Millisecond-Range Time-Resolved Small-Angle X-Ray Scattering Studies of Micellar Transformations

The transformation of mixtures of cationic and anionic micelles to vesicles has been studied by time-resolved small-angle x-ray scattering (SAXS). Equimolar amounts of ionic surfactant solutions, the anionic ${\mathrm{TexaponN}}_{70}-\mathrm{H}$ and the cationic TTAOH, were mixed by a stopped-flow device. Time-resolved SAXS patterns reveal that within the mixing time $(<10\mathrm{ms})$ mixed micelles are formed. These globular micelles dissolve within about 400–1000 ms and form monodisperse unilamellar vesicles in a much slower process of 5–100 s duration.