Polymer Journal最新文献

{"title":"Effect of the ordered network polymer structure of cyclic-siloxane-type liquid crystalline epoxy thermosets on their fracture toughness and thermal conductivity","authors":"Miyuki Harada, Yugo Yokoyama","doi":"10.1038/s41428-024-01003-7","DOIUrl":"10.1038/s41428-024-01003-7","url":null,"abstract":"Liquid crystalline (LC) epoxy thermosets with a cyclic siloxane structure were prepared using two types of aromatic amine curing agents: 4,4’-diaminodiphenylethane (DDE) and p-phenylenediamine (p-PDA). The networked chain structure was investigated in detail via polarized optical microscopy, X-ray diffraction analysis, and transmission electron microscopy. The obtained epoxy thermosets formed an LC domain structure that was approximately 5 μm for the DDE system and 2–5 μm for the p-PDA system. In particular, the LC domains in the p-PDA system were composed of a highly aligned smectic phase. Compared with the DDE system, the p-PDA system had the highest modulus due to the packing structure of the smectic ordered network chains. The effect of the networked polymer structure on the fracture toughness was also investigated. High fracture toughness was observed with the formation of the oriented structures, and a maximum value of 1.15 kJ/m2 was attained for the p-PDA system. The introduction of a flexible siloxane structure in the epoxy backbone slightly suppressed the increase in the thermal conductivity. However, the thermal conductivity of the p-PDA system was slightly greater (0.28 W/(m K)) because of the highly oriented structure. Liquid crystalline (LC) epoxy thermosets with a cyclic siloxane structure were prepared. The obtained epoxy thermosets formed an LC domain structure and exhibited a high modulus and fracture toughness as a result of the packing structure of the smectic ordered network chains. The introduction of a flexible siloxane structure slightly suppressed the increase in thermal conductivity, and the highly oriented structure resulted in a high thermal conductivity value of 0.28 W/(m K).","PeriodicalId":20302,"journal":{"name":"Polymer Journal","volume":"57 4","pages":"395-405"},"PeriodicalIF":2.3,"publicationDate":"2024-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41428-024-01003-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143787396","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structures and properties of temperature-responsive gels with homogeneous networks prepared by photogelation of four-armed star-shaped poly(N-isopropylacrylamide)","authors":"Natsuki Itaya, Chisa Norioka, Kotaro Satoh, Masami Kamigaito, Akifumi Kawamura, Takashi Miyata","doi":"10.1038/s41428-024-01005-5","DOIUrl":"10.1038/s41428-024-01005-5","url":null,"abstract":"The network structures of polymer gels strongly influence their mechanical properties and stimuli responsiveness. Recently, many scientists have attempted to prepare well-defined gels with homogeneous networks from four-armed star-shaped polymers such as four-armed poly(ethylene glycol) (Tetra-PEG). In this study, we synthesized a four-armed star-shaped block copolymer by the copolymerization of N-isopropylacrylamide (NIPAAm) and allylacrylamide (AllAm) via single-electron transfer living radical polymerization (SET-LRP) using a four-branched initiator. The resulting four-armed star-shaped copolymer (Tetra-PNIPAAm-b-PAllAm) was crosslinked with hexa(ethylene glycol) dithiol upon visible light exposure. The resulting gels (Tetra-PNIPAAm gels) exhibited slower temperature responsiveness than the general PNIPAAm gel prepared by the standard free radical copolymerization of NIPAAm and N,N’-methylenebisacrylamide. Dynamic light scattering (DLS) measurements revealed that the Tetra-PNIPAAm gels had more homogeneous networks than the general PNIPAAm gels. The slow temperature responsiveness of the Tetra-PNIPAAm gels is attributable to their more homogeneous network structure than that of the general PNIPAAm gels. Thus, four-armed star-shaped PNIPAAm is a useful building block for designing well-defined temperature-responsive gels with homogeneous networks. Well-defined temperature-responsive gels with homogeneous network structures were prepared by photogelation of a four-armed star block copolymer composed of N-isopropylacrylamide and allylacrylamide upon visible light exposure. The dynamic lightscattering measurements revealed that the resulting gels had homogeneous networks, influencing the kinetics of temperature-responsiveness.","PeriodicalId":20302,"journal":{"name":"Polymer Journal","volume":"57 4","pages":"455-466"},"PeriodicalIF":2.3,"publicationDate":"2024-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41428-024-01005-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143787395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tough polymer gels reinforced by strain-induced crystallization","authors":"Koichi Mayumi","doi":"10.1038/s41428-024-01004-6","DOIUrl":"10.1038/s41428-024-01004-6","url":null,"abstract":"Recently, we reported that strain-induced crystallization (SIC) of the polymer chains occurs in homogeneous polymer gels, such as slide-ring gels and Tri-/Tetra-PEG gels, with sufficiently high polymer concentrations. SIC significantly improves the mechanical toughness of homogeneous gels. Polymer crystals form and dissolve immediately after the polymer gels are stretched and unstretched. The quick formation and dissolution of the strain-induced crystals