Study on superhydrophobicity of composite silica film surface

A superhydrophobic surface originated from strawberry-like or quincunx-shaped composite silica particles modified with fluorosiloxane was obtained. Different kinds of silica particles and fluorosiloxane were used for controlling surface morphology and chemistry, respectively. The dual size particles are obtained by utilizing the graft of different modified silica particles with epoxy functional group and amine functional group. This makes the surface of film form a composite interface to have irregular binary structure which plays an essential role in trapping air between the substrate surface and the liquid droplets to be necessary for high contact angle and low contact angle hysteresis. The maximum contact angle for water on the composite-paticles film is about (174.2 +/- 2)degrees and the contact angle hysteresis is close to 0 degrees. It is shown that the hierarchical irregularly structure with a low roughness factor and high air-trapped ratio is indispensable for superhydrophobic surface by comparing the surface morphologies, roughness and the wettability on the surface of films containing different structural silica particles.