Micro-nano hierarchical superhydrophobic electrospray-synthesized silica layers

This paper reports the preparation of superhydrophobic SiO2 layers with a micro-nano hierarchical surface structure. SiO2 layers, which were rough on the microscale, were prepared using an electrospraying method combined with a sol-gel chemical route. To create a nanoscale structure, the surface of the SiO2 layers was coated with Au nanoparticles using an ultraviolet-enhanced chemical reduction process, resulting in a micro-nano hierarchical surface structure. A subsequent fluorination treatment with a solution containing trichloro(1H,1H,2H,2H-perfluorooctyl)silane resulted in fluorination of the micro-nano hierarchical SiO2 layers. The resulting SiO2 layers showed outstanding repellency toward a range of liquid droplets, for example, a water-repellency of 170 degrees. The surface fraction and work of adhesion of the fluorinated, micro-nano hierarchical SiO2 layers were estimated using the Cassie-Baxter and Young-Dupre equations, respectively. The long-term durability and ultraviolet resistance of the superhydrophobic SiO2 layers prepared in this study highlight their potential in a range of practical applications. (c) 2012 Elsevier Inc. All rights reserved.