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含甲氧基偶氮苯液晶基元超分子的相行为研究 总被引:1,自引:0,他引:1
氢键是分子聚集和识别过程中的重要相互作用,利用分子间氢键,可设计并制备各种超分子体系材料,1989年,Kato等报道了吡啶基和羧酸基通过分子间氢键相互作用形成扩展液晶基元,得到了液晶稳定性增强的超分子液晶复合体系及侧链超分子液晶聚合物;同时,Lehn等报道了带脲嘧啶基和2,6-二酰胺吡啶基两种互补官能团的分子通过三重氢键缔合形成的主链超分子液晶。从此,迅速而广泛的开展利用氢键组装的超分子液晶体系的研究,并已组装合成出低分子型、 相似文献
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以Ullmann偶合反应为关键步骤, 合成了带端氧基链的苯基咪唑苯酯系列化合物, 采用偏光显微镜(POM)、差示扫描量热仪(DSC)及X衍射等手段研究了其液晶行为. 研究表明, 通过改变末端烷氧基链的长度及数目, 这类分子可组装形成向列相(N)和层列相(SmA)等液晶相态, 但随着烷氧基链数目的增多, 这类分子的液晶相消失, 初步找出了这类化合物结构与液晶性能间的关系, 通过对相关化合物的单晶X衍射结构及其液晶相的2D-X衍射测试结果的分析得出, 这类化合物通过分子自组装形成的层列相具有双分子层状结构(SmA2). 相似文献
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选取3种不同结构的苄醚型树枝状分子为分枝,以N-乙酰氨基葡萄糖为内核,合成出一类树枝化碳水化物;利用DSC、热台偏光显微镜、XRD和CD/UV光谱等手段研究该类化合物的液晶性,并命名为树状碳水化合物液晶。研究表明,连接有楔形树枝状单元的化合物形成手性柱状六方相或者向列相,连接有锥形树枝状单元的化合物未能如预期形成立方相,而仍然形成手性柱状六方相.超分子手性很可能源于树枝状单元与糖内核的协同自组装,使得树状分子沿着柱轴螺旋式堆砌;而糖环内核则对超分子柱的手性起调控作用,从而避免了外消旋的发生.该类化合物为研究碳水化合物诱导手性超分子聚集体提供了新的思路. 相似文献
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棒-线(Rod-Coil)型分子的合成及其自组装行为研究是当前超分子材料研究领域的重要研究方向. 与传统的柔性(Coil-Coil)型嵌段聚合物和Rod-Coil型嵌段聚合物相比, Rod-Coil型分子表现出不同的相行为、自组织特性和微结构, 可以自组装形成多种纳米结构. 研究结果显示, 横向分子间氢键是Rod-Coil型分子自组装形成液晶相和(或)有机凝胶等自组装体的主要驱动力. 主要介绍目前文献报道的横向分子间氢键驱动下的Rod-Coil型分子自组装. 相似文献
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我们利用离子自组装的方法以含苯甲酸基团的两亲分子A6包覆了含铕的无机多金属氧簇Na9[EuW10O36]。利用红外光谱、热重分析、元素分析等方法对所得有机无机杂化复合物A6Eu进行了详细的结构表征。苯甲酸基团通过分子间氢键相互作用发生的二聚使有机组分形成了枝杈状的Bola型结构,这种结构导致外围的介晶基元以侧向方式连接在无机簇上。我们通过差示扫描量热法、偏光显微镜和变温X射线衍射对A6Eu的热致液晶性质进行了表征。虽然单独的两亲分子A6组装成了简单的近晶结构,但是复合物A6Eu表现出新颖的层状近晶相液晶结构。层状近晶相液晶结构中介晶基元是平行于层面的。由此可见,介晶基元的侧向连接方式对复合物的热致组装结构具有重要影响。多金属氧簇的荧光性质在液晶材料中得到了很好的保持。 相似文献
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盘状液晶材料的研究进展 总被引:1,自引:0,他引:1
盘状液晶分子容易形成柱状堆积的超分子组装体, 由于分子在液晶态具有一定的流动性, 使得组装体具有良好的结构缺陷自修复功能. 因此具有特定芳香共轭结构的盘状液晶分子可以呈现较高的导电特性, 能够有效传输电荷, 具有制备光电器件的潜在应用价值. 本文主要介绍以苯环、苯并菲、六苯并蔻、苝和肽菁为中心核的盘状液晶材料, 其分子结构的化学修饰对液晶性能的影响, 液晶材料在有机发光二极管(OLED)、有机场效应晶体管(OFET)和太阳能电池器件中的应用, 以及盘状液晶材料相关的动力学研究进展. 相似文献
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超分子液晶结合了超分子化学和液晶两者的特点,是近年来研究的一个热点.在简述超分子化学和超分子液晶概念的基础上,对非共价键结合包括氢键型、离子型和金属络合型的超分子液晶结构和研究现状作了简介,并对超分子液晶常用的表征方法进行了概述. 相似文献
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合成了1个新的手性Schiff碱类液晶并以DSC、偏光显微镜及变温红外光谱等手段对其热致相变过程进行了研究。 相似文献
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Young Jae Jeon Gae Hwang Lee Jae Eun Jang Kyu Young Hwang Farzana Ahmad Muhammad Jamil 《Liquid crystals》2013,40(11):1314-1319
In this paper, multidirectional light-control reflective (LCR) films are developed in order to create an active reflective structure that will enhance the image brightness and contrast ratio of reflective dye-doped polymer-dispersed liquid crystal (D-PDLC) displays at lower viewing angles. Advantages of LCR films are that their production is low cost and they require a simple photolithographic fabrication method. The optimum design prism-type light-control reflective film succeeded in minimising the