On the use of aromatic-functionalized reduced graphene oxide to confine corrosive ions in nanocomposite coatings

Abstract

A simple and fast chemical methodology to obtain reduced graphene oxide (GO) nanoplatelets functionalized with aromatic groups and their anticorrosive performance in an epoxy resin matrix is disclosed for the first time. Through a microwave-assisted method, GO was functionalized with triethoxyphenylsilane (TEPS) within 10 min to obtain Phenyl-GO nanoplatelets. The remaining oxygen-centered groups of the nanoplatelets were removed in a second step under a microwave-assisted reduction for 10 min to obtain Phenyl-rGO nanoplatelets. The proposed methodology produced highly exfoliated, hydrophobic, and thermally stable functionalized graphene nanoplatelets. Phenyl-rGO nanoplatelets were used as an additive (0.5 wt%) within an epoxy resin, resulting in Epoxy Resin/Phenyl-rGO nanocomposite, which was used as an anti-corrosive coating on A36 mild steel. The physicochemical properties of the epoxy resin were improved by the Phenyl-rGO addition, such as density, hardness, adhesion, hydrophobic behavior, and anticorrosive performance. The impedance module was increased up to 5 magnitude orders, reaching up to 1.0 × 106 Ω·cm2, and the corrosion rate (CR) was decreased down to 2 magnitude orders (from 1.67 down to 0.01 mm/year). Moreover, the non-polar character of the Phenyl-rGO, allowed the migration of the reduced nanoplatelets to the interphase and surface of the coating, resulting in nanoplatelets densely packed. The tortuous pathway of the corrosive species, generated by the interaction between nanoplatelets, results in a nanocomposite coating that is able to confine such species and prevent corrosion of the metallic surface.