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Abstract:
Molecules solubilized in the water pools of reversed micelles are redistributed over the micelles when they coalesce to form temporary dimers before breaking apart again. The rates of this solubilizate exchange have been determined for the four-component system dodecyltrimethylammonium chloride (DTAC)/hexanol/ri-heptane/water by following suitable electron transfer indicator reactions using the continuous flow method with integrating observation (CFMIO). A population balance analysis incorporating distribution effects of probe molecules across micellar aggregates yielded solubilizate exchange rate constants of 106-107 (M•s)-1, 2-3 orders of magnitude lower than for molecular diffusion. The results are consistent with opening of the surfactant layer upon coalescence as the rate-determining step, random solubilization of the probe molecules, and proportional increase of rate constant with reversed micellar size.
