分子间自组装盘状液晶材料研究进展

综述了近十年来国内外报道的分子间自组装盘状液晶的研究进展;重点阐述了通过分子间氢键或金属离子配位键自组装的盘状液晶小分子和超分子液晶的液晶性能、掺杂了无机纳米粒子的通过氢键形成的液晶材料的光电性能及其在有机光伏器件中的应用;最后总结了不同类分子间自组装盘状液晶的性能优势。综合文献报道可知,引入分子间氢键或配位键可以更好地实现盘状液晶在特定功能材料中的应用,并且自组装的盘状液晶还可与纳米粒子形成复合物,得到具有特定功能的纳米复合材料。     

The two-step mechanism of nucleation of crystals in solution

The formation of crystalline nanoparticles starts with nucleation and control of nucleation is crucial for the control of the number, size, perfection, polymorph modification and other characteristics of particles. Recently, there have been significant advances in the understanding of the mechanism of nucleation of crystals in solution. The most significant of these is the two-step mechanism of nucleation, according to which the crystalline nucleus appears inside pre-existing metastable clusters of size several hundred nanometers, which consist of dense liquid and are suspended in the solution. While initially proposed for protein crystals, the applicability of this mechanism has been demonstrated for small-molecule organic and inorganic materials, colloids, and biominerals. This mechanism helps to explain several long-standing puzzles of crystal nucleation in solution: nucleation rates which are many orders of magnitude lower than theoretical predictions, nucleation kinetic dependencies with steady or receding parts at increasing supersaturation, the role of heterogeneous substrates for polymorph selection, the significance of the dense protein liquid, and others. More importantly, this mechanism provides powerful tools for control of the nucleation process by varying the solution thermodynamic parameters so that the volume occupied by the dense liquid shrinks or expands.     

Liquid crystals from star‐like clusto‐supramolecular macromolecules

Supramolecular liquid crystals containing inorganic nanoclusters represent a promising avenue in the field of liquid crystals. The main motivation for developing these hybrid materials originates from the value‐added combination between functional properties of inorganic nano‐objects and the self‐assembly behavior of organic liquid crystal molecules. This review highlights the recent progress regarding nanocluster‐containing supramolecular liquid crystals. Important factors affecting the liquid crystalline behaviors are systematically described and summarized. The driving forces behind the molecular self‐assembly are discussed in depth. Finally, potential applications of the liquid‐crystalline nanohybrids are discussed. © 2014 Society of Chemical Industry     

具有聚集诱导发光性质的液晶材料 研究进展

介绍了四苯基乙烯类、二苯基丙烯腈类、二苯基乙炔类、聚集诱导发光分子修饰的苯并菲类以及其他的具有聚集诱导发光性质的液晶材料,重点阐述了它们的聚集诱导发光性质和液晶自组装性质,并说明了各自的构效关系。综合文献报道可知:将发光液晶材料应用在光电器件上能极大地节约成本和减少能耗。最后指出,在合成该类发光液晶材料时,需合理地利用聚集诱导发光基团和液晶基团,且研究重点应集中在此类材料发光机理的研究和应用范围的拓展上。     

镶嵌单层MoS2的生物质基硼氮共掺杂碳纳米片合成与储钠性能

基于可再生生物质在二维层状晶体表面的自组装及其与四硫代钼酸铵的化学配位作用,发展了一种镶嵌单层MoS₂纳米片的超薄硼氮共掺杂碳纳米片的制备策略。此结构中,二维纳米碳结构利于提供更大的电化学活性表面积、连续的电子传导通路并大幅缩短电子传输路径,同时实现单层MoS₂纳米结构的均匀分散;均匀镶嵌其内的单层MoS₂纳米结构则显著提升了钠离子存储容量,并加速其在充放电过程中氧化还原反应动力学速率。应用于钠离子负极材料时,此类二维复合结构表现出了优异的储钠比容量、倍率性能和循环稳定性。     

黏土及类黏土液晶材料的研究进展

黏土矿物(clay minerals)是组成黏土岩和土壤的主要矿物,它是一种含镁、铝为主的水合硅酸盐矿物.研究发现黏土矿物液晶与有机液晶材料相比,具有光、电、磁性能强,热稳定性好,价格低廉等优点.简要介绍了黏土矿物液晶材料的形成机理,概述了片层状黏土液晶材料、纤维型黏土液晶材料、类黏土矿物液晶材料的制备方法和研究现状,同时介绍了不同条件(浓度、离子强度、外电场作用、分散介质、重力作用)对黏土及类黏土分散体系相变的影响,并对黏土矿物液晶材料的应用发展前景进行了概述.     

