Lignin/graphene oxide composite coating loaded with zinc ions and its photothermal conversion and self-healing anticorrosion properties

At present, using biomass materials to modify graphene oxide (GO) to enhance the anticorrosion performance of coatings meets the requirements of future sustainable development. In order to endow lignin/GO coatings self-healing function to reduce maintenance costs and avoid accidents caused by material corrosion failure, this work utilized electrostatic interactions to load zinc ions onto lignin/GO (Zn@LGO). Experimental results indicated that the cured coating exhibited both self-healing anticorrosion and photothermal conversion properties. When the content of Zn@LGO was 0.4 wt%, the surface temperature of cured coating rose to 139.2℃ after 180 s of near-infrared radiation. The cured coating was left for 100 days in salt water, Z_0.01Hz value of coating VER-3 was up to 1.3 × 10⁹ Ω cm², which was two orders of magnitude higher than that of pure resin coating, and fewer corrosion products were observed on the metal surface. The scratch test showed that the damaged coating was soaked in 3.5 wt% sodium chloride for 72 h, the charge transfer impedance of coating VER-3 was 2.61 × 10⁴ Ω cm², which was one order of magnitude higher than that of pure resin coating. This was mainly because during metal corrosion, the hydroxide generated by the combination of hydroxide ions at the cathode and zinc ions covered the damaged area of cured coating, hindering the penetration of the corrosive medium. All in all, this research promoted the application of lignin, and also provided a reference for the design of composite coatings with both photothermal conversion and self-healing anticorrosion properties.