Pub Date : 2024-10-28DOI: 10.1016/j.polymer.2024.127757
Al-Hassan S. Mahdy , Ibrahim M. Ammar , Shanmeng Lin , Kui Tan , Qi Xing , Jin Geng
Herein, we present a strategy for the autonomous regulation of glycopolymer brush construction and cleavage on glass substrates using surface-initiated photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer (SI-PET-RAFT) polymerization. This process involves treating the chain transfer agent with a photocleavable moiety and linking it to glass substrates using 3-Aminopropyl triethoxysilane (APTES). Polymerization initiates at 510 nm with ZnTPP as a photocatalyst, and the glycopolymer brushes can be detached with 305 nm light. This allows GPC and NMR characterization, demonstrating controlled polymer structures with Đ <1.2. Glycopolymers formed on the surface, including d-glucose and d-mannose based polymers, enhance NCM460 cell adhesion compared to non-glycopolymer surfaces, enabling precise cell adhesion and detachment. This suggests potential applications in tissue engineering.
{"title":"Comprehensive characterization of glycopolymer brushes based on controlled light-directed grafting/detachment strategy","authors":"Al-Hassan S. Mahdy , Ibrahim M. Ammar , Shanmeng Lin , Kui Tan , Qi Xing , Jin Geng","doi":"10.1016/j.polymer.2024.127757","DOIUrl":"10.1016/j.polymer.2024.127757","url":null,"abstract":"<div><div>Herein, we present a strategy for the autonomous regulation of glycopolymer brush construction and cleavage on glass substrates using surface-initiated photoinduced electron/energy transfer-reversible addition-fragmentation chain transfer (SI-PET-RAFT) polymerization. This process involves treating the chain transfer agent with a photocleavable moiety and linking it to glass substrates using 3-Aminopropyl triethoxysilane (APTES). Polymerization initiates at 510 nm with ZnTPP as a photocatalyst, and the glycopolymer brushes can be detached with 305 nm light. This allows GPC and NMR characterization, demonstrating controlled polymer structures with <em>Đ</em> <1.2. Glycopolymers formed on the surface, including <span><em>d</em></span>-glucose and <span><em>d</em></span>-mannose based polymers, enhance NCM460 cell adhesion compared to non-glycopolymer surfaces, enabling precise cell adhesion and detachment. This suggests potential applications in tissue engineering.</div></div>","PeriodicalId":405,"journal":{"name":"Polymer","volume":"313 ","pages":"Article 127757"},"PeriodicalIF":4.1,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142519944","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 : 2024-10-28DOI: 10.1016/j.polymer.2024.127759
Yin Qiao , Xun Wang , Cong Yu, Yutong Liu, Zesheng Song, Xinyi Zhang, Haixia Qi, Feng Liu
Hydrogen bonds (H-bonds), usually mainchain amide H-bonds, have been well recognized to play important roles in modulating the properties of polyimides (PIs) by strengthening macromolecular interaction. While the structure-properties relationships of symmetric mainchain amide H-bonded PIs have been extensively researched, the asymmetric H-bonded PIs, particularly those containing rigid-flexible backbone structure, and sidechain-involving H-bonds, have been rarely explored. Herein, starting from designed synthesis of diamine monomers, we present two series of asymmetric PIs containing rigid amide and flexible ether linkages that form mainchain amide-amide and amide-imide H-bonds, lacking or bearing pendent trifluoromethyls (-CF3) that form sidechain-involving amide-CF3 H-bonds. The presence of these three types of H-bonds were revealed by RDF simulation and confirmed by FTIR. Mainchain H-bonded PIs (PI-Ax) show higher Tg than sidechain-involving H-bonded PIs (PI-Tx), while PI-Tx series exhibit higher optical transparency and hydrophobicity, lower dielectric constant (ε′) and better mechanical properties than PI-Ax. The general researches on the PIs’ solubility, WAXD spectra, thermal properties, fluorescence emission and optical transparency, the dihedral angles (φ), fractional free volume (FFV), theoretical gas transport properties, chain geometry optimization and HOMO-LUMO energy gap (ΔE) values have been comprehensively carried out from the aspects of both experiments and theoretical calculation.
