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丁酸壳聚糖液晶的织构研究 总被引:7,自引:0,他引:7
用偏光显微镜研究了一种新的液晶高分子-丁酸壳聚糖液晶的织构。丁酸壳聚糖能溶于十多种溶剂中形成胆甾型液晶相。指纹状织构是主要织构,此外还观察到鲜偏振场织构、滴状织构、平面织构和条带织构等,与纤维素衍生物的液晶态结构很相似。 相似文献
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本文用界面缩聚法合成聚对氧化偶氧苯酚酯系列热致性液晶高分子。并用DSC,X-光衍射和偏光显微镜对其结构和液晶相进行了表征与研究。观察液晶态织态结构,计算液晶态时分子链间距,并观察聚合物取向液晶态的结晶结构。 相似文献
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本文综述了液晶二聚体、多爪型液晶及香蕉形液晶等几类非常规液晶材料的研究进展。结合笔者近几年的研究积累,着重介绍:(1)液晶二聚体的分子结构与液晶态结构及液晶二聚体所特有的奇偶效应与近晶多形性;(2)多爪型液晶的分子结构与液晶态结构的特点及由于兼有棒状分子与盘状分子的结构特点而具备的特殊的相变性质;(3)香蕉形液晶的分子结构与液晶态结构及香蕉形液晶所特有的手性与极化序。在介绍各类液晶材料的特点及研究热点的同时,围绕分子结构与液晶态结构的关系这一主题,深入讨论了各种液晶材料形成特殊分子排列及表现出特殊物理性质的机理。 相似文献
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乙基氰乙基纤维素/聚丙烯酸复合物及大分子胆甾型液晶相的形态结构特征 总被引:2,自引:0,他引:2
对乙基氰乙基纤维素/丙烯酸胆甾型液晶溶液的液晶性,液晶态的织构特征,丙烯酸在液晶溶液中的聚合反应及在反应过程中胆甾型液晶相结构和性能的变化等方面进行了研究, 相似文献
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本文用十三烷二酸和对偶氮氧苯酚合成了具有长链柔性单元的聚十三烷二酸对偶氮氧苯酚酯。用各种方法对其液晶态性质进行了表征和研究,并与结构相似的液晶聚合物聚十二烷二酸对偶氮氧苯酚酯及聚十三烷二酸2,2′-二甲基对偶氮氧苯酚酯进行了比较,用实验数据阐明了产生相转变奇偶效应的主要原因。并由热分析数据从又一方面证实了Flory关于液晶态中各向异性相与各向同性相共存的观点。 相似文献
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Timme A Kress R Albuquerque RQ Schmidt HW 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(27):8329-8339
One of the simplest and most-versatile motifs in supramolecular chemistry is based on 1,3,5-benzenetricarboxamides. Variation of the core structure and subtle changes in the structures of the lateral substituents govern the self-assembly and determine the phase behavior. Herein, we provide a comprehensive comparison between the phase behavior and mesophase structure of a series of 1,3,5-benzene- and 1,3,5-cyclohexanetricarboxamides that contain linear and branched alkyl substituents. Depending on the substituent, different crystalline, plastic crystalline, and liquid crystalline phases were formed. The relatively rare columnar nematic (N(C)) phase was only observed in cyclohexane-based trisamides that contained linear alkyl substituents. Of fundamental interest in liquid crystalline supramolecular systems is the transition from the mesomorphic state into the isotropic state and, in particular, the question of how the order decreases. Temperature-dependent IR spectroscopy and XRD measurements revealed that columnar H-bonded aggregates were still present in the isotropic phase. At the clearing transition, mainly the lateral order was lost, whilst shorter columnar aggregates still remained. A thorough understanding of the phase behavior and the mesophase structure is relevant for selecting processing conditions that use supramolecular structures in devices or as fibrillar nanomaterials. 相似文献
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Jun Hyup Lee Hye Jin Lee Seung Jun Lee Jisun Jang Seung Hoo Yoo Jae Young Jho 《Liquid crystals》2013,40(1):112-119
New conjugated polymeric columns with a hexagonal symmetry were prepared via topochemical polymerisation of star-shaped supramolecular liquid crystals formed by hydrogen bonding between a phloroglucinol core and pyridine derivatives containing a diacetylenic group in the alkyl chain. The mesomorphic properties of the supramolecular monomer and its photopolymerisation behaviour were investigated. The supramolecular liquid crystal exhibited a rectangular columnar mesophase. Photopolymerisation of supramolecular monomer along the column axis in the liquid crystalline state provided well-ordered conjugated polydiacetylenic columns with a two-dimensional hexagonal symmetry. Fourier transform infrared and ultraviolet–visible spectroscopy affirmed that conjugated polydiacetylenes were produced by 1,4-polymerisation of the supramolecular monomer along the column axis. X-ray diffraction analysis showed that a two-dimensional columnar order in the supramolecular monomer was maintained after photopolymerisation, and that the resulting polydiacetylene had a hexagonal array of conjugated columns. Our controlled methodology provides a new route to conjugated polymeric columns with highly ordered structures by self-assembly and polymerisation of star-shaped supramolecular liquid crystals. 相似文献
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Dr. Bixin Jin Qin Li Lingjuan Hu Qianwei Liu Yiqi Chen Prof. Dr. Yunjun Luo Dr. Shumeng Chi Prof. Dr. Xiaoyu Li 《Angewandte Chemie (International ed. in English)》2023,62(18):e202219067
