EFFECTS OF SOL-GEL PROCESSING FACTORS ON TRANSMITTANCE AND SURFACE FREE ENERGY OF TEOS-SIO 2 -PDMS FILMS

Hydrophobic film coatings on ceramic surfaces have been widely studied for decades. Many hydrophobic films have been synthesized but only a few of them have high transmittance and low surface energy. This research investigated the sol-gel processing factors that affect the transmittance and surface free energy of hydrophobic films. In this study, films were made of TEOS (tetraethyl orthosilicate), nano-particle size silica and PDMS (poly-dimethylsiloxane). The amount of silica (0.5, 5, and 10 wt%), the size of the silica (12 and 20 nm), and the heat treatment temperature (300 and 400 o C were varied as independent factors. Transmittance and surface free energy were observed to be dependent factors. Design-Expert ® software was used to design and analyze the experiments. The results showed that the transmittance and surface free energy decreased significantly as the amount of silica was increased.The lowest transmittance value (62%) and surface free energy (3 mN/m) were observed when using a silica size of 20 nm at 10wt%with heat treatment at 300 o C. The highest value of the transmittance (90%) was obtained when using a silica size of 12 or 20 nm at 0.5wt%and heat treatment at 300 o C.