Functionalized graphene/polymer composite coatings for autonomous early-warning of steel corrosion

Corrosion protection coatings with autonomous early-warning functions can prevent catastrophic failure of steel structures. We prepared a self-sensing polymer composite coating with functionalized graphene oxide. The graphene oxide (GO) was chemically modified with 1, 10-phenanthroline-5-amine (phen), which can form a red complex with Fe2+, so as to give a signal of corrosion reaction at very early stage. The waterborne polyurethane (PU) was employed as the environmental-friendly coating matrix. The dispersion of the phen-modified GO in the PU matrix was promoted by the addition of laponite RD. The composite coatings with functionalization GO and laponite RD showed higher corrosion resistance than the pure PU coatings, as characterized by salt spray test. Before the accumulation of Fe3+ on the steel plates, the red color change was observed for the composite coatings, showing the onset of the corrosion reaction.