Effect of cetyltrimethylammonium bromide on hydrophobicity of silica thin layer and xerogel derived from sodium silicate and methyltrimethoxysilane

Hydrophobic silica thin films are produced from sodium silicate and methyltrimethoxysilane (MTMS). CTAB has a hydrophobic group that can increase its hydrophobicity. The purpose of this study was to examine the effect of adding CTAB to silica thin film and xerogel with sodium silicate and MTMS as a precursor. Thin film and xerogel were obtained using the sol-gel and dip-coating methods. The results showed that the addition of CTAB affected the hydrophobic properties of the thin film and xerogel samples. The more CTAB added, the greater the water contact angle, with a limit for adding CTAB of 0.064 g. The water contact angle was obtained for the highest addition of CTAB, with values of 91°, 105.4°, and 107.1° respectively for thin films, non-calcined xerogel, and calcined xerogel. The FTIR results showed that in the calcined and non-calcined xerogel samples, the Si-OH/Si-O-Si ratio tended to decrease.