| Abstract
| - Various amounts of N,N-dimethylformamide (DMF) with the weight percentage of DMF varying withinthe range 0−20, were added to aqueous micellar solutions of hexadecyl-, tetradecyl-, and dodecyltrimethylammonium bromides (CTAB, TTAB, and DTAB, respectively). Information about changes in the criticalmicelle concentrations, in the micellar ionization degrees, in the aggregation numbers, and in the polarityof the interfacial region of micelles upon changing the weight percent of DMF was obtained throughconductivity and fluorescence measurements. Surface tension measurements permitted the estimation ofthe Gordon parameter of the water−DMF mixtures. The thermodynamic and structural changes provokedby the addition of DMF to the cationic micellar solutions were evidenced through the micellar kineticeffects observed in the reaction methyl 4-nitrobenzenesulfonate + Br-, investigated in the water−DMFcationic micellar solutions. The pseudophase kinetic model was adequate to quantitatively rationalize thedependence of the observed rate constant on surfactant concentration as well as on the weight percent ofDMF.
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