A continuous increase of the surface hydrophobicity
is seen by an increasing amount of added simethicone
(2.5, 5, and 10%). Apparent contact angles against water
are 129◦ for TiO2 T-2000, 145◦ for TiO2 36, and 152◦
for TiO2 37. A different organic coating consisting of 10%
stearic acid (sample TiO2 66) leads to a further increase
of hydrophobicity up to an apparent contact angle value
of 162◦. It can be demonstrated that the chemical structure and the amount of each coating material is decisive for the
order of magnitude of surface hydrophobicity.