Conformation changes of a polyelectrolyte chain in a poor solvent

Overview & Synopsis

We study theoretically the behaviour of an isolated polyelectrolyte chain in a poor solvent in the presence of salt. The conformation properties of the chain result from the competition between the repulsive Coulomb interactions and the attractive short-range excluded volume interactions. We show in particular that if the solvent is sufficiently poor, the shape of the chain may change abruptly between cylindrical and spherical configurations at a certain critical salt concentration, rather than following a smooth crossover between scaling regimes. The predicted conformational change is not an effect of counterion condensation, and comes only from the competing interactions between the monomers.