Fast Modulation of Surface Amphiphobicity/Amphiphilicity via Bidirectional Substitution between Perfluorinated Surfactants and Polyanions throughout Pre-Assembled Polyelectrolyte Multilayers

Superamphiphobic Magnesium Alloys with Extraordinary Environmental Adaptability

The application of magnesium alloys is seriously limited by their poor environmental adaptability. In this work, we report a robust superamphiphobic coating, which endows magnesium alloys with extraordinary environmental adaptability. The coating was fabricated on magnesium alloys by a facile, cost-effective, and scalable method, one-step particle-free spraying. The as-treated magnesium alloys show excellent superamphiphobicity with the static contact angles (CAs) of water, ethylene glycol, benzyl alcohol, and cyclohexanol droplets of 157.5°, 155.1°, 151.7°, and 151.3°, respectively. These samples also display small dynamic CAs (0° for water and 10° for ethylene glycol) and water super-repellency, which endow magnesium surfaces with droplet impact resistance, self-cleaning, and oil-resistance functions. The simulating environmental-adaptability tests demonstrate that the as-treated magnesium alloys can remain superamphiphobic under various mechanical, chemical, and physical damages including sand impact (⩾10 cycles), water impact (v = 4.5 m·s^-1, 2 impacts·s^-1, 20 h), abrasion (1.0 kPa, 50 cycles), strong acid/alkaline solution (pH = 1-14), organic solvents immersion (ethylene glycol, n-hexane, ≥48 h), high temperature (200 °C, 72 h), and ultraviolet irradiation (λ = 254 nm, 672 h). The natural environmental-adaptability tests in the acidic industrial atmosphere for 40 days further confirm the robustness of the as-treated magnesium alloys under harsh environments. This work not only provides a promising method for industrially fabricating environmental-adaptable coatings on metallic materials but also paves the way for the much wider applications of magnesium alloys.