Fabrication of robust superhydrophobic organic-inorganic hybrid coating through a novel two-step phase separation method

Artificial superhydrophobic coatings inspired by nature are expected to have extensive applications in several aspects of our daily lives once their poor mechanical and chemical durability is overcome. In this study, we developed a robust superhydrophobic organic-inorganic hybrid coating through the combination of fluorinated ethylene propylene (FEP) and aluminum dihydrogen phosphate (ADP) using a novel two-step phase separation method. An inorganic adhesive of ADP was introduced as a building block to enhance the structural robustness of the superhydrophobic coating. Carboxylated carbon nanotubes (C-CNTs) with good dispersibility in both water and ethanol were employed as emulsifiers to promote the liquid phase separation of FEP and ADP, which was beneficial for the formation of abundant microspheres in aqueous ethanol. After spraying and thermal treatment, the uniform mastoid micro-/nanostructures were formed on the coating surface due to the thermal phase separation of microspheres, which can provide excellent superhydrophobicity with a water contact angle of 162 ± 1.1° and a sliding angle of 5 ± 0.5°. The prepared coating can maintain its outstanding hydrophobicity even after 1000 abrasion cycles with sandpaper and upon jetting with high pressure water flow (200 kPa). Moreover, owing to the chemical inertness of the hybrid micro-/nanostructures, the prepared coating can provide a high level of corrosion protection against strong corrosive mediums as well as weather protection against UV radiation (300 W/m2). Therefore, it is believed that the robust organic-inorganic hybrid superhydrophobic coating prepared by facile phase separation method would present new avenues for expanding the practical applications of superhydrophobic coatings.