Superhydrophobicity of electrospray-synthesized fluorinated silica layers

The preparation of superhydrophobic SiO2 layers through a combination of a nanoscale surface roughness and a fluorination treatment is reported. Electrospraying SiO2 precursor solutions that had been prepared by a sol-gel chemical route produced very rough SiO2 layers. Subsequent fluorination treatment with a solution containing trichloro(1H,1H,2H,2H-perfluorooctyl)silane resulted in highly rough, fluorinated SiO2 layers. The fluorinated rough SiO2 layers exhibited excellent repellency toward various liquid droplets. In particular, water repellency of 168 degrees was observed. On the bases of Cassie-Baxter and Young-Dupre equations, the surface fraction and the work of adhesion of the rough, fluorinated SiO2 layers were respectively estimated. In light of the durability in water, ultraviolet resistance, and thermal stability, the superhydrophobic SiO2 layers prepared in this work hold promise in a range of practical applications. (C) 2011 Elsevier Inc. All rights reserved.