Synthesis of polyurethane/polyurea microcapsules carrying diisocyanate in self-healing epoxy coating

Recently, self-healing coating has been emerged and become one of the most crucial and critical materials with an excellent potential to repair physical damage and prevent cracks from expansion as an anticorrosion element to lengthen the coating lifespan. The determining factor in self-healing coating is that the microcapsules containing a self-curing liquid, which quickly fills up the cracks when the coatings are cut. Microcapsule embracing isophorone diisocyanate (IPDI) as a strong self-healing agent requiring no catalyst has been continuously innovated to be utilized in reality; however, its core content is still low (50-70 %) and the effects on it were not systematically investigated. Therefore, this study aimed to synthesize polyurethane/polyurea microcapsules carrying a higher content of IPDI to be potentially applied in self-healing epoxy coating. As a result, the newly developed spherical microcapsules were obtained with a core content of nearly 80 %, which is far higher than previous research. Moreover, the self-healing ability of epoxy coating containing 10 wt.% of these microcapsules was apparently demonstrated as illustrated in SEM images, along with its excellent anticorrosion, preventing 92.5 % of cracks from corrosion after immersed in 3.5 % NaCl solution for 72 hours.