TRANSIENT ADSORPTION OF A TRI(ETHYLENEGLYCOL) POLYACRYLATE ON A PLASMAPHERESIS MEMBRANE

We study the absorption of polyacrylate of tri(ethyleneglycol) in water on a plasmapheresis membrane, whose main constituent is a copolymer of acrylonitrile and methylmethacrylate. The amount of adsorbed polymer has a strong dependence on pH. Adsorbance is high at low pH and very low at high pH, while in the intermediate range the interfacial concentration GAMMA is not a monotinic function of the solution concentration C. Viscosimetry and UV adsorbance measurements in solution suggest the existence of plurimolecular structures, aggregates, or micelles. We propose a kinetic model, where these latter objects act as detergents at high C and, therefore, contribute to decreasing the interfacial concentration GAMMA when increasing C.