含有扭曲晶界相手性液晶AEMBB的合成

根据具有强扭曲的扭曲晶界相(TGB)理论,设计并合成了一种含有TGBC*相态的手性液晶单体(+)4-(2-丙烯酰氧基)乙氧基苯甲酰氧基-[4′-(2-甲基)丁氧基]联苯酯(AEMBB).通过红外光谱分析反应物的羧酸基和羟基峰的消失判断反应完成;通过核磁共振确定各氢原子位置以确定目标产物的实现;并通过偏光显微镜和DSC研究了目标产物的液晶性能和相转变类型.结合偏光显微镜和DSC证明单体AEMBB存在胆甾、扭曲晶界和手性近晶C等多种相态,为互变液晶.     

Liquid crystal phase transitions in suspensions of polydisperse plate-like particles

Colloidal suspensions that form periodic self-assembling structures on sub-micrometre scales are of potential technological interest; for example, three-dimensional arrangements of spheres in colloidal crystals might serve as photonic materials, intended to manipulate light. Colloidal particles with non-spherical shapes (such as rods and plates) are of particular interest because of their ability to form liquid crystals. Nematic liquid crystals possess orientational order; smectic and columnar liquid crystals additionally exhibit positional order (in one or two dimensions respectively). However, such positional ordering may be inhibited in polydisperse colloidal suspensions. Here we describe a suspension of plate-like colloids that shows isotropic, nematic and columnar phases on increasing the particle concentration. We find that the columnar two-dimensional crystal persists for a polydispersity of up to 25%, with a cross-over to smectic-like ordering at very high particle concentrations. Our results imply that liquid crystalline order in synthetic mesoscopic materials may be easier to achieve than previously thought.     

Liquid crystal 'blue phases' with a wide temperature range

Liquid crystal 'blue phases' are highly fluid self-assembled three-dimensional cubic defect structures that exist over narrow temperature ranges in highly chiral liquid crystals. The characteristic period of these defects is of the order of the wavelength of visible light, and they give rise to vivid specular reflections that are controllable with external fields. Blue phases may be considered as examples of tuneable photonic crystals with many potential applications. The disadvantage of these materials, as predicted theoretically and proved experimentally, is that they have limited thermal stability: they exist over a small temperature range (0.5-2 degrees C) between isotropic and chiral nematic (N*) thermotropic phases, which limits their practical applicability. Here we report a generic family of liquid crystals that demonstrate an unusually broad body-centred cubic phase (BP I*) from 60 degrees C down to 16 degrees C. We prove this with optical texture analysis, selective reflection spectroscopy, K?ssel diagrams and differential scanning calorimetry, and show, using a simple polarizer-free electro-optic cell, that the reflected colour is switched reversibly in applied electric fields over a wide colour range in typically 10 ms. We propose that the unusual behaviour of these blue phase materials is due to their dimeric molecular structure and their very high flexoelectric coefficients. This in turn sets out new theoretical challenges and potentially opens up new photonic applications.     

含β-环糊精液晶聚合物的合成与性能

将修饰的β-环糊精衍生物单-(6-丙烯酰乙二氨基-6-去氧)-β-环糊精二十乙酸酯(M1)作为手性单体,4-十一烯酰氧基苯甲酰氧基-4’-乙氧基苯甲酰氧基对联苯酚双酯(M2)作为液晶单体,与聚甲基含氢硅氧烷接枝共聚,得到含β-环糊精基元的液晶聚合物P1～P7.通过FT-IR,1H NMR,DSC,POM,TGA,XRD,旋光分析等手段对所获单体及聚合物的结构、相行为等性能进行了表征与测试.结果表明,单体M1为非液晶手性单体,其比旋光度为+95.30,单体M2呈现向列相的丝状织构,聚合物P1～P7均有液晶性,它们的热稳定性良好,热失重5%时的温度均在300℃左右,随着手性单体M1含量的增加,聚合物的液晶区间变窄,比旋光度值增加.     

