MICELLE FORMATION IN MG DODECYL-SULFATE SURFACTANT SOLUTIONS STUDIED BY SANS

Small-angle neutron scattering (SANS) has been used to study micelle f ormation in salt-free heavy water solutions of Mg dodecyl sulfate at v arious concentrations and temperatures. The mean aggregation number of micelles was determined by fitting a spherical or ellipsoidal shape m odel to the measured scattering pattern. Because of the interparticle interaction, the spatial structure of micelles has to be considered in the fit at higher concentrations. This made it possible to determine the effective fractional charge of micelles in addition to the aggrega tion number. The fractional charge is significantly smaller, while the aggregation number is significantly larger than those obtained for Na dodecyl sulfate.