Intermediate phases of surfactant-water mixtures

Intermediate phases have been identified in some concentrated surfactant-water mixtures between hexagonal and lamellar phases, where usually bicontinuous cubic phases would be expected. It has been shown that they are anisotropic in structure, birefringent and more fluid than bicontinuous cubic phases. There is still discussion in the literature as to which structures are possible. The observed or proposed structures divide topologically into three types, according to symmetry: rectangular or ribbon structures, layered mesh structures and bicontinuous structures. In the past year, structures of mesh phases have been presented together with their epitaxial relationships with adjacent phases.