Covalent adaptable network (CAN) with the ability of structural rearrangement has attracted great attentions in recent years because it breaks the limitations in reprocessability and recyclability of traditional thermosetting polymers. Developing catalyst-free dynamic chemistry that proceeded in mild condition would make significant advances in the field of CAN and hold great promise for real applications. Here, we report a new class of highly dynamic imidazole-urea bonds for developing dynamically crosslinked poly (imidazole-urea) (PIU). The reversible reaction and the reaction kinetics between different imidazoles and isocyanate were first studied by model compounds. PIUs with varied crosslinking structures were then constructed from biobased histamine and commercially available isocyanates. Rheological and stress relaxation analysis revealed the rearrangement ability of PIUs at elevated temperature, while thermogravimetric and tensile tests showed their good thermal stability and mechanical properties. The reprocessed PIUs also demonstrated high recovery efficiency of mechanical properties after several cycles of reprocessing. It is expected that this study could broaden the scope of imidazole compounds for novel dynamic polymers.

中文翻译：

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用于设计可回收和交联聚（咪唑-脲）的动态咪唑-脲键

具有结构重排能力的共价自适应网络（CAN）由于打破了传统热固性聚合物在可再加工性和可回收性方面的限制，近年来引起了人们的广泛关注。开发在温和条件下进行的无催化剂动态化学将在 CAN 领域取得重大进展，并为实际应用带来巨大前景。在这里，我们报告了一类新的高动态咪唑-脲键，用于开发动态交联聚（咪唑-脲）（PIU）。首先通过模型化合物研究了不同咪唑与异氰酸酯之间的可逆反应和反应动力学。然后用生物基组胺和市售异氰酸酯构建具有不同交联结构的 PIU。流变学和应力松弛分析揭示了PIU在高温下的重排能力，而热重和拉伸测试则显示了其良好的热稳定性和机械性能。经过多次再处理后，再处理的 PIU 还表现出机械性能的高恢复效率。预计这项研究可以拓宽咪唑化合物用于新型动态聚合物的范围。