Self-consistent mode-coupling theory for the viscosity of rod-like polyelectrolyte solutions

Abstract

A self-consistent mode-coupling theory is presented for the viscosity of solutions of charged rod-like polymers. The static structure factor used in the theory is obtained from polymer integral equation theory; the Debye-Hückel approximation is inadequate even at low concentrations. The theory predicts a non-monotonic dependence of the reduced excess viscosity, ${\eta }_R$, on concentration from the behaviour of the static structure factor in polyelectrolyte solutions. The theory predicts that the peak in ${\eta }_R$ occurs at concentrations slightly lower than the overlap threshold concentration, $c^{\ast }$. The peak height increases dramatically with increasing molecular weight and decreases with increased concentrations of added salt. The position of the peak, as a function of concentration divided by $c^{\ast }$ is independent of salt concentration or molecular weight. The predictions can be tested experimentally.

9 pages, 9 figures (2 figures added in the revise version)