The self-assembly morphologies of subunits are largely governed by thermodynamics, which plays a less important role in dimensional control. Particularly for one-dimensional assemblies from block copolymers (BCPs), the negligible energy difference between short and long ones imposes great challenges in length control. Herein, we report that by incorporating additional polymers to induce in situ nucleation and trigger the subsequent growth, controllable supramolecular polymerization driven by mesogenic ordering effect could be realized from liquid crystalline BCPs. The length of the resultant fibrillar supramolecular polymers (SP) is controlled by tuning the ratio between nucleating and growing components. Depending on the choice of BCPs, the SPs can be homopolymer-like, heterogeneous triblock, and even pentablock copolymer-like. More interestingly, with insoluble BCP as a nucleating component, amphiphilic SPs are fabricated, which can undergo spontaneous hierarchical assembly. 相似文献
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Atsushi Isobe Deepak D. Prabhu Sougata Datta Takumi Aizawa Prof. Shiki Yagai 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(41):8997-9004
Beyond phenomenon, self-assembly of synthetic molecules, is now becoming an essential tool to design supramolecular materials not only in the thermodynamically stable state but also in kinetically trapped states. However, an approach to design complex self-assembly processes comprising different types of self-assembled states remains elusive. Herein, an example of such systems is demonstrated based on a unique supramolecular polymer mediated by supermacrocyclization of hydrogen-bonding π-conjugated molecules. By adding an aromatic solvent into nonpolar solutions of the monomer, spontaneous nucleation triggered by supermacrocyclization was suppressed so that isothermal supramolecular polymerization could be achieved from kinetically formed topological variants and amorphous agglomerates to afford helicoidal structures hitherto obtainable only with very slow cooling of a hot solution. By increasing the proportion of aromatic solvent further, another self-assembly path was found, based on competing extended hydrogen-bonded motifs affording crystalline nanowires. 相似文献
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Andreas Timme Roman Kress Prof.Dr. Rodrigo Q. Albuquerque Prof. Dr. Hans‐Werner Schmidt 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(27):8329-8339
One of the simplest and most‐versatile motifs in supramolecular chemistry is based on 1,3,5‐benzenetricarboxamides. Variation of the core structure and subtle changes in the structures of the lateral substituents govern the self‐assembly and determine the phase behavior. Herein, we provide a comprehensive comparison between the phase behavior and mesophase structure of a series of 1,3,5‐benzene‐ and 1,3,5‐cyclohexanetricarboxamides that contain linear and branched alkyl substituents. Depending on the substituent, different crystalline, plastic crystalline, and liquid crystalline phases were formed. The relatively rare columnar nematic (NC) phase was only observed in cyclohexane‐based trisamides that contained linear alkyl substituents. Of fundamental interest in liquid crystalline supramolecular systems is the transition from the mesomorphic state into the isotropic state and, in particular, the question of how the order decreases. Temperature‐dependent IR spectroscopy and XRD measurements revealed that columnar H‐bonded aggregates were still present in the isotropic phase. At the clearing transition, mainly the lateral order was lost, whilst shorter columnar aggregates still remained. A thorough understanding of the phase behavior and the mesophase structure is relevant for selecting processing conditions that use supramolecular structures in devices or as fibrillar nanomaterials. 相似文献
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Tu C Zhu L Li P Chen Y Su Y Yan D Zhu X Zhou G 《Chemical communications (Cambridge, England)》2011,47(21):6063-6065
A supramolecular drug delivery system has been developed via the self-assembly of a supramolecular amphiphilic polymer, which is constructed by the host-guest interaction of hydrophilic PEGylated calix[4]arene and hydrophobic photosensitizer chlorin e6. It provides a new strategy for the preparation of supramolecular polymeric micelles, and plays an important role in biological applications. 相似文献
