A study of the microstructure of CTAB/1-butanol/octane/ water system by PGSE-NMR and Cryo-TEM
- 63 Downloads
In this work, the effect of octane concentration on the phase behavior of CTAB/water/1-butanol system was studied by using pulsed field gradient spin-echo NMR measurements and freeze fracture electron microscopy (Cryo-TEM and FFEM). When the octane concentration increases, the liquid crystalline phase is destabilized and a continuous single-phase microemulsion region from the water apex to the oil apex is formed. The conductivity behavior has a distinct percolative phenomenon, which indicates that the single-phase microemulsion is changed continuously from oil-in-water (o/w) structure via a bicontinuous structure to water-in-oil (w/o) structure. This result is consistent with those of the PGSE-NMR, Cryo-TEM, and FFEM. In the w/o region, the self-diffusion coefficient of water is relatively high ((1–6)×10−10 m · s−1) due to the higher solubility of water in the continuous phase consisting of octane (10% by weight) and 1-butanol. The penetration of a large amount of octane molecules between surfactant chains results in the much lower self-diffusion coefficient of octane.
Keywordscetyltrimethylammonium bromide microstructure Cryo-TEM PGSE-NMR FFEM
Unable to display preview. Download preview PDF.
- 1.Eicke, H.-F., Topic in Current Chemistry: Micelles, Berlin: Springer-Verlag, 1980, 85–135.Google Scholar
- 2.Lindman, B., Stilbs, P., Microemulsion System (eds. Rosana, H. L., Clausse, M.), Surfactant Science Series, Vol. 24, New York: Marcel Dekker, 1987, 125–168.Google Scholar
- 7.Regev, O., Ezrahi, S., Aserin, A. et al., A study of the microstructure of a four-component nonionic microemulsion by Cryo-TEM, NMR, SAXS, and SANS, Langmuir, 1996, 12: 668.Google Scholar
- 13.Eicke, H. F., Denss, A., Solution Chemistry of Surfactants (ed. Mitta, K. L.), New York: Plenum Press, 1979, 699–745.Google Scholar