不同主链"甲壳型"高分子的合成及其液晶性研究

"甲壳型"液晶高分子(MJLCP)的概念是周其凤等[1]在1987年首次提出的,随后分别被文献[2～8]所证实.由于液晶基元对空间的要求,液晶高分子主链采取尽可能伸展的构象.虽然它们在化学结构上属于侧链型,但在分子形态上更接近于主链型液晶高分子,但至今尚不清楚其产生液晶性的原因.     

侧基甲壳效应和甲壳型液晶高分子

侧链液晶高分子体系里,液晶基元可以通过尾接或腰接的方式与主链相连.一般认为,在液晶基元与主链间插入一段长度合适的＂柔性间隔基＂可有效实现主、侧链间的动力学去偶合,从而有利于侧基液晶基元之间的有序排列.作为一类特殊的腰接型侧链液晶高分子,甲壳型液晶高分子中体积较大的侧基（如棒状液晶基元）通过非常短的间隔基或仅通过一个碳-碳键直接横挂至主链上,这导致了强烈的甲壳效应,使得主链被迫伸展.因此,可从与＂柔性间隔基＂完全不同的角度出发,充分利用主链和侧基间的偶合作用,设计甲壳型液晶高分子.本文综述了腰接型侧链液晶高分子中的侧基甲壳效应、甲壳型液晶高分子中由主链与侧基相互作用所导致的特殊构象以及液晶相结构.研究表明,侧基甲壳效应在调控甲壳型液晶高分子的形状、尺寸以及螺旋结构等方面有重要作用.甲壳型液晶高分子可作为刚-柔嵌段共聚物的刚性链段,也可作为主/侧链结合型液晶高分子的主链部分参与到多层次分级超分子有序结构的构筑之中.     

含1,3,4-噁二唑甲壳型液晶聚合物的合成与表征

甲壳型液晶聚合物（mesogen-jacketed liquid crystal polymer,MJLCP）是1987年由周其凤教授[1]首先提出的概念.从化学结构看,甲壳型液晶聚合物属于侧链型,由烯类单体经链式聚合制得,容易得到高分子量的产物,具有一般柔性侧链型液晶聚合物的一些优点.但是与柔性侧链型液晶聚合物不同的是,MJLCP分子中的刚性液晶基元是通过腰部或重心位置与主链相联结的,在主链与刚性液晶基元的侧基之间只有很短或者没有柔性间隔基.由于在这类液晶聚合物的分子主链周围空间内刚性液晶基元的密度很高,分子主链被由液晶基元形成的外壳所包裹并被迫采取相对伸直的刚性链构象.因此,这类液晶聚合物又和主链型刚性链液晶聚合物相似,具有较明显的链刚性.近年来,周其凤课题组围绕甲壳型液晶聚合物深入开展了分子设计与合成、分子结构与性能等多方面的研究.其中,设计合成具有特定功能的甲壳型液晶聚合物是在以往研究工作和学科交叉融合的基础上发展起来的一项新的研究工作.将一些有特殊功能的基团引入到甲壳型液晶聚合物中会使其具有崭新的特性.     

甲壳型液晶高分子30周年专辑前言

<正>《高分子学报》于2017年先后出版了超分子聚合物专辑、庆祝颜德岳院士80华诞专辑、庆祝《高分子学报》创刊60周年专辑,以及钱人元先生诞辰100周年纪念专辑,迎来了回顾历史和展望未来的发展新阶段.本期是为纪念甲壳型液晶高分子30周年而出版的专辑.传统的液晶高分子有主链型和侧链型之分.前者的液晶基元在高分子主链     

含手性三联苯腰接型液晶聚乙炔的合成及其“甲壳效应”

