Preparation of Tung Oil‐Loaded PU/PANI Microcapsules and Synergetic Anti‐Corrosion Properties of Self‐Healing Epoxy Coatings

Abstract Tung oil is used as a catalyst‐free repair agent. Tung oil‐loaded polyurethane (PU) microcapsules are prepared by interfacial polymerization in a SiO 2 ‐stabilized Pickering emulsion system, polyaniline (PANI) is deposited in situ on the PU microcapsule surface, and tung oil‐loaded PU/PANI double‐layer shell microcapsules are obtained. Synthesized PU/PANI microcapsules showed the characteristic dark‐green color of conductive PANI. The average particle size is 31.1 ± 8.1 µm and the core content is 45.1 ± 4.3 wt%. The microcapsules have a good thermal stability, and the chemical structure of the PU/PANI wall and tung oil core is confirmed by Fourier transform infrared analysis. Self‐healing anti‐corrosion coatings are prepared by adding 10 wt% microcapsules into epoxy resin. The corrosion resistance properties of the self‐healing coating are evaluated by immersing scratched coatings in 10 wt% NaCl solution for 15 days. The self‐healing coating with 10 wt% tung oil‐loaded PU/PANI microcapsules have the best anti‐corrosion property, and slight corrosion do not occur until 15 days after immersion in salt solution. The self‐healing and anti‐corrosion mechanism are revealed. The tung oil core and the PANI wall of microcapsules contributed synergistically to the excellent self‐healing and anti‐corrosion properties of the coating through the formation of self‐healing films and passivation layers.