Electro-optic and molecular relaxation behaviour of fluoro substituted achiral unsymmetrical four-ring bent-core mesogen
Electro-optic and molecular relaxation behaviour of fluoro substituted achiral unsymmetrical four-ring bent-core mesogen
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DOI：
10.1080/02678292.2013.871078
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发表时间：
2014-03
期刊：
影响因子：
2.2
通讯作者：
M. K. Paul;R. Kumar;N. Chakraborty;K. Raina;N. V. Rao
中科院分区：
文献类型：
--
作者：
M. K. Paul;R. Kumar;N. Chakraborty;K. Raina;N. V. Rao
本文研究了一种新的非手性非对称四环弯芯介质物的电光和分子弛豫特性。该化合物由侧向氟取代的3，4‘-二取代联苯单元组成，其中两个苯环之间的酯键为中心单元。用偏光显微镜和差示扫描量热仪对其介晶性能进行了表征。该化合物具有对映异构体B7-Bx相序。电光研究表明，在电场作用下，B7相发生了从平面到同向异性的双稳态转变。在去除B7相中的电场后，观察到平面织构和同向织构之间的进一步记忆效应。随温度变化的介电常数随频率变化的研究表明，B7相的分子弛豫随温度升高而增大，而Bx相的分子弛豫随温度升高而增大。
Electro-optic and molecular relaxation studies in a new achiral unsymmetrical four-ring bent-core mesogen are presented in this study. The compound consists of a laterally fluoro-substituted 3,4′-disubstituted biphenyl unit with an ester linkage between the two phenyl rings as the central unit. The mesomorphic properties were characterised by polarising optical microscopy and differential scanning calorimetry. The compound exhibited enantiotropic B7–Bx phase sequence. The electro-optic studies revealed a bistable switching from planar to a homeotropic state under an electric field in B7 phase. Further memory effect was observed between planar and homeotropic textures after the removal of electric field in B7 phase. Temperature dependent permittivity studies as a function of frequency revealed that the molecular relaxation increases with the increasing temperature in B7 phase than in Bx phase.