SURFACE-REACTIONS ON THIN-LAYERS OF SILANE COUPLING AGENTS

The reactivity of immobilized functional groups in thin layers of (3-a minopropyl)triethoxysilane (APS), (3-mercaptopropyl)trimethoxysilane, (3-bromopropyl)trimethoxysilane, and (8-bromooctyl)trimethoxysilane on oxidized aluminum substrates was studied with reflection-adsorption i nfrared spectroscopy (RAIR), optical ellipsometry and contact-angle me asurements. Mass changes on the surface associated with the surface-co nfined reactions were measured with the quartz crystal microbalance (Q CM). Single layers of (3-aminopropyl)triethoxysilane on oxidized alumi num react with chlorodimethylsilane to give [(-O)3Si(CH2)3NH2+SiMe2H]C l- and single layers of (3-mercaptopropyl)trimethoxysilane on oxidized aluminum react with phenylmercuryhydroxide to give [(-O)3Si(CH2)3SHgP h], while no substitution reaction of (3-bromopropyl)trimethoxysilane and (8-bromooctyl)trimethoxysilane monolayers occurred with cyanide. F ilms of APS were further utilized to immobilize pepsin. It is discusse d to which extent known reactions from solution can be -transferred to interface reactions.