新型光学活性含氰基三联苯液晶聚噻吩合成与分子构象

合成了一种含有长柔性间隔基和氰基三联苯液晶基元的发光性聚噻吩衍生物{—[thiopheneyl—CH2—COO—(CH2)6—O—terphenyl—CN]n—, PT(6)TPhCN}. 利用傅里叶变换红外(FT-IR)光谱、核磁共振(1HNMR)、差示扫描量热(DSC)仪、偏光显微镜(POM)、紫外-可见(UV-Vis)吸收光谱和荧光(PL)光谱对单体和聚合物的结构及性质进行了表征. 单体都呈现出良好的液晶性能, 由于长间隔基的存在, 聚合物PT(6)TPhCN也呈现出良好SmAd相. 氰基三联苯的存在还赋予了聚合物良好的光致发光性能, 同时, 长间隔基也有效地降低了分子间的相互作用, 进一步增强了聚合物的发光性能. 另外, 研究发现, 在未引入任何手性元素的情况下, 聚合物主链在圆二色(CD)光谱中还呈现出明显的Cotton 效应, 这可能是由于大体积液晶基元的位阻效应和取向作用, 液晶基元环绕主链进行取向的同时诱导聚噻吩主链在长程范围内呈螺旋取向.     

一类含萘环结构的聚酯酰亚胺液晶聚合物的结构与性能研究

利用Higashi芳香聚酯直接缩聚法的原理,采用分步投料的方法,以N,N′-1,6-亚己基-双苯偏三酸酰亚胺二酸(IA6)、6-羟基-乙-萘甲酸(HNA)和4,4′-二羟基二苯酮(DHBP)为单体原料,合成了一系列聚酯酰亚胺共聚物.用核磁共振(NMR)、差热分析(DSC)、偏光显微镜(PLM)、广角X射线衍射(WAXD)、热重分析(TGA)等手段对所合成的聚酯酰亚胺的液晶行为、结构以及热性能进行了表征.研究结果表明,当HNA投料量占单体总投料量高于33mol%时,所得聚合物均呈明显的向列型热致液晶特性.但是,此类液晶聚合物仅在升温过程中出现液晶的相转变,而在降温过程中并未观察到液晶的相转变行为.由DSC结果分析可知,此类聚合物具有较高的玻璃化转变温度(Tg)和较低的熔融温度(Tm),有望成为一类既具有较低加工温度又有较高使用温度的液晶聚合物材料.     

侧链接枝低聚对亚苯基亚乙烯基聚芴衍生物的合成及其电致发光性能

采用Wittig-Horner反应,将少量端基为磷脂的黄光发射客体低聚对亚苯基亚乙烯基链段(MOPV)接枝到含有醛基单体的蓝光发射主体材料聚芴的侧链上,合成了一种新型的接枝聚芴衍生物PF-g-MOPV.这种接枝聚合物具有很好的热稳定性,可溶于常用的有机溶剂.以接枝共聚物PF-g-MOPV为发光层的单层器件发射出黄绿光,色坐标为(0.30,0.57),最大发光亮度达到1550cm/m2,这说明蓝光聚芴主链向侧链MOPV进行了有效地能量转移.     

Nd/Eu混合稀土配位聚合物的原位合成及光致发光性质研究

在溶剂热条件下合成了系列混合稀土草酸配位聚合物Nd_xEu_(1-x)(C_2O_4)_(1.5)(H_2O)_3·2H_2O,配体α-酮戊二酸经过原位分解生成了草酸。利用X射线单晶衍射、傅里叶变换红外、热重、X射线粉末衍射和荧光光谱等对配位聚合物的结构、热稳定性及光致发光性能进行表征测试。研究结果表明:稀土Nd~(3+)能够替代Eu配位聚合物中的部分Eu~(3+)。当引入Nd~(3+)为3.66%时,配位聚合物中Eu~(3+)的发光发生能量转移淬灭;当Nd~(3+)为16.63%时,配位聚合物中Eu~(3+)的发光发生能量转移淬灭不明显。     

