Effects of modifiers on the hydrophobicity of SiO2 films from nano-husk ash

Nano-husk ashes were prepared by burning rice-husk with self-propagating method. The super-hydrophobic SiO2 films from nano-husk ash were prepared by sol–gel method using hydroxy silicone oil (HSO), hexamethyldisilazane (HMS), or methyl triethoxysilane (MTS) as modifiers. The effects of modifiers on the hydrophobic property of SiO2 films were studied, and the performances were characterized by the XRD, UV–vis, BET, EDS, SEM, IR, and Contact Angle Analyzer. The results showed that the contact angle of SiO2 films was more than 160° when volume ratio of the modifiers to silicon-sodium solution (SSS) was 0.15. The mechanism of modifiers on SiO2 surfaces is a graft copolymerization. The hydrophobic groups in the modifiers replace the hydroxy groups on SiO2 surfaces and make SiO2 surfaces present super-hydrophobicity.