碟状胶体：软物质的新兴前沿

回顾了微纳米碟状胶体的研究发展近况,侧重于合成、自组装和它们在软凝聚态物质及材料科学中的角色.首先讨论了各种合成碟状胶体的方法, 包括选择性表面活性剂吸附下的纳米晶体生长、受控沉淀、剥离层状结构化合物、液晶乳液形状变化等等.介绍了这些碟状胶体颗粒在液晶相的形成和悬浮液流变性质等方向的研究应用.特别要提到的是碟状颗粒-聚合物纳米复合材料,如尼龙黏土混合材料、α-ZrP-环氧树脂等在先进功能材料工程中的广泛应用,以及研究人体红细胞的流动性质和形变性质对医疗研究的重大意义.     

Novel WV film for wide‐viewing‐angle TN‐mode LCDs

Abstract— A new optical compensation film refered to as WV‐EA film for TN‐mode TFT‐LCDs has been developed, resulting in higher contrast ratio, wider‐viewing‐angle characteristics, and improved color shift than their predecessors, especially in the horizontal direction. These features of the new WV film were achieved as a result of haze reduction and optimizing the optical characteristics of the polymerized discotic material layer and TAC film. These features are suitable for large‐sized and wide‐aspect‐ratio LCD monitors and TVs.     

基于异烟酸酯类衍生物的超分子盘状液晶构建

将异烟酸酯类棒状小分子代替苯乙烯基吡啶作为质子受体;与对称型盘状质子供体间苯三酚形成了氢键复合超分子盘状液晶结构。通过红外光谱和变温红外光谱表征了氢键的存在及稳定性,并通过POM和DSC研究了复合体系的相转变行为,通过变温XRD详细表征了中间相结构。研究表明,酯键代替乙烯基链接键能够在不影响分子间氢键稳定性的情况下降低体系的有序度,从而得到有序度较低的盘状向列相中间相。     

Stable,Low‐Temperature Discotic Nematic Superstructures by Incorporating a Laterally Substituted Sidearm in Hexakis(phenylethynyl)benzene Discogens

A new strategy for preparing room‐temperature discotic nematic materials is proposed and developed stepwise to improve various discotic nematic properties. This approach replaces one sidearm of the discotic hexakis(4‐hexyloxyphenylethynyl)benzene with a tris(alkoxy) sidearm, 1‐ethynyl‐2,3,4‐tris(hexyloxybenzene), to lower transition temperatures, manipulate discotic nematic ranges, and preserve the discotic nematic superstructure while preventing column formation. Although symmetry considerations play a role in the resulting mesogenic properties, steric hindrance and van der Waals interactions are ascribed to the superior discotic nematic properties of the newly prepared discogens containing a laterally substituted sidearm.     

The Mobility and Decay Kinetics of Charge Carriers in Discotic Hexabenzocoronenes

The temperature dependence of the mobility and decay kinetics of charge carriers in discotic hexa‐peri‐hexabonzocoronene derivatives has been measured using the pulse‐radiolysis time‐resolved microwave conductivity technique (PR‐TRMC). For both the racemic and chiral dimethyloctyl, and the isomeric n‐decyl substituted derivatives, the mobility decreases at the crystalline solid (K)–liquid crystalline (Col) transition from 0.5±0.1 to 0.30±0.05 cm² V^–1 s^–1 with the transition temperature ca. 30 °C lower for the branched chain compounds. The charge recombination kinetics are similar for the branched chain isomers in the Col phase but a faster decay is found for the racemic compound in the K phase. The fact that the mobility values for an asymmetrically substituted butylanthraquinone (C4 AQ) derivative are a factor of 2–3 lower than for the fully hexakis‐alkyl substituted compounds is attributed to the similar intracore mobilities for holes and electrons in the latter materials and the electron localization on the AQ moiety in the former. Charge recombination is found to be orders of magnitude faster in the Col phase of the C4 AQ derivative than in the K phase, this is attributed to the motional freedom of the AQ^– group in the liquid‐crystalline phase.     

盘状液晶的性能及应用

简要介绍了盘状液晶的基本概念、分子结构和相态,综述了盘状液晶的分子结构对相的影响、自组装性能、电导性能、光学性能、磁学和铁电性能方面的最新研究进展.盘状液晶柱状相拥有高的有序性和电荷传输速率,作为新型有机半导体材料具有广阔的应用前景.最后,系统概述了盘状液晶材料的应用,并指出了盘状液晶在应用方面存在的问题以及解决问题的方法和建议.     

Elasticity of hexagonal liquid crystals

An investigation of the elastic properties of hexagonal phases of typical liquid crystal samples on an ordered hexagonal discotic hexa‐n‐octyloxytriphenylene (C₈HET), a disordered one a triphenylene hexa‐n‐dodecanoate (C₁₁HAT) and a hexacatenar phasmid was carried out. Characterization of their mechanical stability and analysis of light scattering were used; the same results were obtained for the three samples in spite of the differences in their molecular shapes and molecular orders in columns. From the instability of undulating columns submitted to a dilative strain normal to columns, we deduced an anomalously large value of the correlation length m (m ≈ 0.1 µm), compared to that of the smectic liquid crystals (m ≈ 20 Å). Results from depolarized Rayleigh scattering showed that, although consisting of one‐dimensional liquid‐like structures, the studied samples in their hexagonal phases behaved elastically like three‐dimensional solids. Considering the differences in molecular shapes and orders, this elastic behaviour was attributed to regular defects. Therefore, one can probably generalize this elastic behaviour as being due to the columnar hexagonal structure. © 2001 Society of Chemical Industry