Interaction between carboxylic acid based model adhesive molecules and aluminium substrates with different surface treatments

The chemical bonding of carboxylic acid functional groups with a set of different aluminium oxide surfaces has been studied using model adhesion compound molecules. Two types of molecules have been selected which represent a maleic anhydride co-polymerized or grafted polyolefine polymer and a poly(acrylic acid) (PAA) polymer. The model compound molecules were applied on the aluminium oxide surface as a monolayer and the chemical bonding of the molecules with different types of aluminium oxides has been investigated using infrared reflection-absorption spectroscopy (FTIR-RAS). The oxides were obtained by giving different surface treatments to the aluminium. It was found that for all types of oxides, the carboxylic acid functional groups in the model adhesion molecules react to form a carboxylate anion, which is involved in bridging bidentate bonding. Besides this, it was found that the amount of bonding molecules showed to be dependent on the amount of hydroxyls on the oxide surfaces, which was determined from XPS measurements.