含氟二苯乙炔类蓝相液晶的研究进展

蓝相液晶具有高度流动的自聚集的三维立方缺陷结构,在高度手性的液晶中,它们存在于狭窄的温度区间。分子中引入适当的手性中心可以制得蓝相液晶。由于氟原子的特殊性,在液晶核分子中引入含氟二苯乙炔,可以得到黏度低、双折射率及清亮点高的液晶材料。文中介绍了6类含手性端基的含氟液晶化合物(其中有一个化合物不含氟原子)。通过偏光显微镜和DSC对其相变行为进行了研究。结果表明:共有13个化合物显示蓝相;化合物结构中手性中心的细微差别都会导致蓝相的出现或消失。

Progress of Fluorinated Biphenyl Acetylene Blue-phase Liquid Crystals

Liquid crystal "blue phases" are highly fluidic, self-assembled, and three dimensional cubic defect structures that exists over narrow temperature ranges in highly chiral liquid crystals. Application of an appropriate chiral center may produce blue phase liquid crystals. Due to the unique property of fluorine, liquid crystalline materials with low viscosity, high birefringence (Δn), and high clearing points can be obtained by introduction of Fluoro-tolane. In this paper series of chiral compounds (one exception) containing 2, 3, 5, 6-tetrafluorodiphenyl acetylenes were synthesized. Their liquid crystalline behaviour was investigated by optical polarizing microscopy and DSC. The results show that 13 compounds show blue phase. Moreover, the slight difference of the chiral center results in appearance/disappearance of blue phase.