VISCOSITY OF POLYELECTROLYTE SOLUTIONS-THE GENERALIZED FUOSS LAW.

Early studies of the viscosity of semidilute and moderately dilute 'salt-free' polyelectrolyte solutions have led to the empirical relation between the reduced viscosity and the monomeric concentration known as the Fuoss law. The anomalously large values of the intrinsic viscosity obtained by this method are taken as an indication that polyions become fully stretched in the dilute limit. In fact, the intrinsic viscosity is of the same order of magnitude as that of neutral polymers of similar molecular weight, indicating that, even in this limit, the macroion conformation bears a closer resemblance to an expanded coil than to a rigid rod. Using a modified version of the theory originally developed by Hess and Klein for suspensions of highly charged, spherical particles, the authors obtained the new expression for the viscosity, the generalized Fuoss formula for analyzing the results of experiments on the viscosity of the dilute and semidilute polyelectrolytes. 21 Refs.