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Abstract: 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°. 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. [Copyright &y& Elsevier]

Abstract: We describe the preparation of superhydrophobic SiO2 layers through a combination of surface roughness and fluorination. Electrospraying SiO2 precursor solutions that were prepared by a sol–gel route and included trichloro(1H,1H,2H,2H-perfluorooctyl)silane as a fluorination source produced highly rough, fluorinated SiO2 layers. In sharp contrast to the fluorinated flat SiO2 layer, the fluorinated rough SiO2 layer showed much enhanced repellency toward liquid droplets of different surface tensions. The surface fraction and the work of adhesion of the superhydrophobic SiO2 layers were determined, respectively, based on Cassie–Baxter and Young–Dupre equations. The satisfactory long-term stability for 30 days, the ultraviolet resistance and the thermal stability up to 400 oC of the superhydrophobic SiO2 layers prepared in this work confirm a promising practical application. [Copyright &y& Elsevier]

Abstract: 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° 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. [Copyright &y& Elsevier]

Abstract: Silica layers with different microstructures were prepared by electrospraying. The microstructure of the layers was changed by controlling the viscosity of the precursor solutions in the electrospray deposition. Precursor solutions of low viscosity produced particulated silica layers, exhibiting superhydrophobicity. In contrast, fibrous silica layers exhibiting superhydrophilicity were attained with viscous precursor solutions. In particular, the particulated silica layers showed a good durability and resistance to ultraviolet illumination. The dramatic change in the wettability of silica layers without any chemical treatment is promising in speeding up their use in many fields. [Copyright &y& Elsevier]