共查询到20条相似文献,搜索用时 15 毫秒
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Michel Mitov 《Advanced materials (Deerfield Beach, Fla.)》2012,24(47):6260-6276
The cholesteric‐liquid‐crystalline structure, which concerns the organization of chromatin, collagen, chitin, or cellulose, is omnipresent in living matter. In technology, it is found in temperature and pressure sensors, supertwisted nematic liquid crystal displays, optical filters, reflective devices, or cosmetics. A cholesteric liquid crystal reflects light because of its helical structure. The reflection is selective – the bandwidth is limited to a few tens of nanometers and the reflectance is equal to at most 50% for unpolarized incident light, which is a consequence of the polarization‐selectivity rule. These limits must be exceeded for innovative applications like polarizer‐free reflective displays, broadband polarizers, optical data storage media, polarization‐independent devices, stealth technologies, or smart switchable reflective windows to control solar light and heat. Novel cholesteric‐liquid‐crystalline architectures with the related fabrication procedures must therefore be developed. This article reviews solutions found in living matter and laboratories to broaden the bandwidth around a central reflection wavelength, do without the polarization‐selectivity rule and go beyond the reflectance limit. 相似文献
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Jianguo Zhao Utku Gulan Takafumi Horie Naoto Ohmura Jun Han Chao Yang Jie Kong Steven Wang Ben Bin Xu 《Small (Weinheim an der Bergstrasse, Germany)》2019,15(18)
Biological liquid crystals, a rich set of soft materials with rod‐like structures widely existing in nature, possess typical lyotropic liquid crystalline phase properties both in vitro (e.g., cellulose, peptides, and protein assemblies) and in vivo (e.g., cellular lipid membrane, packed DNA in bacteria, and aligned fibroblasts). Given the ability to undergo phase transition in response to various stimuli, numerous practices are exercised to spatially arrange biological liquid crystals. Here, a fundamental understanding of interactions between rod‐shaped biological building blocks and their orientational ordering across multiple length scales is addressed. Discussions are made with regard to the dependence of physical properties of nonmotile objects on the first‐order phase transition and the coexistence of multi‐phases in passive liquid crystalline systems. This work also focuses on how the applied physical stimuli drives the reorganization of constituent passive particles for a new steady‐state alignment. A number of recent progresses in the dynamics behaviors of active liquid crystals are presented, and particular attention is given to those self‐propelled animate elements, like the formation of motile topological defects, active turbulence, correlation of orientational ordering, and cellular functions. Finally, future implications and potential applications of the biological liquid crystalline materials are discussed. 相似文献
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溶致液晶材料在水中会形成聚合物,聚合物的长度会随着温度而改变,因此可以通过改变溶液的温度来改变聚合物的长度,从而在一定的温度和浓度范围内产生液晶相.研究了一种名为蓝色27的阴丹酮衍生物(C28-H18O10N4C12)的溶致液晶材料.实验发现,20℃时封装在玻璃盒中的浓度为4.5%的蓝色27水溶液样品的透光率随着搁置时间的延长明显增加,计算结果表明,样品的有序度会随着时间的延长而增加,这种增加与系统中聚合物长度随着搁置时间变长有关. 相似文献
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Lei Zhang Sourav Maity Kai Liu Qing Liu Robert Göstl Giuseppe Portale Wouter H. Roos Andreas Herrmann 《Small (Weinheim an der Bergstrasse, Germany)》2017,13(34)
Over the last decades, water‐based lyotropic liquid crystals of nucleic acids have been extensively investigated because of their important role in biology. Alongside, solvent‐free thermotropic liquid crystals (TLCs) from DNA are gaining great interest, owing to their relevance to DNA‐inspired optoelectronic applications. Up to now, however, only the smectic phase of DNA TLCs has been reported. The development of new mesophases including nematic, hexagonal, and cubic structures for DNA TLCs remains a significant challenge, which thus limits their technological applications considerably. In this work, a new type of DNA TLC that is formed by electrostatic complexation of anionic oligonucleotides and cationic surfactants containing an azobenzene (AZO) moiety is demonstrated. DNA–AZO complexes form a stable nematic mesophase over a temperature range from ?7 to 110 °C and retain double‐stranded DNA structure at ambient temperature. Photoisomerization of the AZO moieties from the E‐ to the Z‐ form alters the stiffness of the DNA–AZO hybrid materials opening a pathway toward the development of DNA TLCs as stimuli‐responsive biomaterials. 相似文献
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A Dual Modulated Homochiral Helical Nanofilament Phase with Local Columnar Ordering Formed by Bent Core Liquid Crystals: Effects of Molecular Chirality 下载免费PDF全文
Lin Li Antal Jákli Torsten Hegmann 《Small (Weinheim an der Bergstrasse, Germany)》2016,12(29):3944-3955
