Pub Date : 2026-01-24DOI: 10.1016/j.polymer.2026.129651
Jianwei Deng, Haibao Lu
Thermally activated shape memory polymers (SMPs) are popularly employed in advanced engineering applications, such as soft actuators, soft robotic systems, and active metamaterials. Engineering design of SMP structures underscores the need for robust and fast numerical modeling approaches. However, existing constitutive models, though theoretically comprehensive, often suffer from parameter calibration difficulties and high computational costs. This study develops a novel deep learning methodology based on Long Short-Term Memory (LSTM) neural networks for modeling thermo-mechanical shape recovery behaviors of SMPs. An experimentally-validated thermo-visco-hyperelastic constitutive model and finite element simulations are employed to generate the datasets. Subsequently, a series of deep learning models are developed and trained to predict the free and constraint recovery behaviors. The developed deep learning models deliver precise real-time predictions while maintaining good generalization ability. Furthermore, we extend the proposed framework to free recovery behaviors under 3D stress-strain states. The outstanding performance of these deep learning models highlights their significant potential as a real-time and effective alternative for design and analysis of SMPs in comparison with traditionally theoretical and semi-empirical approaches.
{"title":"Deep learning of long short-term memory neural networks in shape memory polymers towards shape memory behaviors","authors":"Jianwei Deng, Haibao Lu","doi":"10.1016/j.polymer.2026.129651","DOIUrl":"10.1016/j.polymer.2026.129651","url":null,"abstract":"<div><div>Thermally activated shape memory polymers (SMPs) are popularly employed in advanced engineering applications, such as soft actuators, soft robotic systems, and active metamaterials. Engineering design of SMP structures underscores the need for robust and fast numerical modeling approaches. However, existing constitutive models, though theoretically comprehensive, often suffer from parameter calibration difficulties and high computational costs. This study develops a novel deep learning methodology based on Long Short-Term Memory (LSTM) neural networks for modeling thermo-mechanical shape recovery behaviors of SMPs. An experimentally-validated thermo-visco-hyperelastic constitutive model and finite element simulations are employed to generate the datasets. Subsequently, a series of deep learning models are developed and trained to predict the free and constraint recovery behaviors. The developed deep learning models deliver precise real-time predictions while maintaining good generalization ability. Furthermore, we extend the proposed framework to free recovery behaviors under 3D stress-strain states. The outstanding performance of these deep learning models highlights their significant potential as a real-time and effective alternative for design and analysis of SMPs in comparison with traditionally theoretical and semi-empirical approaches.</div></div>","PeriodicalId":405,"journal":{"name":"Polymer","volume":"346 ","pages":"Article 129651"},"PeriodicalIF":4.5,"publicationDate":"2026-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146047993","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-24DOI: 10.1016/j.polymer.2026.129633
Yui Ikemoto , Masayuki Yamaguchi
The effect of the addition of polyvinylpyrrolidone (PVP) on the structure and properties of poly(acrylonitrile-co-styrene) (AS) was investigated to develop transparent, heat-resistant, and hydrophilic engineering plastics. Atomic force microscopy images, dynamic mechanical analysis, and thermal analysis revealed that PVP is miscible with AS. This was attributed to strong hydrogen bonds between carbonyl groups in PVP and nitrile groups in AS, as indicated by the infra-red spectroscopy. Because of the miscibility, the AS/PVP blends were highly transparent in the visible wavelength range, with a low haze value. Furthermore, the glassy region expanded to a high temperature by the PVP addition due to the enhancement of the glass transition temperature, i.e., improvement of heat resistance. Measurements of the water contact angle and water absorption rate demonstrated that PVP provided the hydrophilic nature while preserving transparency after immersion. These results suggest that PVP is an effective modifier for AS, enabling simultaneous control of thermal performance and surface hydrophilicity by a simple melt-blending technique, which will widen its application.