五种新型高分子液晶研究进展及应用前景

阐述了高分子液晶的形成条件,综述了纤维素液晶、甲壳素液晶、铁电液晶、盘状液晶、卤代液晶等五种新型高分子液晶材料的结构、性能及其应用前景,并对高分子液晶的发展方向进行了展望。     

NO2 gas sensing properties of Au-functionalized porous ZnO nanosheets enhanced by UV irradiation

Porous ZnO nanosheets were synthesized by thermal evaporation. The morphology, crystal structure, and sensing properties of the ZnO nanosheets to NO₂ gas at room temperature under UV illumination were examined. Au nanoparticles with diameters of a few tens of nanometers were distributed over the ZnO nanosheets. The responses of the multiple networked nanosheet gas sensors were improved 1.8–3.3 fold by Au functionalization at NO₂ concentrations ranging from 1 to 5 ppm. Furthermore, the Au-functionalized ZnO nanosheet gas sensors showed a considerably enhanced response at room temperature under ultraviolet (UV) illumination. In addition, the mechanisms through which the gas sensing properties of ZnO nanosheets are enhanced by Au functionalization and UV irradiation are discussed.     

Electrochemical properties of graphene nanosheet/carbon black composites as electrodes for supercapacitors

Graphene nanosheet/carbon black composites were prepared by the ultrasonication and in situ reduction methods. Microstructure measurements show that most carbon black particles deposit on the edge surfaces of nanosheets by the ultrasonication method, and on the basal surfaces of nanosheets by in situ reduction method. The electrochemical performances of hybrid materials are superior to pure graphene material, demonstrating that carbon black particles as spacers ensured the high electrochemical utilization of graphene layers as well as the open nano-channels provided by three-dimensional graphene nanosheet/carbon black hybrid material. Therefore, the resulting composite is a promising carbon material for supercapacitors.     

含氟盘状液晶研究进展

近年来，在分子中引入氟原子进行改性成为材料研究的热点之一。分子中引入氟原子后，可以影响其热性能、电荷输运性能以及液晶的相行为等，最终改善材料的热、光、电和磁等性质。含氟盘状液晶由于具有较高的载流子迁移率，其合成方法和性质得到了广泛的关注。在含氟盘状液晶分子的平面核上、外围侧链或桥体上取代的氟原子均能显著改变液晶的相变性质，如提升液晶相的热稳定性和柱状相的有序度等。该文综述了近十年来具有代表性的利用氟原子改性盘状液晶的研究进展，进一步证实了氟化有利于改善液晶性质，并进一步归纳了含氟盘状分子在其他领域的应用。盘状液晶氟化后所表现出的优异性能，有助于启发科研工作者在药物合成、无机材料等领域引入含氟材料。     

Modifying Crystallinity,Morphology, and Photophysical Properties of Carbon Nitride by Using Crystals as Reactants

Here we show a general method to improve the crystallinity of carbon nitride nanosheets by using melamine crystals as reactants for the high temperature synthesis. Additionally, the crystals were calcined in a sealed ampoule, which provides a pressurized environment, yielding crystalline carbon nitride nanosheets that display altered morphology and photophysical properties compared to the reference materials. Electronic microscopy, optical and photoelectrochemical measurements prove the modifications of parameters such like band structure, charge recombination or inter-layer distance. The new growth strategy presented here opens many opportunities for the design of crystalline materials with tailored properties for different applications.     

Improvement of the Performance of Liquid Crystal Displays by Doping with Supramolecule-Protected Metal Nanoparticles

Metal nanoparticles are now creating a new class of materials that are different from either conventional bulk materials or atoms, giving one of the smallest building blocks of matter. Metal nanoparticles have various properties based on high surface area and quantum size effects. Here we focus on the application of metal nanoparticles to liquid crystal displays, which is providing a new field in science and technology. The doping of nanoparticles into liquid crystal materials induces the modification of almost all of the physical properties of the liquid crystal, causing a reduction in the response time of liquid crystal displays. These techniques may be an alternative approach for improving the properties of liquid crystals other than chemical synthesis.     

