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在胆甾型液晶蓝相的缺陷结构强约束效应
Effect of strong confinement on defect structures of cholesteric blue phases |
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| 课程网址: |
http://videolectures.net/clc2010_fukuda_escdscbp/
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| 主讲教师: |
Jun-ichi Fukuda
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| 开课单位: |
国家先进工业科学技术研究所
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| 开课时间: |
2010-08-05
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| 课程语种: |
英语
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| 中文简介: |
在高手性液晶中发现的胆固醇蓝相 (bp) [1] 是软材料中三维有序结构的有趣例子。它们出现的原因是, 在局部偏好双扭曲配置而不是单一扭曲配置与全局拓扑约束 (双扭曲配置无法填满整个空间) 之间出现挫折。虽然具有立方对称性的块状 bp 结构已经建立了很好的基础, 但目前还不了解围面的锚固是如何影响 bp 结构的顺序的。在这里, 我们讨论了在一个强封闭的手性液晶的拓扑缺陷的结构 [2]。我们的研究是基于使用兰道 – 的基因理论的数值计算, 在这个理论中, 定向顺序是用二阶张量来描述的。平面单元中的缺陷结构在表面施加正向锚定的结构与块状 bp 的缺陷结构不相似, 当电池厚度为散装 bp 单位细胞的维数顺序时, 确实可以在热力学上保持稳定。这些新的缺陷结构可以被看作是一个规则的一系列偏好的局部首选结构和约束表面的锚定所施加的约束之间的不同挫折的结果。我们的研究结果表明, 在液晶中, 由于更复杂的挫折, 仍有未知有序结构的可能性。我们感谢斯洛文尼亚研究机构 (arrs 研究计划 J1-2335 和项目 j1-2335) 和 kakenhi (科学研究补助金) 从教育、文化部获得的财政支持,日本的体育、科学和技术。
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| 课程简介: |
Cholesteric blue phases (BPs) [1] found in highly chiral liquid crystals are interesting examples of three-dimensional ordered structures in soft materials. They appear as a result of frustrations between local preference of a double-twist configuration over a single twist, and a global topological constraint that a double-twist configuration cannot fill the whole space. Though the structures of bulk BPs with cubic symmetry are now well established, it is not yet understood how the anchoring of confining surfaces affects the order of structures of BPs. Here we discuss the structures of topological defects in a strongly confined chiral liquid crystal [2]. Our study is based on numerical calculations using a Landau–de Gennes theory, in which the orientational order is described by a second-rank tensor. Defect structures in a planar cell imposing homeotropic anchoring at the surfaces do not resemble those of bulk BPs and can indeed be thermodynamically stable when the cell thickness is of the order of the dimension of the unit cell of bulk BPs. These novel defect structures can be regarded as a consequence of a different frustration between the local preferred structure of a regular array of disclinations, and the constraint imposed by the anchoring of confining surfaces. Our results indicate that there are still possibilities for unknown ordered structures in liquid crystals arising from more complex frustrations. We acknowledge financial support by Slovenian Research Agency (ARRS research program P1- 0099 and project J1-2335) and KAKENHI (Grant-in-Aid for Scientific Research) on Priority Area “Soft Matter Physics” from the Ministry of Education, Culture, Sports, Science and Technology of Japan.
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| 关 键 词: |
胆甾蓝相; 缺陷结构; 强约束效应; 未知有序结构; 软物质物理
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| 课程来源: |
视频讲座网
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| 最后编审: |
2020-06-29：wuyq
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| 阅读次数: |
83
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