Heptafluorobutyric ahhydride (HFBA) monolayer was prepared on polyethyleneimine (PEI) coated single crystal silicon substrate. It could be a promising candiated as lubricant for MEMs and micro- machines. The ultra-thin film was characterized by means of contact- angle measurement and X-ray photoelectron spectroscopy (XPS). The great variations of contant angles on the modified substrate indicated that an ordered monolayer of HFAB was obtained. The XPS results showed that the HFBA monolayer on PEI coating came into being in the presence of a covalent amide bond between the carboxylic groups and the amine groups. Furthermore, the adsorption of HFBA onto PEI surface could be described with Langmuir chemical monolayer adsorption.

Key words: POLYETHYLENEIMINE, MONOMOLECULAR FILMS, X-RAY PHOTOELECTRON SPECTROMETRY, ADSORPTION, REACTION KINETICS