Statistical Theory of Surface Tension and Molecular Orientations in Nematic Liquid Crystals. III. On Hard Flat Walls
Statistical Theory of Surface Tension and Molecular Orientations in Nematic Liquid Crystals. III. On Hard Flat Walls
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向列液晶表面张力和分子取向的统计理论。
DOI：
10.1143/jpsj.62.2725
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发表时间：
1993
影响因子：
1.7
通讯作者：
H. Kimura
中科院分区：
文献类型：
--
作者：
H. Kimura
假设分子是非极性刚性棒，并通过吸引色散力和硬核斥力相互作用，用平均场近似计算了硬平面壁上向列液晶的表面张力。发现色散力的各向同性部分倾向于在壁面上的正常分子取向，而由于壁面与分子之间以及分子之间的硬核斥力而产生的排除体积效应则促进了表面上的平面排列。随着温度的降低，壁面上可能发生的取向相变要么是不连续的平面向正常转变，要么是连续的平面向倾斜转变。因此，在氰联苯中观察到的前一种转变可以很好地解释。
The surface tension of nematic liquid crystals on a hard flat wall is calculated in the mean field approximation assuming that the molecules are non-polar rigid rods and interacting via attractive dispersion forces as well as hard-core repulsions. It is found that the isotropic part of the dispersion force prefers the normal molecular orientation at the wall surface, while the excluded volume effects due to the hard-core repulsions between the wall and molecules and among the molecules both promote the planar alignment on the surface. Possible orientational phase transitions on the wall are predicted to be either a discontinuous planar to normal transition or continuous planar to tilted transition as the temperature is lowered. Therefore, the former type of transition observed really in cyanobiphenyls can be well explained.