylamide (DMA), methyl methacrylate (MMA), N-vinylpyrrolidone (NVP), vinyl acetate (VAc), isobutyl vinyl ether (IBVE), and norbornene (NB) under 405 nm light. We show that efficient copolymerization is obtained with the use of the photoinitiator (diphenylphosphoryl)(mesityl)methanone (TPO). In its absence, ELp undergoes photolysis to produce only low-molecular-weight oligomers (Mn = 1–2 kg mol–1) with limited monomer conversion (≤20%). In contrast, with TPO, all comonomers, except for styrene and allyl alcohol, achieve efficient polymerization, yielding high molecular weight copolymers (Mn > 19 kg mol–1). In addition, we compared the TPO initiated photopolymerization at ambient temperature with AIBN-initiated conventional thermal polymerization at 70 °C. We found that ELp exhibits significantly higher conversion under photopolymerization. Monomers such as VAc, IBVE, and NB show much better incorporation when using photoinitiated polymerization conditions, whereas methyl methacrylate and styrene are more suitable for thermal polymerization. Using VAc as a representative case, we further examine how the ELp: VAc feed ratio influences copolymerization kinetics and final copolymer composition. Finally, the resulting VM–ELp copolymers undergo thiolate-promoted disulfide exchange, with Mn values decreasing significantly from 19–82 kg mol–1 to 1–2 kg mol–1. Finally, we evaluated the thermal properties of the copolymers. The VAc-co-ELp copolymer containing 15 mol % ELp shows comparable thermal stability to the corresponding VAc homopolymer. However, TGA analysis reveals that the copolymer undergoes a more complete thermal decomposition at lower temperatures. Collectively, this work highlights a substantial, untapped potential of photoinduced lipoate–vinyl copolymerization for creating degradable and functional polymeric materials.
硫辛酸衍生物与乙烯基单体（vm）的自由基开环共聚是一种制造可降解共聚物的通用途径，可以调节乙烯基聚合物的性能。虽然丙烯酸酯、苯乙烯和丙烯酰胺的热引发体系已经很好地建立起来，但光诱导聚合的探索相对较少。在这项工作中，我们研究了在405 nm光下，脂酸乙酯（ELp）与不同vm（包括丙烯酸丁酯（BA）， N，N-二甲基丙烯酰胺（DMA），甲基丙烯酸甲酯（MMA）， N-乙烯基吡罗烷酮（NVP），醋酸乙烯（VAc），异丁基乙烯醚（IBVE）和降冰片烯（NB））的光聚合。我们发现，使用光引发剂（二苯基磷基）（甲酰基）甲烷（TPO）可以获得高效的共聚反应。在没有它的情况下，ELp进行光解只产生低分子量低聚物（Mn = 1-2 kg mol-1），单体转化率有限（≤20%）。相反，在TPO中，除苯乙烯和烯丙醇外，所有共聚物都能实现高效聚合，生成高分子量共聚物（Mn > 19 kg mol-1）。此外，我们比较了室温下TPO引发的光聚合和70℃下aibn引发的常规热聚合。我们发现ELp在光聚合下表现出明显更高的转化率。在光引发聚合条件下，VAc、IBVE和NB等单体的结合效果更好，而甲基丙烯酸甲酯和苯乙烯则更适合热聚合。以VAc为代表，我们进一步研究了ELp: VAc进料比如何影响共聚动力学和最终共聚物组成。最后，得到的VM-ELp共聚物经过硫酸盐促进的二硫交换，Mn值从19-82 kg mol-1显著降低到1-2 kg mol-1。最后，我们对共聚物的热性能进行了评价。含有15 mol % ELp的VAc-co-ELp共聚物与相应的VAc均聚物具有相当的热稳定性。然而，TGA分析表明，共聚物在较低的温度下经历了更彻底的热分解。总的来说，这项工作突出了光诱导脂肪-乙烯共聚在创造可降解和功能性聚合物材料方面的巨大潜力。
{"title":"Light-Induced Copolymerization of Ethyl Lipoate and Vinyl Monomers: Increased Efficiency and Degradability","authors":"Shiwei Han,Kenny Lee,Parker T. Morris,Maxime Michelas,Graeme Moad,Christopher M. Bates,Craig J. Hawker,Cyrille Boyer","doi":"10.1021/acs.macromol.5c02734","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c02734","url":null,"abstract":"Radical ring-opening copolymerization of lipoic acid derivatives with vinyl monomers (VMs) is a versatile route to create degradable copolymers and enables tuning of vinyl polymer properties. Although thermally initiated systems with acrylates, styrene, and acrylamide are well established, photoinduced polymerization remains comparatively underexplored. In this work, we investigate the photopolymerization of ethyl lipoate (ELp) with diverse VMs, including butyl acrylate (BA), N,N-dimethylacrylamide (DMA), methyl methacrylate (MMA), N-vinylpyrrolidone (NVP), vinyl acetate (VAc), isobutyl vinyl ether (IBVE), and norbornene (NB) under 405 nm light. We show that efficient copolymerization is obtained with the use of the photoinitiator (diphenylphosphoryl)(mesityl)methanone (TPO). In its absence, ELp undergoes photolysis to produce only low-molecular-weight oligomers (Mn = 1–2 kg mol–1) with limited monomer conversion (≤20%). In contrast, with TPO, all comonomers, except for styrene and allyl alcohol, achieve efficient polymerization, yielding high molecular weight copolymers (Mn > 19 kg mol–1). In addition, we compared the TPO initiated photopolymerization at ambient temperature with AIBN-initiated conventional thermal polymerization at 70 °C. We found that ELp exhibits significantly higher conversion under photopolymerization. Monomers such as VAc, IBVE, and NB show much better incorporation when using photoinitiated polymerization conditions, whereas methyl methacrylate and styrene are more suitable for thermal polymerization. Using VAc as a representative case, we further examine how the ELp: VAc feed ratio influences copolymerization kinetics and final copolymer composition. Finally, the resulting VM–ELp copolymers undergo thiolate-promoted disulfide exchange, with Mn values decreasing significantly from 19–82 kg mol–1 to 1–2 kg mol–1. Finally, we evaluated the thermal properties of the copolymers. The VAc-co-ELp copolymer containing 15 mol % ELp shows comparable thermal stability to the corresponding VAc homopolymer. However, TGA analysis reveals that the copolymer undergoes a more complete thermal decomposition at lower temperatures. Collectively, this work highlights a substantial, untapped potential of photoinduced lipoate–vinyl copolymerization for creating degradable and functional polymeric materials.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"141 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145717323","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}
Epoxy resins, which comprise a major portion of thermosetting polymers, are widely used across diverse applications due to their outstanding thermal and mechanical properties. Their limited recyclability, a major challenge arising from permanent covalent cross-linking, can be addressed by incorporating dynamic covalent linkages. Yet these linkages often compromise the thermal and chemical robustness of the material. Moreover, dynamic ether linkages, despite being the fundamental linkages in epoxy networks and imparting their robustness, have remained unexplored for the design of a recyclable epoxy network. Addressing these gaps, the present report introduces the design of recyclable epoxy thermosets by incorporating dynamic ether linkages, which endow the network with robustness while simultaneously imparting dynamic functionality and degradability. The epoxy networks were prepared via a solvent-free approach via melt transetherification of a difunctional benzyl ether-based epoxy with two different triols. The incorporation of robust ether linkages enabled excellent thermal stability and remarkable chemical and solvent resistance. Besides, a strategy to enhance the mechanical properties of the polymer was presented, wherein it was improved by further cross-linking and increasing the cross-link density. Varying the cross-link density, the polymer’s properties, including thermal stability, tensile strength, glass transition temperature, and dynamic behavior, were regulated. Transetherification-mediated bond exchange within the network enabled efficient reprocessability and viscous flow at elevated temperatures. Finally, in pursuit of a sustainable end-of-life solution, degradation and chemical recycling of the epoxy network were demonstrated. To the best of our knowledge, this is the first study that employs dynamic ether linkages for the design of robust and reprocessable epoxy networks and demonstrates their degradability. This study broadens the scope of designing a recyclable epoxy network.