氢键（H-bonds），通常是主链酰胺 H-bonds，通过加强大分子相互作用而在调节聚酰亚胺（PIs）性能方面发挥着重要作用，这一点已得到广泛认可。虽然对称主链酰胺 H 键聚酰亚胺的结构-性能关系已得到广泛研究，但对非对称 H 键聚酰亚胺，尤其是那些含有刚柔相济骨架结构和侧链参与 H 键的聚酰亚胺的研究却很少。在此，我们从二胺单体的设计合成入手，提出了两个系列的不对称 PI，它们含有刚性酰胺和柔性醚链，可形成主链酰胺-酰胺和酰胺-酰亚胺 H 键，缺乏或含有下垂的三氟甲基（-CF3），可形成侧链参与的酰胺-CF3 H 键。通过 RDF 模拟揭示了这三种类型 H 键的存在，并通过傅立叶变换红外光谱进行了确认。与侧链参与 H 键的 PI（PI-Tx）相比，主链 H 键的 PI（PI-Ax）显示出更高的 Tg，而 PI-Tx 系列比 PI-Ax 显示出更高的光学透明度和疏水性、更低的介电常数（ε'）和更好的机械性能。从实验和理论计算两个方面对 PIs 的溶解度、WAXD 光谱、热性能、荧光发射和光学透明度、二面角 (φ)、自由体积分数 (FFV)、理论气体传输性能、链几何优化和 HOMO-LUMO 能隙 (ΔE)值等进行了全面研究。
{"title":"Mainchain and sidechain-involving H-bonded asymmetric polyimides containing rigid amide and flexible ether linkages","authors":"Yin Qiao , Xun Wang , Cong Yu, Yutong Liu, Zesheng Song, Xinyi Zhang, Haixia Qi, Feng Liu","doi":"10.1016/j.polymer.2024.127759","DOIUrl":"10.1016/j.polymer.2024.127759","url":null,"abstract":"<div><div>Hydrogen bonds (H-bonds), usually mainchain amide H-bonds, have been well recognized to play important roles in modulating the properties of polyimides (PIs) by strengthening macromolecular interaction. While the structure-properties relationships of symmetric mainchain amide H-bonded PIs have been extensively researched, the asymmetric H-bonded PIs, particularly those containing rigid-flexible backbone structure, and sidechain-involving H-bonds, have been rarely explored. Herein, starting from designed synthesis of diamine monomers, we present two series of asymmetric PIs containing rigid amide and flexible ether linkages that form mainchain amide-amide and amide-imide H-bonds, lacking or bearing pendent trifluoromethyls (-CF<sub>3</sub>) that form sidechain-involving amide-CF<sub>3</sub> H-bonds. The presence of these three types of H-bonds were revealed by RDF simulation and confirmed by FTIR. Mainchain H-bonded PIs (PI-A<sub>x</sub>) show higher <em>T</em><sub>g</sub> than sidechain-involving H-bonded PIs (PI-T<sub>x</sub>), while PI-T<sub>x</sub> series exhibit higher optical transparency and hydrophobicity, lower dielectric constant (<em>ε′</em>) and better mechanical properties than PI-A<sub>x</sub>. The general researches on the PIs’ solubility, WAXD spectra, thermal properties, fluorescence emission and optical transparency, the dihedral angles (<em>φ</em>), fractional free volume (FFV), theoretical gas transport properties, chain geometry optimization and HOMO-LUMO energy gap (Δ<em>E</em>) values have been comprehensively carried out from the aspects of both experiments and theoretical calculation.</div></div>","PeriodicalId":405,"journal":{"name":"Polymer","volume":"313 ","pages":"Article 127759"},"PeriodicalIF":4.1,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142519526","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 : 2024-10-28DOI: 10.1016/j.polymer.2024.127758
Caiqi Liu , Fei Liu , Tao Yang , Caohong Chen , Yanyan Lin , Jinggang Wang , Jin Zhu
The preparation of copolymers containing lactyl unit by direct melt polymerization of lactic acid has been a big challenge, especially for those with high molecular weight (Mn). In this paper, lactic acid was converted to bifunctional monomer (i.e. SLA) suitable for direct polycondensation via alcoholysis of cyclic anhydride. A series of PBALT copolyesters were synthesized by replacing adipic acid with SLA in order to introduce lactyl unit to poly(butylene adipate-co-terephathalate) (PBAT) for enhanced barrier property and biodegradability. Results showed that a series of PBALT copolyesters with high Mn of more than 41 000 g/mol can be successfully synthesized. The elongation at break remained high as the SLA content increased, while the melting temperature, the tensile modulus and strength gradually decreased. More importantly, the water vapour and gas barrier (towards CO2 and O2) property were increased by a factor of up to 1.62 and 4.3–4.4, respectively. In addition, the compost and enzymatic degradation rates of the copolyesters were accelerated by the introduction of the lactyl unit, which is mainly due to the reduction of the crystallinity. This study provides a facile strategy for the direct polycondensation of lactic acid, rather than using lactide, and thus establishes a new method for the development of biodegradable copolyesters containing lactyl unit with enhanced properties.
