Graphene/V2O5@polyaniline ternary composites enable waterborne epoxy coating with robust corrosion resistance

Tannic acid (TA), as a biodegradable corrosion inhibitor, was used to modify the graphene (Gr) for improving the water-dispersibility of Gr. Further, the polyaniline (PANI) was enwrapped on the vanadium pentoxide (V2O5) surface to increase its conductivity, thus promoting rapid formation of passivation film. Besides, the PANI enwrapped vanadium pentoxide (PV) was self-assembled with the Gr-TA through pi-pi interaction. Then, the waterborne epoxy coating (WEC) filled with the Gr-TA@PV hybrids were prepared, and the corrosion protection performance of the nanocomposites WEC were investigated through electrochemical and salt spray tests. The results confirmed that the outstanding corrosion protection performance of Gr-TA@PV/WEC derived from the superior barrier property of Gr nanosheets for corrosion agents and its self-healing effect. The self-healing process includes the formation of TA-Fe-TA complex and a passive Fe2O3/ Fe3O4 layer at the interface of coating/substrate.