Counterion condensation in solutions of rigid polyelectrolytes

We present a simple theory to examine counter ion condensation in isotropic solutions of finite-length rigid polyelectrolytes. Electrostatic interacti ons are described by an extension of Debye-Huckel theory, in which a waveve ctor-dependent screening length takes into account the connectivity of the polyions. The counterions are divided into two classes, free and condensed, in chemical equilibrium. We demonstrate that trends in counterion condensa tion are affected by the polyion concentration, the polyion shape, and the solvent quality and that these trends in counterion condensation in turn af fect the phase behavior and osmotic pressure of the polyelectrolyte solutio n.