Wettability in air and oleophobicity in water for sol-gel derived silica-based coating films on glass substrates

Abstract

Inorganic-organic hybrid films from 2-(diethoxyphosphoryl) ethyltriethoxysilane (DPTS) and Na⁺-added SiO₂ films were prepared by the sol-gel method on glass substrates, and contact angles for water and oil droplets were evaluated in air and in water. Contact angle for water droplet in air on DPTS-based coating films was 60 degrees and for oleic acid droplet in water was 108 degrees. The addition of Na⁺ to SiO₂ was found to markedly improve the oleophobicity of the resultant films. The oleic acid droplet on the Na⁺-added SiO₂ films was spontaneously detached by immersion in water.