Corrosion protection properties of functionalised graphene–acrylate coatings produced via cataphoretic deposition

The multiple properties of graphene can be exploited in the production of composite coatings to obtain multifunctional layers. To homogeneously disperse graphene in a polymer matrix, its sheets must be oxidised and properly functionalised. In this study, a fast, simple, and alternative method for the oxidation of graphene with nitric acid was studied. The obtained product was functionalised with three different organoalkoxysilanes. The obtained graphene flakes were subjected to infrared and X-ray analyses to study the oxidation grade and organosilane grafting. Several samples were produced by adding functionalised graphene oxide powder to an acrylic-based cataphoretic bath operating at four voltage values to evaluate the effective protective role of the powders. The morphology of the coatings was observed via optical and scanning electron microscopy (SEM) whereas their corrosion resistance properties were evaluated via salt spray chamber exposure and electrochemical impedance measurements. Although the oxidation level of graphene was low, the functionalisation was successful. The differences among the samples depended on the chemical properties of silane. By using (3-aminopropyl)trimethoxysilane (at sufficiently high voltages during the electrodeposition process), coatings with excellent properties, owing to the presence of functionalised graphene oxide sheets, were obtained.