Centre for Soft Matter Research, Jalahalli, Bangalore, India.
J Phys Chem B. 2012 Jan 19;116(2):782-93. doi: 10.1021/jp210383p. Epub 2012 Jan 4.
Bent-core nematic electroconvection is a relatively less explored area, particularly in the low frequency regime. We focus here mainly on the instabilities occurring below 100 Hz in an initially planar monodomain of a bent-core nematic liquid crystal, which is negative in both conductivity and dielectric anisotropies. An unprecedented observation is the occurrence of three distinct bifurcation modes in a narrow region (10-17 Hz) that manifest, in the order of increasing threshold, as longitudinal, oblique and normal rolls. Whereas the second of these is the flexoelectrically enabled Carr-Helfrich mode, the other two are nonstandard electroconvection modes. Significantly, the first two instabilities remain unquenched even after bifurcation into the normal roll state below their respective codimension-2 points. The hybrid roll states display complex flows and morphologies. The study includes measurement of electrical parameters relevant to the discussion of results.
扭曲向列型电动力学是一个相对较少被探索的领域，特别是在低频范围。我们主要关注初始平面单畴扭曲向列型液晶中低于 100 Hz 的不稳定性，该液晶在电导率和介电各向异性方面均为负。一个前所未有的观察结果是，在一个狭窄的区域（10-17 Hz）中出现了三种不同的分岔模式，按照阈值增加的顺序依次为纵向、倾斜和正常滚转。其中第二个是由挠曲电引起的 Carr-Helfrich 模式，而另外两个是非标准的电动力学模式。重要的是，即使在分别低于它们的二维分岔点进入正常滚转状态后，前两种不稳定性仍然没有被消除。混合滚转状态显示出复杂的流动和形态。研究包括对与结果讨论相关的电参数的测量。
