THEORY OF THE PHASE-DIAGRAMS OF LYOTROPIC NEMATIC AND LYOTROPIC CHOLESTERIC SYSTEMS

A theoretical model of the isotropic-to-nematic or isotropic-to-choles teric transitions is proposed, which applies to biaxial micellar aggre gates undergoing a change in their shape. The current isotropic-biaxia l-nematic theoretical model needs to be completed by considering an ad ditional noncritical order parameter that expresses the change in the form of the micelles and produces a topological metamorphosis of the s tandard effective two-component order-parameter diagrams. This transfo rmation results in a drastic restructuring of the phase diagrams, whic h involves a symmetric folding of the phases and singularities. A nonz ero trace is assumed for the second-rank-tenser nematic order paramete r.