{"title":"Enabling the Recyclability of Epoxy Networks via Dynamic Ether Linkages","authors":"Rahul Patwal,Pawan Kumar,Vatsalya Gupta,Ramkrishna Sarkar","doi":"10.1021/acs.macromol.5c02289","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c02289","url":null,"abstract":"Epoxy resins, which comprise a major portion of thermosetting polymers, are widely used across diverse applications due to their outstanding thermal and mechanical properties. Their limited recyclability, a major challenge arising from permanent covalent cross-linking, can be addressed by incorporating dynamic covalent linkages. Yet these linkages often compromise the thermal and chemical robustness of the material. Moreover, dynamic ether linkages, despite being the fundamental linkages in epoxy networks and imparting their robustness, have remained unexplored for the design of a recyclable epoxy network. Addressing these gaps, the present report introduces the design of recyclable epoxy thermosets by incorporating dynamic ether linkages, which endow the network with robustness while simultaneously imparting dynamic functionality and degradability. The epoxy networks were prepared via a solvent-free approach via melt transetherification of a difunctional benzyl ether-based epoxy with two different triols. The incorporation of robust ether linkages enabled excellent thermal stability and remarkable chemical and solvent resistance. Besides, a strategy to enhance the mechanical properties of the polymer was presented, wherein it was improved by further cross-linking and increasing the cross-link density. Varying the cross-link density, the polymer’s properties, including thermal stability, tensile strength, glass transition temperature, and dynamic behavior, were regulated. Transetherification-mediated bond exchange within the network enabled efficient reprocessability and viscous flow at elevated temperatures. Finally, in pursuit of a sustainable end-of-life solution, degradation and chemical recycling of the epoxy network were demonstrated. To the best of our knowledge, this is the first study that employs dynamic ether linkages for the design of robust and reprocessable epoxy networks and demonstrates their degradability. This study broadens the scope of designing a recyclable epoxy network.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"22 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-12-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145717302","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}
Pub Date : 2025-12-09DOI: 10.1021/acs.macromol.5c03164
Angxuan Wu,Rui Sun,Xiaolin Qian,Baosheng Guo,Zhiwei Li,Daqi Li,Wenwen Yu,Yilan Ye,Zhenzhong Yang
Biomineralization achieves intricate hybrid nanostructures through the biomolecule-directed organization of ionic clusters. However, the regulation of ionic clusters remains challenging for biomimetic mineralization. Herein, we establish hydrogen bonding–stabilized calcium phosphate (CaP) clusters in ethanol using poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) as polymeric capping agents. Through tunable hydrogen bonding, we obtain PDMAEMA-regulated CaP clusters of diverse metastable states: (i) concentration-dependent reversible aggregation of CaP clusters, which form hybrid networks; (ii) thermally triggered irreversible aggregation of CaP clusters, which render enhanced networks; (iii) H2O-induced coassembly of CaP clusters and PDMAEMA into hybrid nanochains and phase separation, leading to metastable interfaces. By progressively destabilizing hydrogen bonding through the stepwise addition of H2O, competitive capping agents, and mild heating, sequential mineralization is enabled . Such a sequential pathway drives the controlled transformation of CaP clusters within the PDMAEMA matrix, achieving hydroxyapatite nanorods with tunable aspect ratios under mild conditions, providing new avenues for nanomaterial design.
