Altering the X-ray Scattering Contrast of Triton X-100 Micelles and Its Trapping in a Supercooled Solvent.

The structure of core-shell micelles formed by non-ionic surfactant Triton X-100 (TX-100) in a supercooled glucose-urea melt is investigated by contrast variation small angle x-ray scattering (SAXS), small angle neutron scattering (SANS) and HR-TEM. Cooling a molten mixture of glucose-urea (weight ratio of 3:2) to room temperature yields a supercooled solvent without crystallisation that can be used for trapping micelles of TX-100. By using a combination of water and glucose-urea mixture at different proportions as solvent for micellisation, the scattering length density (SLD) of the solvent can be tuned so as to match the shell contrast of the micelles. A systematic analysis of SAXS and SANS data with different SLD of solvent permits a quantitative evaluation of electron density profile of micelles in different matrices. The core of TX-100 micelles shows significant swelling in glucose-urea melt, as compared to that in water. The dimension and morphology of micelles were evaluated by scattering techniques and HR-TEM. DLS studies suggest that, unlike micelles in water, the diffusion of micelles in supercooled glucose-urea melt decreased by several orders of magnitude.