title: Thermally induced fluid reversed hexagonal (H(II)) mesophase.
abstract: In the present study we characterized the microstructures of the Lc and HII phases in a glycerol monooleate (GMO)/tricaprylin (TAG)/water mixture as a function of temperature. We studied the factors that govern the formation of a low-viscosity HII phase at relatively elevated temperatures (>35 degrees C). This phase has very valuable physical characteristics and properties. The techniques used were differential scanning calorimetry (DSC), wide- and small-angle X-ray scattering (WAXS and SAXS, respectively), NMR (self-diffusion and (2)H NMR), and Fourier transform infrared (FTIR) spectroscopies. The reverse hexagonal phase exhibited relatively rapid flow of water in the inner channels within the densely packed cylindrical aggregates of GMO with TAG molecules located in the interstices. The existence of two water diffusion peaks reflects the existence of both mobile water and hydration water at the GMO-water interface (hydrogen exchange between the GMO hydroxyls and water molecules). Above 35 degrees C, the sample became fluid yet hexagonal symmetry was maintained. The fluidity of the HII phase is explained by a significant reduction in the domain size and also perhaps cylinder length. This phenomenon was characterized by higher mobility of the GMO, lower mobility of the water, and a significant dehydration process.
authors.affiliation: Casali Institute of Applied Chemistry, The Institute of Chemistry, and Wolfson Centre for Applied Structural Biology, The Hebrew University of Jerusalem, Jerusalem 91904, Israel.
authors.forename: Idit
authors.initials: I
authors.lastname: Amar-Yuli
authors.forename: Ellen
authors.initials: E
authors.lastname: Wachtel
authors.forename: Deborah E
authors.initials: DE
authors.lastname: Shalev
authors.forename: Hagai
authors.initials: H
authors.lastname: Moshe
authors.forename: Abraham
authors.initials: A
authors.lastname: Aserin
authors.forename: Nissim
authors.initials: N
authors.lastname: Garti
mesh_terms: D002152:Calorimetry, Differential Scanning; D005990:Glycerol / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D012542:Scattering, Radiation; D013696:Temperature
chemical_list: D005990:Glycerol