一类新的刚性链侧链型液晶高分子的合成

以自由基聚合方法，合成了一系列含有三个苯环通过酯键相联的液晶性单体及其聚合物．在这类新的液晶高分子中，刚性液晶基元不通过柔性间隔基而直接竖挂在聚甲基丙烯酸酯大分子主链上．这些高分子有很高的玻璃化转变温度，表明其分子链刚性较大，因而代表了一类新的刚性链侧链型液晶高分子．它们的液晶行为用ＤＳＣ、偏光显微镜和Ｘ－光衍射进行了表征．发现所有单体和聚合物均为向列型热致性液晶．     

刚性链侧链型液晶高分子合成与研究

以自由基聚合方法，合成了一系列含有３个苯环通过酯键相联的液晶性单体及其聚合物，这类刚性液晶基元不通过柔性间隔基而直接竖挂在聚丙烯酸酯大分子主链上，具有很高的Ｔｇ·ＤＳＣ及偏光显微镜结果表明，所有的单体和聚合物均为向列型热致性液晶。     

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…     

具有串型结构的液晶高分子的研究

以2,5-二羟基-1,4-亚苯基双-(对烷氧基苯甲酸酯)和1,12-十二酰氯为单体,采用低温溶液缩聚方法,合成了液晶基元垂直于分子主链的串型结构的液晶高分子系列。通过对其液晶行为的研究,发现包括甲氧基取代在内的所有四种聚合物在DSC图和偏光显微镜上都显示液晶现象。     

STATISTICS OF A NOVEL CLASS OF LIQUID CRYSTAL POLYMERS

A novel class of the liquid crystal polymers with mesogens laterally attached to flexible main chain backbones has been synthesized recently by us. While the flexible backbones tend to take configuration of maximum entropy the mesogenic side groups tend to orientate because of the anisotropie soft dispersion forces. A mean field theory is presented to describe the competition between these two trends which makes it possible for this class of polymers to show anisotropic (liquid crystal) phase within certain temperature range where the polymer main chains and the side chain mesogens will take approximately parallel arrangement, which is different from the normal side chain liquid crystal polymers. The temperature range of the liquid crystal phase, its ordering and phase transition all depend on the flexibility of the backbone, the strengthof the anisotropic forces of the side groups and the hinge elasticity. The results show that the liquid crystalisotropic phase transition is of the first order. The phase diagram, i. e. the dependence of the transition temperature on the structure of the polymers is also given.     

Mesogen-jacketed Liquid Crystal Polymers With Mesogens of Aromatic Amide Structure

The synthesis and property of a new series of "mesogen-jacketed liquid crystal polymers" are reported. These polymers have aromatic amide structures as the mesogenic groups and are represented by poly-2,5-bis(4-methoxy- benzamido)styrene. The preliminary study on properties shows that the polymers have very high glass transition temperatures as well as very low critical concentrations for the formation of the lyotropic liquid crystal phase. The results indicate a high degree of chain rigidity. However, the liquid crystalline order of molecular organization in bulk samples disappears upon heating to the glass transition temperature as revealed by polarizing microscopy and by X-ray diffractometer. Therefore, the liquid crystalline order of these polymers forms only through solution but not through heating. This behavior is different from that of the previously studied poly-2,5-bis[(4-methoxybenzoyl)oxy]styrene and its homologs. The latter polymers are liquid crystals both lyotropically and thermotropically. © 1997 John Wiley & Sons, Ltd.     

甲壳型液晶高分子的一种非寻常热致液晶行为

根据液晶相的稳定性 ,热致性液晶有双向性和单向性之分 .前者在升温和降温过程中都能形成液晶 ,而后者只能在降温过程中形成液晶 .原因是单向性液晶的液晶相不稳定 ,清亮点Ｔｉ 低于熔点Ｔｍ .升温时 ,样品熔融后直接进入各向同性的熔体 ;降温时 ,由于结晶过程的过冷 ,冷结晶温度Ｔｃ 低于Ｔｉ,样品先从各向同性态进入液晶态 ,然后才结晶 .一般情况下 ,如果液晶化合物自身是非晶的 ,所形成的有序结构不会由于冷却而遭到破坏 .最近 ,我们在研究分子量和液晶基元末端长度对甲壳型液晶高分子液晶性影响的时候发现 ,聚 [2 ,5 双 ( 4′ 正己氧基…     

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.     

SYNTHESIS AND PROPERTIES OF NEW SIDE-CHAIN LIQUID CRYSTALLINE POLYMER WITH LATERALLY ATTACHED MESOGENS BY ESTER GROUP*

New liquid crystalline monomer, 2,5-bis[(4'-methoxyphenoxy)carbonyl]phenyl acrylate wassuccessfully synthesized. Polyacrylate with laterally attached mesogens via ester linkage was also derived.This polymer forms an enantiotropic liquid crystal phase while its monomer exhibits a metastable nematicphase with respect to the crystalline state. However, its liquid crystallinity is very low as compared to that ofpoly{2,5-bis[(4'-methoxyphenoxy)carbonyl]-styrene}.     

