Static Structure and Chain Conformations in Polyelectrolyte Solutions

Abstract

A microscopic approach is described for the static structure and conformational properties of polyelectrolyte solutions. The theory predicts liquid like structure on long lengthscales in dilute solutions, which diminishes at concentrations higher than the overlap threshold concentration, only to reappear in concentrated solutions. The predictions for the static structure factor are in good agreement with scattering experiments on solutions of rigid tobacco mosaic virus particles if the charge on the particles is treated as adjustable. The theory predicts that k _max ~ ρ ^v, where k _max is the position of the maximum in the structure factor and ρ is the concentration with v=1/3 and 1/2 in dilute and semi-dilute solutions, respectively, in agreement with experiment. The theory is in good agreement with computer simulations of flexible polyelectrolytes, both for the conformational properties and the static structure factor. It is argued that a reversible binding of counterions to the polyions must be invoked in order to understand the experimental results in the framework of this theory.