设计、合成了一种新单体,并由[Rh(nbd)Cl]2/Et3N(nbd =2,5-降冰片二烯)催化聚合反应制备了一种具有较高相对分子质量(质均相对分子质量为30300)的含手性三联苯液晶聚乙炔PAM3OCO(TPh)(OR*)2{一[(CH=C(CH2)3OCO-terphenyl(OR*)2]n—,R*=(S)-2-甲基丁基}.由于手性基团和三联苯液晶基元的引入,单体具有互变手性近晶C相,而聚合物则呈现互变的手性近晶A相液晶行为.三联苯液晶基元以重心位置连接于聚合物主链并围绕主链所产生的“甲壳效应”赋予了聚合物很高的热稳定性(356℃)、发光性能和聚集诱导增强发光特性.其薄膜状态下的发光强度明显大于其在稀溶液状态下的发光强度,且内量子效率和外量子效率分别为0.214和0.023.紫外光激发下,聚合物在液晶状态下的发光强度明显优于溶液和薄膜状态,并且发光谱带发生了红移.     

一种新型甲壳型液晶高分子的设计与合成

甲壳型液晶高分子是我国科学家最早设计和合成、受到国际学术界广泛关注的一类新型液晶高分子[1～ 6 ] .迄今已合成出 1 0个系列 1 0 0多种甲壳型液晶高分子 ,其中多数以乙烯基氢醌 [7] 、乙烯基对苯二胺 [8] 、乙烯基对苯二甲酸 [9] 和 2 -羟基 - 5-氨基苯乙烯 [10 ] 为关键中间体 .液晶核由 3个苯环以— COO—或— CONH—连接而成 .由于— COO—和— CONH—易与阳离子和阴离子相互作用 ,故已报道的甲壳型液晶高分子都是由自由基聚合反应制得 ,而很难用离子型聚合反应合成 .本文设计合成了一类未见文献报道的小分子液晶化合物 ,由此…     

具有左手性螺旋链的两个三维钐配合物的合成、结构表征及性质研究

通过溶剂热合成法,合成了两种具有左手性双螺旋链的钐配合物,Sm(HCO2)(SO4)(H2O)(1)和KSm(H2O)(SO4)2(2)。在没有添加任何手性配体的情况下合成了含有左手性螺旋链的钐配合物1;在添加手性配体的情况下,合成了含有左手性双重螺旋链的钐配合物2。但是在化合物2中,手性配体没有进入到无机骨架中去而是起诱导手性化合物形成的作用。化合物1结晶于四方晶系P41空间群,而化合物2结晶于三方晶系P31空间群。单晶X-射线衍射分析表明:化合物1中含有两种L型[Sm-O]n螺旋链,相邻的两种螺旋链通过共用Sm(Ⅲ)进一步形成交叉的左手性双螺旋链;化合物2中存在着由[Sm-O-S1-O]n以及[Sm-O-S2-O]n形成的左手性的螺旋链,并且2个相邻的手性螺旋链通过共用Sm(Ⅲ)形成了1个二重螺旋链,2个二重螺旋链相互缠绕并通过钾离子相连在一起形成了手性双螺旋链。此外,我们还对化合物1和2的荧光性质以及二阶倍频效应进行了研究。     

侧链聚硅氧烷液晶高分子的合成与表征及应用研究

液晶高分子既具有独特的液晶性 ,又具有高分子的良好材料性能 ,引起了人们的广泛注意[1～ 9] .侧链液晶高分子大多可以作为功能材料 ,对它们的研究有很大的理论与现实意义 .以往报道的此类化合物的介晶基元大多是通过烷氧基与间隔基相连[10 ] .我们以催化活性很高的铂络和物为催化剂 ,通过硅氢加成反应制备了间隔基与介晶基元通过酰氧基相连的两种侧链聚硅氧烷液晶高分子 ,并对它们的性质进行了初步表征 .发现它们具有很好的液晶性 .已有研究表明侧链聚硅氧烷液晶在气相色谱分离结构近似的物质方面 ,具有易涂渍、选择性及热稳定性优于低分子…     

