抄録
We studied thermal behavior of thermotropic liquid crystal materials by a high-sensitivity differential scanning calorimetry. We report the results of precise heat capacity measurements on two types of materials: antiferroelectric liquid crystal and bent-core liquid crystal. In the former case, phase transitions in chiral smectic-C subphases were investigated. It was found that the transitions observed are intrinsically first order with a thermal hysteresis and little thermal fluctuation. The effect of the thermal fluctuation from the smectic-A – smectic-C*α transition on the smectic-C*α – smectic-C* transition was examined. For bent-core liquid crystal, our study focused on the thermal property of the B4 phase exhibiting a novel helical nanofilament structure. A distinctive thermal behavior characterizing the B4 structure was obtained upon cooling. Moreover we investigated a mixture system of bent-core and rodlike molecules involving a nanophase-separated structure due to the asymmetric viscoelastic properties of two components. We show that the technique plays a very powerful role for the study of liquid crystalline systems.