Director Distortion and Phase Modulation in Deformable Nematic and Smectic Liquid Crystal Spheroids
Director Distortion and Phase Modulation in Deformable Nematic and Smectic Liquid Crystal Spheroids
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可变形向列和近晶液晶球体中的指向畸变和相位调制
DOI：
10.1021/acs.langmuir.2c02461
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发表时间：
2022
期刊：
影响因子：
3.9
通讯作者：
Sadati, Monirosadat
中科院分区：
文献类型：
--
作者：
Norouzi, Sepideh;Zhang, Rui;Munguia-Fernández, Juan G.;de Pablo, Luis;Zhou, Ye;Taheri-Qazvini, Nader;Shapiro, Harrison;Morin, Samuel;Martinez-Gonzalez, Jose A.;Sadati, Monirosadat
人们对将液晶(LCS)集成到柔性和微型化技术中的兴趣与日俱增，这就需要了解空间曲面几何图形、表面锚定和与这些材料相关的顺序之间的相互作用。在这里，我们结合实验方法和计算模拟来探索单轴和双轴拉伸的向列相和近晶微滴中表面诱导取向和可变形曲线边界的影响之间的竞争。我们发现，单轴应变作用下向列相液晶的指向矢场重新定向并形成一个更大的扭曲缺陷环，以适应拉伸液滴的新的形变几何。在双向拉伸时，指向矢场最初在现在扁平的几何形状中扭曲，随后在高应变下转变为均匀的垂直方向。另一方面，在近晶微滴中，在界面力和膨胀力的折衷下，液晶取向从径向近晶层状转变为准平坦层状。去除机械应变后，近晶LC恢复其初始的径向构型；然而，扁平的几何形状使向列相LC处于亚稳态垂直状态。这些发现为基于LC的柔性设备的合理设计提供了基础，包括可穿戴传感器、柔性显示器和智能窗户。
The growing interest in integrating liquid crystals (LCs) into flexible and miniaturized technologies brings about the need to understand the interplay between spatially curved geometry, surface anchoring, and the order associated with these materials. Here, we integrate experimental methods and computational simulations to explore the competition between surface-induced orientation and the effects of deformable curved boundaries in uniaxially and biaxially stretched nematic and smectic microdroplets. We find that the director field of the nematic LCs upon uniaxial strain reorients and forms a larger twisted defect ring to adjust to the new deformed geometry of the stretched droplet. Upon biaxial extension, the director field initially twists in the now oblate geometry and subsequently transitions into a uniform vertical orientation at high strains. In smectic microdroplets, on the other hand, LC alignment transforms from a radial smectic layering to a quasi-flat layering in a compromise between interfacial and dilatation forces. Upon removing the mechanical strain, the smectic LC recovers its initial radial configuration; however, the oblate geometry traps the nematic LC in the metastable vertical state. These findings offer a basis for the rational design of LC-based flexible devices, including wearable sensors, flexible displays, and smart windows.