具有液晶性新型聚芳醚酮的合成与表征

通过联苯二酚(介晶基元)、取代对苯二酚(破坏结晶基元)与4,4'-二氟二苯酮的亲核取代反应合成了一系列具有液晶性的新型聚芳醚酮,采用DSC、PLM和WAXD等方法对聚合物的研究表明:联苯含量为70%时聚合物表现为向列相,联苯含量为50%时聚合物出现近晶相,在外力场作用下,向列相液晶容易形成明暗交替的条带织构.     

含茋生色团聚醚的合成与热致液晶行为

β 氯乙基缩水甘油醚 (GCE)和GCE/羟丁基乙烯基醚 (HBVE)分别通过阳离子聚合、光引发共聚合 ,获得两种聚醚 ,然后再分别与 4 硝基 4′ 羟基 (NHS)反应 ,制备了两种侧链含生色团的液晶聚合物(PSEG、PSV) .用FTIR、1H NMR和EA对其化学结构及生色团含量进行了表征 ,以POM、DSC、TGA和WAXD对聚合物介晶相转变温度、织构、热稳定性及相行为进行了研究 .结果表明 ,这类聚合物属向列型热致双向性液晶 ,液晶相转变温度较低、范围较宽 ;聚合物热稳定性较好 ,开始分解温度在 30 0℃以上 .     

新型液晶材料细菌纤维素苯甲酸酯的合成与表征

以细菌纤维素（BC）为原料，通过酯化反应制备了细菌纤维素苯甲酸酯（BBC）．用红外（FT-IR）表征了产物结构，并且通过DSC、POM和WAXD研究了产物的热致液晶织构及其性能．从DSC和POM研究得知，细菌纤维素苯甲酸酯在281．7℃-356．3℃之间可以形成近晶型液晶相．     

光致变色液晶高分子的研究(Ⅰ)─含胆甾介晶基无侧链聚硅氧烷及其单体的液晶行为

用POM、DSC和WAXD研究了十一烯酸胆甾酯及含胆甾介晶基元侧链聚硅氧烷的液晶行为。单体呈现明甾相的油条及螺旋织构,单致变近晶相的扇形织构和固-固相变。均聚物显示S_A相的扇形织构。     

含对硝基偶氮苯侧基的丙烯酸酯类液晶聚合物的超分子结构

利用DSC、偏光显微镜和广角X射线衍射(WAXD)等手段研究了含对硝基偶氮苯侧基的丙烯酸酯类均聚物HP_n(n=3,4.6)及其与丙烯酸的共聚物P_n(n=3,4,6,8)的相行为,结果表明:HP₆可形成向列型液晶相,其相态特征可表示为:T_g,308.9K、T_KN342K、T_NI401K,HP₃和NP₄为非液晶聚合物;P_n可形成近晶型液晶相。WAXD结果指出其d/l介于1.40～1.54之间,故其液晶相具有S_Ad型分子排布特征。对共聚物P_n的变温FTIR研究表明:P_n中存在着-COOH和-NO₂的氢键作用,使介晶基团之间的各向异性相互作用增强,有利于形成更加有序和稳定的近晶型液晶相。结合WAXD和FTIR的结果,给出了P_n液晶相的分子排布模型。     

含不同柔性链的(甲基)丙烯酸酯类液晶高分子的合成及其液晶行为研究

通过改变侧链中柔性间隔基的长度,合成了一系列含有两个手性中心的侧链液晶（甲基）丙烯酸酯类聚合物.红外、核磁和GPC表征各中间体、单体及聚合物的结构和分子量.通过DSC和热台偏光显微镜系统地研究了单体和聚合物的液晶态织构.结果表明,含有六个碳的柔性间隔基的丙烯酸酯类聚合物表现为近晶SA和手性近晶SC^＊液晶相.     

含硝基偶氮苯侧基的丙烯酸酯液晶聚合物的合成、结构与性质研究(Ⅲ)——分子结构对结晶的影响

以含硝基偶氮苯侧基的丙烯酸酯液晶聚合物为研究对象,利用DSC、WAXD、偏光显微镜等手段研究了分子结构对侧链液晶聚合物结晶行为的影响.结果表明:丙烯酸酯类液晶聚合物的晶区是由介晶基团的规整排列形成的,大分子主链和柔性间隔基不参与结晶.随着柔性间隔基长度的增加,晶区分子排列有序性提高,结晶度增大;非晶共聚组分MA含量的增加,限制了介晶基团的有序排列,当MA含量超过83％后,只得到非晶共聚物.     

甲壳型液晶高分子的独特液晶行为*

通过ATRP合成了低分散度的甲壳型液晶高分子PBPCS. 用GPC测定了聚合物的分子量及其分布; 用热分析仪测定了聚合物的玻璃化转变温度; 用POM, WAXD, DSC, Rheometrics ARES流变仪等多种手段表征了PBPCS的独特液晶行为: 升温过程中, PBPCS在玻璃化转变温度之上存在一个各向同性相, 进一步升温进入液晶相——六方柱状向列相; 降温过程中, 液晶相消失, 重新进入各向同性相. 这种独特相转变发生的关键因素是熵的增加, 是一个熵驱动过程.     

