论文标题
弯曲式列液晶体的近晶状流变学和伪层压缩弹性常数
Smectic-like rheology and pseudo-layer compression elastic constant of a twist-bend nematic liquid crystal
论文作者
论文摘要
在弯曲弯曲列（N \ TextSubscript {TB}）液晶（LCS）中，平均分子取向表现出具有纳米级周期性的旋转结构。在介质量表上，n \ textsubscript {tb}类似于分层系统（如emectics），其中螺旋螺距等同于没有真正的质量密度波的“伪层”。我们研究了N \ TextSubscript {TB}相的流变特性，并将结果与通常的SMA相的结果进行比较。分析剪切响应并适应简化的物理模型，以用于缺陷介导的层状系统的流变学，我们测量了N \ TextSubScript {tb}相位的伪层压缩弹性常数$ b_ {eff} $，从动态modulus $ g^{*}（*}（ω））中的测量值We find that $B_{eff}$ of the N\textsubscript{TB} phase is in the range of $10^{3}-10^{6}$ Pa and it follows a temperature dependence, $B_{eff}\sim (T_{TB}-T)^{2}$ as predicted by the recent coarse-grained elastic theory.我们的结果表明，尽管$ b_ {eff} $的温度依赖性比粗粒模型所预测的，但n \ textSubscript {tb}的结构性流变与通常的近晶型LC相似。
In twist-bend nematic (N\textsubscript{TB}) liquid crystals (LCs), the mean molecular orientation exhibits heliconical structure with nanoscale periodicity. On the mesoscopic scale, N\textsubscript{TB} resembles layered systems (like smectics), where the helical pitch is equivalent to "pseudo-layers" without a true mass density wave. We study rheological properties of a N\textsubscript{TB} phase and compare the results with those of an usual SmA phase. Analysing the shear response and adapting a simplified physical model for rheology of defect mediated lamellar systems we measure the pseudo-layer compression elastic constant $B_{eff}$ of N\textsubscript{TB} phase from the measurements of dynamic modulus $G^{*}(ω)$. We find that $B_{eff}$ of the N\textsubscript{TB} phase is in the range of $10^{3}-10^{6}$ Pa and it follows a temperature dependence, $B_{eff}\sim (T_{TB}-T)^{2}$ as predicted by the recent coarse-grained elastic theory. Our results show that the structural rheology of N\textsubscript{TB} is strikingly similar to that of the usual smectic LCs although the temperature dependence of $B_{eff}$ is much faster than smectic LCs as predicted by the coarse-grained models.
