Fourier transform-IR and H-1 NMR studies on the structure of water solubilized by reverse aggregates of calcium bis(2-ethylhexyl) sulfosuccinate in organic solvents
Lp. Novaki et al., Fourier transform-IR and H-1 NMR studies on the structure of water solubilized by reverse aggregates of calcium bis(2-ethylhexyl) sulfosuccinate in organic solvents, COLLOID P S, 278(2), 2000, pp. 143-149
The structure of water solubilized by reverse aggregates of calcium bis(2-e
thylhexyl) sulfosuccinate in deuterobenzene and toluene has been probed by
Fourier transform-IR and H-1 NMR spectroscopies. The v(OD) band of solubili
zed HOD (4% D2O in H2O) has been recorded as a function of the [water]/[sur
factant] molar ratio, W/S. Curve fitting of this band showed the presence o
f a main peak at 2550 +/- 13 cm(-1) and a small one at 2405 +/- 15 cm(-1).
As a function of increasing W/S, the frequency of the main peak decreases,
its full width at half-height increases, and its area increases linearly. T
he H-1 NMR chemical shift of solubilized H2O-D2O mixtures at W/S = 18.1 has
been measured as a function of the deuterium content of the aqueous nanodr
oplet. These data were used to calculate the so-called "fractionation facto
r" of the aggregate-solubilized water, the value of which was found to be u
nity. The results of both techniques show that reverse aggregate-solubilize
d water, although different from bulk water, does not seem to coexist in "l
ayers" of different degrees of structure, as suggested, for example by the
two-state water-solubilization model.