Ultrarobust, Rapidly Recoverable Superhydrophobic Coatings with Self-Similar Micro/Nanostructures and Reinforced Interface for Aluminum Alloy Protection

Abstract In the field of aluminum alloy protection, constructing durable superhydrophobic coatings through a simple strategy is always a great challenge. Here, we report a functional coating with high mechanical robustness and superhydrophobic recoverability, composed of 1H, 1H, 2H, 2H-perfluorooctyltriethoxysilane (PTES) bonded octyltrimethoxysilane-functionalized titanium dioxide nanoparticles (OTMS-TiO2 NPs) and high-viscosity epoxy resin (EP). The coating combines a hierarchical micro/nanostructure, an EP adhesive interface, and a surface enriched with fluorinated and alkyl functionalities. The synergy between the hierarchical roughness and the low-polarity surface chemistry enables excellent water repellency. After 100 cycles of sandpaper abrasion or tape peeling, the coating retained its superhydrophobic water repellency, with WCA values remaining above 160°. The newly exposed surfaces preserved sufficient hierarchical roughness and low-surface-energy components to sustain superhydrophobic. Even after continuous water flow impact or stirred sand-slurry abrasion for 48 h, the superhydrophobicity of the coating does not show significant degradation (WCA > 150°). In addition, the coating shows great stability in strong acidic (pH = 2) or strong alkaline (pH = 12) environments. More importantly, when the coating encounters mechanical damage, corrosion by 36.5 wt % HCl, or complete contamination by industrial oil/paint, its superhydrophobic properties can be quickly restored through a simple sandpaper rubbing treatment. This easily prepared superhydrophobic coating with both recoverability and excellent robustness provides new technical support for protecting aluminum alloy.