Research On The Phase Diagram, Viscosity And Conductivity For Two Pseudo–Ternary Systems

Microemulsion is composed of oil, surfactant, cosurfactant and water. By using themicroemulsion of water-in-oil, or oil-in-water, drugs were encapsulated in thenano-droplets, their solubility and bioavailability were improved significantly. All thesemerits of microemulsion make it shown significant enhancement effect on transdermaldelivery over conventional formulation, and was widely used in pharmaceutical drugdelivery techniques. The phase diagram and physical and chemical property are importantto the structural and application research. In this research, two microemulsion systems arestudied：A microemulsion system composed of benzene as oil, sodium cholate (SC) assurfactant, propanol as cosurfactant, and water as the hydrophilic phase has been prepared.The ternary phase diagram of {Benzene (1)+Propanol (2)+Water (3)} and thepseudo-ternary phase diagram of {Benzene (1)+[SC (21)/Propanol (22)](2)+Water (3)}at303K have been constructed by a titration and visual method. The addition of sodiumcholate has a big impact on the phase equilibrium. The phase diagram of ternary systemcan be simply divided into the liquid-liquid phase region and the homogeneous region.After adding sodium cholate, the phase diagram is composed of solid-liquid phase region,the liquid-liquid phase region, the liquid crystal phase region and the homogeneous region.The influence of the water content on viscosity and conductivity for the pseudo-ternarysystem in the microemulsion region at303K and313K has been studied. The result ofconductivity shows that: the phenomenon of conductivity percolation didn’t occur forsodium cholate contented system. With the increasing in water content, the conductance isincreased, and the viscosity is reduced. The conductivity activation energy of the systemhas been estimated according to the Arrhenius formulation. The low activation energy maybe the reason that no percolation threshold.Another microemulsion system composed of isopropyl myristate (IPM) as oil, polyoxyethylene sorbitan monooleate (Tween-80) as surfactant, propanol as cosurfactant,and water as the hydrophilic phase has been prepared. The pseudo-ternary phase diagramof system of {IPM (1)+[Tween-80(21)/Propanol (22)](2)+Water(3)} at303.15K and ata constant surfactant/cosurfactant mass ratio of0.5has been constructed. The phasediagram has been constructed by a titration and visual method. The phase diagram iscomposed of homogeneous microemulsion region and the liquid-liquid two phases region.The influence of the water content on density at303.15K and313.15K has been studied.For the system of [IPM(1)+(Tween-80+propanol)(2)], density decreases with theincrease in w1. For systems of [(tween80+propanol)(2)+water(3)] and pseudo-ternarymixtures, density increases with the increase in w3, and decreases with the addition of IPM.The influence of the water content on the viscosity and conductivity for the pseudo-ternarysystem at303.15K and313.15K has been studied. The conductivity result shows that itgrows up slowly at first, after the water content reaches a certain threshold, it will increaserapidly. This phenomenon can be explained by the conductivity percolation theory. Thevariation of viscosity shows that, a maximum viscosity is observed along the water dilutionline, which indicates a structural transition from water-in-oil, to a bicontinuous state, andinverse to the state of oil-in-water. With the increase in the content of IPM, thisphenomenon becomes more noticeable.