{"title":"Effects of polyvinylpyrrolidone addition on structure and properties of poly(acrylonitrile-co-styrene)","authors":"Yui Ikemoto , Masayuki Yamaguchi","doi":"10.1016/j.polymer.2026.129633","DOIUrl":"10.1016/j.polymer.2026.129633","url":null,"abstract":"<div><div>The effect of the addition of polyvinylpyrrolidone (PVP) on the structure and properties of poly(acrylonitrile-co-styrene) (AS) was investigated to develop transparent, heat-resistant, and hydrophilic engineering plastics. Atomic force microscopy images, dynamic mechanical analysis, and thermal analysis revealed that PVP is miscible with AS. This was attributed to strong hydrogen bonds between carbonyl groups in PVP and nitrile groups in AS, as indicated by the infra-red spectroscopy. Because of the miscibility, the AS/PVP blends were highly transparent in the visible wavelength range, with a low haze value. Furthermore, the glassy region expanded to a high temperature by the PVP addition due to the enhancement of the glass transition temperature, i.e., improvement of heat resistance. Measurements of the water contact angle and water absorption rate demonstrated that PVP provided the hydrophilic nature while preserving transparency after immersion. These results suggest that PVP is an effective modifier for AS, enabling simultaneous control of thermal performance and surface hydrophilicity by a simple melt-blending technique, which will widen its application.</div></div>","PeriodicalId":405,"journal":{"name":"Polymer","volume":"346 ","pages":"Article 129633"},"PeriodicalIF":4.5,"publicationDate":"2026-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146047994","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this work, epoxidized solution styrene-butadiene rubber (ESSBR) with low functionality was successfully synthesized using an in-situ green epoxidation reaction. The ESSBR x/Si69-Silica nanocomposites were prepared by compounding the ESSBR with Si69-modified silica. The effects of different low epoxy degrees on the structure and properties of the nanocomposites were investigated. The results demonstrate that the ESSBR with a small number of epoxy groups, combined with Si69 modification, can play a synergistic role in improving silica dispersion and enhancing filler-rubber interaction. When the epoxy degree was 1.0 mol%, the nanocomposite exhibited excellent comprehensive performance. Compared to the SSBR/Si69-Silica nanocomposite, the ESSBR 1.0/Si69-Silica nanocomposite exhibited a 29 % increase in tan δ at 0 °C, a 20 % decrease in tan δ of 60 °C at 7 % strain, a 5.4 % reduction in Akron abrasion volume, and almost no change in elongation at break and Tg. Therefore, Si69-modified silica filled slightly ESSBR provides a new approach for the preparation of green tire treads.
{"title":"Silica filled slightly epoxidized solution styrene-butadiene rubber nanocomposites with excellent performance for tire tread","authors":"Botao Zhao, Ling Liu, Jiong Hui, Jiawei Gao, Haoyang Sun, Liqun Zhang","doi":"10.1016/j.polymer.2026.129653","DOIUrl":"10.1016/j.polymer.2026.129653","url":null,"abstract":"<div><div>In this work, epoxidized solution styrene-butadiene rubber (ESSBR) with low functionality was successfully synthesized using an in-situ green epoxidation reaction. The ESSBR <em>x</em>/Si69-Silica nanocomposites were prepared by compounding the ESSBR with Si69-modified silica. The effects of different low epoxy degrees on the structure and properties of the nanocomposites were investigated. The results demonstrate that the ESSBR with a small number of epoxy groups, combined with Si69 modification, can play a synergistic role in improving silica dispersion and enhancing filler-rubber interaction. When the epoxy degree was 1.0 mol%, the nanocomposite exhibited excellent comprehensive performance. Compared to the SSBR/Si69-Silica nanocomposite, the ESSBR 1.0/Si69-Silica nanocomposite exhibited a 29 % increase in tan δ at 0 °C, a 20 % decrease in tan δ of 60 °C at 7 % strain, a 5.4 % reduction in Akron abrasion volume, and almost no change in elongation at break and <em>Tg</em>. Therefore, Si69-modified silica filled slightly ESSBR provides a new approach for the preparation of green tire treads.</div></div>","PeriodicalId":405,"journal":{"name":"Polymer","volume":"346 ","pages":"Article 129653"},"PeriodicalIF":4.5,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146033793","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-23DOI: 10.1016/j.polymer.2026.129649
Yanhong Zeng , Weitao Tang , Chao Ji , Jingchao Geng , Xinwang Li , Qiang Zhang