新型手性液晶单体、交联剂及其弹性体的合成与表征

报道了一种含薄荷基的手性单体(MLC)、液晶交联剂(CA)及胆甾弹性体(LCE),采用FT-IR与1 H-NMR等手段表征了它们的化学结构,液晶的热性能与光学织构采用DSC、TGA、POM等仪器进行测试研究。结果表明:单体MLC呈现手性近晶C相的破碎扇形织构及胆甾相的油丝织构和焦锥织构,交联剂CA在升降温过程中均呈现典型的近晶A相的扇形织构和向列相的线状织构,而弹性体LCE呈现胆甾相的Grandjean彩色织构,为互变热致液晶聚合物,此外,轻度的化学交联并没有显著影响弹性体的液晶性质,其对应的玻璃化温度和清亮点分别是10.5℃和176.2℃。TGA表明液晶弹性体具有良好的热稳定性,热分解温度为339℃。     

含二苯并-18-冠-6酰胺型液晶冠醚钾配合物的合成和性质

合成了2个系列酰胺型液晶冠醚钾配合物，配合物的结构通过元素分析、IR、UV-Vis和AAS等方法表征。液晶行为通过DSC、POM、XRD等方法表征。实验结果表明，所有配合物均具有热致液晶性，且随分子末端烷氧基碳原子数增加，其熔点和清亮点呈规律性变化。与配体相比，配合物液晶态温度范围变宽。液晶相态类型发生改变，配体只有近晶相，而配合物既有近晶相，又有向列相。     

新型手性近晶C相液晶共聚酯的设计与合成

以对苯二甲酰氯 ,2 ,5 二 [4 ((s) 2 甲基丁氧基 )苯甲酰氧基 ]对苯二酚和乙二醇、一缩乙二醇、二缩三乙二醇、三缩四乙二醇和聚乙二醇为单体 ,采用低温溶液缩聚方法 ,合成了一系列新的手性近晶C相串型液晶共聚酯 .共聚酯通过GPC、DSC、TG、WAXD、偏光显微镜和旋光仪等方法表征 .发现所有的共聚酯加热至各自的熔点以上都能形成液晶态 ,在液晶态可以观察到近晶相的焦锥织构 ,所有的手性化合物和共聚酯都有较高的旋光性 .通过变温X 射线衍射研究结合偏光显微镜观察和旋光分析证明它们为手性近晶C相 .所有共聚酯的熔融温度 (Tm)和各向同性温度 (Ti)随共聚酯中不同柔性链段长度的增加逐渐降低 ,液晶态温度范围变宽     

壳聚糖液晶溶液的性能

制备了聚糖液晶溶液,并采用偏光显微镜(POM)、流变仪、差示扫描量热仪(DSC)等分别对液晶织构、黏度、相转变性能进行了研究.结果表明:壳聚糖呈现典型的胆甾相液晶织构;其溶液黏度随浓度及剪切力的变化规律符合高分子液晶溶液的变化规律;在DSC升、降温曲线上分别存在吸热峰和放热峰.     

Surface Anchoring Stabilized High Strength Disclinations in Smectic C Phase of a Schiff-base Liquid Crystal

The observation of disclination cores of high strength S= -2, -3, -4, -5, -6, -7, -8 in a smectic C phase of Schiff-base type liquid crystal (LC) is reported. The results of polarizing optical microscope (POM), differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) prove that the sample exhibits smectic C phase. It is suggested that the formation of the high strength disclination is mainly ascribed to the stronger anchoring of LC molecules on the substrate due to the formation of hydrogen bonds between the pendent hydroxyl of the LC molecule and the substrate.     

含有联苯和肉桂酸酯基团的侧链液晶共聚物的合成与表征

合成了两种含有联苯刚性基元的甲基丙烯酸酯单体M1和M2,其中M1为含有可光交联的肉桂酸酯端基的单体.通过溶液自由基聚合,得到一系列含不同比例M1和M2单体单元的聚丙烯酸酯类侧链液晶共聚物.采用1H-NMR、FT-IR等方法对单体和聚合物的结构进行了详细表征.用示差扫描量热法、偏光显微镜以及广角和小角X-射线衍射对单体和聚合物的液晶性进行了研究.结果表明,末端为肉桂酸酯基团的单体M1无液晶性,其均聚物P1有微弱的液晶性,而端基为正丁基的单体M2及其均聚物P9则表现出近晶相液晶行为.共聚物P2~P5均为向列型液晶,P6~P9则为近晶型液晶.随在聚合物中M2单体含量的增加,共聚物的玻璃化转变温度、熔点及清亮点温度均呈现增加趋势.     

