Thermal response of cholesteric liquid crystal elastomers
Thermal response of cholesteric liquid crystal elastomers
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DOI：
10.1103/physreve.92.022501
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发表时间：
2015-08-21
影响因子：
2.4
通讯作者：
Urayama, Kenji
中科院分区：
文献类型：
--
作者：
Nagai, Hama;Urayama, Kenji
研究了温度变化对无机械约束和有机械约束两种几何构型下液晶弹性体（CLCE）光子特性的影响。在不受约束的几何形状中，在无约束状态下的冷却引起选择性反射带向较短波长的相当大的移位和在垂直于螺旋指向矢配置的轴的两个方向上的有限程度的宏观膨胀。热变形是由底层微结构S的取向顺序的变化驱动的，并且在各向异性高斯链网络模型的基础上解释了宏观应变与S之间的关系。在温度变化的情况下，螺距以仿射方式随膜厚度变化。在严格禁止热变形的约束几何结构下的CLCE显示，当受到温度变化时，反射带没有偏移。这也揭示了宏观尺寸和螺旋指向矢配置的节距之间的强相关性。
The effects of temperature variation on photonic properties of cholesteric liquid crystal elastomers (CLCEs) are investigated in mechanically unconstrained and constrained geometries. In the unconstrained geometry, cooling in the cholesteric state induces both a considerable shift of the selective reflection band to shorter wavelengths and a finite degree of macroscopic expansion in the two directions normal to the axis of the helical director configuration. The thermal deformation is driven by a change in orientational order of the underlying nematic structure S and the relation between the macroscopic strain and S is explained on the basis of the anisotropic Gaussian chain network model. The helical pitch varies with the film thickness in an affine manner under temperature variation. The CLCEs under the constrained geometry where thermal deformation is strictly prohibited show no shift of the reflection bands when subjected to temperature variation. This also reveals the strong correlation between the macroscopic dimensions and the pitch of the helical director configuration.