A highly transparent self-cleaning superhydrophobic surface by organosilane-coated alumina particles deposited via electrospraying

A highly transparent self-cleaning superhydrophobic surface was prepared by electrospraying an organosilane-coated alumina precursor. By simply controlling the spraying time, a coating with excellent superhydrophobicity as well as transparency in the visible range was achieved. Increased spraying time increased the water contact-angle, while reducing the transparency of the coatings. Organosilane-coated alumina particles prepared with a spraying time of 300 s showed ∼90% transmittance at a wavelength of 550 nm. A water drop acquired a perfect spherical shape with a contact angle of 162° and eventually rolled off a coated surface at an extremely low sliding angle <3°. This robust superhydrophobicity retained its intrinsic wettability even after 30 min of continuous water jet impact. Dust particles accumulated on the coating surface were washed off completely by rolling a few water drops, leaving behind a perfectly clean surface. Such self-cleaning and transparent superhydrophobic coatings have potential applications in the optical industry.