Polyelectrolyte complex formation at the interface of solutions

Abstract

The reaction between oppositely charged polyelectrolytes at the interface between their aqueous solutions, being the basis for the formation of flat membranes or microcapsules, has been studied with sodium cellulose sulphate and poly(diallyldimethylammonium chloride) as reaction components. By supplemental monitoring of the kinetics of membrane formation at thin ring layers additional informattion was obtained supporting the proposed mechanism of the process. In the very beginning at the boundary a semipermeable primary membrane is formed, which controls further membrane growth by its diffusion resistance. Osmotic pressure differences resulting from difference counterion concentrations inside and outside the capsule additionally remarkably affect the process. Capsule properties depend directly and indirectly on the polymerchemical features of the used polyelectrolytes and vary in a wide range. For each specific combination the capsule properties can be additionally controlled by the main process variables as reaction time, polyer concentrations and presence of low molecular electrolytes.