leads to elastic mechanical responses with minimal hysteresis under cyclic stretching. Tough and elastic polymer gels have potential applications in biomedical materials (ex. artificial ligaments and tendons) and soft electric devices (ex. soft actuators and flexible batteries) under repeated deformation. We have discovered that strain-induced crystallization (SIC) of the polymer chains occurs in homogeneous polymer gels, such as slide-ring gels and Tri-/Tetra-PEG gels, with sufficiently high polymer concentrations. SIC significantly improves the mechanical toughness of homogeneous gels. Polymer crystals form and dissolve immediately after the polymer gels are stretched and unstretched. The quick formation and dissolution of the strain-induced crystals leads to elastic mechanical responses with minimal hysteresis under cyclic stretching. Tough and elastic polymer gels have potential applications in biomedical materials and soft electric devices under repeated deformation.","PeriodicalId":20302,"journal":{"name":"Polymer Journal","volume":"57 4","pages":"449-453"},"PeriodicalIF":2.3,"publicationDate":"2024-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41428-024-01004-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143787383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of network heterogeneity on the nanoscale mechanical properties of epoxy resins","authors":"Hung K. Nguyen, Atsuomi Shundo, Satoru Yamamoto, Keiji Tanaka, Ken Nakajima","doi":"10.1038/s41428-024-01006-4","DOIUrl":"10.1038/s41428-024-01006-4","url":null,"abstract":"The presence of structural heterogeneities in glassy epoxy networks can strongly affect the adhesiveness and mechanical properties of epoxy-based materials. Recent studies have demonstrated that the size and architecture of structural heterogeneities can be monitored during the curing process, thus providing an effective way to control multiple physical properties of epoxy resins. However, because the size of heterogeneities is believed to be at the nanoscale, obtaining insights into the direct correlation between the local behavior of heterogeneities and the preparation conditions remains challenging. Here, we combine two recently developed atomic force microscopy (AFM)-based methods, bimodal amplitude and frequency modulation and nanoscale dynamic mechanical analysis (nDMA), to directly visualize and quantify the nanoscale mechanical properties of epoxy resins obtained via different curing conditions. Our AFM maps clearly show a correlation between the curing conditions and the heterogeneous behavior of the resulting epoxy networks, which is in excellent agreement with those predicted from macroscopic measurements. Notably, our nDMA results revealed a relationship between network heterogeneity and the glass transition behavior of the epoxy resins. A combination of AFM-based AM-FM and nDMA methods evidences the effect of the curing temperature on the structural heterogeneities in epoxy networks: a lower pre-curing temperature provides a less heterogeneous network, which in turn can control the thermal and mechanical properties of resultant epoxy resins.","PeriodicalId":20302,"journal":{"name":"Polymer Journal","volume":"57 4","pages":"367-375"},"PeriodicalIF":2.3,"publicationDate":"2024-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41428-024-01006-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143787387","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Facile synthesis of macroscopic bilayer gels by one-shot radical polymerization in phase-separated binary solvent systems","authors":"Shohei Ida, Ryuto Soma, Iori Ono, Takumitsu Kida, Shokyoku Kanaoka","doi":"10.1038/s41428-024-01002-8","DOIUrl":"10.1038/s41428-024-01002-8","url":null,"abstract":"A macroscopic bilayer gel material has potential for great research interest because of its unique anisotropic behavior; however, studies using a facile synthetic method for preparing a bilayer gel are limited since the gel layers need firm adhesion. In this study, we developed a simple and versatile one-shot synthetic method for preparing bilayer gels using radical polymerization in a phase-separated binary solvent system. Photopolymerization of t-butyl acrylate and acrylamide in a toluene/water phase-separated solution in the presence of an amphiphilic crosslinker produced a highly reproducible bilayer gel. The obtained bilayer gels exhibited selective swelling behavior and unique mechanical properties derived from the properties of each polymer layer. In addition, the mechanical properties of the bilayer gels were significantly affected by the volume of the mixed solvent layer or the emulsified layer formed at the interface. Importantly, this synthetic method has broad applicability to various solvents and monomers. For example, we successfully synthesized a bilayer hydrogel containing a thermoresponsive polymer layer using appropriate reaction solvents; these reaction solvents were substituted for water using a simple solvent substitution process. The resulting bilayer hydrogel exhibited unique functions, such as thermoresponsive anisotropic deformation and water pumping behavior. A facile and versatile one-shot synthetic method for preparing bilayer gels was developed through photoinduced radical polymerization using a phase-separated binary solvent system. The use of an amphiphilic crosslinker soluble in both phases was particularly important for forming a