Temperature Study of Nonionic Polymers Adsorption at the Alumina—Solution Interface

Abstract

The temperature influence of the structures of polyvinyl alcohol (PVA) and polyethylene glycol (PEG) adsorption layers on the alumina surface was studied. The amount of polymer adsorbed, the surface and diffuse layer charge of Al2O3 particles in the absence and presence of the polymer, and the thickness of polymer adsorption layers were determined in the 5°–40°C temperature range. An increase of PVA and PEG adsorption with an increase of temperature was observed. It is caused by conformation changes of polymer macromolecules from the coil structure to more and more stretched conformation when the temperature increases. Such a behavior was confirmed by the parameters calculated from the experimental data (Rh—hydrodynamic radius of a polymer coil in the solution, δ—thickness of the polymer adsorption layer, Rs—radius of a sphere equivalent to the volume that falls per a macromolecule in the adsorbed layer). From the comparison of the values of diffuse layer charge and surface charge, the main factor influencing the ζ potential changes was determined. The free energy of PVA and PEG adsorption was calculated using the ζ potential data.