We reported the preparation of epoxy coatings incorporated with a composite filler of poly(styrenesulfonate)-polyaniline/reduced graphene oxide (PSS-PANI/rGO) and their performance on the mechanical and anticorrosion properties. The rGO platelets were first dispersed in the PSS solution, followed by in situ oxidative polymerization of aniline. The resulting PSS-PANI/rGO composite was then blended with a bisphenol-A type epoxy at different loadings by tri-roller mill, and was subsequently cured with a curing agent. The ultimate tensile strength and tensile toughness of the epoxy composite at a loading of only 0.5 wt% PSS-PANI/rGO were improved by 39% and 127%, respectively, when compared to the respective values of the pristine epoxy. This was ascribed to their strong interfacial bonding upon curing by the reaction between the PANI and epoxy. Furthermore, the potentiodynamic polarization of the carbon steels coated with the epoxy/PSS-PANI/rGO composite revealed that the anticorrosion performance was greatly improved when compared to those with the neat epoxy and epoxy/rGO coatings. The superior anticorrosion effect was attributed to its larger tortuosity of diffusion pathways, improved interfacial strength between the epoxy and filler, and the passivation layer formed by the presence of polyaniline which was confirmed by X-ray photoelectron spectroscopy. The improved anticorrosion and toughness would allow the coatings to withstand externally mechanical impact and prevent corrosion effectively.