一种手性甲壳型液晶高分子的稀溶液行为及链刚性

用激光光散射和粘度法研究了一系列窄分子量分布的新的手性甲壳型液晶聚合物P1～P6的溶液行为及其链刚性.研究发现四氢呋喃是聚合物P1～P6的良溶剂.在四氢呋喃溶液中,聚合物P1～P6的特性粘数[η]和均方根旋转半径z12对重均分子量Mw的依赖关系分别是[η]=(2.75±0.05)×10-3Mw0.78±0.02和z12=(1.53±0.04)×10-2Mw0.60±0.01.按照YamakawaFujiiYoshizaki蠕虫状圆筒模型的粘度理论和BohdaneckyBushin表达式,求得聚合物的单位围长摩尔质量ML=(29.8±1.0)×102nm,构象保持长度q=(15.4±3.0)nm.q和MHS方程指数α的值说明这类在结构上属于侧链型液晶高分子的聚合物在良溶剂四氢呋喃中呈现比较伸展的刚性链构象,其链刚性与半刚性主链液晶高分子的相似.     

侧基含纳米构筑单元的甲壳型液晶高分子的多层次自组装

甲壳型液晶高分子可以呈现超分子柱或片层的链构象,因此可以作为超分子液晶基元形成多种液晶相态,如六方柱状相、柱状向列相、六方柱状向列相、近晶相等.将纳米构筑单元,如一维的二联苯、二维的苯并菲、三维的多面体低聚倍半硅氧烷(POSS)等,引入到甲壳型液晶高分子中,所得聚合物可以自组装形成在亚十纳米和近纳米尺度的多级有序结构.这些结构具有尺寸可控及单分散的优点,可望在有机光电、纳米多孔膜以及纳米光刻等领域有着广阔的应用前景.本文主要介绍了将二联苯、偶氮苯、棒状多苯结构、苯并菲和POSS基元引入到甲壳型液晶高分子中制备多级组装结构的相关工作.     

乙烯基二联苯单体的螺旋选择性自由基聚合

为了深入理解乙烯基二联苯单体自由基聚合过程中的手性传递,进行了手性单体(+)-2-[(S)-异丁氧羰基-5-(4′-己氧基苯基)苯乙烯、非手性单体2-丁氧羰基-5-(4′-己氧基苯基)苯乙烯的均聚反应及它们二者的共聚反应,探讨了聚合温度和溶剂性质对手性单体均聚物旋光活性、手性单体含量对共聚物旋光活性以及聚合反应溶剂的超分子手性对共聚物旋光活性的影响.研究发现,降低聚合温度、采用液晶性反应介质有利于得到旋光度大的聚合物;少量手性单体的引入即可诱导共聚物形成某一方向占优的螺旋构象,比旋光度随手性单体的含量增加呈线性增长;在胆甾相液晶中制备的非手性单体聚合物不具有光学活性.这些结果表明,该类乙烯基二联苯聚合物具有动态螺旋构象,其光学活性主要依赖于主链的立构规整度和侧基不对称原子的手性.     

Synthesis and mesomorphic behaviour of novel chiral nematic side chain liquid crystalline polysiloxanes

A series of novel thermotropic side chain liquid crystalline polymers was synthesized by grafting copolymerization of a mesogenic monomer, 4-allyloxybenzoyl-4′?-(4-n-alkylbenzoyl)–p-benzenediol bisate and a chiral monomer, menthyl undecylenate. The mesogenic monomers exhibited nematic threadlike textures during heating and cooling. The polymers showed thermotropic liquid crystalline properties with a broad mesomorphic region over a range of 100°C. The polymers exhibited a cholesteric mesophase with a colourful Grand-Jean texture when the content of chiral units was greater than 15?mol?%; the others exhibited nematic threadlike textures. All of the polymers were thermally stable over 300°C, and most were laevorotatory as the chiral monomer.     

