Graphene oxides enhanced polyurethane based composite coating with long term corrosion resistance and self-healing property

Coating technology has a wide range of applications in the field of metal corrosion prevention, but traditional coatings have limitations such as the inability to actively heal the damaged area. In this work, we designed and synthesized an anticorrosion self-healing composite coating based on hydrogen bonding interactions and physical shielding effect of graphene oxide nanosheets. The self-healing property and the mechanical property were balanced by adjusting the content of crosslinker molecules in the polymer network. The original polyurethane coating with the optimal structure exhibits a tensile strength of 6.32 MPa and a toughness of 36.65 MJ/m 3 , it can also repair damage after 6 h self-healing at 60 °C showing a self-healing efficiency of 97.3 % in terms of the recovery of toughness. In addition, the polyurethane coating doped with a proper content (0.75 wt%) of graphene oxides (i.e., PU/GO-0.75 coating) shows a significantly improved anti-corrosion performance, although graphene oxides hinder the migration of the molecular chain and thus make the self-healing process become difficult and require a higher temperature. The impedance at 0.01 Hz of original PU/GO-0.75 coating was 3.8 × 10 7 Ω·cm 2 , and it did not show obvious decrease after the self-healing of artificial scratch. The original and healed PU/GO-0.75 coatings can also withstand 20-day salt spray testing without obvious corrosion. This work provides a new strategy for the development of the next generation of anti-corrosion self-healing coatings with favorable comprehensive performances.