Determination of intrinsic viscosity of polyelectrolyte solutions

Intramolecular hydrodynamic contribution eta (intra)/C to the reduced viscosity eta (SP)/C of polyelectrolyte solutions is derived as a function of polymer concentration C by separating the theoretically calculated intermolecular electrostatic contribution eta (inter)/C from the observed reduced viscosity, assuming an additivity, eta (SP)/C = eta (intra)/C + eta (inter)/C. The resulting intramolecular part eta (intra)/C reflects nearly the net effect of the polyion conformation; it increases monotonously with decreasing polymer concentration and levels off to a constant in sufficiently dilute concentrations. The leveling-off value of eta (intra)/C corresponds to the intrinsic viscosity [eta]. From the estimated values of [eta], the ionic strength I dependence of the polyion conformation has been visualized, resulting in a similarity between two relations, eta (intra)/C vs. C and [eta] vs. I. (C) 2001 Elsevier Science Ltd. All rights reserved.