Nanocarpet Effect Induced Superhydrophobicity

Abstract

By coating a fluorocarbon monolayer on a bundled Si nanorod array substrate, a superhydrophobic surface with contact angle approximately 167 degrees and sliding angle approximately 2 degrees is created due to the nanocarpet effect. Without forming the nanocarpet, we can only obtain a moderately hydrophobic surface with contact angle <151 degrees and sliding angle >17 degrees. Comparison between nanocarpets formed from nanorods with low and high densities confirms that the main reason for the superhydrophobicity is the formation of sharp pyramidal bundles, which effectively reduces the area of solid-liquid contact. Video recording and analysis of millimeter-sized water droplets bouncing on the solid surface are used to ascertain the superhydrophobicity, and the energy dissipation during a low speed impact is estimated to be several nanojoules.