XPS study of polymer/organometallic interaction: Trimethyl aluminum on polyvinyl alcohol polymer

The interaction of trimethyl aluminum, (CH3)3Al, with polyvinyl alcohol (PVA) polymer, −(CH2CHOH)n−, at 300 K was studied by X-ray photoelectron spectroscopy. Trimethyl aluminum (TMA) undergoes facile reaction with the alcoholic HC;OH group of the polymer with resultant loss of all three methyl groups and deposition of a monolayer of carbon-free aluminum. The aluminum is incorporated in an oxy-carbide complex, AIOC, which exhibits a stoichiometry of 1:1:1 for Al, O and C. Within this complex, Al is bridge bonded to both C and O of the HC;OH group as indicated by the appearance of low binding energy peaks in both C(1s) and O(1s) spectra. Polar angle resolved XPS measurements show that the triangular AlOC complex is oriented such that Al is on top and the C;O axis below it is aligned parallel to the surface. The Al modified surface was hydrophobic compared to the hydrophilic PVA.