{"title":"Hydrogen Bonding–Assisted Sequential Mineralization of Polymer–Stabilized Ionic Clusters","authors":"Angxuan Wu,Rui Sun,Xiaolin Qian,Baosheng Guo,Zhiwei Li,Daqi Li,Wenwen Yu,Yilan Ye,Zhenzhong Yang","doi":"10.1021/acs.macromol.5c03164","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c03164","url":null,"abstract":"Biomineralization achieves intricate hybrid nanostructures through the biomolecule-directed organization of ionic clusters. However, the regulation of ionic clusters remains challenging for biomimetic mineralization. Herein, we establish hydrogen bonding–stabilized calcium phosphate (CaP) clusters in ethanol using poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) as polymeric capping agents. Through tunable hydrogen bonding, we obtain PDMAEMA-regulated CaP clusters of diverse metastable states: (i) concentration-dependent reversible aggregation of CaP clusters, which form hybrid networks; (ii) thermally triggered irreversible aggregation of CaP clusters, which render enhanced networks; (iii) H2O-induced coassembly of CaP clusters and PDMAEMA into hybrid nanochains and phase separation, leading to metastable interfaces. By progressively destabilizing hydrogen bonding through the stepwise addition of H2O, competitive capping agents, and mild heating, sequential mineralization is enabled . Such a sequential pathway drives the controlled transformation of CaP clusters within the PDMAEMA matrix, achieving hydroxyapatite nanorods with tunable aspect ratios under mild conditions, providing new avenues for nanomaterial design.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"40 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145711583","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}
Pub Date : 2025-12-09DOI: 10.1021/acs.macromol.5c02893
Gopika Krishnan,Kenneth S. Schweizer
A microscopic statistical mechanical theory of the structure, self-assembly, and activated segmental relaxation is employed to study associating copolymer melts with high attractive sticker fractions, local clustering, and disordered microphase ordering. The stickers are dynamically pinned in a manner that does not affect equilibrium structure which mimics the much slower physical bond breaking process or postassembly cross-linking of sticky monomers. Local sticker clustering and microdomain spatial correlations significantly modify the activated relaxation of nonstickers and glass transition temperature, Tg. A re-entrant glass-melting feature is predicted as sticker attraction strength is initially increased corresponding to a speed up of segmental relaxation, and hence reduction of Tg relative to the cross-linked homopolymer network. A mechanistic analysis reveals three competing effects: a purely kinetic slowing down of nonstickers down due to cross-linking, disordering of the nonsticker local cage and weakening of effective forces they experience due to sticker physical clustering, and a longer range impact of microdomain scale correlations that results in nonmonotonic dynamical effects. At high enough attraction strength, a qualitative change emerges corresponding to a sticker fraction dependent elevation of Tg, which eventually surpasses that of the cross-linked homopolymer network. Dynamically, the new physics arises from a complex evolution of the amplitude of the collective elastic field that dresses the large amplitude mobile segment hopping within a coupled local-nonlocal description of the alpha relaxation. The results are qualitatively consistent with recent experiments on associating PDMS and PPG telechelics of fixed sticker fraction but with chemically different end groups of variable attraction strengths. Possible tests using simulation and the influence of material or model specific interaction potentials and other real world complications are discussed.
