Dihydrazone-based Dynamic Covalent Epoxy Networks with High Creep Resistance, Controlled Degradability, and Intrinsic Antibacteria from Bioresources
Covalent adaptable networks (CANs) provide a promising approach to the recycle issue of thermosets due to their dynamic cross-linked networks. However, CANs are susceptible to creep at relatively low temperatures, and their chemical stability is also inevitably doubted. Here, we designed novel dihydrazone CANs from cross-linking of a dihydrazone-containing epoxy monomer which was synthesized from the condensation of lignin derivative vanillin and hydrazinium hydrate, followed by reacting with epichlorohydrin. Beside the excellent malleability and reprocessability, the dihydrazone CANs exhibited high initial creep temperature of ~105 °C, which was ascribed to the superior stability of hydrazone bond at around 100 °C and favorable hydrazone exchangeability at elevated temperatures. Meanwhile, the degradation of the dihydrazone CANs exhibited temperature, solvent and acidity dependence. Moreover, on account of the high antibacterial property of hydrazone bond, the CANs presented high killing rate (95.8%) to Gram-negative bacteria (E. coli). Thus, this work disclosed an effective dynamic covalent motif for the development of CANs with excellent dimensional stability, chemical resistance and intrinsic antibacteria.