Constructing dual-ligand Ce-MOF on graphene oxide modified with polydopamine endowing polyurethane coating with long-term smart anti-corrosion and mechanical robustness.

Traditional mono-functional anti-corrosion coatings are unable to meet the long-term corrosion resistance requirements of metal materials, therefore developing multifunctional anti-corrosion coatings have broad application prospects. In this work, long-lasting anti-corrosion coatings with superhydrophobic and self-healing properties were successfully prepared by in-situ growth of dual-ligand cerium-based metal-organic framework (Ce-MOF) on the surface of graphene oxide (GO), followed by chemical modification with polydopamine (PDA), resulting in 5B level of adhesion and excellent mechanical robustness. The superhydrophobic surface, as the external armor of the coating, can effectively block the penetrating path of corrosive media. Meanwhile, the MOF structure formed by the coordination of 2-mercaptobenzimidazole (2-M) with cerium ions endows the coating with smart self-healing properties and long-lasting corrosion resistance. Electrochemical tests showed that the low-frequency impedance modulus value of the superhydrophobic coating still reached 3.82 × 10 Ω cm after 30 days salt immersion. Due to the formation of protective films and insoluble precipitates at the defect site by 2-M and cerium ions, the scratches on the coating were significantly reduced after 40 days salt spray experiment, demonstrating the self-healing ability of the coating. This multifunctional anti-corrosion coating provides a new approach for preparing coatings with long-term effective corrosion resistance.