我国手性液晶的研究进展与应用

阐述了手性液晶的结构和分类,介绍了近年来国内手性液晶的合成与研究进展情况,并着重讨论了胆甾相手性液晶的热色效应及其作为手性添加剂在显示领域的应用以及铁电液晶的非线性光学效应.     

含异山梨醇结构的液晶用手性搀杂剂的应用研究

介绍了胆甾相液晶显示(Ch-LCD)原理和对液晶材料的要求,分析了近年来对用于胆甾相液晶材料的含异山梨醇的手性搀杂剂的一些研究,初步阐述了该类手性搀杂剂的结构与液晶性能及在液晶材料中的应用前景。     

基于光控二芳基乙烯的手性向列相液晶体系研究进展

光控手性分子开关结合到液晶材料体系中,可以有效利用其光诱导的手性变化,实现远程光刺激液晶材料的自组装螺旋超结构。二芳基乙烯（DAE）是一类新型的、有前景的光致变色分子,作为智能光响应开关,在手性向列相液晶材料体系中表现出优异的性能。本文重点围绕结构设计,总结了一系列具备不同螺旋扭曲力（HTP）的手性DAE分子及其在液晶自组装螺旋结构中所产生的特定性能,如光可逆宽范围调控和光控手性反转。该类光控DAE手性向列相液晶体系在手性调控、光学显示、可调谐激光等领域具有巨大的应用潜力。最后讨论了该领域面临的挑战和机遇,并指出了未来可能的发展方向。     

基于光控二芳基乙烯的手性向列相液晶体系研究进展

光控手性分子开关结合到液晶材料体系中,可以有效利用其光诱导的手性变化,实现远程光刺激液晶材料的自组装螺旋超结构。二芳基乙烯（DAE）是一类新型的、有前景的光致变色分子,作为智能光响应开关,在手性向列相液晶材料体系中表现出优异的性能。本文重点围绕结构设计,总结了一系列具备不同螺旋扭曲力（HTP）的手性DAE分子及其在液晶自组装螺旋结构中所产生的特定性能,如光可逆宽范围调控和光控手性反转。该类光控DAE手性向列相液晶体系在手性调控、光学显示、可调谐激光等领域具有巨大的应用潜力。最后讨论了该领域面临的挑战和机遇,并指出了未来可能的发展方向。     

一种手性薄荷单体对侧链液晶聚合物性能的影响研究

由非液晶手性薄荷单体M1和胆甾醇类液晶单体M2与聚甲基含氢硅氧烷（PMHS）接枝共聚合成了系列新型侧链液晶聚合物。运用红外光谱分析（FTIR）、氢核磁共振谱分析（1H NMR）、差示扫描量热分析（DSC）、热失重（TG）分析、偏光显微分析（POM）、旋光分析（SORT）和X-射线衍射分析（XRD）等进行表征。单体M2在升温和降温过程中呈现胆甾相液晶织构，M2均聚物P1为手性近晶A相，P2～P7为胆甾相液晶。实验结果显示，随着单体M1含量的增加，聚合物的左旋光活性越来越强，玻璃化温度强呈现先降低后升高趋势，清亮点温度Ti降低，液晶相范围变窄。     

光活性联苯酯类液晶研究：液晶性能及织构转变

将手性碳原子引入分子结构,合成了6个具有光学活性的联苯酯类液晶,用旋光检测、XRD、DSC、POM等对其进行表征,结果表明6个化合物都是胆甾型互变液晶,液晶性能良好;柔性端基链的增长有利于胆甾相指纹织构的稳定存在,端基链最长的化合物存在焦锥织构和指纹织构间的可逆转变。     

手性表面活性剂在手性合成、识别及拆分中的应用

当今社会对单一对映体的需求越来越大,由于手性表面活性剂具有区域选择性、手性催化能力及手性识别能力,因而在手性合成、手性识别及手性拆分中的应用也越来越受封重视。文章综述了近年来手性表面活性剂在不对称催化、乎性识剐及手性拆分中的应用。     

方兴未艾的手性化学

简要介绍了手性化学中的手性合成、手性拆分的重要性。重点介绍了:1新型手性化合物的合成拆分及应用;2聚集诱导荧光在手性化学中的应用;3手性化学在反应机理研究中的应用。并对手性化学的发展进行了展望。     

