Self-assembly of spherical interpolyelectrolyte complexes from oppositely charged polymers

Abstract

The formation of inter-polyelectrolyte complexes from the association of oppositely charged polymers in an electrolyte is studied. The charged polymers are linear oppositely charged polyelectrolytes, with possibly a neutral block. This leads to complexes with a charged core, and a more dilute corona of dangling chains, or of loops (flower-like structure). The equilibrium aggregation number of the complexes (number of polycations m₊ and polyanions m₋) is determined by minimizing the relevant free energy functional, the Coulombic contribution of which is worked out within Poisson–Boltzmann theory. The complexes can be viewed as colloids that are permeable to micro-ionic species, including salts. We find that the complexation process can be highly specific, giving rise to very localized size distribution in composition space (m₊, m₋).