Colorful nanostructured TiO2 film with superhydrophobic–superhydrophilic switchable wettability and anti-fouling property

Abstract

Superhydrophobic nanostructured TiO2 film was successfully fabricated on the Ti plate by anodic oxidation and lauric acid modification. By varying the applied voltage, TiO2 films with various nanostructures and colors were prepared. The water contact angles (WCA) on the modified TiO2 film increased as the applied voltage increased, and the highest WCA on the TiO2 nanovesuvianite film was about 161.23°. When the applied voltage was 5 V and 20 V, the obtained TiO2 nanopores and TiO2 nanotubes could be used to build two improved Cassie models for designing superhydrophobic surface. Moreover, the superhydrophobic TiO2 film showed good anti-fouling property, particularly it could maintain superhydrophobicity both when immersed in and taken out from the organic solvents. The superhydrophobic film could be changed into superhydrophilic under ultraviolet (UV) irradiation, and the superhydrophilic film recovered to hydrophobic or superhydrophobic gradually at 60 °C in the dark. Additionally, the superhydrophilic film showed underwater superoleophobicity, which exhibited excellent anti-fouling property by degrading the oil under UV light.