Mixed micelles of sds and sodium cholate. A nuclear magnetic resonance diffusion and relaxation study

A nuclear magnetic resonance diffusion and relaxation investigation of the mixed micellar system sodium dodecylsulfate (SDS)/sodium cholate (SC) is presented. The concentration of SDS is kept constant at 15 mM and the concentration of SC is varied up to a total SC concentration of 100 mM. The diffusion coefficients of SDS and SC and the 2H relaxation rates of specifically 2H labeled SDS are measured. These quantities are used in the description of the distribution of the two surfactants in the various environments (as monomers in solution and associated into micelles). A theoretical framework based on the Bragg-Williams model is used to qualitatively describe the data.