Self-healing performance and anti-corrosion mechanism of microcapsule-containing epoxy coatings under deep-sea environment

Abstract

The isophorone diisocyanate @ polyurea (IPDI@SPUA) microcapsules were prepared by interfacial polymerization based on the optimal process parameters. Prepared coatings with different microcapsule additions for protective performance comparison. The addition of microcapsules enhanced the protective performance of the coatings. When the IPDI in the microcapsules was in contact with water, the formed polymer could fill the defects in the IPDI@SPUA/EP coatings. After immersion at 15 MPa for 1008 h, the impedance value of the IPDI@SPUA/EP coatings was 6.32 × 10⁶ Ω·cm², whereas the EP coatings dropped to 9.88 × 10³ Ω·cm². The IPDI@SPUA/EP coatings exhibited the wet adhesion loss of 41.3 %, while the EP coatings showed a higher loss of 72.9 %. The high hydrostatic pressure made the corrosive particles diffuse faster into the coatings, leading to the rupture of the microcapsules, suggesting that the high hydrostatic pressure exerted a beneficial influence on the self-healing capabilities of the IPDI@SPUA/EP coatings.