Soft capacitive pressure sensors have been widely utilized in the fields of flexible electronics and smart devices. While expanding its pressure sensing range, enhancing the sensitivity of sensors has attracted attention. Currently, the problems that need further solution also include improving the pressure sensing linearity and force detection resolution, enabling sensors to identify tiny pressure changes under high pressure. To address this issue, this study presents a strategy utilizing direct ink writing (DIW) 3D printing technology to construct a double-sided sawtooth structure, which can significantly enhance sensitivity while improving pressure resolution. Traditional flexible dielectric layers are mostly bulk polymer. As the applied pressure increases, the compression of the dielectric layer reduces the distance change between the electrode plates under the same pressure, making it difficult to achieve linear variation of capacitance. This paper designs a double-sided sawtooth structure, which squeezes out the air in the dielectric layer with the increase of pressure to realize linear detection of a wide range of pressures. The thermal expansion microspheres (TEM) introduces micro-pores in PDMS to further expand the linear detection range. In addition, the interfacial polarization effect of CB is utilized and improve the sensitivity. Comparing the double-sided sawtooth structured sensors based on PDMS, PDMS&TEM and PDMS&TEM&CB, the results show that the PDMS&TEM&CB sensor exhibits the highest sensitivity (6.8 × 10−3 kPa−1), excellent linear response across a wide pressure detection range of up to 150 kPa, ultra-low detection limits (∼3.2 Pa), and outstanding dynamic response and repeatability (over 8000 cycles). Additionally, the high pressure resolution of the sensor renders it exceptionally suitable for various applications, including minute pressure detection, spatial pressure mapping, Braille recognition, and mapping changes in object curvature.
{"title":"A flexible capacitive pressure sensor with a double-sawtooth structure for high resolution pressure sensing","authors":"Yanhong Zeng , Weitao Tang , Chao Ji , Jingchao Geng , Xinwang Li , Qiang Zhang","doi":"10.1016/j.polymer.2026.129649","DOIUrl":"10.1016/j.polymer.2026.129649","url":null,"abstract":"<div><div>Soft capacitive pressure sensors have been widely utilized in the fields of flexible electronics and smart devices. While expanding its pressure sensing range, enhancing the sensitivity of sensors has attracted attention. Currently, the problems that need further solution also include improving the pressure sensing linearity and force detection resolution, enabling sensors to identify tiny pressure changes under high pressure. To address this issue, this study presents a strategy utilizing direct ink writing (DIW) 3D printing technology to construct a double-sided sawtooth structure, which can significantly enhance sensitivity while improving pressure resolution. Traditional flexible dielectric layers are mostly bulk polymer. As the applied pressure increases, the compression of the dielectric layer reduces the distance change between the electrode plates under the same pressure, making it difficult to achieve linear variation of capacitance. This paper designs a double-sided sawtooth structure, which squeezes out the air in the dielectric layer with the increase of pressure to realize linear detection of a wide range of pressures. The thermal expansion microspheres (TEM) introduces micro-pores in PDMS to further expand the linear detection range. In addition, the interfacial polarization effect of CB is utilized and improve the sensitivity. Comparing the double-sided sawtooth structured sensors based on PDMS, PDMS&TEM and PDMS&TEM&CB, the results show that the PDMS&TEM&CB sensor exhibits the highest sensitivity (6.8 × 10<sup>−3</sup> kPa<sup>−1</sup>), excellent linear response across a wide pressure detection range of up to 150 kPa, ultra-low detection limits (∼3.2 Pa), and outstanding dynamic response and repeatability (over 8000 cycles). Additionally, the high pressure resolution of the sensor renders it exceptionally suitable for various applications, including minute pressure detection, spatial pressure mapping, Braille recognition, and mapping changes in object curvature.</div></div>","PeriodicalId":405,"journal":{"name":"Polymer","volume":"346 ","pages":"Article 129649"},"PeriodicalIF":4.5,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146047995","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-22DOI: 10.1016/j.polymer.2026.129644
M.T. Expósito , V. Souza-Egipsy , B. Paredes , J. Ramos , J.F. Vega
The increasing demand for recyclable multilayer polymer packaging requires a deeper understanding of the interactions between barrier and tie-layer materials to enable circular design strategies. In this study, the compatibility between polyethylene–co–vinyl alcohol (EVOH) copolymer and typical tie-layer copolymers—polyethylene–co–ethyl acrylate, polyethylene–co–vinyl acetate, and a polyethylene–co–methacrylic acid ionomer partially neutralized with sodium—was investigated. EVOH crystalline nanoaggregates were prepared and embedded in the different matrices to evaluate physical and thermal interactions. Differential Scanning Calorimetry revealed a pronounced melting temperature depression of EVOH crystals when blended with functionalized matrices, particularly with the ionomer, indicating strong intermolecular interactions. In contrast, non-interacting systems retained their original melting behaviour, confirming the absence of chemical affinity. Fourier Transform Infrared Spectroscopy further corroborated these findings, showing hydrogen-bonding interactions between the hydroxyl groups of EVOH and the carbonyl or carboxylate groups of the functionalized tie layers. The combination of the results obtained from the different techniques provides a comprehensive understanding of the molecular mechanisms governing compatibility, offering valuable insights for the eco-design and recyclability enhancement of polyolefin-based multilayer packaging materials.
