含氟三苯乙炔异硫氰酸酯液晶合成及其微波性能  

Synthesis and Microwave Properties of Fluorinated Triphenylacetylene Isothiocyano Liquid Crystals

作　　者：李世伟 胡旭 罗晨潇 刘之禾 张智勇 汪相如 LI Shi-Wei;HU Xu;LUO Chen-Xiao;LIU Zhi-He;ZHANG Zhi-Yong;WANG Xiang-Ru(Department of Chemistry and Envionmental Engineering,Wuhan Polytechnic University,Wuhan 430023,China;School of Electronic Science and Engineering,University of Electronic Science and Technology,Chengdu 611730,China)

机构地区：[1]武汉轻工大学化学与环境工程学院,武汉430023 [2]电子科技大学光电科学与工程学院,成都611730

出　　处：《应用化学》2023年第12期1682-1692,共11页Chinese Journal of Applied Chemistry

基　　金：中央军委装备发展部重大预研项目基金(No.61409230701);广东省重点领域研发计划(No.2019B010158001)资助。

摘　　要：近年来,随着液晶微波移相器技术的研究发展,如何降低液晶材料高频介电损耗已成为微波通讯器件发展的关键问题。本文设计合成了7种具有较宽向列相温度范围(89.5~127.7℃)的含氟三苯乙炔异硫氰酸酯液晶化合物(Ⅰ1-Ⅰ7),其中Ⅰ1-Ⅰ3具有相对较低的熔点(45.8~67.2℃);将其与溶剂液晶侧乙基三苯二炔类组合物(M)按一定质量比混合后,采用矩形谐振腔微扰法测试其在微波频段(11~33 GHz)时的介电性能,并通过分子模拟计算探讨了分子结构和取代基对液晶在高频下介电性能的影响。结果表明,对于所合成的液晶化合物,其分子偶极矩和极化率越大,其介电常数和高频介电损耗也越大;在分子末端烷基引入支链不仅可以降低熔点,还会减小分子的偶极矩和介电常数,使其损耗降低;在苯环之间插入乙炔键不仅能够增加分子的π-电子共轭体系、介电常数和双折射率,还能降低其介电损耗;与异硫氰基相连的苯环侧位被二氟原子对称取代(X1和X2)化合物的介电各向异性(Δεr>1.025)大于中心苯环侧位二氟原子对称取代化合物(X_(3)和X_(4)),但后者的介电损耗较低。In recent years,with the research and development of liquid crystal microwave phase shifter technology,how to reduce the high frequency dielectric loss of liquid crystal materials has become a key issue in the development of microwave communication devices.In this paper,seven liquid crystal compounds(Ⅰ1−Ⅰ7)containing triphenylacetylene isothiocyanate with a wide nematic temperature range(89.5~127.7℃)were designed and synthesized,andⅠ1−Ⅰ3 had a relatively low melting point(45.8~67.2℃).These compounds are mixed with a solvent liquid crystal M composed of a variety of side ethyl triphenyldiacetylene liquid crystals in certain proportions,and their dielectric properties in the microwave frequency band(11~33 GHz)are tested by the rectangular resonant cavity perturbation method.The effects of the molecular structure and substituents on dielectric properties of liquid crystal at high frequency are investigated by molecular simulation.The experimental results show that the higher the dipole moment and polarizability,the higher the dielectric constant and higher frequency dielectric loss of the synthesized liquid crystal compounds;the introduction of branched chains in the terminal alkyl group not only reduces the melting point,but also decreases the dipole moment of the molecule,resulting in the decrease of the dielectric constant;the introduction of acetylene bond between benzene rings can increase theπ-electron conjugation system and dielectric constant of the molecule,which can reduce the dielectric loss at high frequency;The dielectric anisotropy(Δεr>1.025)of the isothiocyano-linked(—NCS)phenyl ring(X1 and X2)compounds is greater than that of the central phenyl ring(X_(3)and X_(4))compounds,but the dielectric loss of the latter is lower.

关 键 词：含氟三苯乙炔 异硫氰基液晶 高介电各向异性 低介电损耗 

分 类 号：O621.3[理学—有机化学]