Conclusions
Uniform, transparent and hydrophobic silica thin films based
on TMOS precursor with TMES as a co-precursor were produced.
Silica thin films with water contact angle (u) as high as 1308 have
been produced by increasing the TMES/TMOS molar ratios (M) to
3.8. The IR spectra showed an increase in the intensity of Si–C and
C–H peaks and decrease in the intensity of O–H peaks with
increase in M value, clearly indicating the increased chemical
modification of silica surface by the organic groups. With increase
in surface roughness, hydrophobicity increases but the optical
transmission of the film decreases. By modification of silica sols
with trimethylethoxysilane, sol–gel coatings could be prepared on
glass substrate at room temperature owning to excellent water
repellent properties without any addition of fluorine containing
compounds.