Viscosity of Polyelectrolytes: Influence of Counterion and Solvent Type.

We study the viscosity of polystyrenesulfonate with sodium and tetrabutylammonium counterions in aqueous and organic solvent media. We find that at low concentrations the Fuoss law (η sp ∼ c 1/2 ) is approximately obeyed, but at higher concentrations, an exponential dependence on the polymer volume fraction sets in. These findings are discussed in terms of Fujita's free volume theory.