Electrokinetics of polyelectrolyte solutions in capillary tubes

Abstract

The electrokinetic behaviour of polyelectrolyte solutions in capillary tubes has been investigated. The experiments were carried out with polystyrene sulphonate and carboxymethyl cellulose polyelectrolytes in glass capillaries with diameters in the range 0.3–1.5 mm. The electrokinetic effects were very large compared to similar effects in simple salt solutions and could not be explained in terms of the classical theory of electrokinetic phenomena. To interpret the electrokinetic behaviour of polyelectrolyte solutions a more general theory based on non-equilibrium thermodynamics was developed, which was found to be in essential agreement with the experiments. According to the theory, the main cause of the large electrokinetic effect is the high wall-friction coefficient of the polyion, which is a manifestation of large frictional interactions in the polyion matrix.