Fabrication of excellent anti-corrosion epoxy coating based on GON-An composites

Polyaniline/graphene oxide (GON-An) composites were synthesized by chemically grafting <i>p</i>-phenylenediamine (PPDA)-modified graphene oxide (GO) with polyaniline (PANI), which was confirmed by FT-IR, XRD, SEM, TEM, Raman spectroscopy, and XPS analyses. The electrochemical impedance spectroscopy test, brine immersion, and Tafel slopes analysis revealed that compared with GO and PPDA-modified GO (GON), GON-An composites which combined the unique corrosion resistance of both PANI and GO exhibited relatively obvious superiority in improving the corrosion resistance of epoxy coating with the same contents. After being immersed in brine for 35 days, the composite epoxy coating containing 1 wt-% of GON-An(1:2) composites in which the mass ratio of GO and PANI was 1:2, possessed a high impedance of 4×10⁹ Ω cm², a high corrosion potential of −0.25 V, and a low corrosion current of 4.119×10⁻¹¹ A cm⁻². Furthermore, the anti-corrosive mechanisms of PANI/GO epoxy coatings were discussed.