Aqueous mixtures containing ionic surfactants and polymers show significant modifications in their physico-chemical properties when the surfactant concentration exceeds a critical value. Addition of surfactants, in fact, promotes the adsorption of micelle-like aggregates onto the polymer backbone, up to saturation of its binding-sites. On increasing the surfactant content above the saturation threshold free micelles coexist -with the surfactant-saturated polymer. Temperature, ionic strength and the nature of surfactant and polymer play a significant role in the interactions between polymers and surfactants.

Polymer-surfactant interactions influence the phase behaviour of systems containing water, surfactant and polymer. Significant differences are observed when the polymer is non-ionic or bears opposite charges with respect to the surfactant. In the latter case electrostatic effects become dominant with respect to ion-dipole, or hydrophobic, interactions, with dramatic consequences on the solution behaviour and on the equilibrium between coexisting phases.

NMR, thermodynamic and kinetic methods were extensively used to investigate some physico-chemical properties of polymer-surfactant systems, PSS. From the above findings information on the adsorption of micelles onto polymer binding-sites (and on the related thermodynamic properties), on aggregate size and on the kinetics of matter exchange between the bulk and polymer-bound micelles is obtained.