Probing the internal dynamics of reverse micelles formed in highly compressible solvents: Aerosol-OT in near-critical propane

In normal liquids, the rate of water reorganization within the interior of AOT (sodium bis(2-ethylhexyl) sulfosuccinate or Aerosol-OT) reverse micelles in a strong function of water loading and temperature. In this report, we discuss our most recent efforts to understand the internal dynamics of reverse micelles maintained in highly compressible solvents (near-critical propane). By using steady-state and time-resolved fluorescence spectroscopy, we report the first evidence for pressure-assisted control of the rate of solvent relaxation within the core region of a reverse micelle maintained in a highly compressible fluid. Three factors are taken into account in this study: amount of water loading, temperature, and bulk fluid density. The key conclusion is that the continuous phase density can influence the rate of solvent reorientation within the interior of AOT micelles formed in near-critical propane.