Study of the reaction between methyl 4-nitrobenzenesulfonate and bromide ions in mixed single-chain-gemini micellar solutions: Kinetic evidence for morphological transitions

The reaction between methyl 4-nitrobenzenesulfonate and bromide ions has been studied in mixed single-chain-gemini micellar solutions of n-dodecyltrimethylammonium bromide, DTAB, and dodecyl tricosaoxyethylene glycol ether, Brij(35), with alkanediyl-alpha-omega-bis(dodecyldimethylammonium) bromide, 12-s-12,2Br(-) (s = 3, 4, 5). Kinetic micellar effects show that an increase in the solution mole fraction of the single-chain surfactant, Xsingle-chain, results in a diminution of the mixed micelles tendency to form spherocylindrical aggregates upon increasing surfactant concentration. The dependence of the surfactant concentration at which the sphere-to-rod transition occurs, C*, on Xsingle-chain showed through kinetic data was in agreement with results obtained by means of fluorescence measurements. (C) 2008 Elsevier Inc. All rights reserved.