Reduced Graphene Oxide Nanoplatelets Functionalized with Nonpolar Aliphatic Groups for High-Performance Coatings against Corrosion

A fast and straightforward chemical method to attain reduced graphene oxide (rGO) nanoplatelets that highly functionalized with nonpolar aliphatic groups and their high performance against corrosion is disclosed for the first time. Graphene oxide (GO) was functionalized with trimethoxy(propyl)silane (TMPS) to obtain Propyl-GO through a microwave-assisted method in just 10 min. Scanning electron microscopy-energy-dispersive X-ray revealed a homogeneous distribution of TMPS on the GO surface. Propyl-GO was reduced to obtin highly exfoliated and functionalized nanosheets (Propyl-rGO). Moreover, Propyl-rGO and Propyl-GO were used as additives (0.5 wt %) within an epoxy resin (ER) to obtain ER/Propyl-rGO and ER/Propyl-GO nanocomposite coatings, respectively. ER/Propyl-rGO deposited on A36 structural steel (ER/Propyl-rGO/A36SS) exhibited a hydrophobic behavior, strong adhesion, and significant corrosion protection in a saline medium (1 M NaCl; 58.4 g/L). Interestingly, this functional nanocomposite coating, diminished the corrosion current density by 6 orders of magnitude (icorr = 3.6 × 10-12 A/cm2) compared with A36SS coated with ER (icorr = 1.6 × 10-6 A/cm2). Also, the corrosion potential (Ecorr) was noticeably decremented from -530 mV (neat ER) to -190 mV (ER/Propyl-rGO). Electrochemical impedance spectroscopy assessments suggested a corrosion mechanism controlled by a charge-transfer adsorption process promoted by basal-plane restructuration from rGO. The strategy proposed herein offers an original pathway to achieve nanocomposites with outstanding hydrophobicity, hardness, adhesion, and exceptional protection against corrosion.