A tunable method for nonwetting surfaces based on nanoimprint lithography and hydrothermal growth

In nature, some living things exhibit special wettability properties such as superhydrophobicity. Many scientists have tried to mimic these properties for utilizing them in various applications. Especially, surface morphology is as important as the surface energy to create the superhydrophobicity. In this study, we used a hybrid method-a combination of sol-gel-based nanoimprint lithography and hydrothermal growth-to tune the surface morphology. Ten kinds of TiO2 structures were fabricated using this method and their wetting properties for various liquids and evaporation of water were analyzed. In particular, TiO2 nano-and hierarchical structures, which possess superhydrophobicity, were compared on the basis of these measurements. From these analyses, we confirmed that TiO2 hierarchical structures formed the most stable superhydrophobic state, which have the contact angles over 160 degrees for water and the longest time for natural evaporation of water, compared to other ten kinds of TiO2 structures.