Preparation Of Transparent Superhydrophobic SiO₂ Film By Sol-Gel Approach

A surface with a water contact angle higher than 150°is called a superhydrophobic surface. Such a surface has many unique properties, like self-cleaning, anti-stain, hydrophobic, oleophobic and low friction, etc. These properties make the superhrophobic surfaces potentially applicable in many areas. The transparent superhydrophobic surface with high transmittance of the visible light is one of the special hydrophobic surfaces, which can be used not only in windshields of cars and aircrafts, building glass, but also for the hulls of ships and tubes or pipes. Because of their enormous application potential, these surfaces have received great interest and been the subject of extensive studies in recent years. But only a few methods have been developed to fabricate transparent superhydrophobic surfaces so far, including plasma enhanced chemical vapor deposition (PE-CVD), sol-gel, sublimation, phase separation and so on. These methods have some disadvantages, such as high-cost, rigorous experimental conditions and equipment, and difficulties in scaling-up. Therefore, it is important to make the fabrication of transparent superhydrophobic surface controllable, low-cost and applicable in large-scale.In the present study, we used a sol-gel technique to balance the surface roughness and visible light transmittance, and explored a method of fabricating transparent superhydrophobic coatings on glass substrate. A transparent superhydrophobic film was prepared from composite silica particles modified with fluorosiloxane by using tetraethoxysilane (TEOS) as a precursor. The composite silica particles were obtained by utilizing two kinds of silane coupling agent. The properties of the film were characterized by using scanning electron microscope (SEM), Transmission electron microscope (TEM), XPS and contact angle instrument. The results show that the average static water contact angle of the film can reach 160°and sliding angle below 3°, indicating that the film has excellent superhydrophobic properties. The transparency of the films reaches 80%. The method we found is simply operable, controllable, low-cost and large-scale applicable.