CHARGE EFFECTS ON THE DIFFUSION OF POLYSTYRENE SULFONATE THROUGH POROUS MEMBRANES

The diffusion coefficient of potassium polystyrene sulfonate was determined in dilute bulk aqueous solution and in track-etch porous membranes. Polymer molecular weight, salt concentration, and membrane pore radius were varied. Size and charge parameters of the polymer and the membrane pores were determined to allow comparison of the experimental results with predictions based on a recently reported theory for partitioning of linear polyelectrolytes between pores and bulk solution. The membrane diffusion data and the theory exhibited fairly good aggreement under most of the conditions studied; the theory underestimated the measured effective diffusivity by 1% on average, and the root-mean-square difference between the theory and measurements was 19%. A comparison of results at various ionic strengths indicates that electrostatic effects can greatly influence membrane transport rates by altering the partitioning of polymers between pores and bulk solution. © 1992.