Wetting Characteristics on Micro/Nanostructured Zinc Oxide Coatings

Abstract

The wetting property of nanoimprinted sol–gel-derived ZnO coating has been studied. The deposited ZnO gel film exhibits hydrophilicity owing to the adsorption of OH groups on the surface. The regular micro/nanopattern fabricated by nanoimprinting will prevent water from completely contacting the solid surface by trapping air bubbles at the water–solid interfaces, and the wetting properties are hydrophobic. Furthermore, the micro/nanopatterned surfaces served as substrates for ZnO nanostructure deposition, and the patterned composite structures are obtained. The wetting properties of the composite structure can be adjusted to more hydrophobic or hydrophilic, and the mechanism is demonstrated. In the present study, the water contact angle can be tuned from 9.2 to 109.2° by sawtooth patterns fabricated, and can further be enhanced to nearly 140.8° by nanostructures deposited without modifying the surface chemistry.