{"title":"Molecular interactions between ethylene-vinyl alcohol copolymers and functionalized tie layers for recyclable multilayer films","authors":"M.T. Expósito , V. Souza-Egipsy , B. Paredes , J. Ramos , J.F. Vega","doi":"10.1016/j.polymer.2026.129644","DOIUrl":"10.1016/j.polymer.2026.129644","url":null,"abstract":"<div><div>The increasing demand for recyclable multilayer polymer packaging requires a deeper understanding of the interactions between barrier and tie-layer materials to enable circular design strategies. In this study, the compatibility between polyethylene–co–vinyl alcohol (EVOH) copolymer and typical tie-layer copolymers—polyethylene–co–ethyl acrylate, polyethylene–co–vinyl acetate, and a polyethylene–co–methacrylic acid ionomer partially neutralized with sodium—was investigated. EVOH crystalline nanoaggregates were prepared and embedded in the different matrices to evaluate physical and thermal interactions. Differential Scanning Calorimetry revealed a pronounced melting temperature depression of EVOH crystals when blended with functionalized matrices, particularly with the ionomer, indicating strong intermolecular interactions. In contrast, non-interacting systems retained their original melting behaviour, confirming the absence of chemical affinity. Fourier Transform Infrared Spectroscopy further corroborated these findings, showing hydrogen-bonding interactions between the hydroxyl groups of EVOH and the carbonyl or carboxylate groups of the functionalized tie layers. The combination of the results obtained from the different techniques provides a comprehensive understanding of the molecular mechanisms governing compatibility, offering valuable insights for the eco-design and recyclability enhancement of polyolefin-based multilayer packaging materials.</div></div>","PeriodicalId":405,"journal":{"name":"Polymer","volume":"346 ","pages":"Article 129644"},"PeriodicalIF":4.5,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146033794","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-22DOI: 10.1016/j.polymer.2026.129634
Ashraful Islam, Sudip Kumar Lahiri, Md.Akil Akhter, Muhammad Imran, Dong Mengmeng, Yanbo Liu
Air pollution is a major concern due to rising particulate matter (PM) levels, requiring efficient filtration technologies for respiratory protection, and integrating eco-friendly fabrication methods further enhances environmental sustainability. We report water-insoluble nanofibrous membranes that combine high filtration efficiency (FE) with a low pressure drop (ΔP) for use in such masks. Using 18% (w/v) polyvinyl alcohol (PVA) and polyacrylic acid (PAA) solutions in water, we electrospun four types of nanofiber membranes under optimised conditions (25 kV, 20 cm, 25 °C, 50% RH). These included a pure PVA membrane and three PVA/PAA (60/40 wt.%) composite membranes containing PAA of 3 kDa (NFM-1), 50 kDa (NFM-2), and both 3 kDa and 50 kDa (NFM-3). To induce crosslinking, all membranes were heat-treated at 100–160 °C for 25 min. Filtration tests showed that NFM-2 heat-treated at 140 °C achieved ∼99% FE for particles ≥0.5 μm, with a ΔP of only 48 ± 1 Pa. Scanning electron microscopy revealed smooth fibres with an average diameter of ∼192 nm and 59% porosity for NFM-2. Fourier transform infrared (FTIR) spectroscopy confirmed the formation of ester linkages (–C=O–O–R) at ≥120 °C between PVA and PAA, indicating successful thermal crosslinking and improved stability. After crosslinking, NFM-2 also exhibited a water contact angle (θ) of ∼90° and retained 100% of its weight after immersion in 70 °C water, demonstrating complete water insolubility. The nanofiber membranes were further integrated with polypropylene (PP) spunbond and meltblown nonwovens in multilayer assemblies (up to four layers) to evaluate composite filter performance. This water-based, organic-solvent-free electrospinning process offers a green approach to producing high-performance respiratory filters.
