Theoretical calculation of reduced viscosity of polyelectrolyte solutions

Intermolecular electrostatic interactions of polyions contributing to the reduced viscosity are calculated for two molecular models of charged points and skewed rods. These simplified models approximately describe inter-polyion configurations in the actual polyelectrolyte solutions to qualitatively reproduce the characteristic peak of the reduced viscosity appearing at lower concentrations. The long-standing theoretical equation by Rice and Kirkwood was adopted for this calculation because of its simplicity. For the potential term of this equation, we assumed a Debye type screening potential as a function of ionic strength. The results show that the skewed rods model well fits with the experimental data. Furthermore, it should be pointed out that the configurations of this model correspond to the basic constituents of the so-called isotropic model proposed by de Gennes et al.