Photothermal-Responsive Wormlike Polydopamine-Wrapped Ethylene-Vinyl Acetate Copolymer toward Triple-Action Self-Healing Anticorrosion Coating

The design and synthesis of smart polymeric coatings with excellent self-healing and interfacial adhesion capability are highly pursued for anticorrosion applications. Herein, a unique strategy for triple-action self-healing anticorrosion coatings was applied by the cooperation of the crack closure, healing agent filling, and corrosion inhibition effects. The coating system was constructed by the combination of wormlike polydopamine wrapped ethylene vinyl acetate microspheres (PDA@EVA) and a shape memory epoxy network. Owing to the prominent photothermal characteristic of PDA, the shape memory coating exhibits rapid crack closure property with near-infrared (NIR) irradiation. Meanwhile, the local high temperature promotes the melting and flow of designed wormlike EVA to fill the defects. Morphology investigations revealed that the coating scratch can be promptly healed with 90 s of NIR irradiation. Except as a photothermal agent, PDA can also coordinate with metal substrate, further inhibiting localized corrosion and strengthening the coating/metal interfacial interaction. Electrochemical measurements proved that the local corrosion reactivity was significantly inhibited and the coating resistance also recovered. In addition, the adhesion strength of PDA@EVA embedded coating reaches 7.6 MPa after a healing process, which is about 84% of intact coating. This strategy presented here provides avenues for developing smart protective coatings with high healing efficiency and service durability.