{"title":"Green engineering of water-insoluble PVA/PAA nanofiber respiratory membranes for efficient particulate matter filtration with low pressure drop","authors":"Ashraful Islam, Sudip Kumar Lahiri, Md.Akil Akhter, Muhammad Imran, Dong Mengmeng, Yanbo Liu","doi":"10.1016/j.polymer.2026.129634","DOIUrl":"https://doi.org/10.1016/j.polymer.2026.129634","url":null,"abstract":"Air pollution is a major concern due to rising particulate matter (PM) levels, requiring efficient filtration technologies for respiratory protection, and integrating eco-friendly fabrication methods further enhances environmental sustainability. We report water-insoluble nanofibrous membranes that combine high filtration efficiency (FE) with a low pressure drop (ΔP) for use in such masks. Using 18% (w/v) polyvinyl alcohol (PVA) and polyacrylic acid (PAA) solutions in water, we electrospun four types of nanofiber membranes under optimised conditions (25 kV, 20 cm, 25 °C, 50% RH). These included a pure PVA membrane and three PVA/PAA (60/40 wt.%) composite membranes containing PAA of 3 kDa (NFM-1), 50 kDa (NFM-2), and both 3 kDa and 50 kDa (NFM-3). To induce crosslinking, all membranes were heat-treated at 100–160 °C for 25 min. Filtration tests showed that NFM-2 heat-treated at 140 °C achieved ∼99% FE for particles ≥0.5 μm, with a ΔP of only 48 ± 1 Pa. Scanning electron microscopy revealed smooth fibres with an average diameter of ∼192 nm and 59% porosity for NFM-2. Fourier transform infrared (FTIR) spectroscopy confirmed the formation of ester linkages (–C=O–O–R) at ≥120 °C between PVA and PAA, indicating successful thermal crosslinking and improved stability. After crosslinking, NFM-2 also exhibited a water contact angle (θ) of ∼90° and retained 100% of its weight after immersion in 70 °C water, demonstrating complete water insolubility. The nanofiber membranes were further integrated with polypropylene (PP) spunbond and meltblown nonwovens in multilayer assemblies (up to four layers) to evaluate composite filter performance. This water-based, organic-solvent-free electrospinning process offers a green approach to producing high-performance respiratory filters.","PeriodicalId":405,"journal":{"name":"Polymer","volume":"36 1","pages":""},"PeriodicalIF":4.6,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146021910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The application potential of flexible electronic technologies across diverse interdisciplinary domains has become increasingly evident. Owing to their unique combination of flexibility, biocompatibility, and skin-mimetic mechanical properties, hydrogels have emerged as a central material for wearable flexible sensors. Nevertheless, conventional hydrogel-based sensors often suffer from inadequate mechanical performance under high stress and large strain conditions, along with limited toughness. Gelatin, a natural protein, possesses a molecular structure abundant in hydroxyl and amino functional groups, enabling the formation of a highly extensible, hydrogen-bonded flexible network and exhibiting excellent biocompatibility. In this study, a thermally induced free-radical polymerization approach was employed to construct a covalently cross-linked rigid framework using polyacrylamide (PAM), while incorporating gelatin to establish a hydrogen-bond-reinforced flexible network. Concurrently, Zr4+were introduced to coordinate with anionic functional groups on both gelatin and PAM chains, resulting in the fabrication of a polyacrylamide/gelatin/zirconium ion composite hydrogel sensor (PMGxZy). The PMGxZy hydrogel sensor demonstrates exceptional toughness, rapid response dynamics, high sensitivity, and a broad sensing range. It achieves a strain of up to 924 % under a stress of 0.26 MPa, with a fracture energy of 1.12 MJ m−3. The sensor not only enables real-time monitoring of large-amplitude human motions but also facilitates sound recognition, handwritten pattern detection, and information transmission via integration with Morse code encoding. This work effectively overcomes the mechanical limitations of traditional hydrogel sensors, offering a promising new material platform for wearable sensing applications in fields such as outdoor sports monitoring and rehabilitation training.
