A study of the deposition of 3-glycidoxypropyltrimethoxysilane on aluminum

The effect of solution pH and hydrolysis time on the adsorption of 3-glycidoxypropyltrimethoxysilane from 1% aqueous solutions onto FPL-etched aluminum surfaces is measured by using grazing-angle Fourier transform infra-red spectroscopy. An analysis of the Si-O-X region of the spectra indicates the presence of only two fundamentally different species on the aluminum surface. One of these species appears to be correlated with adherent silane films that cannot be removed readily by rinsing off the substrate, and the other with non-adherent silane that can be rinsed off. It is shown that hydrolysis time in solution has no effect on the amount of silane adsorbed onto the surface, indicating that the primary adsorption process is not through the interaction of silanol bonds with the substrate but probably involves interaction between the silane molecule and the thin layer of contamination present on all aluminum surfaces. The pH of the solution affects the nature of the adsorbed silane layer but has only a minor influence on the amount of adsorbed silane. (C) 1998 Elsevier Science Ltd. All rights reserved.