Size effect and electric field dynamics of spherical droplets in concentric configurations

He MA; Si-bo CHEN; Jin-bing WU; Xuan ZHOU; Zhi-dong ZHANG

doi:10.3788/YJYXS20203504.0293

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Size effect and electric field dynamics of spherical droplets in concentric configurations

Materials and Devices | 更新时间：2020-07-05

- Size effect and electric field dynamics of spherical droplets in concentric configurations
- Chinese Journal of Liquid Crystals and Displays Vol. 35, Issue 4, Pages: 293-305(2020)
- 作者机构：
  
  1.河北工业大学应用物理系, 天津 300401
  2.河北工业大学电子信息工程学院, 天津 300401
  3.天津市材料器件重点实验室, 天津 300401
- 作者简介：
- 基金信息：
- DOI：10.3788/YJYXS20203504.0293
  CLC： O753.2
- Received：30 September 2019，
  
  Revised：18 November 2019，
  
  Accepted：18 November 2019，
  
  Published：05 April 2020
- 稿件说明：
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He MA, Si-bo CHEN, Jin-bing WU, et al. Size effect and electric field dynamics of spherical droplets in concentric configurations[J]. Chinese journal of liquid crystals and displays, 2020, 35(4): 293-305.
DOI：

He MA, Si-bo CHEN, Jin-bing WU, et al. Size effect and electric field dynamics of spherical droplets in concentric configurations[J]. Chinese journal of liquid crystals and displays, 2020, 35(4): 293-305. DOI： 10.3788/YJYXS20203504.0293.

摘要

基于Landau-de Gennes理论，研究了向列相同轴结构球形液滴的尺寸效应以及电场下的动力学过程。结果表明：同轴结构在半径

≥ 6.5 μm的范围内稳定存在。当

≤ 5.1 μm时只存在双极结构，5.2 μm ≤

6.5 μm时为双极结构与同轴结构均存在的双稳态。外电场存在时，当0 ≤

≤ 0.002 4（使用

对电场进行约化，

=33.7 V/μm）时，液晶分子逐渐沿电场方向排列；当0.002 7 ≤

≤ 0.003时，弹性能、表面能和电场能相互竞争诱导出第一次结构转变，使液滴内出现类双极结构；当0.003 3 ≤

0.013 4时，赤道面内及附近指向矢垂直电场方向排列，其余部分上下对称且沿电场方向排列；当电场强度达到阈值

=0.013 4时，发现第二次结构转变，液滴内大部分液晶分子通过动力学过程实现了从中心轴到边界逐点沿电场方向的转动，该现象首次在同轴结构液滴中出现。

Abstract

Based on Landau-de Gennes theory

the size effect of spherical droplets with nematic concentric structure and the dynamic process under electric field are investigated. Results show that the concentric structure is stable in the range of radius

≥ 6.5 μm. When

≤ 5.1 μm

there is only bipolar structure. When 5.2 μm ≤

6.5 μm

it is degenerate state between bipolar structure and concentric structure. When an electric field is present

at 0 ≤

≤ 0.002 4 (reducing the electric field with

=33.7 V/μm)

the liquid crystal molecules are gradually arranged in the direction of the electric field. When 0.002 7 ≤

≤ 0.003

the elastic energy

surface energy and electric field energy compete with each other to induce the first structural transition

which causes a similar bipolar structure in the droplet. When 0.003 3 ≤

0.013 4

the directors are arranged in the direction perpendicular to the electric field near the equatorial plane

the upper and lower parts of the sphere are symmetrical and the directors are along the direction of the electric field. When the electric field strength reaches the threshold

=0.013 4

the second structural transition is found

which occurs for the first time in the concentric structure. Most of the liquid crystal molecules in the droplets realize the rotation from the central axis to the boundary point by point in the direction of the electric field through the dynamic process.

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Related Author

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Related Institution

Department of Applied Physics, School of Sciences, Hebei University of Technology

School of Science, Hebei University of Technology, Tianjin 300401, China

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