THE VISCOSITY OF POLYMER-SURFACTANT MIXTURES IN WATER

The viscosity of aqueous solutions of poly(ethyleneoxide) (PEO) in the dilute and semidilute regimes exhibits a maximum as a function of sod ium dodecyl sulfate (SDS) concentration. The maximum is shown to corre spond to the point at which the polymer coils are saturated with surfa ctant. From intrinsic viscosity and small angle neutron scattering (SA NS), we obtain a value of 0.65 for the excluded volume exponent of PEO at saturation. Carbon-13 nuclear magnetic resonance (NMR) relaxation measurements indicate that the correlation time for local segmental mo tion for polymer segments attached to micelles is reduced from about 1 0(-11) to 10(-9) s. However, only a relatively small fraction of the t otal coil is in direct contact with the micelles at saturation. A mode l for the polymer-surfactant complex is presented based on these consi derations.