{"title":"Segmental Dynamics and Vitrification in Associating Copolymer Melts: Role of Cluster Formation, Microdomains, and Cross-Linking","authors":"Gopika Krishnan,Kenneth S. Schweizer","doi":"10.1021/acs.macromol.5c02893","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c02893","url":null,"abstract":"A microscopic statistical mechanical theory of the structure, self-assembly, and activated segmental relaxation is employed to study associating copolymer melts with high attractive sticker fractions, local clustering, and disordered microphase ordering. The stickers are dynamically pinned in a manner that does not affect equilibrium structure which mimics the much slower physical bond breaking process or postassembly cross-linking of sticky monomers. Local sticker clustering and microdomain spatial correlations significantly modify the activated relaxation of nonstickers and glass transition temperature, Tg. A re-entrant glass-melting feature is predicted as sticker attraction strength is initially increased corresponding to a speed up of segmental relaxation, and hence reduction of Tg relative to the cross-linked homopolymer network. A mechanistic analysis reveals three competing effects: a purely kinetic slowing down of nonstickers down due to cross-linking, disordering of the nonsticker local cage and weakening of effective forces they experience due to sticker physical clustering, and a longer range impact of microdomain scale correlations that results in nonmonotonic dynamical effects. At high enough attraction strength, a qualitative change emerges corresponding to a sticker fraction dependent elevation of Tg, which eventually surpasses that of the cross-linked homopolymer network. Dynamically, the new physics arises from a complex evolution of the amplitude of the collective elastic field that dresses the large amplitude mobile segment hopping within a coupled local-nonlocal description of the alpha relaxation. The results are qualitatively consistent with recent experiments on associating PDMS and PPG telechelics of fixed sticker fraction but with chemically different end groups of variable attraction strengths. Possible tests using simulation and the influence of material or model specific interaction potentials and other real world complications are discussed.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"4 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145711597","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}
The construction of polymer gels with well-defined and ordered network structures remains a significant challenge due to inherent heterogeneities arising from conventional cross-linking methods. In this study, we report the synthesis and photoinduced gelation of a star-shaped poly(N-isopropylacrylamide) (PNIPA) derivative, terminal anthracene (AN) 4-armed star PNIPA, functionalized with photodimerizable anthracene groups at each chain terminus. This precursor was prepared via reversible-deactivation radical polymerization using a tetrafunctional initiator, followed by postpolymerization modification through click chemistry. Semidilute solutions of the modified polymer in dimethylformamide (DMF), a good solvent, were irradiated with 395 nm light to initiate anthracene dimerization-driven cross-linking without the addition of chemical cross-linkers. Dynamic light scattering (DLS) measurements during the cross-linking reaction revealed that gelation occurred without creating noticeable spatial heterogeneities. Swelling experiments, 1H NMR spectroscopy, and methanolysis followed by molecular weight analysis confirmed efficient covalent bond formation through photodimerization. Small-angle X-ray scattering (SAXS) profiles of swollen gels further revealed a highly ordered internal network structure. Although the formation of loop defects cannot be entirely excluded, the network more closely reflects the molecular symmetry and architecture of the star-shaped precursors compared to conventional gels. Moreover, the photo-cross-linked gels were fully depolymerizable back to their building blocks upon 254 nm light exposure, enabled by the absence of chain entanglements. This reversible network formation strategy, based solely on photochemistry and structurally defined polymers, offers a promising approach toward recyclable, structurally regular soft materials, contributing to sustainable materials design.
{"title":"Preparation of Polymer Gel with Homogeneous Network Structure Composed of Photoreactive Star-Shaped N-Isopropylacrylamide Polymers","authors":"Yuria Otsuka, Ikuya Ohshima, Mitsuo Hara, Takahiro Seki, Taiki Hoshino, Masashi Ohhira, Xiang Li, Yukikazu Takeoka","doi":"10.1021/acs.macromol.5c01724","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c01724","url":null,"abstract":"The construction of polymer gels with well-defined and ordered network structures remains a significant challenge due to inherent heterogeneities arising from conventional cross-linking methods. In this study, we report the synthesis and photoinduced gelation of a star-shaped poly(<i>N</i>-isopropylacrylamide) (PNIPA) derivative, terminal anthracene (AN) 4-armed star PNIPA, functionalized with photodimerizable anthracene groups at each chain terminus. This precursor was prepared via reversible-deactivation