Epidermis microstructure inspired mica-based coatings for smart corrosion protection

Two-dimensional (2D) graphene-like nanomaterials have gained interest in anticorrosion coatings due to their enable to act as physical barriers to aggressive species, yet 2D coatings are not always effective or sustainable. Inspired by the epidermis microstructure, herein we designed a high-performance anticorrosion coating with rapid self-healing ability via integrating the excellent adhesion property of polydopamine (PDA) and superior barrier properties of natural mica nanosheets (MNSs) for the first time. Such the coating comprises a protective hard top layer with MNSs constituents ("sealing" agents) and a bottom hybrid soft polymer multilayer, forming a stratified epidermis microstructure, can realize a complete restoration of coating defects under water owing to their mutual benefit. These MNSs not only can enhance the barrier performance of the coating matrix to retard the diffusion of aggressive species and hamper polymer release into water, but also induce an anisotropic diffusion to promote the self-healing of the polymer chains. The microstructures of the bioinspired coatings were systemically investigated by scanning electron microscopy (SEM) and optical microscopy (OM) measurements. Electrochemical results confirmed the anticorrosion performance of the coatings were significantly improved. This work provides a new insight for the design and fabrication of 2D nanomaterials reinforced high-performance and smart anticorrosion coatings.