KINETICS AND REVERSIBILITY OF THE ADSORPTION OF POLY(VINYL ALCOHOL) ONTO POLYSTYRENE LATEX-PARTICLES

The kinetics and reversibility of the adsorption of poly(vinyl alcohol) onto polystyrene latex were studied by dynamic light scattering. The adsorption was found to proceed in two stages: an initial rate which was 200 times slower than the prediction based on Smoluchowski's theory and a final rate, more than 10 times slower than the initial rate. Hydration of the polymer chains is likely responsible for the low initial rate, while the second stage involves diffusion through the layer of polymers deposited in the first stage. The pseudoequilibrium coverage obtained after the second stage was found to depend on polymer concentration. This is ascribed to a competition between the rate of adsorption and the rate of rearrangement, found to be of the order of a few seconds. The transfer of polymer from coated to uncoated spheres was assumed to occur via the formation of temporary doublets as opposed to a desorption/adsorption mechanism on the basis of the results obtained for systems in which the number and force of the interparticle interactions were varied.