Design of liquid crystals with ‘de Vries-like’ properties: the effect of carbosilane nanosegregation in 5-phenyl-1,3,4-thiadiazole mesogens
Design of liquid crystals with ‘de Vries-like’ properties: the effect of carbosilane nanosegregation in 5-phenyl-1,3,4-thiadiazole mesogens
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具有“德弗里斯样”性质的液晶设计：碳硅烷纳米偏析在 5-苯基-1,3,4-噻二唑介晶中的影响
DOI：
10.1039/c4tc01364f
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发表时间：
2014
影响因子：
6.4
通讯作者：
R. Lemieux
中科院分区：
文献类型：
--
作者：
Kirk M. Mulligan;A. Bogner;Qingxiang Song;C. Schubert;F. Giesselmann;R. Lemieux
具有“类德弗里斯”性质的近晶相液晶的特征在于从正交SmA相转变为倾斜SmC相时的最大层收缩≤1%。大多数“德弗里斯样”材料的定义结构特征是强烈促进近晶层形成的纳米偏析元素。本文中，我们显示了不同长度的nanosegregating碳硅烷端基的效果上的“德弗里斯样”的性质在三个系列的5-苯基-1，3，4-噻二唑介晶与氯封端的烷氧基链（QL 13-n，QL 18-n和QL 19-n）。缩短从三碳硅烷到单碳硅烷的端基导致“德弗里斯样”特征的减少，如通过减少因子R所测量的，这与纳米偏析和层状有序质量的减少一致。通过近晶单畴的2D X射线散射的取向序参数S2的测量显示伴随的S2的增加，这与在这些材料中的“德弗里斯样”行为产生于高层状序和低取向序的组合的假设一致。通过对氯封端的液晶基元2-（6-氯己氧基）-5-（4-己氧基苯基）-1，3，4-噻二唑（QL 28 -6/6）的表征证实了实现“德弗里斯样”行为的纳米偏析结构元件的要求，该液晶基元经历SmA-SmC转变，最大层收缩为4.1%，并且表现得像常规的smectogen。
Smectic liquid crystals with ‘de Vries-like’ properties are characterized by a maximum layer contraction of ≤1% upon transition from the orthogonal SmA phase to the tilted SmC phase. A defining structural characteristic of most ‘de Vries-like’ materials is a nanosegregating element that strongly promotes the formation of smectic layers. We show herein the effect of varying the length of a nanosegregating carbosilane end-group on ‘de Vries-like’ properties in three series of 5-phenyl-1,3,4-thiadiazole mesogens with chloro-terminated alkoxy chains (QL13-n, QL18-n and QL19-n). Shortening the end-group from a tricarbosilane to a monocarbosilane causes a decrease in ‘de Vries-like’ character, as measured by the reduction factor R, which is consistent with a decrease in nanosegregation and quality of the lamellar ordering. Measurements of the orientational order parameter S2 by 2D X-ray scattering of smectic monodomains show a concomitant increase in S2 that is consistent with the hypothesis that ‘de Vries-like’ behavior in these materials arises from a combination of high lamellar order and low orientational order. The requirement of a nanosegregating structural element to achieve ‘de Vries-like’ behavior is confirmed by the characterization of the chloro-terminated mesogen 2-(6-chlorohexyloxy)-5-(4-hexyloxyphenyl)-1,3,4-thiadiazole (QL28-6/6), which undergoes a SmA–SmC transition with a maximum layer contraction of 4.1% and behaves like a conventional smectogen.
调节不同分子长度液晶二元混合物中的“德弗里斯式”特性
影响因子：
4.9
作者：
Q. Song;A. Bogner;F. Giesselmann;R. P. Lemieux
通讯作者：
R. P. Lemieux
阐明棒状液晶中卤素端基的近晶A促进作用
影响因子：
6.4
作者：
I. Rupar;K. Mulligan;J. Roberts;D. Nonnenmacher;F. Giesselmann;R. Lemieux
通讯作者：
R. Lemieux