Mechanically robust, thermally stable, highly transparent superhydrophobic coating with low-temperature sol-gel process

The wetting behavior of transparent superhydrophobic surfaces has attracted much attention in our daily life as well as in engineering applications. Optically transparent superhydrophobic silica films were synthesized by sol-gel method. The coating was formed by in a solution containing silica nanoparticles and silicic acid, in which the silica nanoparticles and silicic acid had different proportions to modulate the roughness of the coating. Comparing with the HMDZ modified films (140 + 2 degrees), the films modified by TMCS showed very high water contact angle (164 +/- 2 degrees), which indicating the excellent waterproof behavior of the films. When the TMCS modified films were heated at temperature above 350 degrees C and 400 degrees C, it became superhydrophilic. The transmittance of coated glasses were above 80% for wavelengths at 400-800 nm. Moreover, the properties of the film were almost unchanged after acid corrosion and immersion in salt solution, and still retained the superhydrophobicity. Even after the impact of water flow and sand impact abrasion, it can still maintain good performance of superhydrophobicity.