Computational modelling of tactoid dynamics in chromonic liquid crystals
Computational modelling of tactoid dynamics in chromonic liquid crystals
复制标题
有色液晶中团聚体动力学的计算模型
DOI：
10.1080/02678292.2017.1410240
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发表时间：
2017
期刊：
影响因子：
2.2
通讯作者：
Lavrentovich, Oleg D.
中科院分区：
文献类型：
--
作者：
Zhang, Chiqun;Acharya, Amit;Walkington, Noel J.;Lavrentovich, Oleg D.
受最近实验的启发，研究了有色液晶中的各向同性-非均匀相变。随着温度的降低，晶核成核、生长和聚结，在各向同性液体中产生类晶显微结构。这些类晶在畴结处产生拓扑缺陷（体中的向错或表面上的点缺陷）。我们模拟这样的tactoid平衡和他们的粗化动力学与模型使用程度的顺序，可变长度的董事和界面正常的状态描述符。我们采用Ericksen的工作，并引入了一个增强的Oseen-Frank能量，与非凸性的界面能和依赖的能量的程度的顺序。这种能量的梯度流动动力学不能成功地再现一些简单的预期特征的tactoid动力学。因此，一个策略的基础上设计的连续运动学和热力学来表示这些功能。该模型可用于预测相变过程中类晶的形核、膨胀和聚并。我们重现实验中观察到的行为，并进行实验测试的参数研究散装弹性和tactoids界面能参数的相互作用的界面和散装领域的tactoids的效果。
Motivated by recent experiments, the isotropic–nematic phase transition in chromonic liquid crystals is studied. As temperature decreases, nematic nuclei nucleate, grow and coalesce, giving rise to tactoid microstructures in an isotropic liquid. These tactoids produce topological defects at domain junctions (disclinations in the bulk or point defects on the surface). We simulate such tactoid equilibria and their coarsening dynamics with a model using degree of order, a variable length director and an interfacial normal as state descriptors. We adopt Ericksen’s work and introduce an augmented Oseen–Frank energy, with non-convexity in both interfacial energy and the dependence of the energy on the degree of order. A gradient flow dynamics of this energy does not succeed in reproducing some simple expected feature of tactoid dynamics. Therefore, a strategy is devised based on continuum kinematics and thermodynamics to represent such features. The model is used to predict tactoid nucleation, expansion and coalescence during the process of phase transition. We reproduce observed behaviours in experiments and perform an experimentally testable parametric study of the effect of bulk elastic and tactoid interfacial energy parameters on the interaction of interfacial and bulk fields in the tactoids.