Self-Healable and Recyclable Dynamic Covalent Networks Based on Room Temperature Exchangeable Hydrazide Michael Adduct Linkages

Dynamic covalent networks (DCN) possessing room temperature exchangeable covalent linkages are desirable for sustainable material development. In this report, a dynamic Michael addition system is designed based on carbonyl hydrazide donor and suitably activated alpha,beta-unsaturated double bonds as acceptor, in which the formation of adduct and exchange of donors in the adduct both occur readily under catalyst-free and ambient conditions. The model compound study supported the room temperature exchangeability of the adducts. The DCNs based on the above hydrazide Michael addition possess an adequate tensile strength and a Young's modulus value up to similar to 23.8 MPa and similar to 2.5 GPa, respectively. The stress relaxation study revealed that these DCNs with a freeze transition temperature of -9.2 degrees C are malleable under ambient conditions. The DCNs are self-healable and easily recyclable under room temperature conditions. The depolymerization of the network to the corresponding precursors is possible in the presence of NH2NH2. Owing to the simplicity, swiftness, and large availability of similar precursors, this dynamic covalent chemistry may find applications in various areas of material development in the future.