Enhanced corrosion and wear resistance via dopamine-functionalized Ti3C2Tx MXene/waterborne polyurethane coating on magnesium alloy

The anti-corrosion/anti-wear advantages of Ti 3 C 2 T x MXenes are limited in environmentally friendly water-based resins due to their instability in aqueous environments and poor compatibility with polymers. In this study, a dual-functional waterborne polyurethane (WPU)/Ti 3 C 2 T x MXene hybrid coating with excellent corrosion resistance and wear resistance is designed. This strategy uses dopamine-grafted Ti 3 C 2 T x MXene sheets to enhance the dispersibility and compatibility of Ti 3 C 2 T x MXene nanosheets in WPU through covalent and hydrogen bonds and can alleviate the oxidation of Ti 3 C 2 T x MXene in aqueous solution. In 3.5 wt% NaCl solution, PMXene and WPU composite (WPU@PMXene) coating has the lowest corrosion current density of 7.73 × 10 −8  A cm −2 and the highest polarization resistance of 1.22 × 10 7  Ω cm 2 , which is better than that of bare Mg alloys 3 orders of magnitude. The |Z| f = 0.01Hz value of WPU@PMXene coating is 3 orders of magnitude higher than that of pure WPU coating. In addition, the wear rate of WPU@PMXene coating is reduced from 2.93 × 10 −3 mm 3 /(N·m) of pure WPU to 0.9 × 10 −3 mm 3 /(N·m) (reduced by 3 times). The improved performance is due to the “labyrinth effect” and increased compatibility of dopamine modified Ti 3 C 2 T x MXene. This synergistic effect exploits a novel and convenient approach of expanding the application of Ti 3 C 2 T x MXene in aqueous coatings to enhance corrosion and wear resistance.