IN-SITU FTIR STUDY OF THE FORMATION OF AN ORGANOSILANE LAYER AT THE SILICA/SOLUTION INTERFACE

An FTIR experiment especially designed to study the growth of an organosilane layer at the interface between a solution and a fiat silica surface is presented. High sensitivity is achieved by using the attenuated total reflection (ATR) technique in a liquid flow cell. The ATR crystal, either silicon or germanium, is covered with a very thin silica layer. Chemical reactions of a mono- and a di-hydrolyzable silane with the silica substrate have been investigated. The grafting of a submonolayer of the first reagent has been monitored by following the C-H and SiO-H vibrations. The density of grafted molecules has been estimated and information on the nature of the chemical bonding has been achieved. Evidence for the chain-polymerization of the dihydrolyzable silane at the substrate/solution interface has been inferred from the appearance of a Si-O-Si absorption band.