Synthesis and properties of poly(acrylamide)s containing both long chain alkyl groups and phosphatidylcholine analogues in the side chains

A series of new phospholipid analogous acrylamide monomers ( 4a–e ) containing long alkyl chains as hydrophobic groups and containing phosphatidylcholine analogues as hydrophilic group were synthesized in high yields. The homopolymerizations and copolymerization ( 4b with 4e ) were carried out in the presence of a radical initiator. The structures and thermal properties of these polymers were investigated by x-ray diffraction analysis, DSC, and polarizing microscopy measurements. It has been revealed that these homopolymers ( 5b, 5c , and 5d ) which bear saturated long-hydrocarbon chains in the side chains exhibited not only orderly stacked bilayer structures at room temperature but also clear liquid crystalline behavior within a wide temperature range. The viscosity behavior of all polymers was found similar to usual polyelectrolytes in porlar solvent. The polymers obtained were also characterized by ¹H-NMR, IR, and melting point, respectively. © 1996 John Wiley & Sons, Inc.     

利用混合溶剂消除ATRP反应制备多臂星形聚合物的凝胶现象

研究了带有苄氯基团的超支化聚苯乙烯引发苯乙烯和甲基丙烯酸甲酯的ATRP反应的动力学,在良溶剂氯苯中,该反应很容易发生凝胶.如果在氯苯溶剂中反应一段时间后,加入1,4-二氧六环作为不良溶剂,则能有效阻止凝胶反应,最终得到分子量超过百万的星形聚合物.     

ATOM TRANSFER RADICAL POLYMERIZATION OF 2,5-BIS[（4-HEXYLOXYPHENYL）OXYCARBONYL]STYRENE

A side-on liquid crystalline monomer, 2,5-bis[(4-hexyloxyphenyl)oxycarbonyl]styrene) (HPCS), was successfully polymerized via atom transfer radical polymerization (ATRP). The polymerization was catalyzed by CuBr/PMDETA in chlorobenzene at 90℃ with (1-bromoethyl)benzene as the initiator. The polymers have narrow MWD. It is the second example of mesogen-jacketed liquid crystalline polymer (MJLCP) prepared by ATRP.     

Synthesis and characterization of novel liquid‐crystalline copolymers containing thermally stable photochromic groups

To overcome the defects of the thermal instability of azobenzene, a series of novel photochromic, chiral, liquid‐crystalline monomers and polymers were synthesized from (+)‐camphor. The copolymerization of the photochromic monomers with comonomers was carried out. The synthesized monomers and polymers were identified with nuclear magnetic resonance, Fourier transform infrared, and elemental analysis. The composition of the copolymers was estimated with elemental analysis. The specific rotation of the chiral compounds and polymers was evaluated. The thermal stability and phases of the polymers during heating and cooling cycles were studied with differential scanning calorimetry and thermogravimetric analysis. The phases of the polymers were identified with polarized optical microscopy textures and X‐ray diffraction analysis. The distance between the layers of smectic liquid crystals was estimated from the diffraction angles. Photoisomerization of the configurational E/Z structures was investigated with an ultraviolet–visible spectrophotometer with 300‐nm ultraviolet irradiation. The thermal stability of the Z‐structural segment in the polymers was confirmed through the heating of the polymer at 70 °C for over 10 h. The photoisomerization and thermal stability of the C?C bond in the polymeric materials were demonstrated through a series of novel chiral polymers synthesized in this investigation. Both the polarity of the center part and the molecular length at the ends of the molecules were found to be necessary factors for the formation of liquid‐crystalline molecules. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2026–2037, 2007     