{"title":"Incorporation of lactyl unit to PBAT for enhanced gas barrier property and biodegradability by direct polycondensation via alcoholysis of cyclic anhydride with lactic acid","authors":"Caiqi Liu , Fei Liu , Tao Yang , Caohong Chen , Yanyan Lin , Jinggang Wang , Jin Zhu","doi":"10.1016/j.polymer.2024.127758","DOIUrl":"10.1016/j.polymer.2024.127758","url":null,"abstract":"<div><div>The preparation of copolymers containing lactyl unit by direct melt polymerization of lactic acid has been a big challenge, especially for those with high molecular weight (<em>M</em><sub>n</sub>). In this paper, lactic acid was converted to bifunctional monomer (<em>i.e.</em> SLA) suitable for direct polycondensation <em>via</em> alcoholysis of cyclic anhydride. A series of PBALT copolyesters were synthesized by replacing adipic acid with SLA in order to introduce lactyl unit to poly(butylene adipate-<em>co</em>-terephathalate) (PBAT) for enhanced barrier property and biodegradability. Results showed that a series of PBALT copolyesters with high <em>M</em><sub>n</sub> of more than 41 000 g/mol can be successfully synthesized. The elongation at break remained high as the SLA content increased, while the melting temperature, the tensile modulus and strength gradually decreased. More importantly, the water vapour and gas barrier (towards CO<sub>2</sub> and O<sub>2</sub>) property were increased by a factor of up to 1.62 and 4.3–4.4, respectively. In addition, the compost and enzymatic degradation rates of the copolyesters were accelerated by the introduction of the lactyl unit, which is mainly due to the reduction of the crystallinity. This study provides a facile strategy for the direct polycondensation of lactic acid, rather than using lactide, and thus establishes a new method for the development of biodegradable copolyesters containing lactyl unit with enhanced properties.</div></div>","PeriodicalId":405,"journal":{"name":"Polymer","volume":"313 ","pages":"Article 127758"},"PeriodicalIF":4.1,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142519939","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 : 2024-10-26DOI: 10.1016/j.polymer.2024.127729
Yiwen Zhang , Chenhao Li , Hao Wang , Zhao Yang , Wentao Zhang , Zhencai Zhang , Ruixia Liu , Fei Xu
Developing materials that combine superhydrophobic properties with high optical transmittance poses a significant challenge. In this study, hydroxyl-terminated polydimethylsiloxane (HT-PDMS) and isosorbide (ISB) were polymerized in a single step to create a covalently bonded optical polycarbonate material. By inducing the formation of micro-papillary and lotus-shaped nanoscale structures via a solvent-triggered process, we significantly enhanced the “air cushion” effect, achieving a structure scale of approximately 5–7 μm. This resulted in a water contact angle of 157° while maintaining over 90 % optical transmittance. The structures were uniformly distributed throughout the polymer matrix, leading to a 500 % increase in tensile strength at break compared to pure isosorbide polycarbonate, with a maximum strength exceeding 50 MPa. These multifunctional materials show great promise for applications in smart windows, solar panels, camera lenses, and other optoelectronic devices.
{"title":"Facile fabrication of hemicrystalline bio-based polycarbonate with superhydrophobic and high transmittance","authors":"Yiwen Zhang , Chenhao Li , Hao Wang , Zhao Yang , Wentao Zhang , Zhencai Zhang , Ruixia Liu , Fei Xu","doi":"10.1016/j.polymer.2024.127729","DOIUrl":"10.1016/j.polymer.2024.127729","url":null,"abstract":"<div><div>Developing materials that combine superhydrophobic properties with high optical transmittance poses a significant challenge. In this study, hydroxyl-terminated polydimethylsiloxane (HT-PDMS) and isosorbide (ISB) were polymerized in a single step to create a covalently bonded optical polycarbonate material. By inducing the formation of micro-papillary and lotus-shaped nanoscale structures via a solvent-triggered process, we significantly enhanced the “air cushion” effect, achieving a structure scale of approximately 5–7 μm. This resulted in a water contact angle of 157° while maintaining over 90 % optical transmittance. The structures were uniformly distributed throughout the polymer matrix, leading to a 500 % increase in tensile strength at break compared to pure isosorbide polycarbonate, with a maximum strength exceeding 50 MPa. These multifunctional materials show great promise for applications in smart windows, solar panels, camera lenses, and other optoelectronic devices.</div></div>","PeriodicalId":405,"journal":{"name":"Polymer","volume":"313 ","pages":"Article 127729"},"PeriodicalIF":4.1,"publicationDate":"2024-10-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142519533","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 : 2024-10-24DOI: 10.1016/j.polymer.2024.127754
Zhichao Wang , Yu Hu , Jianhua Hu, Haitao Wang
One-pot aqueous-phase synthesis of polyimides (PIs) offers great economic and environmental benefits and improves the hydrolytic stability of the precursor (polyamic acid) obviously. However, this method is only suitable for the polymerization of very limited dianhydride and diamine monomers up to now. In this study, the most commonly used dianhydrides and diamines for the preparation of commercially available PI products were selected for one-pot aqueous-phase synthesis of various polyamic acid salts (PAAS). The effects of the structure of monomers, the reaction temperature and the adding process of the organic base on the polymerization reaction were explored by rotational rheology, nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopy. The polymerization products obtained via the aqueous-phase route show high molecular weight when the reaction conditions have been optimized. Various PI films prepared by the thermal imidization of corresponding PAAS demonstrate good optical transparency, excellent thermal stability, and outstanding mechanical and electrical properties. This work proposes the reaction mechanism of PAAS via one-pot aqueous-phase route and utilizes this novel polymerization strategy to synthesize high-molecular-weight PIs from typical aromatic dianhydride and diamine monomers.
