Attractive interactions and phase transitions in solutions of similarly charged rod-like polyelectrolytes

We have calculated the effective interaction and thermodynamic behavior of semidilute solutions of rod-like polyelectrolytes. The model is based on a bare potential energy constructed from the Debye-Huckel potential but extended to include the anisotropic contributions arising from the rod-like conformation. We have calculated the bare and effective potential energy between two Kuhn segments in different polyelectrolyte rods, the isotropic-to-nematic transition, the orientational order parameter of the nematic phase and the phase diagram of the system. Moreover, the effects of molecular weight, monomer, and salt concentration on the different quantities are discussed. (C) 1999 American Institute of Physics. [S0021-9606(99)50627-2].