Thin Sol-Gel Silica Films on (3-Mercaptopropyl)trimethoxysilane-Modified Ag and Au Surfaces

The results presented here demonstrate the utility of (3-mercaptopropyl)trimethoxysilane (3MPT) for attachment of a strongly adherent thin layer of silica to Ag and Au surfaces. The thin silica surfaces are formed by standard sol-gel procedures and are shown to be representative of other silica systems. The basis of the adhesion between these two surfaces is covalent bonding between the 3MPT and both the metal and the silica. If 3MPT is not used, the thin silica layer is poorly adherent to the Au surface and only moderately adherent to the Ag surface. Ellipsometry, X-ray photoelectron spectroscopy, Raman spectroscopy, scanning electron microscopy, and qualitative and quantitative adhesion tests are used to characterize this system.