A PROTON AND C-13 NMR-STUDY ON THE STATE OF WATER SOLUBILIZED BY DETERGENT AGGREGATES IN ORGANIC-SOLVENTS

The state of water solubilized by the reversed micelles of the surfactants cetyltrimethylammonium bromide (CTAB) and sodium bis (2-ethylhexyl) sulfosuccinate (AOT) in organic solvents was examined by a novel, noninvasive technique. It is based on measuring the dependence of the 1H chemical shift of solubilized water, 1H and 13C chemical shifts of the discrete groups of the surfactant on the deuterium content of solubilized water, and the [water]/[surfactant], W/S, ratio. Graphs of the chemical shifts vs the atom fraction of deuterium in the micelle-solubilized water were strictly linear (W/S 4 to 20), and were used to calculate the so-called ’fractionation factor,’ φ, for solubilized water. A value of unity was obtained in all cases, indicating that the structure of the micelle-solubilized water is the same over the whole volume of the aqueous nanodroplet, i.e., water does not seem to coexist in ’layers’ of different degrees of structure. © 1994 by Academic Press, Inc.