Super-anticorrosive inverse nacre-like graphene-epoxy composite coating

Abstract

Graphene-based coatings (GCs) have emerged as attractive candidates for engineering applications. Despite recent progresses, efforts to achieve high-performance and durable GCs through conventional blending have been frustrated due to the uncontrolled distribution and orientation of graphene nanosheets, which degrades anticorrosion properties. By mimicking the nacre's microstructure, here we successfully fabricated a bioinspired GC, in which graphene nanosheets self-assembly in smectic can order in the epoxy matrix. As the bioinspired coating (∼98 wt% of epoxy polymer) shows an inverse composition to nacre (∼96 wt% of aragonite nanoplatelets), thus which is called an ‘‘inverse nacre-like’’ coating. The resultant bioinspired coating has high compactness and alignment degree, resulting in greatly enhanced physical barrier property and anticorrosion performance. Electrochemical tests reveal that the impedance modulus is 3 orders of magnitude much higher than that of blank coating. More importantly, the bioinspired coating shows a highly anisotropic conductivity due to the anisotropic graphene layers, preventing local galvanic corrosion through eliminating the current leakage in the out-of-plane direction.