Unusual sequences of tilted smectic phases in liquid crystals of bent-shape molecules.
The first theoretical description of the experimentally often-observed isotropic-polar smectic phase transitions of symmetric and asymmetric bent-shape molecules is presented. The isotropic-tilted polar smectic phase transition requires a coupling among three types of ordering processes: polar packing, director tilt, and layer ordering. For explaining the unusual triclinic-monoclinic phase transition with the lower symmetry phase at higher temperature, observed in fluoro-containing compounds recently, a mechanism is proposed in which the layer ordering triggers the simultaneous onset of the tilt and polar order.
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Liquid Crystal Institute, Kent State University, Kent, OH 44242, USA.
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