One-Step Hydrothermal Creation of Hierarchical Microstructures toward Superhydrophilic and Superhydrophobic Surfaces

This article describes a simple and convenient method to fabricate hierarchically structured coatings on glass substrates from soda lime glass by one-step hydrothermal method. The surfaces of the coatings are rough and are composed of flower-like particles assembled by nanoflakes or urchin-like particles constructed by nanowires. These rough surfaces exhibit superhydrophilicity, their water contact angles reaching 0° in less than 40 ms. After surface modification by 1H,1H,2H,2H-perfluorooctyltriethoxysilane, the wetting properties of these coatings switch from superhydrophilicity to superhydrophobicity, with water contact angles as high as 160° and slide angle as low as 1°. The formation mechanism of the hierarchically structured coatings is discussed in detail on the basis of experimental results.