Rheology of nematic liquid crystals with highly polar molecules.
Rheology of nematic liquid crystals with highly polar molecules.
复制标题
具有高极性分子的向列液晶的流变学。
DOI：
--
复制
发表时间：
2014
期刊：
影响因子：
--
通讯作者：
S. Dhara
中科院分区：
文献类型：
--
作者：
J. Ananthaiah;R. Sahoo;M. Rasna;S. Dhara
本文报道了几种高极性分子液晶（CCH-7，PCH-7，CB-7）的流变学实验研究。所选分子具有相同的烷基链（-C（7）H（15））和氰基（-CN）端基。在分子的核心部分，CCH-7有两个环己烷环，PCH-7有一个环己烷和一个芳环，CB-7有两个芳环。测量作为温度的函数的两种粘度，即η（2）（平行于剪切方向的指向矢）和η（1）（垂直于剪切方向的指向矢）。使用小角光散射技术研究了指向矢的取向。η（2）是在预剪切样品中测量的，而η（1）是用电流变技术测量的。结果表明，液晶的粘度与芳环数和柯克伍德相关因子有关。温度依赖性粘度可以基于高极性分子的分子内π-电子共轭和分子间缔合来理解。
We report experimental studies on the rheology of a few nematic liquid crystals with highly polar molecules (CCH-7, PCH-7, CB-7). The selected molecules have the same alkyl chain (-C(7)H(15)) and cyano (-CN) end group. In the core part of the molecule, CCH-7 has two cyclohexane rings, PCH-7 has one cyclohexane and one aromatic ring, and CB-7 has two aromatic rings. Two viscosities were measured as a function of temperature, namely, η(2) (director parallel to the shear direction) and η(1) (director perpendicular to the shear direction). The orientation of the director was studied using small angle light scattering techniques. η(2) was measured in presheared sample, whereas the electrorheological technique was used to measure η(1). We show that both viscosities of the liquid crystals depend on the number of aromatic rings and Kirkwood correlation factor. The temperature dependent viscosities can be understood based on the intramolecular π-electron conjugation and intermolecular association of highly polar molecules.