Ionic surfactants with polymeric counterions.

This review summarizes recent progress in our understanding of aquoeus "complex salts" of ionic surfactants with polymeric counterions. Complex salts are simplified versions of the much-studied mixtures of oppositely charged polyelectrolytes and surfactants, and are also good model systems to study the fundamentals of polyion-mediated forces in colloidal systems. Comparisons are made with conventional ionic surfactants, which have monomeric counterions, and with surfactants having oligomeric counterions containing two, three or four charged groups. Complex salts form similar aggregates as conventional ionic surfactants, but as the degree of polymerization of the counterion increases, the interaction between the surfactant aggregates becomes attractive rather than repulsive. Introducing uncharged comonomers in the polyions affects both the shape and the organization of the surfactant aggregates.