FLUORESCENCE STUDY OF THE AGGREGATION BEHAVIOR OF DIFFERENT SURFACTANTS IN AQUEOUS-SOLUTIONS IN THE PRESENCE AND IN THE ABSENCE OF GAS

The effect of dissolved gas (air, argon, butane) on the properties of aqueous surfactant micelles (aggregation number, microviscosity and mi cropolarity) has been investigated by means of time-resolved fluoresce nce quenching and spectrofluorometry on a large number of surfactant s ystems differing by the nature of the surfactant (anionic, cationic, z witterionic, and nonionic) and the temperature. The investigated prope rties were found to be independent of the state of the system: air-sat urated, argon-saturated, or degassed. In the particular case of micell ar solutions of cetyltrimethylammonium chloride, where the measurement s involved 10 identical solutions, the average aggregation numbers mea sured for air-saturated, argon-saturated, and degassed solutions diffe red by less than 1%. The results indicate that if the hydrophobic inte raction, which is the driving force for micelle formation, is affected by the dissolved gas, this would be to a very small extent, well belo w the sensitivity level of the methods of investigation of micellar so lutions used in this study.