FLUORESCENCE QUENCHING STUDIES OF THE AGGREGATION BEHAVIOR OF THE MIXED MICELLES OF BILE-SALTS AND CETYLTRIMETHYLAMMONIUM HALIDES

The fluorescence decay of pyrene quenched by dimethylbenzophenone (DMBP) has been used to study the aggregation behavior of cetyltrimethylammonium halide (CTAX) in the presence of varied concentrations of two bile salts, sodium cholate (NaC) and sodium deoxycholate (NaDC). The study showed the different aggregation characteristics of mixed micelles. In both cases it was shown that the probe pyrene migrates from the palisade layer of the micelle to the interior of the mixed micelles with increase in bile salt concentration. The micelles were small for the CTAX/NaC system over the entire concentration range but tended to grow in size into rodlike micelles for the CTAX/NaDC system close to the equimolar concentrations, where phase separation into two micellar phases occurred. Dynamic light scattering and viscosity measurements also support this view.