Interactions between charged colloids in semi-dilute polyelectrolyte

Abstract

Mixtures of like–charged colloids and flexible polymers in solution are studied at the statistical mechanics of liquids level. The spatial correlations between monomers inside the semi–dilute polyelectrolyte are investigated using the polymer reference interaction site model. In the bare Debye–Huckel picture, charged sites (colloids and monomers) interact via ion–averaged, screened coulombic potentials. The network of the entangled charged chains exert a depletion attraction of entropic and electrostatic origins onto the colloidal particles, which leads to a phase separation of the solution between colloid–rich and polymer–rich phases. The presence of hydrophobic sites on partly charged polymer chains (sequential copolymers) alters this picture and induces steric repulsion and bridging attraction between colloids.