Micro-nano hierarchical superhydrophobic electrospray-synthesized silica layers

This paper reports the preparation of superhydrophobic SiO(2) layers with a micro-nano hierarchical surface structure. SiO(2) 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 SiO(2) 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 SiO(2) layers. The resulting SiO(2) layers showed outstanding repellency toward a range of liquid droplets, for example, a water-repellency of 170°. The surface fraction and work of adhesion of the fluorinated, micro-nano hierarchical SiO(2) layers were estimated using the Cassie-Baxter and Young-Dupre equations, respectively. The long-term durability and ultraviolet resistance of the superhydrophobic SiO(2) layers prepared in this study highlight their potential in a range of practical applications.