Interpretation of the intermicellar structure factors in the hypernetted-chain Percus-Yevick approximation.

Abstract

Intermicellar structure factors extracted from small-angle neutron scattering are analyzed in terms of the primitive model of ionic solutions. A well-defined closure to the Ornstein-Zernike equation is shown to be capable of handling colloidal solutions with high charge and size asymmetry. The micelle-micelle structure factor predicted by a combined hypernetted-chain Percus-Yevick approximation compares favorably with the experimental results for lithium and sodium dodecyl sulfate (LiDS and NaDS) solutions with or without added electrolytes. Compared to the mean spherical approximation the hypernetted-chain Percus-Yevick approximation treats the correlations among ions more accurately and, therefore, the full micellar charge and actual size is used in the analyses even at low volume fraction (concentration) of micelles.