Liquid crystalline phases in ternary surfactant systems

3 Liquid crystalline phases in ternary surfactant systems 

Ternary systems are encountered in pharmacy mainly as emulsifier-oil-water systems in emulsions or as surfactant-solubilizate-water systems in the formulation of solubilized systems. Phase equilibria within ternary systems are most conveniently represented by a triangular phase diagram which delineates the phase regions enabling the formulator to select suitable combinations of the three components to produce stable emulsions or clear isotropic solubilized systems. 

Simple phase diagrams are produced for ternary systems in which two of the three components are completely miscible. The essential characteristics of such diagrams are shown in Fig. 2.7 in which liquids A and B and A and C are completely miscible whilst B and C are only partially miscible. The region, 2L, under the curve Imnop is an area of immiscibility. Systems with compositions within this region separate into two liquid phases at equilibrium. From experimental determinations it is possible to draw tie lines connecting those systems within the 2L region which separate at equilibrium into two phases with compositions given by the points of intersection of the tie lines and the curve Imnop. In Fig. 2.7 all systems on the tie line, mo, will separate at equilibrium into 

Region with homogeneous, isotropic aqueous solutions. 

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