Complexation of Ionomers and Surfactant Molecules of the Same Charge in a Nonpolar Solvent

Complexation between sulfonated polystyrene ionomers and bis(2-ethylhexyl) sulfosuccinatesodium salt (aerosol OT, AOT) surfactant molecules in m-xylene was studied by ultracentrifugation, vaporpressure osmometry, viscometry, and dynamic light scattering. When the dilute ionomer solution is mixedwith the AOT soluti6n, complexation takes place for both the slightly aggregated state of AOT and reversedmicelles of AOT containing water. In the presence of excess AOT molecules, some of the AOT are free fromthe ionomers, and there are well-defined limiting compositions for complexes of the ionomer and AOT andfor those of the ionomer and AOT micelles. The limiting composition depends on the species of the salt oracid group of the ionomer and on the state of AOT before mixing. The composition was estimated to be0.21-0.66 reversed AOT micelles per &/acid group for the ionomer-AOT micelle complexes and 14-23 AOTmolecules per &/acid group for the ionomel-AOT complexes. AOT molecules were found to disrupt efficientlythe cluster-forming contacts among &/acid groups, each of them encapsulating a single salt/acid group. TheAOT micelles, however, do not completely disrupt the intrachain aggregation.