论文标题
通过锚定过渡诱导的胆汁乳液液晶体中的不稳定性
Undulation instabilities in cholesteric liquid crystals induced by anchoring transitions
论文作者
论文摘要
胆固醇液体晶体（CLC）具有特征性的长度尺度，该尺度由其组成杆状分子的扭曲堆叠螺距给出。在同型锚固条件下，分子更喜欢向垂直于界面定向，胆固醇接口表现出与音调相称的条纹宽度的条纹相。相反，平面锚定条件的分子保留在界面的平面中，因此CLC扭曲垂直于其。最近的工作[L. Tran等。物理。 Rev. X 7，041029（2017）]表明，改变锚定条件会极大地重新排列CLC条纹模式，在条纹模式中与液晶分子分子方向的缺陷交换缺陷。我们通过实验和数值模拟表明，当我们从同型旋转到平面锚固条件，反之亦然时，CLC条纹也会发生起伏不稳。由于倾斜的螺距轴，该起伏可以解释为由胆汁脱脂层的菌株引起的CLC的短暂放松，其特性类似于经典的Helfrich Hurault不稳定。我们特别关注CLC壳，并表明壳的球形拓扑在塑造起伏方面也起着重要作用。
Cholesteric liquid crystals (CLCs) have a characteristic length scale given by the pitch of the twisted stacking of their constituent rod-like molecules. Under homeotropic anchoring conditions where the molecules prefer to orient perpendicular to an interface, cholesteric interfaces exhibit striped phases with stripe widths commensurate with the pitch. Conversely, planar anchoring conditions have the molecules remain in the plane of the interface so that the CLC twists perpendicular to it. Recent work [L. Tran et al. Phys. Rev. X 7, 041029 (2017)] shows that varying the anchoring conditions dramatically rearranges the CLC stripe pattern, exchanging defects in the stripe pattern with defects in the molecular orientation of the liquid crystal molecules. We show with experiments and numerical simulations that the CLC stripes also undergo an undulation instability when we transition from homeotropic to planar anchoring conditions and vice versa. The undulation can be interpreted as a transient relaxation of the CLC resulting from a strain in the cholesteric layers due to a tilting pitch axis, with properties analogous to the classic Helfrich-Hurault instability. We focus on CLC shells in particular and show that the spherical topology of the shell also plays an important role in shaping the undulations.
