Robust\nSelf-Healing Graphene Oxide-Based Superhydrophobic\nCoatings for Efficient Corrosion Protection of Magnesium Alloys

Abstract

A self-healing coating possesses\na broad application prospect in\nthe metal corrosion protection area due to its pleasurable performance.\nBy far, despite a great deal of research studies that have been reported\nin this field, it is still a challenge to construct an intrinsic self-healing\nsurface that can repair a damaged structure and restore superhydrophobicity\nsimultaneously. Herein, a self-healing superhydrophobic coating was\nfabricated by combining polydopamine (PDA)-functionalized Cu²⁺-doped graphene oxide (GO), octadecylamine (ODA), and polydimethylsiloxane\n(PDMS), which can recover the superhydrophobicity and microstructure\nof the coating after chemical/physical damage. The as-prepared self-healing\ncoating displayed excellent liquid repellency with a water contact\nangle of 158.2 ± 2° and a sliding angle of 4 ± 1°,\nwhich endowed the Mg alloy with excellent anticorrosion performance.\nOnce the coating is scratched, the local damaged structure will be\nautomatically repaired through the chelation of catechol and Cu²⁺. Also, the superhydrophobicity of the coating can be rapidly\nrestored under 1-sun irradiation even after being etched by O₂ plasma. Furthermore, the as-fabricated self-healing coating\nstill exhibited excellent corrosion protection against a magnesium\nalloy after immersion in 3.5 wt % NaCl solution for 30 days, which\nwas attributed to the efficient repair of defects in GO by PDA through\nπ–π interactions and the inherent chemical inertia\nof PDMS. Moreover, the as-fabricated self-healing coating also exhibited\nfavorable mechanical stability, chemical durability, and weather resistance.\nThis study paves a fresh insight into the design of robust self-healing\ncoatings with huge application potential.