A generalized form of the Fuoss law for viscosity of polyelectrolytes in salt solutions of complex composition

Abstract : The viscosity of dilute solutions of flexible-chain and semirigid-chain polyelectrolytes containing high- and low-molecular-mass electrolytes was studied as a function of solute concentration. A generalized relationship was derived, which includes the Fuoss law as the limiting case. A theoretical proof of the validity of the generalized form of the Fuoss law was given on the basis of direct analysis of the set of differential equations describing the concentration distribution of mobile ions inside and outside the macromolecular coil. The obtained generalized expression of the reduced viscosity describes the experimental data well over the entire concentration range in which the polyelectrolyte swelling of polymers is observed.