聚合物稳定液晶材料研究进展

聚合物稳定液晶材料在显示传感、温度调控、智能材料等方面表现出优异性能,成为液晶材料领域的研究热点.针对向列相液晶、胆甾相液晶、铁电相液晶、蓝相液晶和其他相态液晶,分别介绍了聚合物网络在不同相态液晶中的作用,阐述了不同聚合物稳定液晶材料的特点及光学性能,综述了聚合物稳定液晶材料的研究进展,并指出了聚合物稳定液晶材料面临的...     

钙钛矿铁电纳米片诱导的P(VDF-TrFE)取向生长（英文）

半结晶的铁电聚合物在柔性电子器件中极具应用前景,控制晶相生长对其性能优化至关重要。本文通过引入少量(0.2%)单晶单畴的PbTiO_3纳米片对P(VDF-TrFE)(简称PVTF)铁电薄膜的生长进行有效调节,获得了高度取向的铁电薄膜且铁电性能得到了大幅提高。PbTiO_3纳米片铁电极化对PVTF极性分子的诱导作用可能是薄膜取向生长与性能提高的原因。     

侧基横挂偶极单元的液晶聚苯撑乙炔的合成与表征

为了制备电致偏振光发光材料, 以对苯二乙炔和2,5-二溴苯衍生物为单体,通过Sonogashira偶联反应, 采用不同Pd催化剂, 合成了一种侧基横挂偶极基团的液晶聚苯撑乙炔. 单体的化学结构通过IR, NMR和元素分析等方法得到确证. 聚合物外观为黄色粉状固体, 室温下溶于CHCl3和THF等有机溶剂. 将聚合物加热到各自的玻璃化转变温度以上都能形成液晶态并显示双向液晶性. 考察了不同催化剂对合成的聚合物的分子量、聚合物链中单体单元的结构排列以及液晶性质的影响. 结果表明, 两种不同的Pd催化剂对合成的聚合物的分子量以及液晶态温度范围影响不大, 但对聚合物的立构规整性以及聚合物的液晶态织构有较大的影响. Pd(PPh3)4作催化剂合成的聚合物中单体单元的结构排列较单一, 可以观察到清晰的液晶态织构. 以PdCl2(PPh3)2为催化剂合成的聚合物链中单体单元的结构排列相对复杂, 液晶态织构不明显. 变温X 射线衍射研究证实聚合物均为向列相液晶.     

新型光活性串型液晶共聚物合成与表征

以对苯二甲酰氯,２ ,５ 二［４ （（Ｓ） ２ 甲基丁氧基） 苯甲酰氧基］ 对苯二酚和己二醇为单体,采用溶液共缩聚的方法,合成了一系列新的光活性串型液晶共聚物．共聚物通过ＧＰＣ、ＤＳＣ、ＴＧ、ＷＡＸＤ、偏光显微镜和旋光仪等方法表征．发现所有的共聚物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沙地织构或破碎焦锥织构．通过变温Ｘ 射线衍射证明它们为手性近晶Ｃ（Ｓ＊Ｃ） 相．所有共聚物的熔点（ Ｔｍ） 和液晶态清亮点（ Ｔｉ） 随共聚物中己二醇用量的改变呈规律性变化．共聚物有很高的旋光性,在合成反应中旋光性保持．     

热致型液晶聚合物的近晶相结构研究

本文借助于不同热处理样品的WAXD研究和变温FTIR分析,从液晶态与结晶态面间距的变化,晶态、液晶态和各向同性液态下结构构象的差异出发,研究了聚合物液晶态下的近晶相结构模型。     

偶氮苯为探针的液晶聚合物聚集形态研究

利用紫外-可见光谱,对比研究了尾挂侧链液晶聚合物和腰挂侧链液晶聚合物在结晶相和液晶相转变过程中的液晶基元取向情况.研究表明,石英基材表面倾向于诱导偶氮液晶基元垂直于基材排列;观察到了在液晶态尾挂侧链液晶聚合物和腰挂侧链液晶聚合物的不同取向行为.在室温下重新结晶数天后,腰挂液晶聚合物的紫外可见光谱缓慢回复.     

