Cure Kinetics and Thermal Recyclability of Epoxy Vitrimer Based on Triple Dynamic Covalent Bonds

ABSTRACT Epoxy vitrimers have aroused increasing research attention owing to their stable physicochemical properties, recyclability, and reprocessability, and they even achieve rapid self‐healing by the design of multiple dynamic covalent. However, based on the requirement of optimized curing process, research on cure kinetics of multiple dynamic epoxy vitrimer with flexibility is overtly insufficient, compared with single dynamic epoxy vitrimers. Herein, an amine curing agent with imine group (DN) and epoxy with disulfide and β ‐hydroxyl ester groups (EP) were synthesized, respectively, and the thermoset epoxy was fabricated from either diglycidyl ether of bisphenol A (E51) or EP cured with DN. The comparison of E51/DN and EP/DN crosslinked network on cure kinetics, mechanical properties, and self‐healing performance was investigated in detail. The activation energy ( E a ) of curing reaction for E51D 0.25 was low at 31.79 kJ/mol, while EPD 0.25 had a higher E a of 58.81 kJ/mol due to complex reactions. Especially, when the conversion was up to 80%, the E a of EPD 0.25 showed a sharp increment due to the combined effect of crosslinked network and reaction of β ‐hydroxyl groups. In terms of performance, compared with single dynamic network (E51D 0.25 ), the flexibility, self‐healing, and recyclability of vitrimer were all improved through introduction of triple dynamic bonds.