新型侧链液晶M5MPP/MMEANB高聚物的合成与表征

以4,4'-二羟基联苯、4-硝基苯胺、二溴己烷、甲基丙烯酸、氯代乙醇为原料合成了单体甲基丙烯酸[5(4'-甲氧基联苯4氧基)戊基]酯(M5MPP)、4-硝基偶氮苯基甲基-2-甲基丙烯酸酯基乙胺(MMEANB),并完成了单体的聚合和共聚,得到了含有非线性光学活性基团(NLO)的侧链液晶高分子,对其结构进行了表征.结果表明,均聚物PM5MPP及共聚物(M5MPP/MMEANB)属双向液晶高分子;PMMEANB属于非晶性高分子.证实了分子间吸电子与给电子基团相互作用有利于提高液晶高分子热稳定性,共聚物(M5MPP/MMEANB)具有较宽的液晶相温度范围.     

Influence of a liquid crystalline block on the microdomain structure of block copolymers

We report on the phase behavior and microdomain structure of two types of diblock copolymers containing a liquid crystal (LC) block joined to a flexible coil block. Consideration of the symmetry groups of the liquid crystalline phases and of the block copolymer microdomain structures provides a rationale for predicting the possible types of liquid crystalline block copolymer morphologies. Both previously reported and newly discovered structural types are identified. Possible organizational schemes are developed for the mesogens and periodic disclination defects with respect to the intermaterial dividing surfaces separating the liquid crystalline and flexible coil domains. The first type of copolymer investigated has a rod-like LC block whereas the second type copolymer has a side chain LC block. Five different rod-coil diblocks based on poly(hexyl isocyanate-b-styrene) P(HIC-b-S) were synthesized by anionic polymerization. Wavy lamellae, zig-zag and arrowhead microdomain morphologies corresponding to smectic-C and smectic-O structures were observed depending on the composition. These layered phases have the director (PHIC chain axis) tilted at various orientations with respect to the layer normal. Side-chain LC diblocks based on functionalized poly(isoprene-b-styrene) P(I-b-S) were also investigated. These polymers were synthesized using polymer analogous chemistry from P(I-b-S) precursors. Three different mesogenic groups were attached to the PI blocks: one based on biphenyl benzoate and two based on azobenzene. The microdomain structures found for the functionalized poly(isoprene side-chain LC-b-styrene) P(ILC-b-S) diblocks are typical of traditional coil-coil diblocks (lamellae and cylinders). However, these morphologies possess an additional smectic layering of the mesogens within the microdomains of the LC block. In the case of the rod-coil diblocks, the transformation from an initially isotropic state to the final microphase separated solid state occurs via nematic and then smectic liquid crystalline states, whereas for the side-chain LC-coil cases, the microphase separation transition occurs prior to development of orientational order. The long-range microdomain order of LC block-coil block copolymers can extend over very large distances due to the influence of the orientational ordering of the LC block.     

Studies on the Side Chain Liquid Crystalline Copolymer Containing Nonlinear Optical Groups *

ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｏｒｇａｎｉｃｎｏｎｌｉｎｅａｒｏｐｔｉｃａｌｍａｔｅｒｉａｌｓａｒｅｃｕｒｒｅｎｔｌｙｔｈｅｓｕｂｊｅｃｔｏｆｍａｎｙｒｅｓｅａｒｃｈｐｒｏ－ｇｒａｍｓ,ｏｗｉｎｇｔｏｔｈｅｉｒｐｏｔｅｎｔｉａｌａｐｐｌｉｃａｔｉｏｎ...     

Synthesis and characterization of novel epoxy monomers and liquid crystal thermosets

Four new epoxy monomers have been synthesized and characterized as part of a program to prepare novel liquid crystal thermoset (LCT) materials. Three of the new epoxy monomers contained a biphenyl mesogen and were not liquid crystalline (LC). The remaining epoxy monomer, which contained a 1,4-dibenzoyloxybenzene mesogen, was synthesized in an overall yield of 30% and displayed a broad (83°C) nematic liquid crystalline phase. The new liquid crystalline epoxy monomer was cured at 120°C and postcured at 175°C with a stoichiometric amount of 1,4-phenylenediamine. The thermal transitions of the resulting LCT were studied by differential scanning calorimetry (DSC), polarized light optical microscopy (POM), thermomechanical analysis (TMA), and wide angle x-ray diffraction (WAXD) as a function of cure time and temperature. A process characterization diagram was constructed which shows that LCTs based on this new LC monomer can be processed in the liquid crystalline phase over a broad range of times and temperatures. Qualitative agreement with previous epoxy LCT results was found, as LCT's with smectic phases and without clearing temperatures were observed at long cure times (high crosslink densities), whereas nematic phases with clearing temperatures predominated in networks at short cure times (low crosslink densities). © 1993 John Wiley & Sons, Inc.     

一代树状碳硅烷液晶研究-端基含12个4-硝基偶氮苯介晶基元

用发散法合成了以四碳硅烷为核心，周边含12个4-硝基偶氮苯介晶基元（M5） 端基的新的一代树状碳硅烷（D1）液晶，并用元素分析、核磁共振、基质辅助激光 解吸离子化飞行时间质谱（MALDI-TOF-MS）、红外、紫外、偏光显微镜、差示扫描 量热（DSC）和X射线衍射法（WAXD）表征。介晶基元化合物（M5）显示向列相，树 状物D1显示胆甾相和S_E相。D1的液晶相相行为是K70Ch188I185Ch58S_E-48K。