Oleogels from Glycerol-Based Lyotropic Liquid Crystals: Phase Diagrams and Structural Characterization

• Published in: Journal of the American Oil Chemists' Society 2015-03, Vol.92 (3), p.439-447
• Main Authors: Cegla-Nemirovsky, Yael, Aserin, Abraham, Garti, Nissim
• Format: Article
• Language: English
• Subjects: Agriculture; Biomaterials; Biotechnology; calorimeters; Chemistry; Chemistry and Materials Science; Crystals; decane; Diagrams; DSC; Food Science; gels; Genetically modified organisms; Glycerol; Industrial Chemistry/Chemical Engineering; Light microscopy; Liquid crystal polymers; liquid crystals; Monoolein; oils; Original Paper; Phase diagrams; Phase transitions; Pseudo‐ternary phase diagrams; Reverse hexagonal mesophases; Rheology; SAXS; viscoelasticity; viscosity; X-radiation; X-ray diffraction
• ISSN: 0003-021X; 1558-9331
• DOI: 10.1007/s11746-015-2594-7

In the course of our studies on structured reverse lyotropic liquid crystals (LLC) as oleogels, a system was designed with the desired physical and rheology properties for cosmetic and pharmaceutical applications. The aqueous phase was partially replaced by glycerol to minimize bacteriological problems and obtain specific rheology characteristics. The constructed phase diagrams are based on ternary mixtures of glycerol monooleate (GMO), decane, water, and glycerol. The main lyotropic mesophase obtained in this study was reverse hexagonal derived from dilution line 8:2 (72 wt% GMO and 18 wt% decane) and 10 wt% water; or water:glycerol (wt ratios 3:1 and 1:1) mixture. It was found that heat-cool fluctuation caused formation of new pseudo-equilibrium structures with mesomorphic transformations to more fluid and less ordered mesostructures. Replacing up to 50 wt% of the water by glycerol significantly increases the gel phase region in the phase diagram, meaning more structural compositional options. The structural parameters were determined using cross-polarized light microscopy (CPLM), differential scanning calorimeter (DSC), powder X-ray diffraction (PXRD), and small angle X-ray scattering (SAXS). Rheological measurements revealed viscoelastic properties of lyotropic liquid crystals with a decrease in the elasticity (G′), plasticity (G″), and complex viscosity (η*), as a function of increasing the glycerol content.