单锅水相合成聚酰亚胺（PIs）具有巨大的经济和环境效益，并明显提高了前体（聚酰胺酸）的水解稳定性。然而，到目前为止，这种方法只适用于非常有限的二酐和二胺单体的聚合。本研究选择了制备市售 PI 产品最常用的二酐和二胺，用于各种聚酰胺盐（PAAS）的水相一锅合成。通过旋转流变学、核磁共振（NMR）和傅立叶变换红外光谱（FTIR），探讨了单体结构、反应温度和有机碱添加过程对聚合反应的影响。在优化反应条件的情况下，通过水相途径获得的聚合产物显示出较高的分子量。通过热亚胺化相应的 PAAS 制备的各种 PI 薄膜具有良好的光学透明性、优异的热稳定性以及出色的机械和电气性能。本研究提出了一锅水相路线 PAAS 的反应机理，并利用这种新型聚合策略从典型的芳香族二酐和二胺单体中合成了高分子量的 PI。
{"title":"One-pot aqueous-phase synthesis of polyimides from typical monomers","authors":"Zhichao Wang , Yu Hu , Jianhua Hu, Haitao Wang","doi":"10.1016/j.polymer.2024.127754","DOIUrl":"10.1016/j.polymer.2024.127754","url":null,"abstract":"<div><div>One-pot aqueous-phase synthesis of polyimides (PIs) offers great economic and environmental benefits and improves the hydrolytic stability of the precursor (polyamic acid) obviously. However, this method is only suitable for the polymerization of very limited dianhydride and diamine monomers up to now. In this study, the most commonly used dianhydrides and diamines for the preparation of commercially available PI products were selected for one-pot aqueous-phase synthesis of various polyamic acid salts (PAAS). The effects of the structure of monomers, the reaction temperature and the adding process of the organic base on the polymerization reaction were explored by rotational rheology, nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopy. The polymerization products obtained via the aqueous-phase route show high molecular weight when the reaction conditions have been optimized. Various PI films prepared by the thermal imidization of corresponding PAAS demonstrate good optical transparency, excellent thermal stability, and outstanding mechanical and electrical properties. This work proposes the reaction mechanism of PAAS via one-pot aqueous-phase route and utilizes this novel polymerization strategy to synthesize high-molecular-weight PIs from typical aromatic dianhydride and diamine monomers.</div></div>","PeriodicalId":405,"journal":{"name":"Polymer","volume":"313 ","pages":"Article 127754"},"PeriodicalIF":4.1,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142489903","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 : 2024-10-24DOI: 10.1016/j.polymer.2024.127753
Donghyun Jo , Yujin Kong , Chang Seok Ki
Hydrogels composed of polymer networks are widely used in industry and scientific research for high water retention and unique mechanical properties. Nevertheless, in ordinary hydrogel formation, the trade-off relationship between stiffness and mesh size remains a crucial consideration for practical applications. This study describes a facile approach to controlling hydrogel stiffness and mesh size by hybridizing poly (ethylene glycol) diacrylate (PEGDA) and methacrylated TEMPO-oxidized cellulose nanofibers (T-CNFMA). After disintegrating T-CNF by ultrasonication, T-CNFMA was synthesized resulting in a degree of substitution of 2.04 mmol/g. Incorporation of T-CNFMA in the PEGDA network allowed for independent control of hydrogel stiffness and mesh size by reinforcing the whole hydrogel network as a framework. Consequently, the swelling ratio and shear modulus could be manipulated by controlling the PEGDA/T-CNFMA ratio. Structural analyses revealed that an increase in the T-CNFMA content in the presence of a low amount of PEGDA resulted in a large mesh size with a constant stiffness. The diffusivity test was also consistent with the properties of the hydrogels. This result indicates that the incorporation of T-CNF in hydrogel network is useful to control the physical property of the hydrogel, especially for varying mesh size, regardless of stiffness alteration.
