SYNTHESIS AND PROPERTIES OF NEW MESOGEN-JACKETED LIQUID CRYSTALLINE POLYMERS*

Some new mesogen-jacketed liquid crystalline polymers (MJLCP) with polymer backbones, spacers, andmesogenic units of different structures were synthesized by radical polymerization. The mesomorphic behavior of thesepolymers was examined using differential scanning calorimetry (DSC) and polarizing optical microscopy (POM). Theirliquid crystallinity is influenced by the variation of polymer backbone, spacer, mesogenic unit and its terminal groups. Theresults show that 1) a more flexible polymer main-chain is more favorable to the formation of a liquid crystal phase, while 2)a flexible spacer will decrease the "Jacket Effect" and the liquid crystallinity and 3) a subtle modification of the terminalgroups on the mesogenic unit may also have a significant influence on properties of the polymers.     

SYNTHESIS OF NOVEL LIQUID CRYSTALLINE POLY(METH)ACRYLATES CONTAINING SILOXANE SPACER AND TERPHENYLENE MESOGENIC UNIT*

Novel side-chain liquid-crystalline poly(meth)acrylates were synthesized using 1-(3-hydroxyl-propyl)-3-[(4"-cyano-p-terphenyloxycarbonyl)alkyl]-1,1,3,3-tetramethyldisiloxane as the key intermediate. The polymers used a disiloxanemoiety as decoupling spacer with cyano-p-terphenyl as mesogenic unit. The products were characterized by NMR, GPC,DSC and polarizing optical microscopy. All the polymers with cyano-p-terphenyl mesogens formed a stable mesophase.However, if the mesogenic unit is replaced by cyano-p-biphenyl, the liquid crystalline character will be lost. The results alsoshowed that the decoupling is incomplete even if a complex and very flexible decoupling spacer is deliberately incorporatedto obtain the highest possible decoupling effect.     

手性聚甲基丙烯酸酯液晶聚合物的合成及相行为的研究

手性聚甲基丙烯酸酯液晶聚合物的合成及相行为的研究向前，张纪宇，张树范（中国科学院化学研究所北京１０００８０）关键词手性液晶聚合物，相行为手性侧链液晶聚合物在侧链中含有不对称碳原子的末端基，使聚合物显示Ｓｔ相．Ｓ？相层中的分子呈倾斜排列而产生自发极化．...     

TRANSITIONS AND MODRPHOLOGY OF MAIN-CHAIN LIQUID CRYSTALLINE POLYMERS WITH X-SHAPED MESOGENS

The transitions and morphology of a series of main-chain liquid crystalline polymer with X-shaped mesogens were studied by means of DSC,SALS and polarizing microscopy techniques. Aneven-odd effect was observed for samples with different size of the substituents on the mesogenends. The isotropization process was similar to that of main-chain polymers with rod-likemesogens. No crystallization was detected for specimens cooling down from their isotropic meltstate. However two of the samples may crystallize in cooling process directly from the liquidcrystalline state.     

SYNTHESIS AND PHASE BEHAVIOUR OF CHIRAL COMBINED MAIN/SIDE CHAIN LIQUID CRYSTALLINE COPOLYMERS

The synthesis and phase behaviour of chiral combined main/side chain liquid crystallinecopolymers containing pendant group constituted by chiral side group and trans-azobenzenemoiety with nitro end group are described. The formation of liquid crystalline polymorphism ofcopolymers is influenced by various contents of achiral side group.     

A NEW STRATEGY FOR THE DESIGN OF LIQUID CRYSTALLINE POLYMERS WITH FLEXIBLE AND APOLAR BUILDING BLOCKS

The synthesis and characterization of a new series of liquid crystalline polymers, poly(dicycloalkylvinylterephthalate)s, are reported. The basic building blocks of these polymers are not mesogenic by themselves. However,very stable mesophases can be generated by self-assembly of the polymer molecules. This approach suggests a novel designstrategy of liquid crystalline polymers with flexible and apolar building blocks.     

STUDY ON LIQUID CRYSTALLINITY OF POLY(N-VINYLCARBAZOLE)

The liquid crystallinity of poly(N-vinylcarbazole) was studied by using powder X-ray diffraction, polarized opticalmicroscopy, and differential scanning calorimetry. The results show that the lower molecular weight fractions of this polymerdo not form a liquid crystalline phase, while the samples of sufficiently high molecular weight do form a mesophase attemperatures above the glass transition. The lowest value of the degree of polymerization for PVK to form a stable liquidcrystalline phase was found to be in the range of 150 to 200, significantly higher than the value of 50 for most conventionalside chain liquid crystaline polymers.     

