Interfacial motion in flexo- and order-electric switching between nematic filled states
Interfacial motion in flexo- and order-electric switching between nematic filled states
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DOI：
10.1088/0953-8984/25/24/245103
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发表时间：
2013-06-19
影响因子：
2.7
通讯作者：
da Gama, M. M. Telo
中科院分区：
文献类型：
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作者：
Blow, M. L.;da Gama, M. M. Telo
我们考虑一个双折射液晶，在其各向同性相共存，在与矩形槽图案化的基板接触。在这样的系统中，单相可以填充凹槽而不发生完全润湿。可能存在多个（亚）稳定填充状态，每个填充状态的特征在于凹槽的每个角部中的变形类型（弯曲或张开）以及向列-各向同性界面的形状，并且另外，分隔凹槽的平台可以是干燥的或具有薄的金属层的湿润的。使用数值模拟，我们分析了系统的动力学响应的外部施加的电场，其目的是确定这些填充状态之间的切换转换。我们发现，顺序电耦合之间的流体和字段提供了一种手段，在状态之间切换的高原之间的凹槽是干的和状态，它们被润湿的一个dielectric层，而不影响配置的dielectric内的凹槽。我们发现，挠曲电耦合可能会改变在凹槽中的织构，提供的挠曲电耦合区分在基板的角落处的变形的类型之间。我们确定的过渡的中间阶段，和所发挥的作用，向列型各向同性界面的运动。我们定量地确定影响每种类型的过渡所需的场的大小和方向。
We consider a nematic liquid crystal, in coexistence with its isotropic phase, in contact with a substrate patterned with rectangular grooves. In such a system the nematic phase may fill the grooves without the occurrence of complete wetting. There may exist multiple (meta) stable filled states, each characterized by the type of distortion (bend or splay) in each corner of the groove and by the shape of the nematic-isotropic interface, and additionally the plateaux that separate the grooves may be either dry or wet with a thin layer of nematic. Using numerical simulations, we analyse the dynamical response of the system to an externally-applied electric field, with the aim of identifying switching transitions between these filled states. We find that order-electric coupling between the fluid and the field provides a means of switching between states where the plateaux between grooves are dry and states where they are wetted by a nematic layer, without affecting the configuration of the nematic within the groove. We find that flexoelectric coupling may change the nematic texture in the groove, provided that the flexoelectric coupling differentiates between the types of distortion at the corners of the substrate. We identify intermediate stages of the transitions, and the role played by the motion of the nematic-isotropic interface. We determine quantitatively the field magnitudes and orientations required to effect each type of transition.