{"title":"A highly resilient and large-strain wearable hydrogel sensor based on acrylamide/gelatin/Zr4+ and its application in human motion monitoring and information transmission","authors":"Yixue Zhang , Mingxuan Liang , Zhiyan Yan , Shuo Zhang","doi":"10.1016/j.polymer.2026.129635","DOIUrl":"10.1016/j.polymer.2026.129635","url":null,"abstract":"<div><div>The application potential of flexible electronic technologies across diverse interdisciplinary domains has become increasingly evident. Owing to their unique combination of flexibility, biocompatibility, and skin-mimetic mechanical properties, hydrogels have emerged as a central material for wearable flexible sensors. Nevertheless, conventional hydrogel-based sensors often suffer from inadequate mechanical performance under high stress and large strain conditions, along with limited toughness. Gelatin, a natural protein, possesses a molecular structure abundant in hydroxyl and amino functional groups, enabling the formation of a highly extensible, hydrogen-bonded flexible network and exhibiting excellent biocompatibility. In this study, a thermally induced free-radical polymerization approach was employed to construct a covalently cross-linked rigid framework using polyacrylamide (PAM), while incorporating gelatin to establish a hydrogen-bond-reinforced flexible network. Concurrently, Zr<sup>4+</sup>were introduced to coordinate with anionic functional groups on both gelatin and PAM chains, resulting in the fabrication of a polyacrylamide/gelatin/zirconium ion composite hydrogel sensor (PMG<sub>x</sub>Z<sub>y</sub>). The PMG<sub>x</sub>Z<sub>y</sub> hydrogel sensor demonstrates exceptional toughness, rapid response dynamics, high sensitivity, and a broad sensing range. It achieves a strain of up to 924 % under a stress of 0.26 MPa, with a fracture energy of 1.12 MJ m<sup>−3</sup>. The sensor not only enables real-time monitoring of large-amplitude human motions but also facilitates sound recognition, handwritten pattern detection, and information transmission via integration with Morse code encoding. This work effectively overcomes the mechanical limitations of traditional hydrogel sensors, offering a promising new material platform for wearable sensing applications in fields such as outdoor sports monitoring and rehabilitation training.</div></div>","PeriodicalId":405,"journal":{"name":"Polymer","volume":"346 ","pages":"Article 129635"},"PeriodicalIF":4.5,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146033796","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-22DOI: 10.1016/j.polymer.2026.129645
Luis L. Jessen , Naomi Elmer , George Crull , Kameron R. Hansen , C. Allan Guymon
Herein, we use an in situ NMR technique to monitor both solvated and solvent-free photopolymerization reactions benefitting from the rich chemical information and high spectral resolution inherent to NMR. By placing an LED-coupled fiber optic and locking solvent within a concentric capillary situated inside the NMR tube, the photoreaction remains isolated from the solvent, allowing for the monitoring of bulk polymerizations. To optimize acquisition parameters, the relationship between nuclear relaxation and resin viscosity was investigated as a function of monomer conversion. The utility of this technique was explored by monitoring monomer conversion in photocurable hexyl acrylate, revealing remarkable reproducibility and agreement with kinetic theory. Additionally, double bond conversion in a photopolymer hydrogel was measured to illustrate the effect of monomer loading on reaction rate. Lastly, the high resolution of in situ NMR was employed to independently monitor the disappearance of acrylate and methacrylate double bonds in copolymerization reactions, directly demonstrating the preferential consumption of methacrylate over acrylate reactive groups.
