Preparation of super-hydropbobic titanium oxide film by sol–gel on substrate of common filter paper

A rough TiO 2 film was fabricated by sol–gel technique, the film exhibits perfect super-hydrophobicity with a contact angle of 150° and glide angle of about 5° after being modified with octyltrimethoxysilane. The super-hydrophobicity was converted to super-hydrophilicity by the irradiation of ultraviolet light for 20 h, the irradiated super-hydrophilic film evolves to be hydrophobic with a contact angle of about 120° on the condition of being placed in dark for 2 weeks. Finally the property of super-hydrophobicity of TiO 2 film modified with octyltrimethoxysilane was discussed on the basis of Cassie’s theory.