Crystallization from orientationally ordered supercooled liquids

While crystallization of isotropic supercooled liquids has been studied extensively and is well described by the Burke, Broughton, and Gilmer (BBG) theory, crystallization from supercooled liquid crystals has remained largely unexplored. We experimentally study crystallization from the columnar hexagonal (Col_H) phase of a discotic mesogen, HAT6, and observe a martensitic-like crystallization mechanism, where there is a high degree of orientational correlations between the parent fluid and daughter crystal phases. Further, the crystal growth rate from the aligned columnar hexagonal phase deviates from BBG predictions by seven orders of magnitude. Further, we report preliminary results on crystallization from smectic and nematic liquid crystals. While crystallization of the Col_H phase involves loss of only one translational degree of freedom, crystallization of smectics and nematics involves loss of two and three translational degrees of freedom, respectively.  In nematics and smectics, crystallization phenomenon is vastly different. Based on these results, we speculate on the connection between the number of translational degrees of freedom lost during solidification and crystallization mechanism.