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M. B. Palma-Vittorelli 《International journal of quantum chemistry》1989,35(1):113-124
A biological system usually operates under nonstable values of relevant parameters, such as pH, temperature, and ionic strength. The question therefore poses whether such fluctations do affect its relevant processes. Experimental studies on the role of random temperature fluctuations on functional encounters of biostructural polymer molecules, and consequent self-assembly of supramolecular structures, have evidenced an additional, noise-induced order of these structures. This type of effect is the result of nonlinearity in physical systems, and the case of a biosystem is especially interesting. As recent experiments have shown, spinodal decomposition resulting from thermodynamic instability may favor the onset of the supramolecular ordering process. If the random fluctuations of temperature are imposed in such conditions of thermodynamic instability, their ordering effect is further enhanced. 相似文献
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Supramolecular side chain liquid crystalline polymers (SCLCPs) based on poly(3-carboxypropylmethylsiloxane-co-dimethylsiloxane) (PSIX, X=100, 76, 60, 41 or 23, denoting the mole percentage of 3-carboxypropylmethylsiloxane unit in the polymer) and stilbazole derivatives have been obtained through intermolecular hydrogen bonding (H-bonding) interactions between the carboxylic acid and the pyridyl moieties. The formation of H-bonding and self-assembly results in the formation of new mesogenic units, in which H-bonds function as molecular connectors. FTIR shows the existence of H-bonding in the complexes. The polymeric complexes behave as single component liquid crystalline polymers and exhibit stable and enantiotropic mesophases. The liquid crystalline properties of the supramolecular SCLCPs were studied using differential scanning calorimetry, polarizing optical microscopy and X-ray diffraction, and were found to exhibit smectic A phases with focal-conic textures. The thermal stability of the SCLCP increases on increasing the carboxylic acid content in the polysiloxane and the concentration of the stilbazole derivative in the complex. However, the thermal stability decreases on increasing the chain length of the stilbazole derivative. The crystal phase was not formed even on cooling to the glass transition temperature of the polymeric complex. 相似文献
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Percec V Cho WD Ungar G Yeardley DJ 《Chemistry (Weinheim an der Bergstrasse, Germany)》2002,8(9):2011-2025
The synthesis of ten benzyl ether based self-assembling monodendrons containing benzo[15]crown-5 at their focal point is presented. These dendritic building blocks self-assemble either directly or via complexation with NaOTf in two-dimensional smectic B, smectic A, and p6mm hexagonal columnar (Phi(h)) and three-dimensional Pm3n cubic lattices. Retrostructural analysis of these lattices and of the lattices generated from the same monodendrons containing various other functional groups at their focal point by X-ray diffraction experiments provided for the first time a correlation between the molecular structure and the shape of the monodendron, the shape of the supramolecular dendrimer and the symmetry of the lattice. It has been shown that complexation with NaOTf provides the following five different trends: a) stabilization of the three-dimensional Pm3n cubic lattice self-organized from spherical dendrimers that are self-assembled from conic monodendrons; b) stabilization of the two-dimensional S(A) phase generated from parallel-piped monodendrons; c) no effect on the stability of the two-dimensional S(B) phase generated from parallel-piped monodendrons; d) stabilization of the two-dimensional p6mm hexagonal columnar phase self-organized from cylindrical supramolecular dendrimers that are self-assembled from tapered monodendrons; and e) destabilization of the two-dimensional p6mm hexagonal columnar phase self-organized from cylindrical supramolecular dendrimers self-assembled from half-disc monodendrons. Mechanisms of NaOTf mediated self-assembly processes were suggested. These monodendritic crown ethers and their NaOTf complexes provide the largest diversity of liquid crystalline phases encountered so far in any library of supramolecular dendrimers. 相似文献