radical polymerization using a tetrafunctional initiator, followed by postpolymerization modification through click chemistry. Semidilute solutions of the modified polymer in dimethylformamide (DMF), a good solvent, were irradiated with 395 nm light to initiate anthracene dimerization-driven cross-linking without the addition of chemical cross-linkers. Dynamic light scattering (DLS) measurements during the cross-linking reaction revealed that gelation occurred without creating noticeable spatial heterogeneities. Swelling experiments, <sup>1</sup>H NMR spectroscopy, and methanolysis followed by molecular weight analysis confirmed efficient covalent bond formation through photodimerization. Small-angle X-ray scattering (SAXS) profiles of swollen gels further revealed a highly ordered internal network structure. Although the formation of loop defects cannot be entirely excluded, the network more closely reflects the molecular symmetry and architecture of the star-shaped precursors compared to conventional gels. Moreover, the photo-cross-linked gels were fully depolymerizable back to their building blocks upon 254 nm light exposure, enabled by the absence of chain entanglements. This reversible network formation strategy, based solely on photochemistry and structurally defined polymers, offers a promising approach toward recyclable, structurally regular soft materials, contributing to sustainable materials design.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"19 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145704768","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}
Pub Date : 2025-12-09DOI: 10.1021/acs.macromol.5c02864
Chengcheng Zhou,Ding Shen,Boyang Shi,Xiaotong Fang,Xingpeng Chai,Guowei Wang
The rapid advancement of the semiconductor industry has imposed heightened demands on interlayer insulating dielectric materials to meet varying processing requirements. In this contribution, a series of polyolefin-based low-k materials were developed by integrating dual functional groups of benzocyclobutene (BCB) and vinyl together through grafting the BCB group onto the polyisoprene (PI) mainchain. As a comparison, the PI mainchain was also selectively modified as a hydrogenated PI (HPI) counterpart. Both the introduced BCB and the remaining vinyl groups on PI could be selectively cured at 250 and 360 °C, respectively. Notably, with the increase of BCB group contents, the storage moduli, tan δ, and glass transition temperature (Tg) of the cured samples were regularly enhanced, and the coefficients of thermal expansion (CTE) values were correspondingly decreased. Especially, by modulating the curing behavior of BCB and/or vinyl groups, the Tgs could be tailored across a broad range (29 to 240 °C), ensuring adaptability to diverse processing conditions. As expected, the polyolefin-based materials exhibit exceptional dielectric performance with all film samples demonstrating a dielectric constant (Dk) < 2.5 and dielectric loss (Df) < 5 × 10–3 (at 1 MHz). This work illustrated that the PI modified with dual functions of BCB and vinyl groups possessed significant potential as a low-k material for future versatile, integrated circuit applications.
{"title":"Ultralow Dielectric Constant Films from the Polyisoprene Modified with Dual Functions of Benzocyclobutene and Vinyl Groups","authors":"Chengcheng Zhou,Ding Shen,Boyang Shi,Xiaotong Fang,Xingpeng Chai,Guowei Wang","doi":"10.1021/acs.macromol.5c02864","DOIUrl":"https://doi.org/10.1021/acs.macromol.5c02864","url":null,"abstract":"The rapid advancement of the semiconductor industry has imposed heightened demands on interlayer insulating dielectric materials to meet varying processing requirements. In this contribution, a series of polyolefin-based low-k materials were developed by integrating dual functional groups of benzocyclobutene (BCB) and vinyl together through grafting the BCB group onto the polyisoprene (PI) mainchain. As a comparison, the PI mainchain was also selectively modified as a hydrogenated PI (HPI) counterpart. Both the introduced BCB and the remaining vinyl groups on PI could be selectively cured at 250 and 360 °C, respectively. Notably, with the increase of BCB group contents, the storage moduli, tan δ, and glass transition temperature (Tg) of the cured samples were regularly enhanced, and the coefficients of thermal expansion (CTE) values were correspondingly decreased. Especially, by modulating the curing behavior of BCB and/or vinyl groups, the Tgs could be tailored across a broad range (29 to 240 °C), ensuring adaptability to diverse processing conditions. As expected, the polyolefin-based materials exhibit exceptional dielectric performance with all film samples demonstrating a dielectric constant (Dk) < 2.5 and dielectric loss (Df) < 5 × 10–3 (at 1 MHz). This work illustrated that the PI modified with dual functions of BCB and vinyl groups possessed significant potential as a low-k material for future versatile, integrated circuit applications.","PeriodicalId":51,"journal":{"name":"Macromolecules","volume":"11 1","pages":""},"PeriodicalIF":5.5,"publicationDate":"2025-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145711585","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}
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