近晶C(Sc)相串型液晶高分子的合成与表征

以２，５ 二（对烷氧基苯甲酰氧基） 对苯二酚和不同结构的脂族二酰氯为单体，采用低温溶液缩聚的方法，合成了一系列新的液晶基元垂直于分子主链的Ｓｃ相串型液晶高分子．单体的结构通过元素分析、ＩＲ、１Ｈ ＮＭＲ和ＭＳ等方法确证．聚合物通过ＧＰＣ、ＤＳＣ、ＴＧ、ＷＡＸＤ和偏光显微镜等方法测试表征．研究发现，所有的聚合物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纹影或焦锥织构．通过变温Ｘ 射线衍射证明它们为Ｓｃ相．所有聚合物的熔点（Ｔｍ）和液晶态的清亮点（Ｔ１）随分子中末端烷氧基增大和柔性间隔段长度增加逐渐降低，液晶态温度范围变窄．     

聚丙烯酸酯侧链液晶聚合物的合成与表征

以对羟基苯甲酸、氯乙醇和丙烯酸为主要原料,经醚化、酯化和酰氯化反应合成了中间体和含液晶基元的丙烯酸酯单体,后者经自由基聚合合成了聚丙烯酸酯侧链液晶聚合物。用偏光显微镜观察了单体和聚合物的织态结构,用DSC和IR对聚合物进行了表征。结果表明,单体和聚合物均呈现向列型液晶织态结构,聚合物在较宽的温度范围内有很好的液晶性。     

液晶性9-苯亚甲基取代芴-苯共聚物的设计合成及催化剂对聚合物链立构规整性、液晶性和光学性质的影响

为了制备适于制造有机发光场效应管的高分子材料, 通过Suzuki偶联反应, 采用不同Pd催化剂, 合成了一种侧基横挂偶极基团的液晶9-苯亚甲基取代芴-苯共聚物. 考察了不同催化剂对合成的聚合物的分子量、聚合物链中单体单元的结构排列及液晶性质和光学性质的影响. 结果表明, 2种不同的Pd催化剂对合成的聚合物的分子量影响不大, 但对聚合物链的立构规整性以及聚合物的液晶态温度范围有较大的影响. Pd(PPh3)4作催化剂合成的聚合物(PA)中单体单元的结构排列较单一, 立构规整性好, 有较宽的液晶态温度范围. Pd(OAc)2为催化剂合成的聚合物(PB)链中单体单元的结构排列相对复杂, 液晶态温度范围较窄. 聚合物链的立构规整性对其光学性质影响很大. PA具有较高的溶液及固体膜的紫外最大吸收峰值和溶液荧光效率, 其退火膜的激发和发射光谱的半峰宽均比PB的窄, 并且光学性质不随加热条件的变化而变化.     

液晶性芳香醛化合物的合成

以对羟基苯甲醛和对烷氧基联苯酰氯为原料,采用爱因宏反应,合成了一系列4-(4'-烷氧基联苯基-4-羧基)苯甲醛.化合物的结构通过元素分析、红外光谱、核磁共振和质谱等方法确证.化合物的液晶行为用示差扫描量热法、偏光显微镜和旋光仪等方法表征.结果表明,所有的化合物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手性近晶C相、近晶相、胆甾相和向列相的典型织构.含手性中心的化合物都有较高的旋光性,而且在合成反应中旋光性得到保持.随着分子末端烷氧基碳原子数增加,化合物(除2a和4a外)的熔点(T_m)和液晶态的清亮点(T_i)呈规律性变化,近晶相范围和近晶相-向列相转变温度渐增,而向列相温度范围递减,至十二烷基时,仅呈现近晶性.     

Anisotropic networks, elastomers and gels

Anisotropic networks, elastomers and gels exhibit piezoelectric, pyroelectric, ferroelectric and NLO properties of potential interest for use communication and processing technologies. The formation, properties and applications of such anisotropic, mainly liquid crystalline, networks are described. If some of the molecules in a liquid mixture contain at least two reactive groups which can be either photochemically or thermally polymerized, then crosslinked, anisotropic networks, elastomers and gels can be produced. Solid macroscopically aligned elastomers or networks can be formed as required beforehand or simultaneously by orientation of the sample. Anisotropic gels consist of a solid anisotropic network and non-covalently bonded, but strongly oriented domains of low molar mass liquid crystals. Anisotropic networks, elastomers preformed amorphous or liquid crystalline polymers incorporating additional reactive groups, which can be macroscopically oriented in the additional crosslinking reactions. Reversible networks, elastomers and gels can be prepared either non-covalently or covalently by thermally side group polymers and low molar mass molecules, liquid crystalline properties in the pure state. in many electro-optic devices for optical and gels can be prepared from liquid crystalline state and then fixed by reversible linkages between, for example, neither of which necessarily exhibit     

Aliphatic polyimides as alignment layers for surface stabilized ferroelectric smectic C liquid crystal cells

Eight aliphatic polyimides have been synthesized and tested as alignment layers for surface stabilized ferroelectic liquid crystals with a number of room temperature ferroelectric mixtures. The cone angles are used as a quantitative measure of the bistability obtained in these cells. The effect of the structure of the polyimides on the cone angles obtained is discussed. It is shown that the structure of the polymer alignment layer strongly influences the cone angle found between the relaxed states in a surface stabilized ferroelectric liquid crystal cell. Highly crystalline polymers give a larger cone angle than less crystalline homologues.     

