Developing recyclable and biobased thermosetting polymers is of great significance for environmental protection and resource recycling. In this work, three liquid eugenol-based siloxane-containing epoxides (ESI1–3) with different rigid side groups and functionalities were synthesized and cured by anhydride or amine hardeners. The epoxy resins cured by the anhydride hardener (ESI-M) show quite different dynamic properties, reprocessability, and degradability compared to those cured by the amine hardener (ESI-H). Bifunctional epoxides (ESI1 and ESI2) cured with anhydrides exhibit significantly faster stress relaxation at lower temperatures compared to those cured with amines. All the cured resins can be reprocessed by hot pressing due to their dynamic structures. Both the ESI1-M and ESI2-M resins almost fully restore their mechanical properties after reprocessing. However, the ESI1-H and ESI2-H resins exhibit poor reprocessability even when pressed at high temperature. All cured ESI resins degrade rapidly in a tetrabutylammonium fluoride trihydrate/tetrahydrofuran solution, but they exhibit distinctly different degradation behaviors in acidic solutions. Notably, the degraded ESI-H resins in HCl solution can be recycled to prepare new epoxy resins, whose tensile strengths are comparable to those of the original resins. Finally, recyclable carbon fiber reinforced composites and electromagnetic wave absorbing coatings were fabricated based on the ESI2-M resin. Carbon fibers and magnetite powders can be quickly and nondestructively recycled through degrading the ESI2-M resin.

中文翻译：

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丁香酚基含硅氧烷的可回收环氧树脂，具有可调的动态特性、可再加工性和可降解性


开发可回收和生物基热固性聚合物对环境保护和资源回收具有重要意义。在这项工作中，合成了三种具有不同刚性侧基团和官能团的液体丁香酚基硅氧烷基环氧化物 （ESI1-3），并通过酸酐或胺固化剂固化。与胺固化剂 （ESI-H） 固化的环氧树脂相比，酸酐固化剂 （ESI-M） 固化的环氧树脂表现出完全不同的动态特性、可再加工性和可降解性。与胺类固化的双功能环氧化物（ESI1 和 ESI2）相比，用酸酐固化的双官能环氧化物（ESI1 和 ESI2）在较低温度下表现出明显更快的应力松弛。由于其动态结构，所有固化树脂都可以通过热压进行再加工。ESI1-M 和 ESI2-M 树脂在再加工后几乎完全恢复了其机械性能。然而，ESI1-H 和 ESI2-H 树脂即使在高温下压制时也表现出较差的再加工性。所有固化的 ESI 树脂在四丁基氟化铵三水合物/四氢呋喃溶液中均会迅速降解，但它们在酸性溶液中表现出明显不同的降解行为。值得注意的是，HCl 溶液中降解的 ESI-H 树脂可以回收以制备新的环氧树脂，其拉伸强度与原始树脂相当。最后，基于 ESI2-M 树脂制备了可回收碳纤维增强复合材料和电磁波吸收涂层。碳纤维和磁铁矿粉末可以通过降解 ESI2-M 树脂快速无损地回收。