Low-voltage-driven electromechanical effects of swollen liquid-crystal elastomers.
Low-voltage-driven electromechanical effects of swollen liquid-crystal elastomers.
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DOI：
10.1103/physreve.71.061702
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发表时间：
2005-06
期刊：
影响因子：
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通讯作者：
Y. Yusuf;Jong-Hoon Huh;P. Cladis;H. Brand;H. Finkelmann;S. Kai
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文献类型：
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作者：
Y. Yusuf;Jong-Hoon Huh;P. Cladis;H. Brand;H. Finkelmann;S. Kai
我们通过实验详细研究了先前用低分子量液晶（lmwlc）膨胀的液晶弹性体（LCEs）中的机电效应。研究了多域（POLY）和单域（MONO） LCEs。我们使用了一种著名的低分子溶剂，4-n-戊基-4-氰联苯（5CB）作为溶剂。用5CB膨胀POLY和MONO LCE （LSCE）后，通过记录膨胀后LCE边缘在不同电压、电压和温度下的位移来测量形状变化。电极之间的距离为100微米，在小电压（约0.5-10 V）下观察到可测量的形状变化（约1-20微米）。特别是，我们注意到，与未膨胀的L(S) ce相比，膨胀的L(S) ce的机电效应阈值场下降了约200倍。肿胀的MONO lce在平面几何上表现出机电效应，而同向性取向5CB的同向性MONO肿胀则没有。这很容易理解，因为在同向同性的情况下，液晶的首选轴已经与场对齐，所以场没有重新定向的影响。在POLY和MONO中，打开电场时响应时间的倒数与E2成正比，这与lmwlc的响应时间具有相同的场依赖性。当电场关闭时，弛豫时间表现出与LCE网络不同的场依赖性，我们将其归因于LCE网络的弛豫。
We experimentally investigate, in detail, electromechanical effects in liquid-crystal elastomers (LCEs) previously swollen with low-molecular-weight liquid crystals (LMWLCs). Both polydomain (POLY) and monodomain (MONO) LCEs were studied. We used a well known LMWLC, 4-n-pentyl-4-cyanobiphenyl (5CB) as a solvent. After swelling POLY and MONO LCEs (LSCE) with 5CB, shape changes were measured by recording the displacement of the edge of the swollen LCE at different voltages, V, and temperature. With 100 microm distance between electrodes, measurable shape changes (approximately 1-20 microm) are observed with small voltages (V approximately 0.5-10 V). In particular, we note that, compared to unswollen L(S)CEs, a dramatic approximately 200 times decrease of the threshold field was found for electromechanical effects in swollen L(S)CEs. While swollen MONO LCEs showed electromechanical effects in the planar geometry, homeotropic MONO swollen with homeotropically oriented 5CB did not. This is easy to understand because, in the homeotropic case, the liquid-crystal preferred axis is already aligned with the field so the field has no reorienting effect. The inverse of the response time when the field was switched on in both POLY and MONO was proportional to E2, which is the same field dependence as the response time of LMWLCs. When the field was switched off, the relaxation time showed a field dependence different from that of LMWLCs that we attribute to relaxation of the LCE network.