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Contact angle measurements have been done for silanized glass plates with 11 different coatings. For a monomolecular film of tridecafluoro-1,1,2,2-tetrahydrooctyl-1-triethoxysilyl groups on a glass surface, contact angles (water 24°C) have been measured to θ a = 111°, θ r = 99°. The figures are comparable with those obtained for bulk Teflon, but with smaller hysteresis behaviour. The silanes are believed to form chemically anchored monomolecular films with a densest array of aliphatic side chains. MM2 calculations for model compounds reveal significant attractive van der Waals forces between the aliphatic chains, which can be seen as a driving force for a 2D self-assembly on the surface. This high state of order is assumed to play a crucial role for optimum hydrophobization. Furthermore, photochemical crosslinking has been done with films of 7-oct-1-enyltrimethoxysilane to increase the wear resistance of the coatings. |
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