Preparation of PVA/PU/PUA microcapsules and application in self-healing two-component waterborne polyurethane coatings

It is difficult to produce coatings that have good mechanical and self-healing properties. In this study, polyvinyl alcohol/polyurethane/polyurea (PVA/PU/PUA) microcapsules (MCs) loaded with isophorone diisocyanate (IPDI) as core materials were first prepared by interfacial polymerization in an oil-in-water emulsion using different PVA as an emulsifier. The MCs were then uniformly dispersed in the matrix. Optical microscopy and scanning electron microscopy revealed that the size of MCs decreased as alcoholysis and polymerization degree of PVA increased. Thermogravimetric analysis showed that the MCs prepared with the high polymerization or alcoholysis degree of PVA revealed outstanding thermal stability, and the initial decomposition temperature increased by approximately 100°C compared with IPDI. Furthermore, the self-healing performance of the two-component waterborne polyurethane (2K WPU) coating system containing MCs was investigated. The 2K WPU coatings with 9 wt% PVA/PU/PUA MCs exhibited excellent self-healing, mechanical properties, and corrosion resistance, and indicated a high potential for smart coating.