Polymer-modified ionic microemulsions formed in the system SDS/water/xylene/pentanol

The influence of various polymers on the phase behavior of the quaternary system SDS/xylene/pentanol/water was investigated by measurements of conductivity and viscosity. The properties of the different polymers were changed by the gradual introduction of positive charges into the macromolecule. Uncharged polymers poly(N-vinyl-2-pyrrolidone) (PVP), poly(N-methyl-N-vinylacetamide) (PNMVA) and a copolymer show a clear rise of the water solubilization capacity of the microemulsion at an addition of only 2% aqueous polymer solution. Thus a change of the spontaneous curvature of the surfactant film is indicated. High concentrations up to 20% of the polycation PDADMAC could be incorporated into the water-in-oil phase of the microemulsion. The addition of the polycation creates a clear change in the extent of the water-in-oil phase area in the Gibbs phase diagram. There is a distinct shift of water solubilization maximum of the microemulsion with increasing polymer concentration to higher SDS content and lower water content. The change of phase behavior after the addition of PDADMAC is a consequence of the formation of polycation-surfactant complexes.