论文标题
弯曲核列液晶中的微变学到探测近晶簇
Microrheology to Probe Smectic Clusters in Bent-core Nematic Liquid Crystals
论文作者
论文摘要
许多弯曲核列液晶体在列相阶段的存在，称为“ cybotactic”簇，表现出异常的物理特性。这些簇对此类液晶的复杂剪切模量（$ g^*（ω）$）的影响迄今未探索。在这里，我们使用微流变技术研究了两个不对称弯曲式液体晶体的流动粘度和复杂的剪切模量。结果通过曲率弹性常数的测量来证实。具有较短烃链（8och $ _ \ text {3} $）的化合物仅显示列表（n）相，而具有更长链的化合物（16och $ _ \ text {3} $）表现出列（nematic-a）（n）和serectic-a（sma）阶段。我们的结果表明，在SMA到N过渡温度上方的方向性剪切模量16och $ _ \ text {3} $上方与8och $ _ \ text {3} $，由于这些近晶簇的原因有很大不同。因此，微流变学使我们能够在弯曲核列液晶中探测近晶簇。
Many bent-core nematic liquid crystals exhibit unusual physical properties due to the presence of smectic clusters, known as "cybotactic" clusters in the nematic phase. Effect of these clusters on complex shear modulus ($G^*(ω)$) of such liquid crystals hitherto unexplored. Here, we study flow viscosities and complex shear modulus of two asymmetric bent-core liquid crystals using microrheology technique. The results are corroborated with the measurements of curvature elastic constants. Compound with shorter hydrocarbon chain (8OCH$_\text{3}$) exhibit only nematic (N) phase whereas the compound with longer chain (16OCH$_\text{3}$) exhibits both nematic (N) and smectic-A (SmA) phases. Our results show that the directional shear modulus of 16OCH$_\text{3}$, just above the SmA to N transition temperature is strikingly different than 8OCH$_\text{3}$, owing to these smectic clusters. Thus, microrheology enables us to probe smectic clusters in bent-core nematic liquid crystals.
