Force measurements on hydrophobized silica surfaces by using AFM

Force measurements between SiO2 surfaces with and without adsorbed phenyl g roups in aqueous media using the atomic force microscope (AFM) are compared . An oxidized silicon tip and an oxidized silicon wafer were hydrophobized with phenyl groups, and the lone-range attraction induced by hydrophobation is shown in force vs. distance curves. The observed differences prove that the silanol groups of the unmodified Si O2 surface are replaced by the phenyl groups.