Distinctive roles of silane coupling agents on the corrosion inhibition performance of graphene oxide in epoxy coatings

Although graphene oxide (GO) is an unique 2D material for improving the corrosion resistance of polymeric coatings, GO nanosheets easily form aggregates in polymer matrix which provide obstacles in front of achieving high protective coatings. The main goal of this research is to enhance the corrosion inhibiting performance of GO nanofiller in epoxy coatings via modifying the surface of GO sheets with silane coupling agents. We have employed 3-aminopropyl triethoxysilane (APTES) and 3-glysidyloxypropyl trimethoxysilane (GPTMS) as silane agents with amine and epoxy end-groups, respectively, to investigate the effect of silane type on the properties of nanocomposite coatings. The results reveal that silane functionalization of GO significantly improves the adhesion of coatings on metal substrate and increases the water contact angle on epoxy coatings. Although all the prepared nanocomposites show superior barrier properties via tortuousing the diffusion path of corrosive species in epoxy matrix, electrochemical analysis exhibit that incorporation of APTES-GO with amine end-groups more efficiently enhances the corrosion resistance of epoxy coating. The investigation offers new aspects for selecting the kind of silane agent for modifying GO sheets and developing epoxy coatings with high corrosion protection efficiency.