{"title":"Controlled stiffness and diffusivity of poly(ethylene glycol) hydrogel formed with cellulose-nanofiber framework","authors":"Donghyun Jo , Yujin Kong , Chang Seok Ki","doi":"10.1016/j.polymer.2024.127753","DOIUrl":"10.1016/j.polymer.2024.127753","url":null,"abstract":"<div><div>Hydrogels composed of polymer networks are widely used in industry and scientific research for high water retention and unique mechanical properties. Nevertheless, in ordinary hydrogel formation, the trade-off relationship between stiffness and mesh size remains a crucial consideration for practical applications. This study describes a facile approach to controlling hydrogel stiffness and mesh size by hybridizing poly (ethylene glycol) diacrylate (PEGDA) and methacrylated TEMPO-oxidized cellulose nanofibers (T-CNFMA). After disintegrating T-CNF by ultrasonication, T-CNFMA was synthesized resulting in a degree of substitution of 2.04 mmol/g. Incorporation of T-CNFMA in the PEGDA network allowed for independent control of hydrogel stiffness and mesh size by reinforcing the whole hydrogel network as a framework. Consequently, the swelling ratio and shear modulus could be manipulated by controlling the PEGDA/T-CNFMA ratio. Structural analyses revealed that an increase in the T-CNFMA content in the presence of a low amount of PEGDA resulted in a large mesh size with a constant stiffness. The diffusivity test was also consistent with the properties of the hydrogels. This result indicates that the incorporation of T-CNF in hydrogel network is useful to control the physical property of the hydrogel, especially for varying mesh size, regardless of stiffness alteration.</div></div>","PeriodicalId":405,"journal":{"name":"Polymer","volume":"313 ","pages":"Article 127753"},"PeriodicalIF":4.1,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142489135","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 : 2024-10-24DOI: 10.1016/j.polymer.2024.127749
Jian Xiao , Minghui Wu , Wenyu Ma , Xiaohu Bing , Long Wang , Wenge Zheng , Daoling Xiong
Optimizing the cellular structure of polymeric foams has long been considered one of the most economical and effective methods for enhancing their impact properties. However, the relationship between cell size and impact strength has rarely been systematically studied. In this study, styrene-butadiene-styrene (SBS) was used as a toughening agent to improve the toughness of Poly(styrene-co-methyl methacrylate) (SMMA). The expansion ratio of pure SMMA foams and their blended counterparts were controlled by fixing the mold-opening distance, while the cell size was adjusted by changing the blowing agent content and packing time. Notably, the impact strength of the optimized SMMA/SBS blend foam reached 15.5 kJ/m2, representing a significant increase of 1400 % compared to that of the pure SMMA foam. In addition, the impact strength of pure SMMA foams did not change significantly as the cell size increased from 29.7 μm to 278.9 μm. However, for SMMA/SBS blend foams, an optimal cell range (100−150 μm) was identified, where the impact strength was approximately twice that of foams with smaller cell sizes (1−25 μm). Then, examination of the impact-fractured surfaces at different cell sizes revealed that the synergistic effects of an appropriate cell size (100−150 μm) and the presence of SBS particles promoted craze initiation and expanded the plastic deformation area during crack initiation, leading toenhanced impact toughness in the blended foam. This work not only systematically elucidates the relationship between cell size and impact strength but also provides new insights into the synergistic effects of rubber particle and cell size on the mechanical properties of polymeric foams.
