Hierarchical organization in liquid crystal-in-liquid crystal emulsions.
Hierarchical organization in liquid crystal-in-liquid crystal emulsions.
复制标题
液晶包液晶乳液中的分层组织。
DOI：
10.1039/c4sm01651c
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发表时间：
2014
期刊：
影响因子：
3.4
通讯作者：
Abbott,NicholasL
中科院分区：
文献类型：
--
作者：
Mushenheim,PeterC;Abbott,NicholasL
我们报告的形成和表征的系统中的分层有序的微米大小的液滴的热致变色液晶（LC）分散在连续的溶致变色LC（色甘酸二钠（DSCG））的双相。值得注意的是，我们发现两个LC相的取向是耦合的，4′-戊基-4-氰基联苯（5CB）的微滴呈现出双极构型，其对称轴与DSCG相的远场指向矢正交。我们确定，这种取向的耦合不是由非等轴LC液滴形状或界面离子现象引起的，而是与货车范德华相互作用的影响一致，范德华相互作用是由α 5CB（Δn = +0.18）和DSCG（Δn =-0.02）相的各向异性极化引起的。我们还发现，它是可能的旋转和均匀排列的微滴通过使用一个弱磁场（B <$0.3 T）。的5CB液滴的取向的弛豫的动力学分析后，去除磁场揭示了DSCG和5CB液滴耦合的能量为104 kT，与一个简单的理论估计的各向异性货车的范德华相互作用的影响相一致。我们还观察到，通过EPDSCG的弹性介导，EPD 5CB液滴形成二聚体和更大的组装体。总体而言，这些结果表明，LC中LC乳液定义了一类新的分层有序的软物质，其中热致性和溶致性LC在它们的排序耦合。
We report the formation and characterization of hierarchical ordering in systems comprised of micrometer-sized droplets of thermotropic nematic liquid crystals (LCs) dispersed in continuous nematic phases of a lyotropic chromonic LC (disodium cromoglycate (DSCG)). Significantly, we find the orientations of the two LC phases to be coupled, with nematic droplets of 4′-pentyl-4-cyanobiphenyl (5CB) exhibiting a bipolar configuration with an axis of symmetry aligned orthogonal to the far-field director of the DSCG phase. We determine that this coupling of orientations does not result from either anisometric LC droplet shape or interfacial ionic phenomena but rather is consistent with the influence of van der Waals interactions that arise from the anisotropic polarizabilities of nematic 5CB (Δn = +0.18) and DSCG (Δn = −0.02) phases. We also find that it is possible to rotate and uniformly align the nematic droplets by using a weak magnetic field (B ∼ 0.3 T). An analysis of the dynamics of relaxation of the orientations of the 5CB droplets following removal of the magnetic field reveals the DSCG and 5CB droplets to be coupled by energies of ∼104 kT, consistent with a simple theoretical estimate of the influence of anisotropic van der Waals interactions. We also observed the nematic 5CB droplets to form dimers and larger assemblies mediated by the elasticity of the nematic DSCG. Overall, these results reveal that LC-in-LC emulsions define a new class of hierarchically ordered soft matter in which both thermotropic and lyotropic LCs are coupled in their ordering.