Defect topologies in a nematic liquid crystal near a patchy colloid
Defect topologies in a nematic liquid crystal near a patchy colloid
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DOI：
10.1063/1.4717619
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发表时间：
2012-05-21
影响因子：
4.4
通讯作者：
Schoen, Martin
中科院分区：
文献类型：
--
作者：
Melle, Michael;Schlotthauer, Sergej;Schoen, Martin
使用等温等压蒙特卡罗模拟，我们调查缺陷的拓扑结构，由于一个球形的胶体粒子浸没在一个液晶的液晶。缺陷的产生是由于胶体表面的择优取向和帽层（0）上的远场指向矢（n）之间的竞争。考虑一个化学均匀的胶体作为一个特殊的情况下，我们观察到众所周知的表面和土星环缺陷拓扑结构的弱和强垂直锚定，分别为均匀，强平行锚定，我们发现一个boojum缺陷拓扑结构，已被实验[见P. Poulin和D. A. Weitz，Phys.Rev.E57，626（1998）]，但不是在计算机模拟中。我们还考虑了一个异质的，片状的胶体液晶分子的锚优先平面或垂直在胶体的表面。对于一个片状的胶体，我们观察到一个布儒环缺陷拓扑结构，与最近的实验研究一致[见M。Conradi，M.拉夫尼克湾Bele，M. Zorko，S.祖默和我Musevic，Soft Matter 5，3905（2009）]。我们还观察到其他两个新的缺陷拓扑结构，迄今尚未报告，无论是实验上还是理论上。(C)2012年美国物理学会。[http：//dx.doi.org/10.1063/1.4717619]
Using isothermal-isobaric Monte Carlo simulations we investigate defect topologies due to a spherical colloidal particle immersed in a nematic liquid crystal. Defects arise because of the competition between the preferential orientation at the colloid's surface and the far-field director (n) over cap (0). Considering a chemically homogeneous colloid as a special case we observe the well-known surface and saturn ring defect topologies for weak and strong perpendicular anchoring, respectively; for homogeneous, strong parallel anchoring we find a boojum defect topology that has been seen experimentally [see P. Poulin and D. A. Weitz, Phys. Rev. E 57, 626 (1998)] but not in computer simulations. We also consider a heterogeneous, patchy colloid where the liquid-crystal molecules anchor either preferentially planar or perpendicular at the surface of the colloid. For a patchy colloid we observe a boojum ring defect topology in agreement with recent experimental studies [see M. Conradi, M. Ravnik, M. Bele, M. Zorko, S. Zumer, and I. Musevic, Soft Matter 5, 3905 (2009)]. We also observe two other novel defect topologies that have not been reported thus far neither experimentally nor theoretically. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4717619]