方兴未艾的手性化学

简要介绍了手性化学中的手性合成、手性拆分的重要性。重点介绍了:1新型手性化合物的合成拆分及应用;2聚集诱导荧光在手性化学中的应用;3手性化学在反应机理研究中的应用。并对手性化学的发展进行了展望。     

(S)-4-(2-甲基丁基)-4'-(4-丙基环己基)-2-氟联苯的合成及性能研究

以(S)-(2-甲基丁基)苯为原料,经碘代和Suzuki偶联四步反应,合成了手性液晶(S)-4-(2-甲基丁基)-4'-(4-丙基环己基)-2-氟联苯,总收率11.4%,纯度99.2%,并采用IR、MS、1H NMR及元素分析对其结构进行了表征。结合差示扫描量热仪(DSC)和偏光显微镜(POM)研究了目标化合物的介晶性,并采用Cano’s wedge法测定了目标化合物的扭曲力。     

黏土及类黏土液晶材料的研究进展

黏土矿物(clay minerals)是组成黏土岩和土壤的主要矿物,它是一种含镁、铝为主的水合硅酸盐矿物.研究发现黏土矿物液晶与有机液晶材料相比,具有光、电、磁性能强,热稳定性好,价格低廉等优点.简要介绍了黏土矿物液晶材料的形成机理,概述了片层状黏土液晶材料、纤维型黏土液晶材料、类黏土矿物液晶材料的制备方法和研究现状,同时介绍了不同条件(浓度、离子强度、外电场作用、分散介质、重力作用)对黏土及类黏土分散体系相变的影响,并对黏土矿物液晶材料的应用发展前景进行了概述.     

胆甾型液晶的合成及显色示温液晶组成

合成并表征了两种对正烷氧基苯甲酸胆甾醇酯液晶 ,并用于显色示温混合液晶的配制。通过胆甾型液晶的选择及不同含量的调配 ,获得变色温度范围在 1 0～ 40°C、色泽鲜艳、温度感应灵敏、变色可逆的胆甾型混合液晶组成。讨论了混合液晶组成对显色示温的影响     

Nematic-to-Isotropic Phase Transition in Poly(L-Lactide) with Addition of Cyclodextrin during Abiotic Degradation Study

Poly(L-lactide) is capable of self-assembly into a nematic mesophase under the influence of temperature and mechanical stresses. Therefore, subsequent poly(L-lactide) films were obtained and characterized, showing nematic liquid crystal properties both before and after degradation. Herein, we present that, by introducing β-cyclodextrin into the polymer matrix, it is possible to obtain a chiral nematic mesophase during pressing, regardless of temperature and time. The obtained poly(L-lactide) films exhibiting liquid crystal properties were subjected to degradation tests and the influence of degradation on these properties was determined. Thermotropic phase behavior was investigated using polarized optical microscopy, X-ray diffraction, and differential scanning calorimetry. The degradation process demonstrated an influence on the liquid crystal properties of pressed polymer films. The colored planar texture of the chiral nematic mesophase, which was not observed prior to degradation in films without the addition of β-cyclodextrin, appeared after incubation in water as a result of the entrapment of degradation products in the polymer matrix. These unusual tailor-made properties, obtained in liquid crystals in (bio)degradable polymers using a simple method, demonstrate the potential for advanced photonic applications.     

Preparation and characterization of novel polyimide with chiral side chain for twist nematic liquid crystal display

The synthesis of novel polyimide (PI) films containing chirals in side chain was investigated for utilizing in twist nematic (TN) liquid crystal display (LCD). The polyimide with amine side groups (PI4 a.m.) was prepared by two steps copolymerization of 4,4′‐hexafluoroisopropylidene diphthalic anhydride (6FDA), 4,4′‐oxydianiline (ODA), and 3,3′‐diaminobezidine (4 a.m.) in N‐methyl‐2‐ pyrrolidinone (NMP). In the first step, the oligomer of 6FDA and ODA with mole ratio 4 : 3 was synthesized. In the second step, the oligomer was reacted with 4 a.m. by gradually dropping the oligomer into 4 a.m. solution with the mole ratio 4 : 5. By reacting chiral compounds, mandelic acid, menthyl chloroformate, and menthyl glyoxylate hydrate using condensation reaction with amine groups along polyimide molecules, the novel polyimides can be synthesized. Their chemical structures were confirmed by fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy (¹H‐NMR). The coated glass slides pairs were coated with PI4 a.m. and with each Polyimide/chiral. The liquid crystals (LCs) were inserted between two coated glass slides at above the nematic temperature under the polarized light microscope to observe the alignment of LCs. The results showed the alignment of LCs in some certain direction under Polyimide/chiral pair, regardless of the type of the chiral molecule. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Hyperstructured polyacetylene