含氟及手性交联剂的液晶弹性体的合成与性能

合成向列液晶单体:4-((4-烯丙氧基)苯甲酰氧基)苯基-4-氟苯甲酸)酯(M1)和非液晶手性交联剂:双(4-((4-烯丙氧基)苯甲酰氧基)异山梨醇酯)(MC).按不同比例将M1和MC接枝共聚到聚甲基含氢硅氧烷上,得到含氟手性液晶弹性体PI~PVIII.用红外光谱、核磁共振表征单体和聚合物结构,用差示扫描量热仪、热失重仪、偏光显微镜及X射线衍射等手段研究其液晶性能.结果表明,含氟类短而硬的液晶基元更易被手性诱导,出现性能优异的胆甾相.其中,PI为向列型液晶,PII~PVII为出现油丝和Grandjean织构的胆甾型液晶,PVIII没有液晶性.弹性体玻璃化转变温度随着手性交联剂含量的增加先增大后减小,熔点和清亮点均呈下降趋势.所合成的液晶弹性体热稳定性好,质量损失5%时的热失重温度均在300℃以上.     

液晶纤维素及其衍生物材料的结构与性能

基于国内外最新研究文献，系统论述了液晶纤维素及其衍生物薄膜、纤维、功能分离膜、交联凝胶等材料的成型、结构与性能。指出这类液晶聚合物具有胆甾相或向列相液晶态。与各向同性态的同种材料相比，各向异性态的液晶纤维素及其衍生物材料具有更优异性能。双轴取向液晶三乙酸纤维素薄膜的拉伸强度和弹性模量分别可310MPa和6．3GPa；由液晶态干湿法纺丝所获得的高分子量纤维素纤维的抗张强度和弹性模量分别可高达2．2GPa和65GPa。液晶纤维素及其衍生物分离膜也表现出高得多的气体选择透过性能。其液晶交联凝胶中，凝胶所占质量分数高达98％，以及具有显著不同于各向同性态凝胶的液胀行为。液晶纤维素及其衍生物可望作为生产高级包装膜、功能纤维、气体分离膜、各向异性功能凝胶等的重要材料。     

手性液晶的研究 Ⅳ.光活性(+)-对-(对"-烷氧基苯甲酰氧基)-苯甲酸-对′-(2-甲基丁氧基)-苯酚酯液晶的合成和性能

合成了文题所述苯酚酯系列的十个化合物。代号(d)AmPABOB:分子式: R=CH_3、C_2H_5、n-C_3H_7—n-C_(10)H_(21)测定了它们的相变温度,确定了液晶相类型。其中R为C_1—C_3时,具有较宽的胆甾相;C_4—C_7有近晶A相;C_3—C_(10)存在手性近晶C相,且显示电滞回线,说明其具有铁电性。     

手性液晶的研究——Ⅵ.2,5-二苯基吡啶类

设计合成了(+)-2-[4-(2′-甲基丁氧基)苯基]-5-(4″-烷氧基苯基]吡啶和(+)-2-[4-烷氧基苯基]-5-[4′-(2″-甲基丁氧基)苯基]吡啶两个系列共七个手性液晶化合物。进行了结构分析,确证其结构。它们具有右旋近晶相、宽的相变温度、稳定性好等性能。     

小角X光衍射研究HPAP液晶的有序近晶相结构

本文应用小角Ｘ光衍射（位敏探测器法）研究了ＨＰＡＰ液晶所呈现的两种有序近晶相ＳｍＥ和ＳｍＢ结构。测量了近晶相的层厚及其与温度的关系。结论表明．ＨＰＡＰ液晶分子在ＳｍＥ相的层内是倾斜排列的，属于Ｐｇ空间群对称，倾斜角随着温度增加而减小；而在ＳｍＢ相的层内分子是垂直排列的，属于Ｐ６ｍ空间对称群，也因此测量了ＨＰＡＰ分子的长度为３３．６Ａ。在ＳｍＥＳｍＢ相交点附近层厚变化很大。     

一个含有端基双键的席夫碱型液晶化合物的合成与表征

合成了一个带有端烯基席夫碱液晶化合物,通过元素分析,红外光谱,紫外光谱等进行了表征。该化合物的液晶性通过带热台的偏光显微镜进行了表征,初步证明其织态结构为破扇状形态、属于近晶型结构。     

