Flexoelectric and elastic coefficients of odd and even homologous bimesogens
Flexoelectric and elastic coefficients of odd and even homologous bimesogens
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DOI：
10.1103/physreve.85.012701
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发表时间：
2012-01-03
影响因子：
2.4
通讯作者：
Coles, Harry J.
中科院分区：
文献类型：
--
作者：
Atkinson, Katie L.;Morris, Stephen M.;Coles, Harry J.
众所周知，双基液晶在弹性比(有效挠曲电系数与平均弹性系数之比)上表现出显著的“奇偶”效应，其中“奇数”双基液晶(间隔链中含有奇数个烷基的双基液晶)比相邻的偶数间距双基液晶具有更高的奇偶效应。为了确定各种性质对弯曲弹性比的贡献，我们给出了两个具有奇和偶烷基间隔基的同源非对称双生元的挠曲电系数和弹性系数的实验结果。我们的结果表明，尽管弯曲电系数存在差异，但有效弹性系数的差异要大得多。具体地说，奇数双生菌被发现既具有低伸展弹性系数又具有非常低的弯曲弹性系数，当它们组合在一起时，导致显著较低的有效弹性系数，从而产生较高的弯曲弹性比。
It is known that bimesogenic liquid crystals exhibit a marked "odd-even" effect in the flexoelastic ratio (the effective flexoelectric coefficient to the average elastic coefficient), with the ratio being higher for the "odd-spaced" bimesogens (those with an odd number of alkyl groups in the spacer chain) than their neighboring even-spaced counterparts. To determine the contribution of each property to the flexoelastic ratio, we present experimental results on the flexoelectric and elastic coefficients of two homologous nonsymmetric bimesogens which possess odd and even alkyl spacers. Our results show that, although there are differences in the flexoelectric coefficients, there are substantially larger differences in the effective elastic coefficient. Specifically, the odd bimesogen is found to have both a low splay elastic coefficient and a very low bend elastic coefficient which, when combined, results in a significantly lower effective elastic coefficient and consequently a higher flexoelastic ratio.