聚丙烯酸酯型高分子侧链液晶的合成及其对聚乙烯成核结晶行为的影响

基于聚烯烃用成核剂的结构特征设计合成了两种极性基团和非极性基团交替排列的乙烯基单体,并利用自由基引发聚合,制备出相应的侧链型液晶聚合物.采用元素分析、红外光谱和核磁共振氢谱对所合成单体和聚合物的结构进行了确认.并采用热失重(TGA)和差示扫描量热仪(DSC)研究了聚合物的热稳定性和相转变温度.结果表明,所合成聚合物的起始热分解温度均在337℃以上,具有优异的热稳定性;液晶相变温度区间可达186 K,具有较宽的液晶态温度范围.热台偏光显微镜(HS-POM)研究结果表明,聚合物均呈现出纹影织构,证明所合成的聚合物均为热致向列型侧链液晶高分子.采用DSC和HS-POM研究了所合成的侧链液晶聚合物对高密度聚乙烯(HDPE)异相成核结晶行为的影响.结果表明,侧链型液晶聚合物在提高HDPE结晶温度、结晶度以及降低HDPE晶粒的尺寸及分布方面均有优异的效果,是一类HDPE有效的成核剂.     

新的含T-型二维液晶基元的液晶高分子的合成

采用低温溶液聚合方法,以N-(2,5-二羟基苯)亚甲基-4-取代苯胺和不同结构的二酰氯为单体,合成了两类新的高分子。聚合物的液晶行为用DSC、偏光显微镜和X射线衍射进行了表征,发现其中一类为向列型热致液晶高分子,另一类则无液晶性。随单体结构的改变,聚合物的特性粘数、熔点(Tm)和液晶态的清亮点(Ti)均呈现规律性变化。     

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.     

不同低聚乙二醇链长的聚对亚苯基亚乙烯基类交替型发光共聚物

合成了3种分子主链由1,4二苯乙烯基苯(DSB,聚对亚苯基亚乙烯基PPV三单元的低聚物)与不同长度的离子传导型隔离链段低聚乙二醇(OEO,或聚氧乙烯)组成的交替型蓝色发光共聚物DSB二缩三乙二醇(TEO)、DSB五缩六乙二醇(SEO)和DSBPEG1500.研究了3种聚合物在其氯仿溶液中的电荷传输机理.通过多种手段考察了不同长度的OEO链段对聚合物的结晶能力、相结构以及其对锂盐溶解能力的影响,并讨论了此类材料的合理结构设计原则.以DSBTEO为发光层材料,装配了电致发光器件.     

新型聚氨酯基液晶光定向层材料的合成与性能研究

设计并合成了一种新的二醇单体 5 羟基 1 ,3 间苯二甲酸二 (2 羟基 )乙酯 [Di(2 hydroxyethyl) 5 hydroxylisophthalate,DHHI],并用各种手段对其进行了表征 .DHHI与二苯基甲烷 4 ,4′ 二异氰酸酯 (MDI)溶液聚合得到一种侧链含有酚羟基的先驱聚合物PU OH ,通过肉桂酰氯的功能化反应制备出新型光敏聚氨酯 (PU CI) .用示差扫描量热分析 (DSC) ,红外光谱 (FT IR) ,紫外可见光谱 (UV Vis)等对PU CI进行了表征 .研究表明 ,PU CI在紫外光的照射下可发生环 (2 +2 )加成反应 .PU CI经线性偏振光聚合技术 (LPP)处理制成液晶光定向层 ,采用向列型液晶 5CB组装成液晶盒 ,在偏光显微镜下可以观察到均匀的液晶取向 ,表明该聚合物膜具有很好的液晶定向能力 ,是一类具有潜在应用价值的新型液晶光定向层材料     

含噁二唑的聚(间亚苯乙烯)电致发光二极管

1990年英国剑桥大学的Burroughes等人[1]以聚(对亚苯乙烯)为发光材料制备了第一个有机聚合物电致发光二极管,该工作引起了科学工作者的极大兴趣.聚合物材料具有很好的电、热稳定性以及机械加工和成膜性能,发光亮度和效率较高,通过化学修饰可获得三原色发光.而且聚合物电致发光二极管的工作电压较低,可实现大面积平板显示和集成化.     