{"title":"Monitoring bulk acrylate-methacrylate photopolymerization reaction kinetics using in situ NMR","authors":"Luis L. Jessen , Naomi Elmer , George Crull , Kameron R. Hansen , C. Allan Guymon","doi":"10.1016/j.polymer.2026.129645","DOIUrl":"10.1016/j.polymer.2026.129645","url":null,"abstract":"<div><div>Herein, we use an in situ NMR technique to monitor both solvated and solvent-free photopolymerization reactions benefitting from the rich chemical information and high spectral resolution inherent to NMR. By placing an LED-coupled fiber optic and locking solvent within a concentric capillary situated inside the NMR tube, the photoreaction remains isolated from the solvent, allowing for the monitoring of bulk polymerizations. To optimize acquisition parameters, the relationship between nuclear relaxation and resin viscosity was investigated as a function of monomer conversion. The utility of this technique was explored by monitoring monomer conversion in photocurable hexyl acrylate, revealing remarkable reproducibility and agreement with kinetic theory. Additionally, double bond conversion in a photopolymer hydrogel was measured to illustrate the effect of monomer loading on reaction rate. Lastly, the high resolution of in situ NMR was employed to independently monitor the disappearance of acrylate and methacrylate double bonds in copolymerization reactions, directly demonstrating the preferential consumption of methacrylate over acrylate reactive groups.</div></div>","PeriodicalId":405,"journal":{"name":"Polymer","volume":"346 ","pages":"Article 129645"},"PeriodicalIF":4.5,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146033795","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-22DOI: 10.1016/j.polymer.2026.129632
F. Olla, F. Briatico Vangosa
Isotactic poly(1-butene) exhibits pressure-sensitive polymorphism, yet quantitative, phase-resolved volumetric evidence across processing-relevant pressures remains limited. High-pressure PVT dilatometry was employed to monitor specific-volume changes during controlled melt crystallization and remelting between 10 and 200 MPa at a fixed cooling rate. The resulting dilatometric fingerprints enable phase attribution after crystallization under each pressure condition. At low pressures (60 MPa) crystallization proceeds predominantly to form II; in an intermediate window (approximately 75–100 MPa) hydrostatic pressure markedly accelerates the solid–solid III transformation during or shortly after crystallization, yielding form-I–dominated structures. At higher pressures (110 MPa) signatures of form I emerge and intensify, and beyond 175 MPa the melting response is consistent with predominantly form I. Across the series, specific volume of the solid phase follows the expected order (), providing a consistent volumetric basis for phase assignment. Phase-resolved maps for the melt and for forms I, II, and I are assembled from these data, offering practical inputs for shrinkage prediction and process design. The findings delineate pressure protocols that suppress persistence of metastable form II and enable direct access to targeted polymorphs, mitigating delayed post-crystallization dimensional change in polybutene components.
{"title":"Pressure-induced crystallization and polymorphic transitions of polybutene-1: High-pressure PVT study","authors":"F. Olla, F. Briatico Vangosa","doi":"10.1016/j.polymer.2026.129632","DOIUrl":"10.1016/j.polymer.2026.129632","url":null,"abstract":"<div><div>Isotactic poly(1-butene) exhibits pressure-sensitive polymorphism, yet quantitative, phase-resolved volumetric evidence across processing-relevant pressures remains limited. High-pressure PVT dilatometry was employed to monitor specific-volume changes during controlled melt crystallization and remelting between 10 and 200 MPa at a fixed cooling rate. The resulting dilatometric fingerprints enable phase attribution after crystallization under each pressure condition. At low pressures (<span><math><mo>≤</mo></math></span>60 MPa) crystallization proceeds predominantly to form II; in an intermediate window (approximately 75–100 MPa) hydrostatic pressure markedly accelerates the solid–solid II<span><math><mo>→</mo></math></span>I transformation during or shortly after crystallization, yielding form-I–dominated structures. At higher pressures (<span><math><mo>≳</mo></math></span>110 MPa) signatures of form I<span><math><msup><mrow></mrow><mrow><mo>′</mo></mrow></msup></math></span> emerge and intensify, and beyond <span><math><mo>∼</mo></math></span>175 MPa the melting response is consistent with predominantly