Liquid-crystal-mediated self-assembly at nanodroplet interfaces

Technological applications of liquid crystals have generally relied on control of molecular orientation at a surface or an interface. Such control has been achieved through topography, chemistry and the adsorption of monolayers or surfactants. The role of the substrate or interface has been to impart order over visible length scales and to confine the liquid crystal in a device. Here, we report results from a computational study of a liquid-crystal-based system in which the opposite is true: the liquid crystal is used to impart order on the interfacial arrangement of a surfactant. Recent experiments on macroscopic interfaces have hinted that an interfacial coupling between bulk liquid crystal and surfactant can lead to a two-dimensional phase separation of the surfactant at the interface, but have not had the resolution to measure the structure of the resulting phases. To enhance that coupling, we consider the limit of nanodroplets, the interfaces of which are decorated with surfactant molecules that promote local perpendicular orientation of mesogens within the droplet. In the absence of surfactant, mesogens at the interface are all parallel to that interface. As the droplet is cooled, the mesogens undergo a transition from a disordered (isotropic) to an ordered (nematic or smectic) liquid-crystal phase. As this happens, mesogens within the droplet cause a transition of the surfactant at the interface, which forms new ordered nanophases with morphologies dependent on surfactant concentration. Such nanophases are reminiscent of those encountered in block copolymers, and include circular, striped and worm-like patterns.     

含胆甾基偶氮液晶聚合物的合成与表征

将合成的含偶氮基团的液晶单体M与含胆甾基团的手性液晶单体N接枝到含氢甲基硅油上,得到系列手性偶氮类侧链液晶聚合物PY₁~PY₆.利用红外光谱(IR)、核磁共振谱(¹HNMR)对其分子结构进行表征,采用差示扫描量热法(DSC)、偏光显微分析法(POM)、热重分析法(TG)对其介晶性能、相行为及热稳定性进行研究.结果表明,所合成的聚合物PY₁~PY₆为互变热致液晶,均呈现胆甾相的Grandjean织构.从PY₁到PY₆ 随着偶氮单体M含量的增加,t_g呈先降后升的趋势,而t_i则缓慢下降.该系列聚合物热稳定性良好,5%热失重温度在290℃以上,液晶区间在162~189℃之间.     

含供吸电子的手性液晶聚合物的合成与性能

将有供电子基团的手性单体M1和含吸电子基团的单体M2接枝到聚甲基含氢硅氧烷上,得到系列手性液晶聚合物,其中,手性单体的摩尔分数为0～50%.通过红外光谱(IR)、核磁共振谱(1HNMR)、差示扫描量热法(DSC)、偏光显微分析法(POM)、热失重分析法(TGA)、X射线分析等手段研究了手性单体的含量及供吸基团对侧链胆甾型液晶聚合物性能的影响.结果表明P1～P8都有液晶性且为胆甾型液晶聚合物,系列液晶聚合物的tg随手性单体含量的增加而增加,ti随手性单体含量的增加而降低,P1～P8具有较宽的液晶相范围,热稳定性较高,质量损失5%时的热失重温度均在300℃左右.     

液晶p-BDAB的合成及其在不饱和聚酯树脂改性中的应用

以烯丙基溴、对羟基苯甲酸乙酯和联苯二酚为原料合成了二对烯丙基醚苯甲酸联苯二酚酯.用DSC,1H-NMR,FTIR,POM和XRD对其进行了表征,结果表明:该化合物熔点为185℃,在178℃出现一个晶型转变,清亮点为278℃,为近晶型液晶.以此液晶化合物与普通不饱和聚酯(UP)共聚合固化,研究了液晶化合物用量对产物微观形态和性能的影响,结果表明:液晶化合物的加入可提高共聚物的抗冲击强度,但当液晶加入的质量分数超过8%时会产生相分离.     

