四环二氟甲醚桥键液晶化合物性能研究

Properties of four ring chain liquid crystalline compounds with difluoromethyleneoxy linkage group

二氟甲醚桥键类液晶是目前广泛使用的一类液晶化合物,但是其相关相变行为和物理参数很少有系统地报道。本文采用DSC、POM测试,对系列1和2共计7种含环己烷的四环骨架二氟甲醚桥键液晶单体的介晶性进行了研究,并考察了不同单体对混合液晶性能的影响规律,采用加法原理对各系列单体的物理性能参数进行了外推。结果表明,与系列2化合物相比,系列1单体具有更高的清亮点和更宽的向列相温度范围。系列2单体由于氟原子数的增加,介电各向异性值增大。系列1单体可显著改善混合液晶的低温相溶性,有利于拓宽混合液晶的使用温度。

Liquid crystalline compounds with difluoromethyleneoxy linkage group are widely used in liquid crystal mixtures.However,their phase behavior and physical properties have not been reported systematically.The mesomorphic properties of two series of compounds 1 and 2 with cyclohexyl group were thoroughly studied by using differential scanning calorimetry（DSC） and polarizing optical microscopy（POM）.The effect of all the compounds on the mixtures were systematically investigated and their physical parameters were extropolated by using addition principle.The results show that compounds 1 have higher clearing point and wider nematic phase temperature range than that of compounds 2.Due to the increase of a fluorine atom on the skeleton,compounds 2 have higher dielectric anisotropy than that of compounds 1.Compounds 1 can significantly improve low temperature miscibility and broaden the mixed liquid crystal temperature range.