Liquid micellar discontinuous cubic mesophase from ternary monoolein/ethanol/water mixtures

• Published in: Colloids and surfaces. A, Physicochemical and engineering aspects Vol. 299; no. 1; pp. 133 - 145
• Main Authors: Efrat, Rivka, Aserin, Abraham, Kesselman, Ellina, Danino, Dganit, Wachtel, Ellen J., Garti, Nissim
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 15.05.2007; Elsevier
• Subjects: Chemistry; Cryo-TEM; Cubic mesophases; Electrical conductivity; Ethanol effect; Exact sciences and technology; General and physical chemistry; Glycerol monooleate; Phase diagrams; Phase transitions; SAXS; Phase diagrams; Electrical conductivity; Cryo-TEM; Glycerol monooleate; Cubic mesophases; Phase transitions; SAXS; Ethanol effect; Water; Ethanol; Phase diagram; Glycerol; Alcohol; Small angle X ray scattering; Liquid; Transmission electron microscopy; Alkanol; Mesophase
• ISSN: 0927-7757; 1873-4359
• DOI: 10.1016/j.colsurfa.2006.11.029

In constructing the phase diagram of glycerol monooleate (GMO)/ethanol/water mixtures we detected, in addition to the well-characterized regions of lamellar and cubic bicontinuous liquid crystals, three additional isotropic transparent regions that were not previously well-defined: a large isotropic region denoted in early studies as the L 1-phase, an isotropic region with characteristics similar to the sponge L 3-phase, and a third isotropic region which had not been characterized previously. The present study deals with efforts to characterize this unique isotropic region. The isotropic region is an “island” located within a two phase region connecting the three isotropic regions of the cubic, lamellar, and micellar phases. We termed this phase I 2 (Q L) phase or the Q L phase, which stands for cubic liquid mesophase. This phase is a totally transparent and non-birefringent fluid (completely pourable). It is stable even after over 9 months of storage at room temperature. The fluid is of low viscosity and almost Newtonian. The new phase shows many characteristic features of an ordered phase. Small-angle X-ray scattering measurements (SAXS), SAXS-synchrotron temperature-dependent measurements, and cryogenic-transmission electron microscopy (cryo-TEM) observation reveal that the phase has a cubic symmetry. The SAXS diffractions indicate formation of a somewhat less ordered discontinuous cubic micellar mesophase. The cryo-TEM images provide strong evidence for ordered domains with cubic symmetry. Complementary measurements confirm that the phase is a unique case of a micellar cubic phase. We expect that the fluidic ordered mesostructure will have future applications as a liquid vehicle for the solubilization of nutraceuticals, cosmetoceuticals, and pharmaceuticals.