Intrinsically self-healing, reprocessable and recyclable epoxy thermosets based on dynamic reversible urea bonds

Developing self-healable, recyclable and reprocessable polymer materials is one of the effective ways to relieve plastic pollution and save resources. Using dynamic reversible hindered urea bonds (HUBs) to construct self-healing materials have become a hot topic to investigate renewable materials. HUBs have a large substituent on its nitrogen atom, which can be dynamically dissociated into related amines and isocyanates without the need for catalysts. Here, integrating HUBs into the epoxy cross-linking network would obtain dynamic covalent self-healing epoxy resin based on large hindered urea bonds (HUBs-EP), which could endow the crosslinked networks with fast reconfigurability under relatively low temperature. In this work, HUBs-EP has optional recyclability (In N, N-dimethylformamide and tetrahydrofuran), good reprocessability (under simple hot-pressing procedure) and rapid self-healing property under 110 °C within 10 min all due to reversible dissociation and recombination of dynamic covalent urea bonds. The extremely simple manufacturing method of dynamically reversible polymers obtained by integrating dynamic covalent bonds into thermoset will give a major hint for the development of sustainable materials.