Preparation of super hydrophobic films by DIP coating in the presence of nano-particles

Abstract

Self-cleaning property of the lotus leaf is attractive for practical application. To create a superhydrophobic surface as observed at surface of the lotus leaf, modification of surface chemistry is always combined with surface roughness enhancement. Increasing surface roughness and decreasing surface free energy lead to an increase of hydrophobicity. In this present study, the transparent superhydrophobic films were coated on glass surface by two methods: layer-by-layer deposition of the polyelectrolyte multilayer and dip coating of the organic/inorganic hybrid films. Both types of film consisted of oxide particles as surface roughening materials which were employed either as a particulate or sol form. In the first method, the films were prepared by coating of the polyelectrolyte PAH/PAA bilayers, followed by silica and semi fluorinated silane layers. In the latter, the films were prepared by mixing the semi-flourinated silane and surface roughening material with the polymer matrix. The highest contact angle of 174 and 166 degrees, and low surface free energy at 1 and 4 mj/m2 were obtained from the polyelectrolyte multilayer and hybrid films, respectively. Both types of film were transparent, and had good adhesion and good stability.