Morphogenesis of liquid crystal topological defects during the nematic-smectic A phase transition.
Morphogenesis of liquid crystal topological defects during the nematic-smectic A phase transition.
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DOI：
10.1038/ncomms15453
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发表时间：
2017-05-30
影响因子：
16.6
通讯作者：
Yoon DK
中科院分区：
文献类型：
--
作者：
Gim MJ;Beller DA;Yoon DK
物质的液晶相各自具有不同类型的缺陷，这些缺陷引起了拓扑、自组装和材料微图案等领域的极大兴趣。然而，对于一个液晶相中的缺陷如何在跨越相变时由另一相中的缺陷或变形引起的知之甚少。在这里，我们利用实验、理论和数值分析，直接检查水基板上混合排列液晶滴从向列相到近晶 A 的原位热相变缺陷。混合排列的向列相液滴自发地产生 boojum 缺陷。在冷却过程中，复曲面焦锥域通过一系列涉及向列条纹和局部对齐的焦锥域的形态转变而产生。这个简单的实验揭示了一个令人惊讶的复杂途径，通过该途径，不同类型的缺陷可能在向列-近晶 A 相变中相互关联，并为液晶的受控变形和图案化提供了新的可能性。液晶缺陷在确定其结构和动态特性方面发挥着核心作用，但在分子水平上表征缺陷具有挑战性。在这里，吉姆等人。追踪从向列态到近晶态相变过程中缺陷的演化路径。
The liquid crystalline phases of matter each possess distinct types of defects that have drawn great interest in areas such as topology, self-assembly and material micropatterning. However, relatively little is known about how defects in one liquid crystalline phase arise from defects or deformations in another phase upon crossing a phase transition. Here, we directly examine defects in the in situ thermal phase transition from nematic to smectic A in hybrid-aligned liquid crystal droplets on water substrates, using experimental, theoretical and numerical analyses. The hybrid-aligned nematic droplet spontaneously generates boojum defects. During cooling, toric focal conic domains arise through a sequence of morphological transformations involving nematic stripes and locally aligned focal conic domains. This simple experiment reveals a surprisingly complex pathway by which very different types of defects may be related across the nematic–smectic A phase transition, and presents new possibilities for controlled deformation and patterning of liquid crystals. Defects in liquid crystals play a central role in determining their structural and dynamic properties, whilst it is challenging to characterize the defects at a molecule level. Here, Gim et al. trace the evolution pathway of defects during a phase transition from a nematic to a smectic state.