Phase diagram of polyelectrolyte solutions

Abstract

The phase diagram of vinyl polyelectrolyte solutions with the degree of polymerization and the concentration is constructed, based on the theories of de Gennes et al. and Odijk, and the electrostatic persistence length calculated by Le Bret. The polyelectrolyte solutions are differentiated between the dilute and semidilute regions. The semidilute region is separated into three regimes, called isotropic, transition, and lattice in the order of decreasing concentration, while the dilute region is divided into two regimes, termed order and disorder. The isotropic and lattice regimes are depicted by de Gennes et al., and the transition regime is described by Odijk. The order and disorder regimes are distinguished from each other by whether an intermolecular single correlation due to electrostatic repulsive forces exists or not. The dilute-semidilute crossover concentration has been confirmed in a concentration range between 0.01 and 1.0 mol/l from the small-angle X-ray scattering of sodium poly(styrene sulfonate) (NaPSS) solutions. The melting crossover C*m between isotropic and transition regimes is supported by some preliminary results of distance distribution analysis. Until now we have no information on the lattice-transition crossover and the order-disorder crossover