Tetrakis(dimethylamino)ethylene Chemiluminescence (TDE CL) Characterization of the CMC and the Viscosity of Reversed Microemulsions

Abstract

A new technique for the characterization of reversed microemulsions based on tetrakis(dimethylamino)ethylene (TDE) chemiluminescence (CL) has been explored. This method is based on the transport of quenching species from the continuous nonpolar phase to the interior of micelles. The emission intensity of TDE chemiluminescence was measured as a function of time for different concentrations of surfactant. These data were fit as an exponential decay, and the decay constant, k, was found. When k was plotted as a function of surfactant concentration, there was a clear change in the trend with surfactant concentration at a certain concentration; the concentration where this change occurred was concluded to be the critical micelle concentration (CMC). Using this method, the CMC of doctyl sulfosuccinate sodium salt (AOT) was evaluated in short-chain alkanes (including n-dodecane, n-decane, n-octane, n-heptane, and isooctane), cyclohexane, and mineral oil (light), while the CMCs of sodium dodecylbenzenesulfonate (NaDDBs) and Triton X-100 (X-100) were detected in cyclohexane. The CMC values were found to range from 0.61 to 2.10 mM, and they decreased with the carbon chain length of the alkane solvent. In addition, it was found that the emission intensity of TDE chemiluminescence is sensitive to variations in solvent viscosity. TDE CL is suggested as a fluorescent molecular rotor for measuring the viscosity of the system which is nanosized.