Reinforcement of graphene and its derivatives on the anticorrosive properties of waterborne polyurethane coatings

Graphene oxide, mildly reduced graphene oxide (RGO) and functionalized graphene were added to waterborne polyurethane (PU) matrix as the anticorrosive reinforcement, respectively. The anticorrosive properties of the graphene oxide and its derivatives reinforced PU composite coatings were characterized by Electrochemical Impedance Spectroscopy (EIS) and salt spray tests. The dispersion states of graphene in PU matrix varied with the chemical states of graphene. The correlations between the chemical states, dispersion states of graphene, and anticorrosive properties of the composite coatings were discussed. The superior anticorrosive properties of the graphene reinforced PU composite coatings were achieved by the addition of 0.2 wt% of RGO. The EIS results showed that the under-painting corrosion did not occur after 235 h immersion in 3.5 wt% NaCl electrolyte and the impedance modulus at 0.1 Hz remained at 109 Ω, barely changed for 235 h.