Preparation and characterization of self-healing polymeric materials with microencapsulated epoxy and imidazoline derivatives curing agent

Binary self-healing system consisting of epoxy-containing microcapsules and latent curing agent based on anionic polymerization was investigated. When cracks propagated in the composites, the embedded microcapsules would be damaged and the epoxy healing agent would be released. The latent curing agent used in this study can be well dispersed in epoxy matrix during composites manufacturing, and hence activate the released epoxy wherever it is. As a result, self-healing of the cracked sites is successfully achieved through curing of the released epoxy healing agent. This paper also investigated the preparation and performance of microcapsules synthesized by situ polymerization. The mechanism of anionic chain polymerization between epoxy and curing agent was investigated. On the basis of this work, self-healing ability of the epoxy filled with the healing system was evaluated. It was found that the distribution of microcapsules and latent curing agent greatly influences the healing efficiency but not the stoichiometric composition, and the optimal weight ratio of microcapsules and curing agent 2MZ-AZINE are 15 wt.% and 2 wt.%, offering a ~83% healing efficiency.