Synthesis of a series of novel chiral smectic C (Sc*) phase shish‐kebab type liquid crystalline polymers

A series of chiral smectic C phase shish‐kebab type liquid crystal polymers was synthesized by low‐temperature solution condensation polymerization from 2,5‐bis[4‐((S)‐alkoxyl)benzoyloxy]hydroquinone and aliphatic diacylchloride. The monomers and their precursors were identified by using elemental analysis, infrared spectrum, nuclear magnetic resonance and mass spectrometry. The polymers were characterized by gel permeation chromatography, differential scanning calorimetry, thermogravimetric analysis, temperature‐variable X‐ray diffraction, polarimeter and polarizing microscope (POM) with a heating stage. All the polymers entered into liquid crystal phase when heated to above their melting temperature. The Schlieren texture and sanded texture were observed on POM. All the chiral compounds and polymers showed high optical activity. Temperature‐variable, X‐ray diffraction study together with the POM and polarimetric analysis revealed that the polymers synthesized are chiral smectic C phase. Thus, the present report provides examples of shish‐kebab type polymers that form a chiral smectic C phase. The change of the melting temperature and isotropization temperature with the variation in molecular structure was also discussed. Copyright © 2000 John Wiley & Sons, Ltd.     

聚丙烯酸[2,5-双(对甲氧基苯甲酰氧基)苄酯]及聚甲基丙烯酸[2,5-双(对甲氧基苯甲酰氧基)苄酯]的合成

周其凤等曾报道聚丙烯酸［２,５－双（对甲氧基苯甲酰氧基）节酯］［１］和聚甲基丙烯酸［２,５－双（对甲氧基苯甲酰氧基）苄酯］［２］的合成．但后来的研究发现,在合成单体的条件下出现的一种未见报道的异常反应［３］使产物成分复杂化,因此当时报道的聚合物可能不是聚丙烯酸［２,５－双－（对甲氧基苯甲酰氧基）苄酯］或聚甲基丙烯酸［２,５－双（对甲氧基苯甲酰氧基）苄酯］,而可能是共聚物．针对这一问题,我们重新设计了合成路线以避免发生上述副反应,成功地合成了丙烯酸或ａ－甲基丙烯酸［２,５－双－（对甲氧基苯甲酰氧基…     

Synthesis and characterization of mesogen‐jacketed liquid‐crystal polymers based on 2,5‐bis(4′‐alkoxyphenyl)styrene

A series of novel mesogen‐jacketed liquid‐crystal polymers, poly[2,5‐bis(4′‐alkoxyphenyl)‐styrene] (P‐n, n = 1–11), were prepared via free‐radical polymerization of newly synthesized monomers, 2,5‐bis(4′‐alkoxyphenyl)styrene (M‐n, n = 1–11). The influence of the alkoxy tail length on the liquid‐crystalline behaviors of the monomers and the polymers was investigated with differential scanning calorimetry (DSC), thermogravimetry, polarized optical microscopy (POM), and wide‐angle X‐ray diffraction (WAXD). The monomers with n = 1–4, 9, and 11 were monotropic nematic liquid crystals. All other monomers exhibited enantiotropic nematic properties. Their melting points (T_m's) decreased first as n increased to 6, after which T_m increased slightly at longer spacer lengths. The isotropic–nematic transition temperatures decreased regularly with increasing n values in an odd–even way. The glass‐transition temperatures (T_g's) of the polymers first decreased as the tail lengths increased and then leveled off when n ≥ 7. All polymers were thermally stable and entered the mesophase at a temperature above T_g. Upon further heating, no mesophase‐to‐isotropic melt transition was observed before the polymers decomposed. WAXD studies indicated that an irreversible order–order transition for the polymers with short tails (n ≤ 5) and a reversible order–order transition for those with elongated tails (n ≥ 6) occurred at a temperature much higher than T_g. However, such a transition could not be identified by POM and could be detected by DSC only on heating scans for the polymers with long tails (n ≥ 7). © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1454–1464, 2003     

一种新型侧链液晶聚合物的喇曼光谱研究

根据传统的侧链型液晶聚合物理论,在液晶基元和主链之间必须有柔性链相连。最近我们设计并合成了单体为2,3-双(对烷氧基苯甲酰氧基)苯乙烯的侧链液晶聚合物,该聚合物突破了文献[1]的理论,把液晶基元从重心位置横挂于主链之上,其间无柔性链段,只以单键相接。我们用喇曼光谱研究了该新型侧链液晶聚合物,表明它存在上述结构特点。     