sufficiently adhesive interface. This synthetic method provides a wide variety of bilayer structures due to its broad applicability in various solvents and monomers. The resulting bilayer gels exhibited unique functions, such as selective swelling behavior, mechanical properties, and anisotropic deformation derived from the properties of each polymer layer.","PeriodicalId":20302,"journal":{"name":"Polymer Journal","volume":"57 4","pages":"435-440"},"PeriodicalIF":2.3,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41428-024-01002-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143787320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A computational method for characterizing molecular-scale load transfer in polymer systems with structural heterogeneity","authors":"Hongdeok Kim, Joonmyung Choi","doi":"10.1038/s41428-024-00997-4","DOIUrl":"10.1038/s41428-024-00997-4","url":null,"abstract":"Contemporary polymer physics emphasizes polymer material design, which uses nano- and microscale structures to predict and optimize material properties. Despite their importance, predicting the mechanical behavior of polymers remains challenging because of the diverse configurations of their molecular chains. In recent years, quantitative structure‒property relationship modeling based on molecular dynamics (MD) simulations has become increasingly important. MD simulations excel at resolving sub-10-nm-scale morphological features, providing critical insights into network topology, chemical conformation, and molecular transitions. This review highlights recent MD simulation studies that have focused on subcontinuum heterogeneities in polymers from the perspective of their mechanical properties. The theoretical framework for rationally distributing the stress tensor to individual molecular components is revisited, and the key achievements made via this approach are summarized. This review highlights recent MD simulation studies focusing on subcontinuum heterogeneities in polymers from the perspective of their mechanical properties. The theoretical framework for rationally distributing the stress tensor to individual molecular components is revisited, and the key achievements made via this approach are summarized.","PeriodicalId":20302,"journal":{"name":"Polymer Journal","volume":"57 4","pages":"385-394"},"PeriodicalIF":2.3,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41428-024-00997-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143787322","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Surface orientation of amphiphilic block copolymers via thermal annealing","authors":"Hayate Narumi, Yukari Oda","doi":"10.1038/s41428-024-00999-2","DOIUrl":"10.1038/s41428-024-00999-2","url":null,"abstract":"The surface aggregation states of the amphiphilic diblock copolymer films, which are consistent with polyacrylates and polystyrene, were examined. The hydrophilic polyacrylates presented a lower surface free energy (γ) at room temperature, resulting in surface segregation. A perpendicular microdomain orientation was achieved after thermal annealing above the glass transition temperature of both components. As the annealing temperature increased, the surface became hydrophobic while maintaining this orientation due to polystyrene segregation. The key to this process is appropriate thermal annealing, considering the entropic contribution to γ from differences in molecular motion between the two components.","PeriodicalId":20302,"journal":{"name":"Polymer Journal","volume":"57 3","pages":"335-339"},"PeriodicalIF":2.3,"publicationDate":"2024-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143555225","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rapid and highly efficient recombination of crosslinking points in hydrogels generated via the template polymerization of dynamic covalent three-dimensional nanoparticle crosslinkers","authors":"Mahmoud H. Othman, Yoshihiro Ito, Jun Akimoto","doi":"10.1038/s41428-024-00996-5","DOIUrl":"10.1038/s41428-024-00996-5","url":null,"abstract":"Dynamic covalent bonds (DCBs) can be used as crosslinking points to induce self-healing and thermoplastic properties in hydrogels because the bonding and dissociation between molecules can be controlled by external stimuli. However, once DCBs dissociate, molecules diffuse inside the gel, delaying DCB reformation. In this study, a hydrogel was prepared via template polymerization using phenylboronic acid-coated nanoparticles to control the mobility of the molecules and the density of the DCB crosslinking points. Interestingly, the loss modulus, but not the storage modulus, of the hydrogel changed with temperature according to the formation/dissociation of boronic ester bonds. Furthermore, compared with conventional hydrogels, the hydrogels prepared here exhibited very rapid changes in physicochemical properties in response to changes in temperature because the high density of three-dimensional DCB crosslinking points limits the diffusion of molecules inside the gel. As a result, the prepared hydrogel showed rapid self-healing and thermoplastic properties as the temperature changed. A novel hydrogel (TempGel(NP)) was synthesized through template polymerization of phenylboronic-acid-coated nanoparticles with tris(hydroxymethyl)methyl acrylamide (THMAAm). This process forms dynamic boronic ester crosslinks, creating a highly dense and uniform three-dimensional network. The innovative structure