FTIR and optical transmittance investigation of hydrophobic SiO2-Al2O3 composite films

The hydrophobic and transparent SiO 2 -Al 2 O 3 composite films were prepared by the sol-gel process using tetraethoxysliane (TEOS) and aluminium isopropoxide Al(C 3 H 7 O) 3 as precursors, methyltriethoxysilane (MTES) and cetyltrimethylammonium bromide (CTAB) as chemical modifier and surfactant respectively. Optimum condition for the SiO 2 -Al 2 O 3 nano-composite films with hydrophobic and transparent as well as mechanical properties simultaneously is investigated. It was found that the Si/Al molar ratio should be 1:0.008 and the calcined temperature should be 300°C. The infrared spectra of the films indicated that the hydrophobic surface of the film was due by the introduction of the methyl groups.