Helical nanofilament (HNF) phases form as a result of an intralayer mismatch between top and bottom molecular halves in bent‐core liquid crystals (BC‐LCs) that is relieved by local saddle‐splay geometry. HNFs are immensely attractive for photovoltaic and chiral separation applications and as templates for the chiral spatial assembly of guest molecules. Here, the synthesis and characterization of two unichiral BC‐LCs and one racemic mixture with tris‐biphenyl‐diester cores featuring chiral (R,R) and (S,S) or racemic 2‐octyloxy aliphatic side chains are presented. In comparison to the achiral compound with linear side chains forming an intralayer modulated HNF phase (HNFmod), synchrotron small angle X‐ray diffraction indicates that the unichiral derivatives form a dual modulated HNF phase with intra‐ as well as interlayer modulations (HNFmod2) suggesting a columnar local structure of the nanofilaments. Transmission electron microscopy and circular dichroism spectropolarimetry confirm that the unichiral materials exclusively form homochiral HNFs with a twist sense‐matching secondary twist. A contact preparation provides the first example of two identical chiral liquid crystal phases only differing in their handedness that do not mix and form an achiral liquid crystal phase with an entirely different structure in the contact zone. 相似文献
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N. Tamaoki 《Advanced materials (Deerfield Beach, Fla.)》2001,13(15):1135-1147
Fixation of the molecular ordering of cholesteric liquid crystals is essential for use of these materials in color information technology. Methods to achieve this as well as thermal and photochemical control of the cholesteric pitch of the liquid crystals are addressed and applications in rewritable color recording are highlighted. The Figure shows a sample recorded using a laser. 相似文献
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Clean Transfer of Large Graphene Single Crystals for High‐Intactness Suspended Membranes and Liquid Cells 下载免费PDF全文
Jincan Zhang Li Lin Luzhao Sun Yucheng Huang Ai Leen Koh Wenhui Dang Jianbo Yin Mingzhan Wang Congwei Tan Tianran Li Zhenjun Tan Zhongfan Liu Hailin Peng 《Advanced materials (Deerfield Beach, Fla.)》2017,29(26)
The atomically thin 2D nature of suspended graphene membranes holds promising in numerous technological applications. In particular, the outstanding transparency to electron beam endows graphene membranes great potential as a candidate for specimen support of transmission electron microscopy (TEM). However, major hurdles remain to be addressed to acquire an ultraclean, high‐intactness, and defect‐free suspended graphene membrane. Here, a polymer‐free clean transfer of sub‐centimeter‐sized graphene single crystals onto TEM grids to fabricate large‐area and high‐quality suspended graphene membranes has been achieved. Through the control of interfacial force during the transfer, the intactness of large‐area graphene membranes can be as high as 95%, prominently larger than reported values in previous works. Graphene liquid cells are readily prepared by π–π stacking two clean single‐crystal graphene TEM grids, in which atomic‐scale resolution imaging and temporal evolution of colloid Au nanoparticles are recorded. This facile and scalable production of clean and high‐quality suspended graphene membrane is promising toward their wide applications for electron and optical microscopy. 相似文献
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Alexander Ryabchun Federico Lancia Jiawen Chen Dmitry Morozov Ben L. Feringa Nathalie Katsonis 《Advanced materials (Deerfield Beach, Fla.)》2020,32(47):2004420
Unravelling the rules of molecular motion is a contemporary challenge that promises to support the development of responsive materials and is likely to enhance the understanding of functional motion. Advances in integrating light-driven molecular motors in soft matter have led to the design and realization of chiral nematic (cholesteric) liquid crystals that can respond to light with modification of their helical pitch, and also with helix inversion. Under illumination, these chiral liquid crystals convert from one helical geometry to another. Here, a series of light-driven molecular motors that feature a rich configurational landscape is presented, specifically which involves three stable chiral states. The succession of chiral structures involved in the motor cycle is transmitted at higher structural levels, as the cholesteric liquid crystals that are formed can interconvert between helices of opposite handedness, reversibly. In these materials, the dynamic features of the motors are thus expressed at the near-macroscopic, functional level, into addressable colors that can be used in advanced materials for tunable optics and photonics. 相似文献
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Single Crystals: Clean Transfer of Large Graphene Single Crystals for High‐Intactness Suspended Membranes and Liquid Cells (Adv. Mater. 26/2017) 下载免费PDF全文
Jincan Zhang Li Lin Luzhao Sun Yucheng Huang Ai Leen Koh Wenhui Dang Jianbo Yin Mingzhan Wang Congwei Tan Tianran Li Zhenjun Tan Zhongfan Liu Hailin Peng 《Advanced materials (Deerfield Beach, Fla.)》2017,29(26)