INFRARED SPECTRAL INVESTIGATION OF POLYACRYLATE ADSORPTION ON ALUMINA

Diffuse reflectance infrared Fourier transform spectroscopy was used t o investigate the structural nature of polyacrylates adsorbed on alumi na from aqueous solution. The presence of sodium bicarbonate or sodium ions on the alumina surface could inhibit the carboxylate groups on t he polymer chains from forming covalent bonds with aluminium ions on t he surface. More carboxylate groups of the chains were adsorbed on sur face sites at lower polymer concentration and higher pH. Also, an incr eased loop formation of the polyacrylate chains occurred with a decrea se in treatment of pH and an increase in polymer concentration. When t he pH changed from higher to lower values in steps, the adsorbed polym er did not increase as much from the stretched-out form to the coiled form as was noted if one initially only treated the aqueous polyacryla te/alumina slurry at the lower pH. The adsorption of water on the poly acrylate-treated surface changed the ratio between covalently and ioni cally bonded carboxylate groups, causing more ionically bonded species .