侧向邻二氟取代联苯类液晶的相变研究

Mesomorphic Properties of Laterally O-difluoro-substituted Biphenyl Liquid Crystals

利用差示扫描量热仪(DSC)、显微热分析仪和偏光显微镜(POM)对系列侧向邻二氟取代联苯类液晶的介晶性进行了系统研究。结果表明,所有化合物均具高清亮点(119～171℃)及较宽的液晶相温度范围(53～108℃)。在液晶态可观察到部分单体的近晶A相(SA)和所有单体向列相的典型织构。讨论了末端基团对液晶性的影响,发现末端基团的增长会导致液晶的熔点、清亮点的下降及近晶相温度范围的增加。液晶相区间随端基的变化呈现出交替升降的规律性。

A perties homolog of lateral O-difluoro-substituted biphenyl liquid crystals and their mesomorphic prowere systematically investigated by using differential heat analysis and polarizing optical microscopy （POM）. Th pounds exhibit high cl cal textures of SA and properties were the temperature alkoxy. discus range eaning point （119-171℃） and broad scanning calorimetry （DSC）, microscopy e result shows that most of these comrange of mesophase （53-108℃）. Typinematic phase were observed. Influences of terminal grou sed and it is found that the melting point and cleaning point of mesophase varied regularly with the increase of carbon ps on mesomorphic were decreased and number of terminal alkoxy.