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

In this paper, we highlight the relevance of our renovated method for investigating molecular to diffusion dynamics and static structures of aqueous micellar solutions, in which we combine small-angle X-ray scattering (SAXS) and dynamic light scattering (DLS) with dielectric relaxation spectroscopy (DRS). Our unique SAXS/DLS/DRS approach, applied to aqueous solutions of non-ionic amphiphile, poly(oxyethylene) cholesteryl ether, clarifies how hydrated water molecules, which exhibit ca. 3-4 times slower collective reorientational dynamics than bulk water, contribute to the packing fraction, or the effective volume fraction of the non-ionic micelles. The results demonstrate that the excluded volume of the micelles involving the hydrated water molecules determines 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 concentration dependence of the collective diffusion constant measured by DLS can fully be explained only when the excluded volume of the hydrated water molecules is properly accounted for.