Preparation and properties of silica isophorone diisocyanate microcapsules for self-healing anticorrosive coatings

Traditional anticorrosion coatings often suffer from reduced effectiveness or even complete failure due to the formation of microcracks. Isophorone diisocyanate (IPDI) can form a polyurea structure without a catalyst in the presence of water, which can protect the underlying metal from corrosion. In this study, an anticorrosion coating with self-healing properties was developed by incorporating microcapsules containing IPDI into the coating formulation. Silica-based self-healing microcapsules were synthesized via interfacial polymerization, using tetraethyl orthosilicate as the precursor and IPDI as the core material. The effects of core-to-wall ratio, reaction temperature, different emulsifiers, and emulsifier ratios on the microcapsule properties were investigated. The results demonstrated that microcapsules prepared using a composite emulsifier system of cetyltrimethylammonium bromide (CTAB) and OP-10 at a 1:1 ratio, with a core-to-wall ratio of 1:1, and a reaction temperature of 75°C, exhibited a smooth surface, spherical shape, and excellent encapsulation efficiency. The maximum core content achieved was 81.2 wt%. An epoxy coating embedded with these self-healing microcapsules was subjected to scratching damage. After applying water to the surface and allowing it to stand for 2 days, the scratches healed, and the steel plate surface remained free from corrosion, indicating excellent self-healing performance.