Electromechanical effects in ferroelectric liquid crystalline polymers

Electric fields can induce mechanical vibrations in planar aligned sandwich cells of ferroelectric liquid crystals. Measurements on a polysiloxane and a polyacrylate side chain polymer proved that the electromechanical effect also exists in ferroelectric liquid crystalline polymers. The main characteristics of the electromechanical responses of these polymers are described and compared to the response of low molecular weight ferroelectric liquid crystals. According to the proposed interpretation, the vibrations in the direction parallel to both the smectic layers and cell substrates are due to coupling between the director rotation and the flow, while the resonances in the vibrations normal to the plates are connected to layer deformations.     

Chiral liquid crystalline polymers: Recent issues and perspectives

The syntheses and structures of chiral liquid crystalline polymers (LCPs) are briefly reviewed with emphasis on the established structure-property correlations. The most recent advances and future trends in their potential applications in optics and electrooptics are also outlined, with particular reference to the ferroelectric, electroclinic, piezoelectric, and nonlinear optical properties of chiral LCPs.     

钙钛矿铁电纳米片诱导的P (VDF-TrFE)取向生长

Ferroelectric polymers are particularly attractive for applications in flexible electronic devices, and controlling its crystalline phase growth is crucial for obtaining optimized ferroelectric properties. Herein we report that a very low introduction (0.2% (w)) of single-domain ferroelectric PbTiO₃ nanoplates can effectively mediate the nucleation and subsequent growth of a crystalline phase within P (VDF-TrFE) (denoted by PVTF), forming highly oriented films and significantly improving the ferroelectric properties due to an alignment of the polarization directions of the polymer and the nanoplates.     

铁电性液晶高分子的研究进展

铁电性液晶高分子的性能和合成方法，一直是国内外广泛关注与研究的热点。本文概述了铁电性液晶高分子的铁电性，光电效应，非线性光学性质，相转变及其合成的研究进展，并讨论了铁电性液晶高分子在显示和非线性光学领域中的应用前景。     

Specific features of liquid-crystalline comb-like polymers with mesogenic groups

The results of structural investigation of the new type of the liquid-crystalline thermotropic methacrylic polymers are discussed. These polymers contain mesogenic groups as models for cholesteric, nematic and smectic types of low-molecular liquid crystals. The groups are attached to the backbone through methylene bridges of various lengths. The polymers of the first group have amorphous structure; the polymers of the second group are characterized by liquid crystalline structure and those of the third group can exist in both crystalline and liquid-crystalline states, manifesting properties of enantiotropic liquid crystals. The temperatures and heats of phase transitions have been determined. It is shown that the ability to realize the liquid-crystalline state of comb-like polymers with mesogenic groups depends on and is determined by the proceess of ordering of these groups.     

非晶态与晶态的压电热电铁电高聚物

本文综述了晶态与非晶态两类高聚物的压电性,热释电性和铁电性。这些现象近年来研究得愈来愈广泛。文中以聚氯乙烯作为非晶态高聚物的例子;以PVDF及其共聚物,还有尼龙11作为晶态高聚物的例子。按照偶极子模型,高聚物一般假定需具备四个条件,就可显示出较大的压电性,热释电性和铁电性。本文探讨了上述高聚物的结构与性能,这些对识别材料是很重要的。最后,列举了PVDF及其它材料的压电常数,热释电系数和介电常数,以供读者参考。     

Epitaxial growth alignment of ferroelectric smectic C phases on rubbed polymers

Several of the polymers reported for surface alignment of ferroelectric smectic C phases in the literature are tested with a ferroelectric room temperature mixture. The results for this material and the reported findings in the literature are compared to the known crystal structure of the polymers. It is found that polymers with triclinic or monoclinic crystals give good alignment and bistability for the smectic C phase. Other crystal structures or non-crystalline polymers give a poorer performance. The mechanisms for creating a highly crystalline polymer surface are discussed, and the epitaxial growth of smectic phases on the crystalline surface is shown to be in accord with experiment.     

新型液晶聚合物的分子设计及功能

介绍了新型液晶聚合物的分子设计方法；综述了利用分子间氢键，电荷转移相互作用和防子间相互作用设计得到的新型液晶聚合物复合体系的性质和功能，概述了液晶聚合物ＬＢ膜和液晶聚合物弹性体的分子排布特征和功能，这些研究开拓了液晶聚合物研究的新领域，为液晶聚合物分子排布的控制和功能性研究提供了新方法。