{"title":"Achieving high impact toughness in injection-molded SMMA foams via the synergistic effects of cell size and SBS","authors":"Jian Xiao , Minghui Wu , Wenyu Ma , Xiaohu Bing , Long Wang , Wenge Zheng , Daoling Xiong","doi":"10.1016/j.polymer.2024.127749","DOIUrl":"10.1016/j.polymer.2024.127749","url":null,"abstract":"<div><div>Optimizing the cellular structure of polymeric foams has long been considered one of the most economical and effective methods for enhancing their impact properties. However, the relationship between cell size and impact strength has rarely been systematically studied. In this study, styrene-butadiene-styrene (SBS) was used as a toughening agent to improve the toughness of Poly(styrene-co-methyl methacrylate) (SMMA). The expansion ratio of pure SMMA foams and their blended counterparts were controlled by fixing the mold-opening distance, while the cell size was adjusted by changing the blowing agent content and packing time. Notably, the impact strength of the optimized SMMA/SBS blend foam reached 15.5 kJ/m<sup>2</sup>, representing a significant increase of 1400 % compared to that of the pure SMMA foam. In addition, the impact strength of pure SMMA foams did not change significantly as the cell size increased from 29.7 μm to 278.9 μm. However, for SMMA/SBS blend foams, an optimal cell range (100−150 μm) was identified, where the impact strength was approximately twice that of foams with smaller cell sizes (1−25 μm). Then, examination of the impact-fractured surfaces at different cell sizes revealed that the synergistic effects of an appropriate cell size (100−150 μm) and the presence of SBS particles promoted craze initiation and expanded the plastic deformation area during crack initiation, leading toenhanced impact toughness in the blended foam. This work not only systematically elucidates the relationship between cell size and impact strength but also provides new insights into the synergistic effects of rubber particle and cell size on the mechanical properties of polymeric foams.</div></div>","PeriodicalId":405,"journal":{"name":"Polymer","volume":"313 ","pages":"Article 127749"},"PeriodicalIF":4.1,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142489120","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 : 2024-10-24DOI: 10.1016/j.polymer.2024.127755
Dong-Jin Shin , Seok Han , Sang-Woog Ryu
This study demonstrates the necessity of introducing di-n-butylmagnesium (n-Bu2Mg) additives to synthesize precisely controlled polymers through anionic polymerization of p-alkoxystyrene monomers at −40 °C. Without additives, 4-tert-butoxystyrene (BSt) and 4-(1-ethoxy ethoxy) styrene (EESt) are polymerized using sec-butyllithium (s-BuLi) in tetrahydrofuran (THF) solvent, yielding a molecular weight distribution (MWD) of 1.36. However, the MWD is strictly controlled to 1.05–1.06 after adding n-Bu2Mg in more than 30 times the amount of s-BuLi, resulting in an accurately designed molecular weight. Therefore, n-Bu2Mg effectively suppresses side reactions that could occur at the polymerization temperature of −40 °C in the Schlenk reactor. Interestingly, the polymerization reaction of styrene monomer proceeds when n-Bu2Mg is mixed in THF solvent at −40 °C for an extended period, even without s-BuLi. This result suggests that, despite being a weak anionic initiator, n-Bu2Mg can initiate polymerization due to the lower electron density of the styrene double bond compared to BSt or EESt. Based on these results, a precise copolymer with a narrow molecular weight distribution can be synthesized by initiating polymerization with s-BuLi within 20 s of adding n-Bu2Mg to the mixed monomers of styrene and EESt.
{"title":"Synthesis of well-defined poly(p-alkoxystyrene) by anionic polymerization in the presence of di-n-butylmagnesium","authors":"Dong-Jin Shin , Seok Han , Sang-Woog Ryu","doi":"10.1016/j.polymer.2024.127755","DOIUrl":"10.1016/j.polymer.2024.127755","url":null,"abstract":"<div><div>This study demonstrates the necessity of introducing di-<em>n</em>-butylmagnesium (<em>n</em>-Bu<sub>2</sub>Mg) additives to synthesize precisely controlled polymers through anionic polymerization of <em>p</em>-alkoxystyrene monomers at −40 °C. Without additives, 4-<em>tert</em>-butoxystyrene (BSt) and 4-(1-ethoxy ethoxy) styrene (EESt) are polymerized using <em>sec</em>-butyllithium (<em>s</em>-BuLi) in tetrahydrofuran (THF) solvent, yielding a molecular weight distribution (MWD) of 1.36. However, the MWD is strictly controlled to 1.05–1.06 after adding <em>n</em>-Bu<sub>2</sub>Mg in more than 30 times the amount of <em>s</em>-BuLi, resulting in an accurately designed molecular weight. Therefore, <em>n</em>-Bu<sub>2</sub>Mg effectively suppresses side reactions that