二维纳米片基复合相变储热材料研究进展

相变材料（PCMs）作为潜热储存和释放的介质,能够解决热能供需矛盾,从而缓解能源危机。纯相变材料具有能量密度高、温度范围广、能量输出稳定性强等优点,但其热导率低和在相变过程发生渗漏的缺点阻碍了其广泛的应用和发展。通过将PCMs与二维纳米片复合,PCMs热导率低和渗漏问题被有效解决。通过在导热机理方面进行详细阐述的基础上,综述了近几年来有关碳基二维纳米片、六方氮化硼（h-BN）纳米片、二硫化钼等复合储热材料的研究进展,为高性能二维纳米片基复合PCMs的设计提供一定的研究思路。     

Reconstruction and electronic properties of silicon nanosheets as a function of thickness

We have shown, using density functional theory calculations, that the properties of Si nanosheets change as a function of thickness. While Si(111) oriented nanosheets that are 0.56 nm thick (2-layers) display a novel reconstruction, classified as Si(111)-2 × 2 on both surface layers (T. Morishita, M. J. S. Spencer, S. P. Russo, I. K. Snook and M. Mikami, Chem. Phys. Lett., 2011, 506, 221), nanosheets that are up to a thickness of 1.42 nm show the Si(111)-2 × 1 surface reconstruction, that is seen on the bulk Si(111) surface, on both sides of the nanosheet. For these thicker nanosheets, the relative orientation of the π-chain structure on each surface of the nanosheet can either be the same or different, resulting in unique electronic properties. When the orientation is the same, there is a widening of the band gap, indicating that the interaction between the surface π-chains is not present when they are oriented in different directions. The electronic properties of the nanosheets approach those of the bulk by 1.42 nm thick. The variation in structural and electronic properties of Si nanosheets with different thicknesses, as shown in this study, highlights the novelty of these materials and their significance for applications in electronic device technologies.     

Programmed morphing of liquid crystal networks

A promising candidate for the development of stimuli-responsive morphing materials are based on liquid crystal polymer networks. These anisotropic materials will contract along the alignment director and expand perpendicular to it when subjected to an anisotropy-reducing stimulus, such as heat. As the liquid crystals can be aligned prior to polymerization using various alignment techniques, it is possible to create networks with programmed, complex director profiles in three dimensions. This review shows the various designs that can be implemented and the complex morphing behavior that can be achieved in liquid crystal polymer networks.     

四苯基乙烯室温液晶发光材料的制备与表征

发光液晶兼具发光性能和液晶的有序性,作为一种具有重要应用前景的功能材料而受到研究人员的广泛关注。本工作采用离子自组装法制备了一种兼具聚集诱导发光和液晶性质的四苯基乙烯衍生物(TPE-Chol)。通过吸收光谱、荧光光谱和X射线衍射等实验对TPE-Chol的光物理性质和液晶结构进行了详细研究。实验结果表明,TPE-Chol在室温状态下具有液晶结构,并且表现出典型的聚集诱导发光行为,是一种新型室温液晶发光材料,在液晶显示等领域具有潜在的应用价值。     

用液晶模板合成有序中介结构的无机材料

讨论了以溶致液晶为模板合成中孔无机材料的新方法，复合的表面活性剂一无机物组合体的结构取决于无物的性质以及它同表面活性剂的静电和立体空间的相互作用。阐明了转录作用和协同作用两种形成机制，转录合成中稳定的、预组织的有机结构被用作无机材料进行沉积的模板；协同合成中，模板是经无机前体与有机分子之间协同作用形成的有机一无机共组合体。说明了通过调节表面活性剂链长、有机添加物、实验温度和反应时间以及助溶剂来控制     

环氧树脂增韧改性新技术

综述了环氧树脂的增韧改性研究，着重介绍了热致液晶聚合物、柔性链段固化剂、无机纳米材料改性和互穿网络结构等环氧树脂增韧改性新技术。     

可逆示温材料的变色机理及应用进展

本文介绍了无机可逆示温材料和有机可逆示温材料的组成、特点以及热致变色机理等，简要阐述了无机、有机和液晶可逆示温材料在工业、农业、医药以及日常生活方面的应用，充分说明了可逆示温材料具有广阔的应用前景。     

Tube Formation in Nanoscale Materials

The formation of tubular nanostructures normally requires layered, anisotropic, or pseudo-layered crystal structures, while inorganic compounds typically do not possess such structures, inorganic nanotubes thus have been a hot topic in the past decade. In this article, we review recent research activities on nanotubes fabrication and focus on three novel synthetic strategies for generating nanotubes from inorganic materials that do not have a layered structure. Specifically, thermal oxidation method based on gas–solid reaction to porous CuO nanotubes has been successfully established, semiconductor ZnS and Nb₂O₅ nanotubes have been prepared by employing sacrificial template strategy based on liquid–solid reaction, and an in situ template method has been developed for the preparation of ZnO taper tubes through a chemical etching reaction. We have described the nanotube formation processes and illustrated the detailed key factors during their growth. The proposed mechanisms are presented for nanotube fabrication and the important pioneering studies are discussed on the rational design and fabrication of functional materials with tubular structures. It is the intention of this contribution to provide a brief account of these research activities.