Suh Ahram, Gim Min-Jun, Beller Daniel, Yoon Dong Ki
Graduate School of Nanoscience and Technology, KAIST, Daejeon, 34141, Republic of Korea.
Soft Matter. 2019 Jul 24;15(29):5835-5841. doi: 10.1039/c9sm00781d.
We study transformations of self-organised defect arrays at the nematic-smectic A liquid crystal phase transition, and show that these defect configurations are correlated, or "remembered", across the phase transition. A thin film of thermotropic liquid crystal is subjected to hybrid anchoring by an air interface and a water substrate, and viewed under polarised optical microscopy. Upon heating from smectic-A to nematic, a packing of focal conic domains melts into a dense array of boojums-nematic surface defects-which then coarsens by pair-annihilation. With the aid of Landau-de Gennes numerical modeling, we elucidate the topological and geometrical rules underlying this transformation. In the transition from nematic to smectic-A, we show that focal conic domain packings are organised over large scales in patterns that retain a geometric memory of the nematic boojum configuration, which can be recovered with remarkable fidelity.
我们研究了向列相-近晶A液晶相变时自组织缺陷阵列的转变，并表明这些缺陷构型在相变过程中是相关的，或者说是“被记住的”。向列型热致液晶薄膜通过空气界面和水基底进行混合锚定，并在偏振光学显微镜下观察。从近晶A加热到向列相时，焦锥畴的堆积熔化成密集的布居姆-向列型表面缺陷阵列，然后通过成对湮灭而粗化。借助朗道-德热纳数值模型，我们阐明了这种转变背后的拓扑和几何规则。在从向列相到近晶A的转变中，我们表明焦锥畴堆积在大尺度上以保留向列型布居姆构型几何记忆的模式组织起来，并且可以以极高的保真度恢复。
