TMOS is highly hydrophilic in character because of the absence
of non-polar groups. Therefore, the silica films produced using
TMOS precursor are hydrophilic in character [11]. To attain
hydrophobic sol–gel coatings, usually, hydrophobic additives were
added to a sol. The hydrophobic silica thin films are generally
produced by two methods: (i) co-precursor method and (ii) surface
derivatization method. In the present work, the former method
was followed because it is simple and less time consuming
compared to the latter method. To increase the hydrophobicity of
the TMOS based silica films, the TMES was used as the hydrophobic
additive.