SOME ASPECTS ON THE CUBIC PHASES IN SURFACTANT AND SURFACTANT-LIKE LIPID SYSTEMS

Cubic liquid crystalline phases are abundant in systems of surfactants and surfactant-like lipids. Characteristic for them is that there is a three-dimensional crystalline long-range order while the order on atomic level is liquid-like. The cubic phases occur in quite different compositional regions and belong to quite different space groups, both primitive, body-centered and face-centered. Several space groups in the International System are considered, in the first place Nos. 218, 223, 224, 227, 229 and 230. The existence of cubic phases is not always recognised due to optical isotropy and stiffness. There are often difficulties in obtaining the cubic phases in pure state. Membrane lipids participate actively in the functions of living cells and it is probable that the formation of cubic phases here have a role.