Self-consistent integral equation theory for solutions of finite extensible semiflexible polyelectrolyte chains

Abstract

We investigate the structural and conformational properties of solutions containing semiflexible polyelectrolyte chains using a self-consistent integral equation theory approach. A one-component system is considered where the polyelectrolyte chains interact with each other via a Debye–Hückel potential. Nonelectrostatic interactions among the polymers are taken into account by a self-consistently determined solvation potential. The conformational properties of the polymer chain are determined from a variational calculation with a semiflexible reference chain. The finite chain extensibility is taken into account by constraints for the bond lengths and bond angles using Lagrangian multipliers. The scaling relation for the size of an isolated semiflexible chain with respect to chain length exhibits a transition from rodlike to excluded volume type for a given Debye screening length. For flexible chains in solution, the theory provides conformational properties which are in excellent agreement with computer simulation results. The bare chain stiffness has a pronounced influence on the conformational and structural properties of the solution. In the semidilute regime a pronounced liquidlike order is obtained for flexible polyelectrolyte chains which diminishes with increasing bare persistence length. This process is accompanied by a shift of the structural peaks to smaller length scales.