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 degrees 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 degrees and slide angle as low as 1 degrees . The formation mechanism of the hierarchically structured coatings is discussed in detail on the basis of experimental results.