form I<span><math><msup><mrow></mrow><mrow><mo>′</mo></mrow></msup></math></span>. Across the series, specific volume of the solid phase follows the expected order (<span><math><mrow><msub><mrow><mi>V</mi></mrow><mrow><mi>I</mi></mrow></msub><mo>≲</mo><msub><mrow><mi>V</mi></mrow><mrow><msup><mrow><mi>I</mi></mrow><mrow><mo>′</mo></mrow></msup></mrow></msub><mo><</mo><msub><mrow><mi>V</mi></mrow><mrow><mi>II</mi></mrow></msub></mrow></math></span>), providing a consistent volumetric basis for phase assignment. Phase-resolved <span><math><mrow><mi>V</mi><mrow><mo>(</mo><mi>T</mi><mo>,</mo><mi>P</mi><mo>)</mo></mrow></mrow></math></span> maps for the melt and for forms I, II, and I<span><math><msup><mrow></mrow><mrow><mo>′</mo></mrow></msup></math></span> are assembled from these data, offering practical inputs for shrinkage prediction and process design. The findings delineate pressure protocols that suppress persistence of metastable form II and enable direct access to targeted polymorphs, mitigating delayed post-crystallization dimensional change in polybutene components.</div></div>","PeriodicalId":405,"journal":{"name":"Polymer","volume":"346 ","pages":"Article 129632"},"PeriodicalIF":4.5,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146021842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-22DOI: 10.1016/j.polymer.2026.129646
Hui Shen, Ruye Cheng, Yinrui Wang, Qian Huang
Previous study on entangled polystyrene solutions has found that elastic fracture in extensional flow is primarily related to the number of Kuhn segments per entangled strand (Ne), rather than the number of entanglements per chain (Z). In this work, we investigate whether this finding holds for polymer melts with different chemical structures (which also result in different Ne). Four polymer melts have been investigated, including poly (n-butyl methacrylate), poly(methyl methacrylate), poly(4-vinyl biphenyl), and poly(4-methyl styrene). The former two contain alkyl side groups with different lengths, while the latter two contain aromatic side groups which are more rigid than the alkyl side groups. Using a filament stretching rheometer, the critical stress and critical strain at fracture under different stretch rates were obtained. We found that when the stretch rate is fast enough, both critical stress and strain approach a constant value which is related to Ne. Combining extensional measurements with high-speed imaging, the transition from steady flow to fracture has been identified. The critical Rouse-time based Weissenberg number, WiR,c, at this transition seems affected by the specific chemical structures of the side groups.
{"title":"Effect of different chemical side groups on fracture of entangled polymer melts in extensional flow","authors":"Hui Shen, Ruye Cheng, Yinrui Wang, Qian Huang","doi":"10.1016/j.polymer.2026.129646","DOIUrl":"10.1016/j.polymer.2026.129646","url":null,"abstract":"<div><div>Previous study on entangled polystyrene solutions has found that elastic fracture in extensional flow is primarily related to the number of Kuhn segments per entangled strand (<em>N</em><sub>e</sub>), rather than the number of entanglements per chain (<em>Z</em>). In this work, we investigate whether this finding holds for polymer melts with different chemical structures (which also result in different <em>N</em><sub>e</sub>). Four polymer melts have been investigated, including poly (n-butyl methacrylate), poly(methyl methacrylate), poly(4-vinyl biphenyl), and poly(4-methyl styrene). The former two contain alkyl side groups with different lengths, while the latter two contain aromatic side groups which are more rigid than the alkyl side groups. Using a filament stretching rheometer, the critical stress and critical strain at fracture under different stretch rates were obtained. We found that when the stretch rate is fast enough, both critical stress and strain approach a constant value which is related to <em>N</em><sub>e</sub>. Combining extensional measurements with high-speed imaging, the transition from steady flow to fracture has been identified. The critical Rouse-time based Weissenberg number, <em>Wi</em><sub>R,c</sub>, at this transition seems affected by the specific chemical structures of the side groups.</div></div>","PeriodicalId":405,"journal":{"name":"Polymer","volume":"346 ","pages":"Article 129646"},"PeriodicalIF":4.5,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146033792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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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