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}.     

SYNTHESES AND CHARACTERIZATION OF A NEW TYPE OF LIQUID CRYSTALLINE POLYESTERS

A new type of liquid crystalline polyesters with resorcin as one part of the mesogenic unitconnected together by polymethylene, or phenylene group, and lateral groups consisting of arigid azobenzene as another part of the mesogenic unit were synthesized by interfacialpolymerization of diacyl chlorides in 1, 2-dichloroethane and 2, 4-dihydroxy-4'-nitroazobenzen inaqueous alkaline solution. The polyester structures were confirmed by proton NMR and IRspectra. Their phase transition behavior and texture were studied by polarizing microscopy andDSC.     

嵌有长聚醚软段液晶共聚酯的合成

本文用对苯二甲酰氯、对苯二酚、己二醇及分子量为1000或2000的聚丁二醇醚,经溶液缩聚制备了嵌段聚醚聚酯,其介晶单元含量只为21.2重量％(或37.5mol％)即可在宽的温度范围内呈现明显的液晶性.~1H-NMR谱表明,产物的聚酯段呈嵌段微观序列分布.     

INFLUENCE OF BACKBONE RIGIDITY ON THE LIQUID CRYSTALLINITY OF MESOGEN-CONTAINING POLYACETYLENES

Two acetylene polymers containing cyanobiphenyl-based mesogens,poly { 10-[ ((4'- cyano-4-biphenylyl ) oxy ) carbonyl] - 1 -decyne } (PA8CN ), which has a relativelyfiexible polyalkyne backbone, and poly {[4-(((12-((4'-cyano-4-biphenylyl)oxy)dodecyl)oxy)carbonyl) phenyl]-acetylene} (PB12CN), which has a fairly rigid poly (phenylacetylene )backbone, were synthesized using respectively WCl_6 and [Rh(nbd)Cl]_2 as the catalysts.PA8CN exhibits enantiotropic interdigitated smectic A phase (S_(Ad)) over a temperaturerange as wide as ca. 100℃, whereas PB12CN is non-mesomorphic, demonstrating thatthe backbone rigidity plays an important role in determining the liquid crystallinity of thepolyacetylenes.     

LAMELLAR STRUCTURE OF THERMOTROPIC LIQUID CRYSTALLINE POLYMERS

The lamellar structure of a thermotropic aromatic polyester with flexible spacer has beenstudied by using transmission electron microscopy. It was found that the lamellar structure couldbe observed in the crystalline samples of this semirigid polymer crystallized from different states.The thickness of lamellae is around 10 nm, which is similar to that of the conventional polymersof flexible chain molecules. The molecular chains in the lamellae are oriented in the thicknessdirection as determined by electron diffraction. The possibility of molecular chains folding in the lamellae has been discussed.     

CHOLESTERIC LIQUID CRYSTALLINE CHARACTER ON THE SURFACE OF CHITOSAN/POLYACRYLIC ACID COMPOSITES*

The cholesteric liquid crystalline structure in chitosan/polyacrylic acid composite films was studied by surfacetechniques. A periodical lamellar-like structure was observed in the permanganic acid etched film sufface by both scanningelectron microscopy (SEM) and atomic force microscopy (AFM), instead of the thumb-print texture which can be detectedwith polarized optical microscopy. It is suggested that the periodical lamellar-like structure is induced by the etchingselectivity between cholesteric layers due to different molecular arrangement on the film surface. Four kinds of perpendiculardisclinations, i.e. χ→τ→λ~+, χ→λ+τ~+, χ→τ+τ~+ and χ→λ~- +λ~+, were found in the composite films from SEMobservations. The smallest periodicity of lamellar-like structure (equals to half pitch) is 20～40 nm measured with AFM.     

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 .     

SYNTHESIS AND PROPERTIES OF LIQUID CRYSTAL POLYSILOXANES WITH MESOGENIC STILBENE SIDE GROUPS*

A variety of mesomorphic side-chain polysiloxanes were synthesized by using hydrosilylation reaction withdicyclopentadienylplatinum (Ⅱ) (DPPC) as the catalyst. The mesogenic groups are derivatives of stilbene with cyano or nitrotail groups. The products were characterized by DSC, X-ray deffraction and polarizing optical microscopy (POM). All thepolymers were found to have relatively low T_g and can form a smectic liquid crystal phase.     

