Yu Chenglong, Xu Zejun, Wang Yimei, Chen Sufang, Miao Menghe, Zhang Daohong
Key Laboratory of Catalysis and Materials Science of the State Ethnic Affairs Commission & Ministry of Education, South-Central University for Nationalities, Wuhan, Hubei 430074, China.
Key Laboratory for Green Chemical Process of Ministry of Education, Wuhan Institute of Technology, Wuhan, Hubei 430073, China.
ACS Omega. 2018 Jul 20;3(7):8141-8148. doi: 10.1021/acsomega.8b01216. eCollection 2018 Jul 31.
Rapid and highly efficient degradation of cured thermoset epoxy resins is a major challenge to scientists. Here, degradable self-cured hyperbranched epoxy resins (DSHE-, = 1, 2, and 3) were synthesized by a reaction between 3-isocyanato-4-methyl-epoxy-methylphenylcarbamate and degradable epoxy-ended hyperbranched polyester (DEHP-) prepared from maleicanhydride, citric acid, and epichlorohydrin. The chemical structure of DSHE- was characterized by Fourier transform infrared and H NMR spectra. With an increase in DSHE- molecular weight, the adhesion strength of self-cured DSHE- films increases distinctly from class 1 to 4, and their pencil hardness remains about class B-2B. The study on the self-cured behavior and mechanism of DSHE- shows that the carbamate group of the DSHE- is decomposed into diamine group to react with epoxy group and form a cross-linked structure. The self-cured DSHE- films were degraded completely in 2 h at 90 °C in the mixed solution of hydrogen peroxide (HO) and ,-dimethylformamide under atmospheric pressure and produced the raw material citric acid, indicating good degradation performance and recyclable property of DSHE-.
快速且高效地降解固化热固性环氧树脂是科学家面临的一项重大挑战。在此，通过3-异氰酸酯基-4-甲基-环氧甲基苯基氨基甲酸酯与由马来酸酐、柠檬酸和环氧氯丙烷制备的可降解环氧封端超支化聚酯（DEHP-，n = 1、2和3）之间的反应，合成了可降解自固化超支化环氧树脂（DSHE-，n = 1、2和3）。通过傅里叶变换红外光谱和核磁共振氢谱对DSHE-的化学结构进行了表征。随着DSHE-分子量的增加，自固化DSHE-薄膜的粘附强度从1级显著提高到4级，其铅笔硬度保持在B-2B级左右。对DSHE-的自固化行为和机理的研究表明，DSHE-的氨基甲酸酯基团分解为二胺基团，与环氧基团反应形成交联结构。在常压下，自固化DSHE-薄膜在90℃的过氧化氢（H₂O₂）和N，N-二甲基甲酰胺混合溶液中2小时内完全降解，并生成原料柠檬酸，表明DSHE-具有良好的降解性能和可回收性能。