Study of the purifying affects of thermal annealing for polymer‐wall liquid crystal cells

The thermal annealing process was proposed to purify the pixel regions of a liquid crystal (LC) cell with polymer walls. This technique, based on thermal‐induced phase separation, successfully evicts the residual monomers from the LC volume and significantly improves electro‐optical properties of the polymer‐wall LC devices. The influence of the annealing process on the purity of LC‐rich domain and the electro‐optic properties of a LC cell was explored with a series of experiments. According to the experimental results, the annealing technique is extremely prospective for constructing flexible polymer‐wall LC display applications.     

Effect of specific rotation of chiral dopant and polymerization temperature on reflectance properties of polymer stabilized cholesteric liquid crystal cells

A series of polymer stabilized cholesteric liquid crystal (PSCLC) cells were prepared by photo‐polymerization of a cholesteric liquid crystal (Ch‐LC) mixture containing a nonreactive LC, a nematic diacrylate and a novel cholesteryl monomer. The influence of the specific rotation and concentration of the chiral dopants, and the polymerization temperature on reflection properties was investigated. The results demonstrate that the reflection band was broadened after polymerization for all the systems both left‐handed S811 and right‐handed R1011 as the chiral dopant, which is speculated to be a result of an inhomogeneous consumption of the chiral monomer within the system. Additionally, the polymer temperature plays an integral role in the observed reflection spectra, and at optimum polymerization temperature the broadband reflection effect becomes much more pronounced. Scanning electron microscopy (SEM) was used to examine the role of microscopic changes of the polymer network induced by polymerization temperature. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1562–1570, 2008     

A study on the polymer structures and electro-optical properties of epoxy-mercaptan-based polymer dispersed liquid crystal films

ABSTRACT

In this paper, polymer dispersed liquid crystal (PDLC) films based on epoxy-mercaptan system were prepared by thermal-initiated polymerization. The effects of the liquid crystal (LC) content, the proportion and the functionality of epoxy monomers on the polymer structures and electro-optical properties of the as-made PDLC films were investigated systematically. It was found that the morphologies of the polymer matrix can be altered from polymer meshes to polymer balls by increasing the LC content as well as the functionality of epoxy monomers. Accordingly, the electro-optical properties could be regulated by the morphologies of polymer networks. Especially, the as-made PDLC films with homogeneous porous structures exhibited the optimal electro-optical properties. Consequently, this work offers a meaningful approach to control the microstructures and optimize the electro-optical properties of PDLC films, which indeed can form a wonderful footstone for the wide application of PDLC.     

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.     

Dielectric relaxation spectroscopy and alignment behavior of a polymer‐dispersed liquid crystal and its component materials

The dielectric properties of a polymer‐dispersed liquid crystal (PDLC), a liquid‐crystal (LC) mixture (BL036), and three polymer matrices of PN314 containing different amounts of BLO36 were determined over a range of frequencies and temperatures and, for the LC and PDLC, over a range of voltages leading to homeotropic alignment of the LC. The overall dielectric relaxation process was a weighted sum of contributions from (1) the primary (δ) process in the LC arising from the motions of the dipoles about the short molecular axis and (2) dipole motions in the polymer matrix. The dielectric spectra were determined as a function of frequency, temperature, and, when appropriate, applied voltage. An equivalent electrical circuit was used as a working model to describe the dielectric behavior of the PDLC in the absence and presence of applied voltages. Agreement between the dielectric data and this model was achieved if a portion of the LC phase at the interface was assumed to be immobile. The director order parameter for the LC component in the PDLC was determined from dielectric measurements as the material was aligned homeotropically in an applied electric field. © 2001 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 39: 1173–1194, 2001     