SYNTHESIS AND CHARACTERIZATION OF TRIAZOLE CONTAINING LIQUID CRYSTALLINE POLYMERS THROUGH 1,3-DIPOLAR CYCLOADDITION POLYMERIZATION

Liquid crystalline polymers containing 1,2,3-triazole units as linking groups have been synthesized from the monomers containing triad ester diazide and flexible dialkyne ester by 1,3-cycloaddition reaction and were characterized. Click reaction of azide and alkyne functionals catalyzed by Cu(I) yielded target polyesters with 1,2,3-triazole groups.The structure of the polymer was confirmed by spectral techniques.GPC analysis reveals that the polymers have moderate molecular weight with narrow distributio...     

SYNTHESIS AND CHARACTERIZATION OF SOME THERMOTROPIC LIQUID CRYSTALLINE POLYAMIDES

A series of novel mesogenic polyamides containing a flexible pendent side group wassynthesized by solution condensation polymerization. The new monomers, diacids and di-amines containing flexible elements of diferent lengths, were also synthesized and character-ized by ~1HNMR, mass spectroscopy and elemental analysis. The polymers were character-ized by viscosity measurements, differential scanning calorimetry (DSC), X-ray diffiactionand polarizing optical microscopy These studies revealed that polyamides containingflexible elements of a sufficient length exhibited thermotropic liquid crystalline(LC) pro-perties. The melting temperatures of this series of polymers were particularly sensitive tothe length of the flexible segment on the main chain and that of the flexible pendent esterside chain. Lyotropic LC behaviours were also observed in solution.     

AB_2型星形杂臂偶氮液晶聚合物的合成及表征

通过原子转移自由基聚合(ATRP)与ATRP衍生物化学修饰结合的方法,合成了一系列AB2型星形杂臂偶氮液晶聚合物.其中,A为聚苯乙烯,B为聚6-[4-(4′-甲氧基苯基)偶氮苯氧基己酯](PMMAZO).合成分三步进行.首先,以ATRP方法得到ω-溴聚苯乙烯活性链PS(Br).然后对PS(Br)进行化学改性,得到带两个末端溴原子的聚苯乙烯活性链PS(Br)2·最后,以PS(Br)2作为双官能团大分子引发剂,引发6-[4-(4′-甲氧基苯基)偶氮苯氧基]己酯(MMAZO)发生ATRP聚合,得到星形杂臂PS(PMMAZO)2聚合物.进一步对聚合产物进行了GPC和1H-NMR分析.结果表明合成产物是预期的星形杂臂聚合物,产物分子量可控且分子量分布狭窄.同时,以DSC和POM表征了星形杂臂聚合物的液晶性.     

SYNTHESIS AND CHARACTERIZATION OF AZO TYPE SIDE CHAIN LIQUID CRYSTALLINE POLYSILOXANE

A novel side chain liquid crystalline polymer (SCLCP) combining the polysiloxane as main chain with azo-based mesogen moieties as side chain through a flexible spacer has been synthesized by the hydrosilylation reaction using Cp_2PtCl_2 as catalyst. The phase transition behavior of both side chain monomer (AZO-C_6C_(11))and polymer (P-AZO-C_6C_(11))has been characterized via combination of hot-stage polarized microscope, DSC and X-ray diffraction methods (including temperature-variation and quenching techniques). As normal, the transition process included K→S→N→I. Some pretransition features have been observed.     

热致性液晶嵌段共聚酯的合成及表征

以对羟基苯甲酸甲酯和乙二醇为原料，通过熔融酯交换反应合成中间体（Ⅰ）：双（对一羟基苯甲酸）乙二醇酯．用溶液缩合法合成了三种不同嵌段长度的液晶嵌段共聚酯（Ｐ２４７、Ｐ２７７、Ｐ２７４）作为液晶聚合物与热塑性聚合物的“增容剂”．ＦＴＩＲ，Ｈ ＮＭＲ分析表明，嵌段共聚酯的结构和组成与分子设计基本相符；偏光显微镜证实，嵌段共聚酯在一定温度范围内为热致性向列型液晶，在较低温度为均相，在较高温度为两相结构．