Elasticity of Lyotropic Chromonic Liquid Crystals Probed by Director Reorientation in a Magnetic Field

摘要

Using a magnetic Frederiks transition technique, we measure the temperature and concentration dependences of splay K_1, twist K_2, and bend K_3 elastic constants for the lyotropic chromonic liquid crystal sunset yellow formed through noncovalent reversible aggregation of organic molecules in water. K_1 and K_3 are comparable to each other and are an order of magnitude higher than K_2. At higher concentrations and lower temperatures, K_1 and the ratios K_1/K_3 and K_1/K_2 increase, which is attributed to elongation of self-assembled lyotropic chromonic liquid crystal aggregates, a feature not found in conventional thermotropic and lyotropic liquid crystals formed by covalently bound units of a fixed length.