Molecular to diffusion dynamics and static structures of aqueous micellar solutions: A SAXS/DLS/DRS study

Abstract

In this paper, we highlight the relevance of our renovated method for investigating mol. to diffusion dynamics and static structures of aq. micellar solns., in which we combine small-angle X-ray scattering (SAXS) and dynamic light scattering (DLS) with dielec. relaxation spectroscopy (DRS). Our unique SAXS/DLS/DRS approach, applied to aq. solns. of non-ionic amphiphile, poly(oxyethylene) cholesteryl ether, clarifies how hydrated water mols., which exhibit ca. 3-4 times slower collective reorientational dynamics than bulk water, contribute to the packing fraction, or the effective vol. fraction of the non-ionic micelles. The results demonstrate that the excluded vol. of the micelles involving the hydrated water mols. dets. the osmotic compressibility of the uncharged systems manifested in the extrapolated structure factor to zero scattering vector, S(q → 0). The data further prove that the concn. dependence of the collective diffusion const. measured by DLS can fully be explained only when the excluded vol. of the hydrated water mols. is properly accounted for.