Sulfonated polyaniline assisted hierarchical assembly of graphene-LDH nanohybrid for enhanced anticorrosion performance of waterborne epoxy coatings

The strong barrier of well dispersed graphene provides excellent labyrinth effect in organic coating. However, the high conductive graphene sheets are prone to forming conductive path in coating matrix with corrosive medium, resulting in serious micro current corrosion. Although a large number of methods to reduce the conductivity of graphene have been reported, how to balance the conductivity of graphene, the affinity between filler and resin, and the self-healing property of coating are major issues for researchers to consider. Here, we have developed a strategy for insulating graphene with layered double hydroxides via sulfonated polyaniline mediated self assembly approach. Graphene sheets were stripped by sulfonated polyaniline to improve the interlayer spacing of graphene followed by covered with layered double metal hydroxide (LDH) via ionic crosslinking, which reduced the conductivity of graphene and improve the interfacial compatibility between the fillers and the resin. At the same time, the electroactive polyanilines between the graphene layers afford the coating with self healing effect. The novel graphene-LDH nanohybrid material was incorporated into the waterborne epoxy resin to prepare corrosion resistant coatings with a thickness of about 70 +/- 5 mu m. The electrochemical and self-healing properties of the prepared composite coating were characterized by EIS, Tafel and LEIS techniques. This novel sulfonated polyaniline crosslinked graphene-LDH nanohybrid expands in the research and development of graphene based high performance anticorrosive coatings.