Role of counterion of the surfactant molecule on the micellar structure in aqueous solution

This article reports the sizes and shapes of micelles of anionic surfactants of LiDS, NaDS, KDS, RbDS and CsDS in aqueous solutions as studied by the technique of small-angle neutron scattering. The micelles of these surfactants are made up of negatively charged DS - ions, while the positively charged ions such as Na + (referred to as counterions) tend to stay near the micellar surface. The present study shows that the distribution of counterions around the micelle depends on hydrophilicity of the counterions, and this in turn decides the micellar structure.