Green and Catalyst-Free Cross-Linking of Bio-Based Elastomers toward Robust, Reprocessable Abilities and Improved Thermal Aging Resistance Enabled by β-Hydroxyl Esters

作者：Weixiao Song, Zixuan Wang, Yihao Xing, Ganggang Zhang, Xi Zhang, Yonglai Lu, Tianwei Tan, Liqun Zhang · 发表于：ACS Sustainable Chemistry & Engineering · 年份：2023 · DOI：10.1021/acssuschemeng.2c05827 · 被引用次数：46 · 研究领域：Polymer composites and self-healing、Polymer Nanocomposites and Properties、Polyoxometalates: Synthesis and Applications

The bio-based epoxidized natural rubber (ENR) is considered a promising platform to design and fabricate sustainable and high-performance rubber materials. The epoxide sites in the ENR chains contribute to designing a green cross-linking strategy to reduce the release of toxic volatile organic compounds and achieve the recycling of end-of-life rubbers. However, it is still challenging to achieve a catalyst-free and effective cross-linking strategy and obtain a cross-linked ENR with mechanically robust properties. Herein, a series of carboxylic acids with different chain lengths and degrees of functionality were synthesized through the catalyst-free and solvent-free alcoholysis of maleic anhydride and served as cross-linkers for ENR. We demonstrated that the increased chain lengths and degrees of functionality of carboxylic acids were conducive to increasing the rate and efficiency of the epoxy–acid cross-linking reaction and improving the mechanical properties of ENR compared with those of commercial maleic acid. Hence, ENR could be facilely and effectively cross-linked by the modified carboxylic acids without additional additives, producing β-hydroxy ester linkages. The mechanical properties of ENR/carbon black composites could be facilely adjusted via changing the structure and content of the cross-linkers. Due to the introduction of the exchangeable β-hydroxy ester linkages, the covalently cross-linked networks could be able to achieve topological rearrangements via transe...