Bioinspired ultrathin graphene nanosheets sandwiched between epoxy layers for high performance of anticorrosion coatings

The special “brick-mud” layered micro-nano structure of nacre has undergone millions of years of biological evolution, which can withstand the corrosion of seawater in different environments, and has both high strength and toughness. Inspired by mussels and natural nacre, we successfully designed a bionic epoxy-(graphene-dopamine)n-epoxy sandwich composite coating. Not only does dopamine act as a binder to improve the interfacial compatibility and adhesion between epoxy resin and graphene, but due to the hydrogen bonding and the electrostatic interaction of –COO− and –NH3+, graphene interlayers is parallel to the substrate and arranged between two epoxy coatings. This not only gives full play to the barrier effect of graphene, but also shielding the galvanic corrosion by avoiding direct contacting with the substrate. The results show that the composite coating prepared 10 scanning of dopamine functionalized graphene oxide has a low-frequency impedance of 1.30 × 109 O cm2 after immersion in 3.5 wt% NaCl solution for 90 days, which is three orders of magnitude higher than that of pure coating, revealing remarkable long-term anticorrosion. We consider that our strategy can be readily extended to the self-alignment of a variety of two-dimensional nanofillers to facilitate the development of long-term corrosion resistant coatings.