Abstract
Catanionic microemulsions formed by dodecyltrimethylammonium bromide (DTAB), SDS, n-hexanol, dodecane, and citrate buffer have been characterized by using dynamic light scattering (DLS) and spectroscopic studies. While the DLS measurements provide information about the hydrodynamic diams. of the microemulsion droplets formed upon variation of the constituents, steady-state and time-resolved ...
Abstract
Catanionic microemulsions formed by dodecyltrimethylammonium bromide (DTAB), SDS, n-hexanol, dodecane, and citrate buffer have been characterized by using dynamic light scattering (DLS) and spectroscopic studies. While the DLS measurements provide information about the hydrodynamic diams. of the microemulsion droplets formed upon variation of the constituents, steady-state and time-resolved fluorescence emission expts. probe the polarity and the dynamics of the trapped solvent pool inside of the microemulsion droplets of nanometer dimension. In addn., time-resolved fluorescence anisotropy shows the rigidity of the confined solvent pool as well as the coupling between the motion of a solute and those of the solvent mols. The results obtained from the DLS and those from the steady-state and time-resolved fluorescence emission studies have been found to correlate well with the superactivity of horseradish peroxidase enzyme in the catanionic microemulsions. Subsequently, the time-zero est. for the dynamic Stokes shift in these microemulsions reveals that approx. 50% of the total solvent dynamical response is missed due to the limited time resoln. employed in our expts. The amplitude of the missing portion is similar to what has been obsd. recently for nanoscopic water by Fayer and co-workers (Piletic, I. R.; Tan, H.-S.; Fayer, M. D.J. Phys. Chem. B2005, 109, 21273).