手性化合物环境下制备甲壳型液晶高分子

甲壳型液晶高分子的研究是我国独创[1 ,2 ] ,已产生了积极的科学影响 .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[3] .由于庞大的液晶基元对空间的要求 ,液晶高分子主链被迫采取尽可能伸展的构象[4,5] .然而 ,至今尚不清楚主链与液晶基元之间是怎样协同作用以形成有序结构 .本文探索了在不同手性化合物环境下制备单手螺旋链甲壳型液晶高分子的可能性 .尽管最后并未获得螺旋链高分子 ,但仍取得了一些有价值的结果 .手性化合物环境分别是 ( )薄荷醇 ( 1 )作为反应溶剂、( )过氧化 二 (碳酸薄荷醇酯 ( 2 )作…     

Liquid Crystalline Properties of Side-chain Polymers Bearing the Same Mesogenic Group

The synthesis and properties of a series of new ferroelectric liquid crystal side-chain polymers with the same mesogenic side group but different polymer backbones (polyacrylate, polymethacrylate and polysiloxanes) are described. The polymorphism is studied by optical microscopy, differential scanning calorimetry and X-ray diffraction. All the monomers exhibit at least an S_A and a ferroelectric S*_C phase, as the polymethacrylate and the copolysiloxane. These two polymers and the polyacrylate exhibit also an S*_F phase. © 1997 John Wiley & Sons, Ltd.     

一系列含T-型二维液晶基元的液晶高分子配体的合成

以４,４′ （α,ω 亚烷基二酰氧）二苯甲酰氯和２,４ 二羟基 ４′ 烷氧基偶氮苯为单体,通过溶液聚合,合成了一系列新的含Ｔ 型二维液晶基元的液晶高分子配体．单体的结构通过元素分析、ＩＲ、１Ｈ ＮＭＲ和ＭＳ等方法确证．高分子配体通过ＧＰＣ、ＤＳＣ、ＴＧ、ＷＡＸＤ和偏光显微镜等方法测试表征,发现所有的高分子配体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向列型的丝状织构和纹影织构．它们的熔点（Ｔｍ）和液晶态的清亮点（Ｔｉ）随分子中末端烷氧基增大和柔性间隔段长度增加呈规律性变化．特别值得一提的是,发现末端不含取代基的高分子配体也能产生液晶态,这对该类高分子液晶态生成的机制与液晶态的织构提供了一个新的研究课题［１］．     

Photo and electrically switchable behavior of azobenzene containing pendant bent‐core liquid crystalline polymers

New class of photo and electrically switchable azobenzene containing pendant bent‐core liquid crystalline monomers ( AZBM 1, 2 , and 3 ) and their polymers ( AZBP 1, 2 , and 3 ) are reported. The synthesized precursors, monomers, and polymers were characterized by FT‐IR, ¹H, and ¹³C NMR spectroscopy. Thermal stability of polymers was examined by thermogravimetric analysis and revealed stable up to 260 °C. The mesophase transition of monomers and polymers are observed through polarized optical microscopy (POM) and further confirmed by differential scanning calorimetry (DSC). The electrically switching property of monomers and their polymers were studied by electro‐optical method. Among the three monomers AZBM 1, 2 , and 3 , AZBM 1 and 2 exhibit antiferroelectric (AF) switching and AZBM 3 exhibits ferroelectric (F) switching behavior. On the other hand, low molecular weight polymers ( AZMP 1, 2 , and 3 ) show weak AF and F switching behavior. The photo‐switching properties of bent‐core azo polymers are investigated using UV‐vis spectroscopy, trans to cis isomerization occurs around 25 s for AZBP‐1 and 30 s for AZBP‐2 and 3 in chloroform, whereas reverse processes take place around 80 and 90 s. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

含X-型液晶基元的液晶高分子的研究

以4,4′-(烷撑二酰氧)二苯甲酰氯和2,5-二羟基-1,4-苯撑双-(对乙氧基苯甲酸酯)为单体,采用低温缩聚方法,合成了含X-型液晶基元和不同柔性链长度的主链型液晶聚合物。聚合物的液晶行为用DSC、偏光显微镜和X-光衍射进行了表征。对于样品升温消光后又重新出现双折射的异常现象,初步认为是加热过程中分子量提高的结果。     

刚性侧链型液晶高分子与含二维液晶基元的液晶高分子

提出了“刚性侧链型液晶高分子”与“含二维液晶基元的液晶高分子”两个新概念。     

Synthesis and properties of reactive liquid crystal monomers and side-chain liquid crystalline polymers

Two nematic liquid crystal (LC) monomers containing double bonds in the side chain were designed and synthesised. Length of the side groups varied from 1 to 2 methylene units. The side-chain polymers were synthesised by hydrosilylation reaction. The molecular structures of the intermediates and the LC monomers were characterised by Fourier transform infrared, elemental analysis and nuclear magnetic resonance spectroscopy. The thermal phase behaviour of the monomers and polymers were investigated by differential scanning calorimetry and polar optical microscopy coupled with hot stage. The LC monomers showed only one nematic mesophase in the cooling process. And, the two polymers exhibit an enantiotroppic nematic mesophase either in the heating or in the cooling process.