Liquid Crystalline Phases in Simple Binary Systems

Liquid Crystalline Phases in Simple Binary Systems 

In some surfactant systems, more complex phase behavior involving one or more viscous isotropic structures will appear. Such phases usually exhibit an X-ray pattern characteristics of a cubic lattice. Such phases are now recognized as the primarily cubic bicontinuous phases introduced above. More recent research with bulky surfactant molecules has led to the suggestion of wormlike or ribbon micelles that may be best described—conceptually, at least—as super aggrega-tions of smaller miceUar units or twisted hexagonal systems. 

The conditions of temperature and concentration that produce the various solution phases in surfactant-solvent systems can be determined (with a great deal of laboratory work) by the construction of phase diagrams. The construction-interpretation of such diagrams is a complex undertaking that is beyond the scope of this work. However, sufficient literature exists to permit certain generalizations that will help in understanding the activity of most reasonably simple surfactant systems. 

Most of the published work on the phase behavior of anionic surfactants has dealt with the simple carboxylic acid soaps, with less information available on the sulfates, sulfonates, and similar compounds. It is generally found, however, that certain trends hold over a wide range of products so that one can predict events with some degree of confidence. 

Much less work has been reported on the phase behavior of cationic surfactants. In general, the phase diagrams for simple quaternary ammonium halides closely resemble those of anionic surfactants. In some cases, it has been found that the phase behavior of such materials is much more sensitive to counterion effects than is that of anionic species. 

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