ABSTRACT
The sponge phase is claimed to exist not only in binary systems, but also in three- to five-component aqueous surfactant systems. It is essential to determine both the range of compositions within which phases exist, and also their coexistence relationships with other phases, in order to fully know just the most elementary aspects of the thermodynamic state of a system. One of the curious facts of surfactant phase science is that the actual boundaries of liquid crystal regions are comparatively difficult to determine. The phase is regarded as having a structure that is qualitatively similar to a bicontinuous cubic liquid crystal phase, but more highly disordered. A liquid boundary coexisting with a liquid crystal can easily be determined, but the liquid crystal itself cannot. Anomalous swelling has been found to date only among surfactants that are poorly soluble in liquid water, and only at temperatures where the saturated liquid phase coexists with a lamellar liquid crystal.
