Self-healing Coatings Based on Epoxy Vitrimers

The present study focuses on the development of epoxy-based vitrimeric coatings with thermal-healing ability. For this purpose, ethylene glycol diglycidyl ether (EG) is crosslinked with methyl nadic anhydride (MNA) in the presence of 1-methylimidazole (1-MI) as initiator. The heat-induced reprocessability enabled by transesterification-based bond exchange reactions is evaluated by stress relaxation tests as a function of the epoxide/anhydride ratio and the addition of a transesterification catalyst, namely triazobicyclodecene (TBD). The results show that the relaxation process can be accelerated by both TBD and epoxy excess. Furthermore, due to their low viscosity values, the epoxy-based formulations can be easily applied to the substrate using standard deposition techniques and without the aid of solvents or high temperatures. Therefore, the produced epoxy vitrimers are able to provide extended service life while maintaining good protective performance and self-repairability, opening up possibilities for large-scale applications as coatings.