Anti-corrosion and self-healing behaviors of waterborne polyurethane composite coatings enhanced via chitosan-modified graphene oxide and phosphate intercalated hydrotalcite

Surface coating technology has been widely used in anti-corrosion field. A well-stacked layered material offers a strong barrier and labyrinth effect to improve the corrosion resistance of organic coatings. However, as a typical layered material, the hydrotalcite dispersion is unstable and prone to delamination. Herein, a strategy for grafting chitosan on graphene oxide and then electrostatic self-assembling with hydrotalcite was proposed. The graphene oxide was modified with chitosan to enhance its barrier performance and corrosion resistance, and then hydrotalcite was coated on the surface of graphene oxide through electrostatic self-assembly to improve the dispersion of hydrotalcite and the interfacial compatibility with resin. At the same time, PO43− between the hydrotalcite layers provides the coating with self-healing ability. Chitosan, graphene oxide and hydrotalcite nano-hybrid materials were introduced into waterborne polyurethane, and a corrosion-resistant coating with a thickness of about 40 μm was prepared. Excellent anti-corrosion behaviors were obtained through the synergistic effect of graphene oxide and hydrotalcite stacking due to the formation of a dense protective layer and the self-healing characteristics of chitosan and phosphate ions. This new type of waterborne polyurethane composite coatings offers broad application prospects in the research and development of high-performance self-healing anti-corrosive coatings.