could occur at the polymerization temperature of −40 °C in the Schlenk reactor. Interestingly, the polymerization reaction of styrene monomer proceeds when <em>n</em>-Bu<sub>2</sub>Mg is mixed in THF solvent at −40 °C for an extended period, even without <em>s</em>-BuLi. This result suggests that, despite being a weak anionic initiator, <em>n</em>-Bu<sub>2</sub>Mg can initiate polymerization due to the lower electron density of the styrene double bond compared to BSt or EESt. Based on these results, a precise copolymer with a narrow molecular weight distribution can be synthesized by initiating polymerization with <em>s</em>-BuLi within 20 s of adding <em>n</em>-Bu<sub>2</sub>Mg to the mixed monomers of styrene and EESt.</div></div>","PeriodicalId":405,"journal":{"name":"Polymer","volume":"313 ","pages":"Article 127755"},"PeriodicalIF":4.1,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142489121","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 : 2024-10-24DOI: 10.1016/j.polymer.2024.127747
Jie Zhang , Zijia Kong , Qingbo An , Tongshun Wu , Luyi Zou
Thermal interface materials (TIM) are key thermal management components to enhance the performance of electronic products, and how to improve thermal conductivity is a key issue to consider. As a high thermal conductivity material, it is difficult for copper to have both high thermal conductivity and high elasticity when filled into the polymer. In this paper, by growing copper nanoparticles on the surface of carbon felt (Cfelt), a three-dimensional interoperable thermally conductive copper network is formed with carbon fibers as the support, which makes the material both better thermally conductive and elastic at the same time. The vertical thermal conductivity of the prepared Cu-Cfelt/silicon rubber composite material reached 7.3230 W/mK. It is 23 times higher than pure silicon rubber(0.3130 W/mK), 18 times higher than Cu/silicon rubber composite (0.4120 W/mK) and 12 times higher than CFelt/silicon rubber composite (0.6200 W/mK), and successfully improves the thermal conductivity of the interface. The three-dimensional Cu network structure of the prepared Cu-CFelt/silicon rubber composite maximized the thermal conductivity of Cu, and the composite also showed excellent mechanical properties, indicating that the composite has broad application prospects in thermal management and other aspects.
热界面材料（TIM）是提高电子产品性能的关键热管理元件，如何提高热导率是需要考虑的关键问题。作为一种高导热材料，铜填充到聚合物中很难同时具有高导热性和高弹性。本文通过在碳毡（Cfelt）表面生长纳米铜粒子，以碳纤维为支撑形成了三维互通的导热铜网络，使材料同时具有更好的导热性和弹性。制备的铜毡/硅橡胶复合材料的垂直导热系数达到 7.3230 W/mK。是纯硅橡胶（0.3130 W/mK）的 23 倍，铜/硅橡胶复合材料（0.4120 W/mK）的 18 倍，CFelt/硅橡胶复合材料（0.6200 W/mK）的 12 倍，成功地提高了界面的导热性。所制备的 Cu-CFelt/ 硅橡胶复合材料的三维 Cu 网络结构最大限度地提高了 Cu 的热导率，同时该复合材料还表现出优异的力学性能，表明该复合材料在热管理等方面具有广阔的应用前景。
{"title":"A flexible thermal interface composite of copper-coated carbon felts with 3d architecture in silicon rubber","authors":"Jie Zhang , Zijia Kong , Qingbo An , Tongshun Wu , Luyi Zou","doi":"10.1016/j.polymer.2024.127747","DOIUrl":"10.1016/j.polymer.2024.127747","url":null,"abstract":"<div><div>Thermal interface materials (TIM) are key thermal management components to enhance the performance of electronic products, and how to improve thermal conductivity is a key issue to consider. As a high thermal conductivity material, it is difficult for copper to have both high thermal conductivity and high elasticity when filled into the polymer. In this paper, by growing copper nanoparticles on the surface of carbon felt (Cfelt), a three-dimensional interoperable thermally conductive copper network is formed with carbon fibers as the support, which makes the material both better thermally conductive and elastic at the same time. The vertical thermal conductivity of the prepared Cu-Cfelt/silicon rubber composite material reached 7.3230 W/mK. It is 23 times higher than pure silicon rubber(0.3130 W/mK), 18 times higher than Cu/silicon rubber composite (0.4120 W/mK) and 12 times higher than CFelt/silicon rubber composite (0.6200 W/mK), and successfully improves the thermal conductivity of the interface. The three-dimensional Cu network structure of the prepared Cu-CFelt/silicon rubber composite maximized the thermal conductivity of Cu, and the composite also showed excellent mechanical properties, indicating that the composite has broad application prospects in thermal management and other aspects.</div></div>","PeriodicalId":405,"journal":{"name":"Polymer","volume":"313 ","pages":"Article 127747"},"PeriodicalIF":4.1,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142488174","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 : 2024-10-23DOI: 10.1016/j.polymer.2024.127752
Ebuka P. Ezugwu , Esther Lopez , Alberto Ortin , Mrinal Bhattacharya , Susan C. Mantell
