Abstract:
A new type of microcapsule with self-healing and anti-corrosion function was prepared by emulsion template combined with photopolymerization and
in-situ polymerization. Then the dual-functional microcapsules were dispersed in water-based epoxy resin to fabricate smart anti-corrosion coatings. In our strategy, lignosulfonate was used as an emulsifier to stabilize the oil phase composed of Tung oil, glycidyl methacrylate (GMA) and 1, 6-hexanediol diacrylate (HDDA). GMA and HDDA underwent crosslinking and formed the shell of microcapsule initiated by UV light. Aniline monomer was added to the water phase subsequently and adsorbed on the outer surface of the microcapsules through the electrostatic interaction between lignosulfonate and aniline. Finally the polyaniline (PANI) shell was synthesized subsequently via chemical oxidative polymerization of aniline initiated by ammonium persulfate in the water phase. The polyaniline microcapsules (Tung oil-PGMA@PANI) loaded with tung oil were prepared. The microcapsule has a composite shell structure, in which the PGMA shell layer can stabilize the emulsion droplet and improve the toughness of the microcapsule, the PANI shell layer gives the microcapsule anti-corrosion performance, and the loaded tung oil can give the microcapsule self-healing performance. FT-IR, TGA and SEM tests proved the successful preparation of the microcapsules, and the tung oil loading in the microcapsules reached 55.1% (mass fraction). The solvent resistance result showed that the microcapsules had strong resistance to water and common non-polar solvents. The self-healing and corrosion inhibition properties of coatings were tested by microscope and salt spray test. As the mass fraction of microcapsules was 7.5%, the defects of coating could be completely repaired after 3 d and the salt spray test results proved that the microcapsules could significantly improve the anti-corrosion performance of the smart coatings.