surface scattering effect; thus, the contrast ratio is much enhanced. The symmetric and asymmetric LCR films produced multidirectional scattering that enhances the reflectance at lower viewing angles, which has importance in future display applications. In particular, the prism LCR film has been found to be more influential on the reflectance of D-PDLC films due to multidirectional scattering of light by non-symmetric arrays. The improvement in contrast ratio has been confirmed by the enhancement of optical properties for reflective D-PDLC displays at lower viewing angles below 30°. 相似文献
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Fatemeh Jahanbakhsh 《Liquid crystals》2013,40(10):1485-1493
ABSTRACTThe impact of varying the co-doping concentration of a mesogenic and a non-mesogenic monomer in the reactive mixtures used to create a copolymer network LCs was investigated. Use of copolymer has been found to improve the response properties in the obtained liquid crystal composites. The polymer network in the studied copolymer network LCs was examined by scanning electron microscopy and the response times in various samples were investigated. Samples were prepared with various reactive mixtures, each of which had a constant concentration of mesogenic monomer, various concentrations of non-mesogenic monomer, and the same amount of photoinitiator. These reactive mixtures were filled in home assembled test cells with planar alignment and then exposed to UV light. With increasing concentration of the non-mesogenic monomer, the response properties of the resulting copolymer network LC were improved. Usually, if the overall polymer content in a polymer network LC is increased, the threshold voltage is also increased. However, both threshold voltages and response times were lowered and the response properties were thus improved in the studied copolymer network LCs. This unexpected behavior could be traced back to inducing a grainy polymer morphology of the copolymer network by using a non-mesogenic monomer. 相似文献
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两个新的氢键诱导液晶化合物的合成 总被引:3,自引:0,他引:3
通过4-丁氧基苯甲酸(4BA0与两个手性取代的苯乙烯基吡啶(VSZ及LSZ)间的氢键作用合成了2个新的液晶化合物,用DSC、偏光显微镜研究了其液晶行为,并由红外光谱证实了分子间氢键的存在,形成的复合物4BA-VSZ具有手性近晶C相。 相似文献
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Summary We review recent progress in the computer simulation of liquid crystals, with special emphasis on hard particle models. Surprisingly, the simplest molecular models, taking account only of molecular size and shape, are sufficient to generate a wide variety of liquid crystalline phases, closely analogous to those observed in real life. Thermodynamic stability of different phases is very sensitive to shape, and presumably will also be sensitive to further details of intermolecular interactions as they are incorporated into the model. Realistic atom-atom potential models of liquid crystals are available, but the associated simulations are quite expensive. Thus, while idealized models may be used to study quite general, fundamental properties of mesophases, the modelling of specific liquid crystal systems in a realistic way remains a great challenge. Progress continues to be made on both these fronts. 相似文献
