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Using a magnetic Frederiks transition technique, we measured the temperature and concentration dependences of splay K1, twist K2, and bend K3 elastic constants for the lyotropic chromonic liquid crystal (LCLC) Sunset Yellow, formed through non-covalent reversible aggregation of organic molecules in water. K1 and K3 are comparable to each other and are an order of magnitude higher than K2. At higher concentrations and lower temperatures, K1 and the ratios K1/K3, K1/K2 increase, which is attributed to elongation of self-assembled LCLC aggregates, a feature not found in conventional thermotropic and lyotropic liquid crystals formed by covalently bound units of a ?xed length. [ABSTRACT FROM AUTHOR]

We report on measurements of magnetic field induced nematic order in the bent-core liquid crystal 4-chlororesorcinol bis[4-(4-n dodecyloxybenzoyloxy) benzoate]. Using the 31 Tesla solenoid at the National High Magnetic Field Laboratory, we have observed, at temperatures less than one degree above the clearing point, a first-order transition to the nematic phase. The critical magnetic field at which this occurs increases with temperature. We discuss these results within the context of both Maier-Saupe and Landau-deGennes mean field models for the nematic-isotropic transition. The implications of possible tetrahedratic order are also discusse. To our knowledge, this is the first observation of such a magnetic field-induced transition in a thermotropic liquid crystal; the reasons for which this behavior is now attainable are discussed. [ABSTRACT FROM AUTHOR]