Bimodal HDPE with short chain branches (SCBs) has been the focus of recent research to provide long-term durability and improved resistance to cracking for pipe applications. This study aims to identify the structural changes of bimodal HDPE with SCBs when degraded by a chemo-oxidative environment and to interpret the ductile-brittle transition relative to microstructure including the molecular weight distribution (MWD), molecular entanglement and lamellar dimensions. Sheets of commercially available bimodal HDPE with SCBs preferentially placed in the high molecular weight (HMW) region were exposed to an oxidative environment (5 ppm chlorinated water at 65 °C) for up to 3000 h. Sample microstructure was evaluated by FT-IR, DSC, SAXS, GPC-IR, TREF and cross-fractionation chromatography (CFC), while mechanical performance was characterized by tensile tests. Data revealed an increase in carbonyl index, overall mass crystallinity (61–70 %), and crystalline lamellar thickness (98 to 113 ) with exposure time. Also observed was a decrease in weight average molecular weight (242–17 kg/mol) and amorphous lamellar thickness (). Analysis of TREF and CFC indicated that, during chemo-oxidative degradation, chain scission primarily occurs in the high molecular weight tie chains with SCBs. After 1500 h exposure, the strain hardening modulus and strain at break are reduced to 4.57 MPa and 3.04, respectively. This onset of embrittlement was evaluated relative to changes in microstructure: the number of molecular entanglements (which was reduced from 736 to 74) and critical values for HDPE molecular weight (38 kg/mol) and amorphous lamellar thickness (53 ). The data show that these critical values and reduced entanglement standards are comparable to those developed for evaluation of brittle behavior in undegraded HDPE.
{"title":"Relationship between microstructure changes and embrittlement during chemo-oxidative degradation of bimodal HDPE with short chain branches","authors":"Ebuka P. Ezugwu , Esther Lopez , Alberto Ortin , Mrinal Bhattacharya , Susan C. Mantell","doi":"10.1016/j.polymer.2024.127752","DOIUrl":"10.1016/j.polymer.2024.127752","url":null,"abstract":"<div><div>Bimodal HDPE with short chain branches (SCBs) has been the focus of recent research to provide long-term durability and improved resistance to cracking for pipe applications. This study aims to identify the structural changes of bimodal HDPE with SCBs when degraded by a chemo-oxidative environment and to interpret the ductile-brittle transition relative to microstructure including the molecular weight distribution (MWD), molecular entanglement and lamellar dimensions. Sheets of commercially available bimodal HDPE with SCBs preferentially placed in the high molecular weight (HMW) region were exposed to an oxidative environment (5 ppm chlorinated water at 65 °C) for up to 3000 h. Sample microstructure was evaluated by FT-IR, DSC, SAXS, GPC-IR, TREF and cross-fractionation chromatography (CFC), while mechanical performance was characterized by tensile tests. Data revealed an increase in carbonyl index, overall mass crystallinity (61–70 %), and crystalline lamellar thickness (98 <span><math><mrow><mover><mi>A</mi><mo>˙</mo></mover></mrow></math></span> to 113 <span><math><mrow><mover><mi>A</mi><mo>˙</mo></mover></mrow></math></span>) with exposure time. Also observed was a decrease in weight average molecular weight (242–17 kg/mol) and amorphous lamellar thickness (<span><math><mrow><mn>68</mn><mspace></mspace><mover><mi>A</mi><mo>˙</mo></mover><mspace></mspace><mi>t</mi><mi>o</mi><mspace></mspace><mn>48</mn><mover><mi>A</mi><mo>˙</mo></mover></mrow></math></span>). Analysis of TREF and CFC indicated that, during chemo-oxidative degradation, chain scission primarily occurs in the high molecular weight tie chains with SCBs. After 1500 h exposure, the strain hardening modulus and strain at break are reduced to 4.57 MPa and 3.04, respectively. This onset of embrittlement was evaluated relative to changes in microstructure: the number of molecular entanglements (which was reduced from 736 to 74) and critical values for HDPE molecular weight (38 kg/mol) and amorphous lamellar thickness (53 <span><math><mrow><mover><mi>A</mi><mo>˙</mo></mover></mrow></math></span>). The data show that these critical values and reduced entanglement standards are comparable to those developed for evaluation of brittle behavior in undegraded HDPE.</div></div>","PeriodicalId":405,"journal":{"name":"Polymer","volume":"313 ","pages":"Article 127752"},"PeriodicalIF":4.1,"publicationDate":"2024-10-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142488176","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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