手性取代聚(对亚苯基亚乙炔基-alt-间亚苯基亚乙炔基)的设计合成及其手性光性能研究

设计合成了两种主链结构相同、但取代方式不同的带有(-)-trans-桃金娘烷氧基手性侧基的规整连接聚(对亚苯基亚乙炔基-altr-间亚苯基亚乙炔基)(Myr-PMPE-1和Myr-PMPE-2),其中Myr-PMPE-1分子中手性取代基在分子链上均匀分布,而Myr-PMPE-2分子中手性取代基的分布则交替地存在局部"拥挤"和局部"松散".利用紫外-可见吸收光谱、荧光光谱和圆二色谱对两种聚合物膜的手性光性能进行了研究.结果表明,退火处理对Myr-PMPE-1膜的UV吸收和荧光光谱以及光学活性的影响都不明显,其最大不对称因子|gmax|为1.62×10-4;而退火处理对Myr-PMPE-2膜影响显著,未经退火处理或退火温度≤100℃时,Myr-PMPE-2膜几乎不显示光学活性,但当退火温度高于120℃时,随着退火温度的升高和退火时间的延长,Myr-PMPE-2膜的UV吸收和荧光光谱均稍有红移,特别是膜的光学活性显著提高,经140℃退火处理4 h后,其|gmax|可达3.07×10-3,比Myr-PMPE-1膜的高出1个数量级.     

Liquid crystal alignment properties of 2-naphthoxymethyl-substituted polystyrenes

The liquid crystal (LC) alignment properties of LC cells fabricated with films of 2-naphthoxymethyl-substituted polystyrenes with different contents of naphthoxymethyl side groups were investigated. The polymer films exhibited good optical transparency in the visible light region (400–700 nm). The LC cells made from the unrubbed films of polymers having more than 57 mol%?of 2-naphthoxymethyl containing monomeric units showed homeotropic LC alignment with a high pretilt angle of about 90^o. Good electro-optical characteristics, such as the threshold voltage, response time, voltage holding ratio and residual DC voltage were observed for the LC cells fabricated with the polymer having 100 mol%?of 2-naphthoxymethyl containing monomeric units as an LC alignment layer.     

一种带肉桂酸酯基的聚酰亚胺液晶光定向材料研究

利用双酚A二胺单体(BISDA)与4,4-′(六氟异丙基)-双邻苯二甲酸酐(6FDA)的缩聚反应,制备了含有侧羟基的先驱聚合物PI-OH.通过PI-OH与肉桂酰氯的官能化反应,得到接有肉桂酸酯感光侧基的双酚A型聚酰亚胺PI-CI.用红外光谱(FTIR)、氢核磁共振(1H-NMR)分析、热分析(DSC)等方法表征了上述聚合物的结构和热性能.利用紫外-可见光谱(UV-Vis)对PI-CI的感光性能进行了研究.在线偏振紫外光辐照下,上述聚合物膜表现出二色向性.二向色性的强弱随光照能量的变化存在最大值.经线性偏振紫外光(LPUV)辐射后的PI-CI薄膜能诱导液晶盒中液晶分子发生均匀的定向沿面排列.上述实验表明,该聚酰亚胺是一类具有优良性能的潜在液晶光定向材料.     

Characterisation of polymer wall formation in nematic liquid crystal devices

A phase-sensitive measurement technique is proposed to characterise polymer wall formation in a nematic liquid crystal cell. The impact of photopolymerisable monomer concentration and curing time on the electro-optical properties of polymer-wall LC cells was studied. The experimental results indicate that optimum curing conditions for constructing the polymer wall in an LC cell can be easily achieved by means of the proposed method. The structure of the polymer walls was also investigated using scanning electron microscopy and a polarising optical microscope.     

Synthesis and characterization of side chain liquid crystalline polymers exhibiting cholesteric and blue phases

A series of cyclosiloxane-based cholesteric liquid crystalline (LC) polymers were synthesized from a cholesteric LC monomer cholest-5-en-3-yl(3β) 4-(2-propenyloxy)benzoate and a nematic LC monomer butyl 4-[4-(2-propenyloxy)benzoxy]benzoate. All the polymers exhibit thermotropic LC properties and show cholesteric phases. Most of the polymers display four types of phase transition behaviour corresponding to glass transition, melting point, cholesteric phase-blue phase transition and clearing point. The mesophase temperature range of the blue phases are as broad as 20°C. The blue phase was confirmed by the apperance of planar textures and cubic packings. With an increase of non-chiral component in the polymers, the clearing point decreases slightly, while the glass transition and melting temperatures change little. In the reflection spectra of the polymer series the reflected wavelength broadens and shifts to longer wavelength with increase of the non-chiral component in the polymer systems, suggesting that the helical pitch P lengthens.