MONOMOLECULAR SILANE FILMS ON GLASS SURFACES - CONTACT-ANGLE MEASUREMENTS

Contact angle measurements have been done for silanized glass plates w ith 11 different coatings. For a monomolecular film of ecafluoro-1,1,2 ,2-tetrahydrooctyl-1-triethoxysilyl groups on a glass surface, contact angles (water 24 degrees C) have been measured to theta(a) = 111 degr ees, theta(r) = 99 degrees. The figures are comparable with those obta ined for bulk Teflon, but with smaller hysteresis behaviour. The silan es are believed to form chemically anchored monomolecular films with a densest array of aliphatic side chains. MM2 calculations for model co mpounds 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. (C) 1997 Elsevier Sc ience S.A.