Current progress in the synthesis and properties of conjugated polymers is presented by focusing on recently put forward hyperstructured helical polyacetylene. Interfacial polymerization of acetylene has been carried out in an asymmetric reaction field consisting of chiral nematic liquid crystal (N*‐LC) and Ziegler–Natta catalyst. Since the chiral nematic liquid crystal is composed of nematic liquid crystal and a chiral compound such as axially chiral binaphthyl derivative with R‐ or S‐configuration, the screw directions of the polyacetylene chain and fibril bundle and even the spiral morphology are rigorously controlled by selecting the chirality of the chiral compound. Surprisingly, the screw directions of the fibril and the bundle of fibrils in helical polyacetylene were found to be opposite to that of N*‐LC. It is worthwhile to emphasize that the hierarchical spiral morphology involving the primary to higher order structure is generated in a synthetic polymer such as polyacetylene by using N*‐LC as an asymmetric polymerization solvent. Copyright © 2007 Society of Chemical Industry     

Preparation and Characterization of Polymer-dispersed Liquid Crystal Films Using Poly(bornyl methacrylate)

Chiral (+)-bornyl methacrylate and achiral (±)-bornyl methacrylate were synthesized from (+)-camphor and (±)-camphor, respectively. To investigate the influence of the steric environment of the chiral polymers on the electro-optical characteristics of polymer-dispersed liquid crystal (PDLC) films, a commercially available positive nematic liquid crystal E7 was dispersed in the chiral and achiral polymer matrices. The electro-optical characteristics and the microstructures of the PDLC films with chiral and achiral racemized polymers were investigated. It was found that PDLC films with chiral polymers have relatively high contrast ratio and fast falling speed, but there exists a transient damping response when a square pulse of 20ms and 60V is applied. Two distinct morphologies were observed: (1) a ‘continual channel’ with the chiral polymer matrix, and (2) an ‘isolated ball’ with the achiral racemized polymer matrix. The reversible turbid and transparent changes with an applied a.c. electric field were also investigated. © of SCI.     

分子间自组装盘状液晶材料研究进展

综述了近十年来国内外报道的分子间自组装盘状液晶的研究进展;重点阐述了通过分子间氢键或金属离子配位键自组装的盘状液晶小分子和超分子液晶的液晶性能、掺杂了无机纳米粒子的通过氢键形成的液晶材料的光电性能及其在有机光伏器件中的应用;最后总结了不同类分子间自组装盘状液晶的性能优势。综合文献报道可知,引入分子间氢键或配位键可以更好地实现盘状液晶在特定功能材料中的应用,并且自组装的盘状液晶还可与纳米粒子形成复合物,得到具有特定功能的纳米复合材料。     

Bistable Color-Tunable Liquid Crystal Fiber by the Method of Mechanical Drawing with Synchronous Ultraviolet Polymerization

A color-tunable fiber is demonstrated to reflect colors by switching the electric field on a chiral liquid crystal (CLC) with different helical twisting powers. With the purpose of bistability and low power consumption, the mechanism of the CLC fiber proposed in this study is an electric-field-induced phase change. To maintain the balance of wearable flexibility and mechanical stability, the liquid crystal fiber is constructed by the method of mechanical drawing with synchronous ultraviolet polymerization. To be a typical 1D structure, the central core of the CLC fiber is made of an aluminum wire, which is used to load the driving voltage as well as a mechanical support. In addition, there are three claddings surrounding the central core: the color-tunable cladding filling with CLC material, the polymer cladding to anchor the liquid crystal, and the outer transparent electrode cladding. Bistable color change is realized by switching two given voltages corresponding to the planar state (P-state) and focal conic state (FC-state). Furthermore, to knit N fibers together, 2^N colors can be realized by applying electric voltages to the fiber bundle.