Phase Transition in Similarly Charged Rodlike Polyelectrolyte Solutions

We extend an approximate theory in order to examine the properties of the One-Component Plasma of similarly charged rodlike polyelectrolytes model from the weak to the strong coupling regime. In addition to the Coulomb interactions which are present within this system, the excluded volume interaction between the charged rods is also included in our analysis within a reference system which employs a virial expansion truncated at the second order. The electrostatic interaction is decomposed into a long-range component treated within a variational perturbation approximation and a short-range component managed within a strong-coupling expansion. We find that the system undergoes liquid-crystalline ordering driven by both electrostatic and excluded volume interaction. Therefore, the formation of two nematic phases which differ in the value of the variational parameter is predicted. The nematic phase driven by Coulomb interactions exists only in coexistence with the highly ordered phase from relatively intermediate up to large values of the fraction of the charged groups and volume fraction. We also find that the isotropic phase is stable within the whole range of values of the fraction of the charged groups of rods.