Eco-Friendly Fabrication of Transparent Superhydrophobic Coating with Excellent Mechanical Robustness, Chemical Stability, and Long- Term Outdoor Durability

Surfaces that possess both superhydrophobicity and high transparency at the same time recently have attracted extensive attention in outdoor applications. However, fabrication and application of transparent superhydrophobic coating usually face following challenges: the micro-nano hierarchical structure required for superhydrophobicity usually leads to a decrease in the light transmittance due to its light trapping effect; fluorine-containing materials used in the preparation of superhydrophobic surfaces are potentially harmful to humans and the environment; and the superhydrophobic surface is easily destroyed by external factors. In this work, a transparent superhydrophobic coating was fabricated via an inexpensive and eco-friendly two-step method, that is, dipping glass substrate into the polydimethylsiloxane/SiO2 suspension followed by calcination treatment. The prepared coating showed superhydrophobicity with a water contact angle of 164 degrees and a sliding angle less than 1.0 degrees. In the visible light region with the wavelength range of 300-900 nm, the maximal transmittance of the superhydrophobic coating was similar to 91.4%, which is higher than that of the untreated glass substrate (similar to 90.9%). Moreover, the coating can maintain superhydrophobicity and high transmittance after sandpaper abrasion, water flow impact, immersion in strong acid/alkaline solution, UV irradiation, and long-term outdoor exposure. We believing that the coating has huge potential value in outdoor applications.