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设计并合成了4个对称联苯双酯类液晶化合物,化合物结构通过红外和核磁表征,它们的介晶性通过差示扫描量热仪(DSC),X射线衍射仪(XRD)和热台偏光显微镜(POM)进行了研究.并测定了4,4'-3,3',5,5'-四甲基联苯-二(4-甲基苯甲酸酯)(Ⅲa)的单晶结构,结果显示:晶体属于单斜晶系,P21/c空间群,晶胞参数为a=18.525(3)(A),b=12.196(2)(A),c=12.195(2)(A),β=97.142(2)°,V=2733.7(9)(A)3,Z=4,Dc=1.163 Mg/m3,R=0.0521,Rw=0.1161.化合物均为热致型互变液晶,并讨论了氧原子、不饱和端基和端基链长对介晶性的影响. 相似文献
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以不同链长溴代烷烃和N-甲基咪唑反应得到1-烷基-3-甲基咪唑溴化盐,用元素分析和核磁共振对化合物进行了表征.室温下用溶剂蒸发法得到了单晶,并用X射线单晶衍射法测定了晶体结构,该晶体属于三斜晶系,空间群为P-1.化合物采用双分子层结构,水分子参与结构的形成,整个化合物由交叉的线性烷基链、咪唑头基、溴离子和水分子组成,溴离子和水分子之间较强的氢键作用在(010)方向上形成了一个无限的O-H···Br氢键链.用偏光显微镜、差示扫描量热(DSC)技术研究了其液晶行为,证明其一水合物为近晶相热致液晶.液晶区域的温度范围较宽说明水分子起到稳定作用. 相似文献
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Identification of mesophases using a polarising microscope is vital in the area of research and development of the liquid crystal (LC) materials, however, sometimes it is very difficult to distinguish one texture from another. Here, we propose a novel method allowing for the examination of thermotropic phase sequence in polymorphic LCs called dynamic thermo-optical analysis (DTOA). In the DTOA technique the LC subjected to the cooling process is simultaneously influenced by the electric field varying sinusoidally with time. It results in the dynamic changes in the light intensity passing through the layer of such LC observed under a polarised microscope and recorded by a charge-coupled device camera. The magnitude of the changes uniquely depends on the type of the mesophase. The subsequent numerical analysis of the recorded movie (performed with a help of the image-processing software) reveals the changes in the amplitude of the average intensity of the images of the respective textures, i.e. nematic, SmA, SmC, SmI, thereby allowing for their clear identification. Furthermore, the DTOA allows to distinguish easily the SmA from the SmC phase. The azobenzene-based LC known of rich sequence of mesophases has been used here to demonstrate the principle of the DTOA method. 相似文献
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Binary dual-frequency nematic liquid crystals synthesised at the Military University of Technology were measured by dielectric means. All the investigated materials exhibit low crossover frequency. They were composed of only two molecules with longitudinal and transverse dipole moments. The main difference is the molecular weight of the molecules. Results of relaxation parameters of detected mode and crossover frequency are shown. The influence of structure on ion conductivity is discussed. The broad phase transition from an isotropic phase to a nematic one was observed. 相似文献