Phase Behavior of diglycerol monomyristate in different nonpolar organic solvent systems

We have investigated the phase behavior of diglycerol monomyristate (DGM) in a variety of organic solvents over a wide range of temperatures and compositions. At lower temperature, there exists a surfactant solid, which solubilize different amounts of oils depending on the oil nature. The melting temperature of the solid phase is virtually constant in a wide range of composition. In all the systems, a lamellar liquid crystal (L alpha) is formed in surfactant-rich regions at intermediate temperatures between the solid-melt and isotropic two- or single-phase regions. In the dilute regions reverse vesicles are formed in the L alpha+O regions mainly in the case of linear hydrocarbon type oils. In the aromatic and cyclic aliphatic oils, there are isotropic solutions at 25 degrees C. However, there is dispersion of alpha-solid in the case of liner hydrocarbon oils. Two liquid-phase regions above the L alpha phase are observed in the case of tetradecane and hexadecane. In the shorter chain oil systems, such as octane and decane, no two liquid-phase appear above L alpha region. That is the two liquid-phase region is largely dependent on the chain length of the oils, and becomes wider in longer hydrocarbon oil.