Location of solubilizate in water-AOT-isooctane systems using positron lifetime spectroscopy

In the present work, positrons have been used as a probe to locate the interaction site of the additive molecules in a membrane mimetic system similar to reverse micelles. The systems investigated are water-AOT Aerosol OT Sodium bis(2-ethylhexyl) sulfosuccinate)-isooctane solutions. Positron lifetime measurements have been performed in water-AOT-isooctane solutions containing chloroform and dichloromethane, respectively, as additives. The choice of these additives is based on their physiological importance. A comparison of the behavior of positron annihilation parameters in surfactant solutions containing the additives with that in systems without them has been made. It has provided some information about the location of the interaction site of the additive molecules in these solutions. In chloroform, the additive molecules tend to migrate from the bulk solvent to the aggregates and are adsorbed either at the interface or close to it. The dichloromethane molecules, on the other hand, tend to get distributed near the hydrocarbon tail of the AOT molecules closer to the bulk solvent.