title: A new equation of state of a flexible-chain polyelectrolyte solution: Phase equilibria and osmotic pressure in the salt-free case.
abstract: We develop a first-principle equation of state of salt-free polyelectrolyte solution in the limit of infinitely long flexible polymer chains in the framework of a field-theoretical formalism beyond the linear Debye-Hueckel theory and predict a liquid-liquid phase separation induced by a strong correlation attraction. As a reference system, we choose a set of two subsystems-charged macromolecules immersed in a structureless oppositely charged background created by counterions (polymer one component plasma) and counterions immersed in oppositely charged background created by polymer chains (hard-core one component plasma). We calculate the excess free energy of polymer one component plasma in the framework of modified random phase approximation, whereas a contribution of charge densities' fluctuations of neutralizing backgrounds we evaluate at the level of Gaussian approximation. We show that our theory is in a very good agreement with the results of Monte Carlo and MD simulations for critical parameters of liquid-liquid phase separation and osmotic pressure in a wide range of monomer concentration above the critical point, respectively.
authors.affiliation: G.A. Krestov Institute of Solution Chemistry of the Russian Academy of Sciences, Ivanovo, Russia.
authors.forename: Yu A
authors.initials: YA
authors.lastname: Budkov
authors.affiliation: Ivanovo State University, Ivanovo, Russia.
authors.forename: A L
authors.initials: AL
authors.lastname: Kolesnikov
authors.affiliation: Max Planck Institute for Mathematics in the Sciences, Leipzig, Germany.
authors.forename: N
authors.initials: N
authors.lastname: Georgi
authors.affiliation: Ivanovo State University, Ivanovo, Russia.
authors.forename: E A
authors.initials: EA
authors.lastname: Nogovitsyn
authors.affiliation: G.A. Krestov Institute of Solution Chemistry of the Russian Academy of Sciences, Ivanovo, Russia.
authors.forename: M G
authors.initials: MG
authors.lastname: Kiselev