在铁电液晶中形成的聚合体网络及其对液晶载体分子组合排列的影响

在灌装于未经表面处理的样品盒内处于不同状态的液晶中制备聚合体网络。液晶／单体混合物由铁电液晶和双丙烯酸单体制成。单体的聚合通过维持该混合物处在一定的液晶态的条件下经紫外线固化来完成。不同的液晶态可通过控制铁电液晶的温度来获得。双丙烯酸单体或聚合体网络的存在会导致铁电液晶载体的相变温度降低。通过光学显微镜可观察聚合体网络对铁电液晶分子组合排列的影响。结果发现：在某一液晶态中铁电液晶分子的组合排列可被在该液晶态中聚合而成的聚合体网络所稳定,双丙烯酸基聚合体网络的存在可改良铁电液晶的电光开关特性。     

光致变色液晶高分子研究（Ⅱ）──含酰氧基间隔基和苯甲酸苯酯介晶基元侧链聚硅氧烷及其单体的液晶行为

本文讨论了既氧间隔基对聚硅氧烷液晶行为的影响，它比对应的含烷氧间隔基聚合物多了向列相，并给出了十一烯－［１０］酰氧苯甲酸－４－个甲氧基苯酯及合同一个晶基元侧链聚硅氧烷的变温ｘ－射线衍射曲线、热谱图和焓、熵热力学数据．单体呈现向列相纹影织构，均聚物显示向列相微滴状和Ｓｃ相破碎扇形织构，聚合后相态数增加．     

二对烯丙基醚苯甲酸对苯二酚酯液晶的合成与表征

以烯丙基溴、对羟基苯甲酸乙酯和对苯二酚为原料合成了二对烯丙基醚苯甲酸对苯二酚酯(p-PDAB).用DSC,1H-NMR,IR,POM和XRD对其进行了表征,证明该化合物熔点为160℃,清晰点为245℃,为近晶型液晶.     

含氟液晶MB80.5(F)的结构研究

含氟有机化合物Ｃ８Ｈ１７Ｏ－ Ｏ－Ｏ－ＣＯＯ－Ｏ－Ｃ５Ｈ１１（以下简称 ＭＢ８０．５（Ｆ））呈现比较复杂的液晶相。本文对单畴的ＭＢ８０．５（Ｆ）样品，应用Ｘ光衍射技术，采用二维多丝正比位敏计数器来探测，确定了ＭＢ８０．５（Ｆ）呈现的几种液晶相的类型，及其相变温度。本文还测量了ＭＢ８０．５（Ｆ）的分子表现长度、近邻分子的间距、三种近晶相ＳＡ、和ＳＦ的层厚以及ＳＣ相的分子倾斜角与温度的变化关系。     

Colloidal ordering from phase separation in a liquid-crystalline continuous phase

Some binary mixtures exist as a single phase at high temperatures and as two phases at lower temperatures; rapid cooling therefore induces phase separation that proceeds through the initial formation of small particles and subsequent growth and coarsening. In solid and liquid media, this process leads to growing particles with a range of sizes, which eventually separate to form a macroscopically distinct phase. Such behaviour is of particular interest in systems composed of an isotropic fluid and a liquid crystal, where the random distribution of liquid-crystal droplets in an isotropic polymer matrix may give rise to interesting electro-optical properties. Here we report that a binary mixture consisting of an isotropic fluid and a liquid crystal forming the continuous phase does not fully separate into two phases, but self-organizes into highly ordered arrays of monodisperse colloidal droplet chains. We find that the size and spatial organization of the droplets are controlled by the orientational elasticity of the liquid-crystal phase and the defects caused by droplets exceeding a critical size. We expect that our approach to forming monodisperse, spatially ordered droplets in liquid crystals will allow the controlled design of ordered composites that may have useful rheological and optical properties.     

基于液晶高分子聚合物的激光防护器件

本文介绍了一种基于液晶高分子聚合物薄膜的激光防护器件,器件中的液晶高分子以螺旋结构方式排列,可以有效控制反射无偏振激光. 本工作中详细介绍了液晶高分子聚合物薄膜器件制作的过程工艺,关键材料:非手性单体、手性单体、手性掺杂剂、阻聚剂、光引发剂等的配比对器件光学性能的影响.