Tilt-polarization coupling in a homologous series of ferroelectric liquid crystals
作者:Jochen Schacht、Heike Baethge、Frank Giesselmann、Peter Zugenmaier
DOI:10.1039/a708126j
日期:——
The synthesis of the homologous series 4-[(S)-2-chloro-4-methylpentanoyloxy]-4′-[4-alkylbenzoyloxy]biphenyl and their chiral and mesomorphic properties are reported. The enantiomeric excess is deduced from 1H NMR spectroscopy. For the hexyl derivative, a twist grain boundary state (TGBA*) mediates the cholesteric to SmC* phase transition and its stability is discussed in terms of chirality and surface interactions. In the SmC* phase, measurements of the spontaneous polarization are reported and the temperature dependence of the tilt angle is determined from the electro-optical switching process or deduced from X-ray measurements of the smectic layer thickness, respectively. The tilt-polarization coupling is discussed within the framework of the ‘generalized Landau model’ proposed by Žekš and Blinc.
报告了同族系列 4-[(S)-2-氯-4-甲基戊酰氧基]-4′-[4-烷基苯甲酰氧基]联苯的合成及其手性和介形性质。对映体过量是通过 1H NMR 光谱推断出来的。对于己基衍生物,扭转晶界态(TGBA*)介导了胆甾相到 SmC* 相的转变,并从手性和表面相互作用的角度讨论了其稳定性。在 SmC* 相中,报告了自发极化的测量结果,并分别从电光切换过程中确定了倾斜角的温度依赖性,或从 X 射线测量的 Smectic 层厚度中推导出了倾斜角的温度依赖性。在Žekš和Blinc提出的 "广义朗道模型 "框架内讨论了倾斜-极化耦合。