Water-repellent ZnO nanowires films obtained by octadecylsilane self-assembled monolayers

Zinc oxide (ZnO) films with well-controlled morphologies have been prepared by electrochemical deposition. A seed layer of nanocrystallites of ZnO was prepared from which ZnO nanowires were grown from a low concentration of ZnCl2. The nanowires are rough and dense and their superhydrophilicity is enhanced. A treatment with an alkylsilane (octadecylsilane) yields superhydrophobic surfaces with very high advancing and receding contact angles 173°/172° and a very low roll-off angle. Our superhydrophobic films are stable for more than 6 months.