Photothermal cyclic self-healing coating with long-term corrosion protection based on bifunctional graphene

[Display omitted] •Dopamine-coated graphene is used to fabricate a photothermal self-healing coating.•Rapid self-healing achieves 3 min under photothermal effect.•The coating remains excellent protection after 7 times of scratch-healing process.•The coating maintains extraordinary ultraviolet stability more than 30 days.•Efficient light-to-heat conversion obtains active water and ice removal properties. The intrinsic repair ability is a new strategy to prolong the protection life of damaged coatings, but how to maintain long-term corrosion protection during repeated healing remains a challenge. Herein, a self-healing, weather-resistant polyurethane coating with long-term stable corrosion protection enhanced by dopamine-coated graphene oxide (GP) fillers was developed. The formation of hydrogen bond between GP and the amino group in the polyurethane chain enhances the interfacial compatibility of the filler in the coating, thus improves the photothermal, thermal conductivity and barrier properties of the coating. The coating maintains excellent corrosion protection properties after 7 times of scratch-healing cycles, and can withstand up to 15 days of immersion after scratch-healing. The water evaporation rate and deicing rate of the coating are respectively up to 5.57 and 4965.5 kg/(m2·h), achieving a highly photothermal conversion efficiency. In addition, molecular dynamics simulation demonstrates that the hydrogen bonds between GP and polyurethane chains is the key factor for the excellent corrosion protection of the coating. This study opens a new avenue for improving the service life of self-healing coatings in atmospheric environment.