EC2M, UMR 7083 Gulliver, CNRS, ESPCI Paris, PSL Research University, 10 rue Vauquelin, 75005 Paris, France.
Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana, Slovenia.
Soft Matter. 2016 Nov 23;12(46):9280-9288. doi: 10.1039/c6sm01748g.
We investigate experimentally and numerically the defect configurations emerging when a cholesteric liquid crystal is confined to a spherical shell. We uncover a rich scenario of defect configurations, some of them non-existent in nematic shells, where new types of defects are stabilized by the helical ordering of the liquid crystal. In contrast to nematic shells, here defects are not simple singular points or lines, but have a large structured core. Specifically, we observe five different types of cholesteric shells. We study the statistical distribution of the different types of shells as a function of the two relevant geometrical dimensionless parameters of the system. By playing with these parameters, we are able to induce transitions between different types of shells. These transitions involve interesting topological transformations in which the defects recombine to form new structures. Surprisingly, the defects do not approach each other by taking the shorter distance route (geodesic), but by following intricate paths.
我们通过实验和数值研究了胆甾相液晶被限制在球形壳内时出现的缺陷结构。我们揭示了丰富的缺陷结构场景，其中一些在向列相壳中不存在，在这里，新类型的缺陷通过液晶的螺旋有序稳定下来。与向列相壳不同，这里的缺陷不是简单的奇点或线，而是具有较大的结构化核心。具体来说，我们观察到五种不同类型的胆甾相壳。我们研究了不同类型壳的统计分布作为系统两个相关的无量纲几何参数的函数。通过操纵这些参数，我们能够在不同类型的壳之间诱导转变。这些转变涉及到有趣的拓扑变换，其中缺陷通过形成新结构而重新组合。令人惊讶的是，缺陷并没有通过走最短路径（测地线）而是通过复杂的路径相互靠近。
