Liquid Crystals Reviews最新文献

{"title":"Ordering nano- and microparticles assemblies with liquid crystals","authors":"C. Blanc, D. Coursault, E. Lacaze","doi":"10.1080/21680396.2013.818515","DOIUrl":"https://doi.org/10.1080/21680396.2013.818515","url":null,"abstract":"Besides nanostructured materials, individual particles are key elements for nanosciences. The structuring properties of liquid crystals (LCs) are appealing to assemble them, to organize them on substrates or to design functional composites. We present here an overview on particles/LC systems, the size of the dispersed particles being larger than the typical LC length. We first summarize the large number of advances made these last 10 years concerning microparticles assemblies. We then discuss the evolution of the relevant interactions between nanoparticles (NPs) dispersed in LCs when their size decreases from micrometers to nanometers. Various NPs assemblies obtained, either in LC bulk, at interfaces or within LC distorted areas or topological defects are then reported and discussed. Finally, we consider the recent possibilities to use NPs as building elements of complex fluids. We discuss accordingly the LC phases, which can be obtained with pure inorganic NPs in concentrated solution, as well as the self-assemblies which can be obtained when NPs are covered by organic mesogenic ligands.","PeriodicalId":18087,"journal":{"name":"Liquid Crystals Reviews","volume":null,"pages":null},"PeriodicalIF":5.1,"publicationDate":"2013-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/21680396.2013.818515","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60430406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Liquid–crystalline properties of aqueous suspensions of natural clay nanosheets","authors":"E. Paineau, A. Philippe, K. Antonova, I. Bihannic, P. Davidson, I. Dozov, J. Gabriel, M. Impéror-Clerc, P. Levitz, F. Meneau, L. Michot","doi":"10.1080/21680396.2013.842130","DOIUrl":"https://doi.org/10.1080/21680396.2013.842130","url":null,"abstract":"Clay minerals, like beidellite or nontronite, spontaneously exfoliate in water and form colloidal suspensions of nanosheets. In a given range of concentration, these suspensions display a nematic liquid–crystalline phase whose structure and properties can be conveniently studied in detail by polarized-light microscopy and small-angle X-ray scattering (SAXS). Moreover, in situ SAXS investigations of sheared clay suspensions provide information about their flow properties, both in the isotropic and nematic phases. The colloidal nematic phase shows the classical properties of usual nematics, such as surface anchoring and electric-field and magnetic-field alignment. Thus, nematic single domains can be produced. The isotropic phase also displays strong electro-optic effects in moderate electric fields. Finally, we describe a few examples of applications of such systems and we show how these studies could be extended to suspensions of other types of nanosheets.","PeriodicalId":18087,"journal":{"name":"Liquid Crystals Reviews","volume":null,"pages":null},"PeriodicalIF":5.1,"publicationDate":"2013-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/21680396.2013.842130","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60430299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"POLICRYPS composite structures: realization, characterization and exploitation for electro-optical and all-optical applications","authors":"L. De Sio, A. Veltri, R. Caputo, A. De Luca, G. Strangi, R. Bartolino, C. Umeton","doi":"10.1080/21680396.2012.742743","DOIUrl":"https://doi.org/10.1080/21680396.2012.742743","url":null,"abstract":"The acronym POLICRYPS indicates a nano/micro composite structure made of films of well aligned nematic liquid crystal (NLC) alternated to slices of almost pure polymer. Structures are fabricated by curing a homogeneous mixture of mesogenic material, monomer and a curing agent with UV radiation, under suitable physical and geometrical conditions. In particular, geometrical conditions determine (in the range 0.2 ÷ 15 μ m) the spatial periodicity of the realized sample, which can be utilized for transmitting, diffracting or reflecting an impinging light beam, with negligible scattering losses. The spatial modulation of the refractive index (from polymer to NLC) can be switched ON and OFF both by applying an electric field of few V/μ m or, in some cases, by irradiating the sample with a light beam of suitable wavelength. This electrical/optical tuneability is responsible for a series of distinctive characteristics of the optical effects produced by the structure, and determines the range of possible applications. In fact, in different geometries, the POLICRYPS can be exploited as a switchable holographic grating, a switchable optical phase modulator, a switchable beam splitter, a tuneable Bragg filter or it can be exploited as an