exhibits reversible thermal responsiveness, enabling rapid bond dissociation and reformation upon temperature changes. The dense packing around nanoparticles minimizes molecular diffusion, ensuring superior self-healing, high thermal hysteresis, and tunable viscoelastic properties. This innovative design provides a robust platform for advanced applications in smart materials, biomedical devices and responsive hydrogels.","PeriodicalId":20302,"journal":{"name":"Polymer Journal","volume":"57 3","pages":"315-325"},"PeriodicalIF":2.3,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41428-024-00996-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143555247","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Improvement in the toughness and compatibility of poly(lactic acid)/starch acetoacetate through reactive melt-kneading with amine-modified silicone","authors":"Kazuki Shibasaki, Yu-I Hsu, Hiroshi Uyama","doi":"10.1038/s41428-024-00971-0","DOIUrl":"10.1038/s41428-024-00971-0","url":null,"abstract":"Nonbiodegradable plastic pollution has taken centerstage because of its negative impacts on ecosystems, and poly(lactic acid) (PLA)/starch blends, which are biodegradable plastics, have attracted increased attention as sustainable materials. However, the poor compatibility between hydrophobic PLA and hydrophilic starch causes their composites to become brittle. In this study, to improve the compatibility between PLA and starch, the hydroxyl groups of starch were modified with acetoacetate, and amine-modified silicone was used as the compatibilizer. The acetoacetyl group readily reacts with primary amines under mild conditions to form enamines and is expected to react rapidly during the melt-kneading process. The amino groups also react with the decomposed PLA end groups via condensation. Therefore, amine-modified silicone is considered a suitable compatibilizer for PLA and starch acetoacetate (SAA). PLA/SAA/amine-modified silicone blends were prepared via melt-kneading. The toughness of PLA/SAA was improved by approximately 15 times when 3 wt% amine-modified silicone was added. Furthermore, in the SEM observation of the tensile fracture surface, it was found that the dispersibility of SAA in PLA was improved such that SAA and PLA were indistinguishable. This approach can contribute to the widespread use of biodegradable plastics in packaging materials and single-use plastics. In this study, to improve the compatibility of PLA and starch, the hydroxyl groups of the starch were modified with acetoacetic acid, and amine-modified silicone was used as a compatibilizer. PLA/SAA/amine-modified silicone blends were prepared by melt-kneading. The toughness of PLA/SAA was improved by about 15 times by adding 3 wt% amine-modified silicone. This approach can contribute to the widespread use of biodegradable plastics in packaging materials and single-use plastics.","PeriodicalId":20302,"journal":{"name":"Polymer Journal","volume":"57 3","pages":"303-314"},"PeriodicalIF":2.3,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41428-024-00971-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143555233","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Relationship between the heterogeneity in particle dynamics and network topology in transient networks via a microrheological study","authors":"Koshiro Nakamura, Shota Michida, Mitsuru Naito, Ung-il Chung, Takuya Katashima","doi":"10.1038/s41428-024-01000-w","DOIUrl":"10.1038/s41428-024-01000-w","url":null,"abstract":"Soft materials encompass various hierarchical structures that determine their mechanical properties. However, the relationships between these hierarchical structures and mechanical properties remain unclear owing to a lack of studies on local information and the difficulty in controlling hierarchical structures. Herein, we demonstrate a multiple particle tracking method, which is a representative microrheological measurement method, within transient networks with a precisely controlled network topology. This is the most basic parameter of hierarchical structures. Our results reveal that the heterogeneity in particle dynamics is enhanced and reaches a maximum at the percolation threshold, which is a universal phenomenon in sol–gel transitions. Notably, this study is the first to report that the heterogeneity in particle dynamics within transient networks established via reversible bonds exhibits characteristics similar to those of percolation phenomena in hydrogels. These insights provide a basis for examining the relationships between the mechanical properties and hierarchical structures of soft materials. A multiple particle tracking method was used to track probe particles in Tetra-PEG slimes with various network connectivities, revealing that the deviation from the Gaussian distribution of the particle dynamics is greater than the percolation threshold (network connectivity = 0.34). This study is the first to report that the heterogeneity of particle dynamics in transient networks, formed through reversible bonds, exhibits characteristics similar to those observed during sol–gel transitions.","PeriodicalId":20302,"journal":{"name":"Polymer Journal","volume":"57 4","pages":"427-434"},"PeriodicalIF":2.3,"publicationDate":"2024-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41428-024-01000-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143787384","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}