一系列新的席夫碱型液晶高分子冠醚的合成与表征

以 4,4′ (α,ω 烷亚甲基二酰氧 )二苯甲醛和二氨基二苯并 1 5 冠 5为单体 ,采用溶液缩聚方法 ,合成了一类新的席夫碱型液晶高分子冠醚 .一种单体采用脂族二酰氯和对羟基苯甲醛反应制备 ,另一种新的单体采用二硝基二苯并 1 5 冠 5 ,在钯 碳催化剂存在下 ,水合肼还原制备 .合成的二硝基和二氨基 二苯并 1 5 冠 5 ,未能从IR和1 H NMR谱图上区分它们的几何异构体 .聚合物的分子量不高 ,Mn 在 1 0 1 0 0～ 1 3 0 0 0之间 .单体的结构通过元素分析、IR、1 H NMR和MS等方法确证 .聚合物的性质采用GPC、DSC、TG和POM等方法进行了研究 .发现所有的聚合物加热到各自的熔融温度 (Tm)以上都能形成液晶态 ,在液晶态可以观察到向列相的丝状织构和纹影织构 .聚合物的玻璃化转变温度 (Tg)、熔融温度和各向同性温度 (Ti)随聚合物分子中柔性间隔基的变化而变化 ,它们有较高的清亮点温度和宽的液晶态温度范围 .WAXD的研究进一步证实了聚合物的液晶性     

Synthesis and characterization of side chain cholesteric liquid crystalline polymers containing isosorbide as a chiral centre

A series of new side chain cholesteric liquid crystalline polysiloxanes was synthesized by grafting copolymerization of a mesogenic monomer (M₁) and a chiral monomer (M₂). The chemical structures of the monomers and polymers obtained were confirmed by FTIR, and ¹H and ¹³C NMR spectroscopy. The mesomorphic properties were investigated by differential scanning calorimetry, polarizing optical microscopy, and X-ray diffraction. The influence of the content of the chiral unit on phase behaviour of the polymers is discussed. Monomer M₁ showed nematic and smectic phases on cooling. The polymers P₁ and P₂ showed a nematic phase, P₃-P₅ showed cholesteric Grandjean texture, and P₆ and P₇ exhibited smectic short-rod texture. The polymers containing more than 7.2 mol % and less than 28.6 mol % of the chrial unit showed an induced cholesteric phase. Experimental results demonstrated that the glass transition, melting and clearing temperatures decreased with increasing content of the chiral unit.     

Biaryl-based macrocyclic and polymeric chiral (salophen)Ni(II) complexes: synthesis and spectroscopic study.

Polymeric/oligomeric and macrocyclic (salophen)Ni(II) complexes have been synthesized starting from both an achiral biphenol dialdehyde and an optically active BINOL dialdehyde. It was found that these polysalophens contain nonplanar coordination of Ni(II) units that are paramagnetic. This is different from the previously reported (salophen)Ni(II) complexes which are square planar and diamagnetic. The nonplanar (salophen)Ni(II) units make the new polymeric Ni(II) complexes different from the helical structure proposed for chiral biaryl-based polymers containing square-planar (salophen)Ni(II) units. The copolymerization of the chiral binaphthyl monomer with the achiral biphenyl monomer demonstrates that the chirality of the binaphthyl unit is not propagated along the biphenyl polymer chain.     

Synthesis of a nano‐sized chiral imprinted polymer and its use as an (S)‐atenolol carrier in the bulk liquid membrane

In this work, nanosized chiral imprinted polymers containing (S)‐atenolol ((S)‐ATN) selective sites were synthesized by using suspension polymerization in silicon oil. (S)‐ATN, methacrylic acid, and ethylene glycol dimethacrylate were used as enantiomerically pure template, functional monomer, and cross‐linker, respectively. The prepared chiral imprinted polymers were used as the carrier elements in a bulk liquid membrane (BLM). (S)‐ATN transport capability of the chiral imprinted polymers was compared with that of the nonimprinted polymer. It was shown that chiral imprinted polymers could transport (S)‐ATN through the BLM more effectively than (R)‐ATN, whereas no difference in the facilitated transport was observed between (R)‐ATN and (S)‐ATN when using nonimprinted polymer particles as the carrier element in the BLM. A kinetic model was proposed for the transportation of (S)‐ATN through the chiral imprinted polymers based BLM. It was found that the extraction of ATN from the source to the membrane controls the chiral separation process. It was also found that the pH of source and receiving phases as well as the racemic ATN concentration in source phase had very crucial effect on the chiral separation efficiency.