A simple method to fabricate the different extents of superhydrophobic surfaces

Superhydrophobic surface is obtained by combining micro- and nano-scale ZnO nanowires and hydrophobic Teflon material in our recent experiment. We adopt an alkaline hydrothermal method to fabricate a series of ZnO nanowires surfaces with different roughness, which is realized by carefully controlling Zn-AD concentration. The resulted surfaces all exhibit superhydrophilic traits, where a contact angle below 10 degrees for a 3 mu L water droplet sits on these surfaces. The obtained superhydrophilicity comes from the combination of high surface energy of ZnO film and high surface roughness, which is in line with Wenzel's model. Superhydrophobic surface is achieved after spin-coating Teflon. The excellent superhydrophobicity is attributed to the synergistic effect of high roughness and the low surface energy, which is explained by the Cassie model. The Zn-AD concentration of 0.1 M is essential to fabricate the superhydrophobic surfaces. (C) 2009 Elsevier B.V. All rights reserved.