Physicochemical characterization of covalently bonded alkyl monolayers on silica surfaces

Abstract The physicochemical properties of silica surfaces covalently bonded with alkyl monolayers, in a chain length range from C 6 to C 22 , are investigated by using chromatographic, ellipsometric and capacitance measurements. A compact structure is found with an interchain distance of about 0.67 nm; the experimental thickness is very close to the theoretical chain length value. The hydrophobic character of such chemically modified silica surfaces increases with the chain length.