Structure-sensitive bend elastic constants between piconewton and subnanonewton in diphenylacetylene-core-based liquid crystals
Structure-sensitive bend elastic constants between piconewton and subnanonewton in diphenylacetylene-core-based liquid crystals
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二苯乙炔核液晶中皮牛顿和亚纳牛顿之间的结构敏感弯曲弹性常数
DOI：
10.1103/physreve.90.042506
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
K. Ishikawa
中科院分区：
文献类型：
--
作者：
S. Aya;S. Ogino;Y. Hayashi;K. Okano;D. Pociecha;K. V. Le;F. Araoka;S. Kawauchi;E. Gorecka;N. Vaupotic;H. Takezoe;K. Ishikawa
已知液晶的弹性常数在皮牛顿（pN）和几十皮牛顿（pN）的范围内。我们在此报道，弯曲弹性常数根据类似系列的棒状液晶中化学结构的轻微改变而显着变化。与之前报道的具有偶氮键的化合物的创纪录的高弯曲弹性常数（数百 pN 或亚 nN）相比，具有 tolan 和酯键的类似化合物分别显示出几十 pN 和 pN。这些化合物的 X 射线衍射研究表明，仅在具有偶氮键的同系化合物的向列相中才形成类近晶层结构，证实了胞规簇的存在强烈增强的观点。提出了两个理论考虑：（1）基于分子构象计算，具有高扭转势能的扁平分子，例如具有偶氮键的分子，很容易堆积形成胞规簇。 (2) 理论上估计需要多少簇体积比才能达到约100倍大。
Elastic constants in liquid crystals are known to be in the range of pico- and several-tens piconewton (pN). We report herein that a bend elastic constant,, remarkably varies depending on a slight modification of the chemical structure in an analogous series of calamitic liquid crystals. In contrast to the record-high bend elastic constants (hundreds pN or sub-nN) reported previously in a compound with an azo linkage, analogous compounds with tolan and ester linkages show several-tens pN and pN, respectively. X-ray diffraction studies of these compounds reveal that smectic-like layer structuresare formed in the nematic phase of only the homologous compounds with an azo linkage, certifying the idea that the existence of cybotactic clusters strongly enhances. Two theoretical considerations were made: (1) Based on molecular conformation calculation, flat molecules that have high torsional potential energy, such as the one with an azo linkage, easily pack to form cybotactic clusters. (2) Theoretical estimation was made of how much cluster volume ratio is necessary to give about 100-times-larger.