Comparison of monolayer films of stearic acid and methyl stearate on an Al2O3 surface

Both stearic acid and methyl stearate chemisorbs onto an oxide surface of a luminum with an asymmetric coordination of the carboxylate group as conclud ed from infrared (IR) spectroscopy data. Similarities in the IR spectra of the films from the two compounds suggest that the ester is bonded in the sa me way as the acid, and that the ester therefore undergoes hydrolysis durin g the surface reaction. X-Ray photoelectron spectroscopy (XPS) and IR data are interpreted in terms of self-assembled monolayer formation and a more d ense film from the carboxylic acid in comparison with that from the ester. (C) 2001 Elsevier Science B.V. All rights reserved.