electro-optical edge filter in an optical interrogation system.","PeriodicalId":18087,"journal":{"name":"Liquid Crystals Reviews","volume":null,"pages":null},"PeriodicalIF":5.1,"publicationDate":"2013-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/21680396.2012.742743","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60429735","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electrophoretic liquid crystal displays: how far are we?","authors":"S. Klein","doi":"10.1080/21680396.2013.786246","DOIUrl":"https://doi.org/10.1080/21680396.2013.786246","url":null,"abstract":"We are in the middle of another revolution in information processing and distribution. After the invention of script and then print, pictures are taking over again. The number of gadgets with displays is larger than the world population. On average, every single person on earth owns at least one device with a display on it. These displays are the portals to everything we do: communicating, reading, shopping, learning, etc. But are they up to the job? The most successful display technology to date is still the liquid crystal display. It is a well-established technology that can be scaled in size from small to large and, depending on the drive electronics, has no significant inherent limits to resolution. However, poor light efficiency and data congestion caused by high pixel densities are still technical challenges in need of good solutions. Could electrophoresis in a liquid crystal host be the answer? The fundamental basics and technical challenges of this interesting new approach will be discussed.","PeriodicalId":18087,"journal":{"name":"Liquid Crystals Reviews","volume":null,"pages":null},"PeriodicalIF":5.1,"publicationDate":"2013-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/21680396.2013.786246","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60429848","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Liquid crystals of the twenty-first century – nematic phase of bent-core molecules","authors":"A. Jákli","doi":"10.1080/21680396.2013.803701","DOIUrl":"https://doi.org/10.1080/21680396.2013.803701","url":null,"abstract":"Bent-core (BC) materials that form nematic liquid crystals (BC nematics (BCNs)) are known only since 2000, but since then they have been intensively studied. In this review we give a comprehensive summary of the main research directions and results. After discussing representative examples of molecules making BCNs, we review theoretical predictions and experimental findings about macroscopic symmetries, such as chirality of achiral and chiral molecules, tetrahedratic symmetry and phase biaxiality versus uniaxiality. Then we describe the properties of smectic nano clusters often observed in BCNs, and discuss rheological properties that reveal unusually large viscosities and small twist and bend elastic constants. Finally, we focus on the electric properties of BCNs, such as dielectric and ferroelectric properties, electroconvection (EC) and electromechanical effects.","PeriodicalId":18087,"journal":{"name":"Liquid Crystals Reviews","volume":null,"pages":null},"PeriodicalIF":5.1,"publicationDate":"2013-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/21680396.2013.803701","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60430277","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Liquid crystal polymer networks: switchable surface topographies","authors":"Danqing Liu, D. Broer","doi":"10.1080/21680396.2013.766410","DOIUrl":"https://doi.org/10.1080/21680396.2013.766410","url":null,"abstract":"Coating of liquid crystal (LC) networks modified with azobenzene moieties as crosslinks was reviewed to create surface topographies in the micrometer range by exposure with UV light. Various configurations were worked out. Homogeneous cholesteric networks and homeotropic nematic networks could form well-defined protrusions by local exposure. The protrusions can be dynamic, i.e. disappear as soon as light is switched off, or be permanent keeping stable topological structures even after the exposure stops. The formation of the protrusions was proven to be induced mainly by a decrease in density when the order in the LC network is reduced under the trans to–cis isomerization of the azobenzene units. Next to the photochemical effect also heating by absorption played a role. When the polymer network coating was build up from alternating cholesteric and homeotropic areas a uniform exposure led to the surface topography. When exposed, the cholesteric areas are protruding and the homeotropic areas are indenting. In this the deformation is enhanced by the orchestrated linear geometric shear deformations in the neighboring areas where the homeotropic areas tend to expand in the lateral direction and the cholesteric areas in the direction perpendicular to the coating.","PeriodicalId":18087,"journal":{"name":"Liquid Crystals Reviews","volume":null,"pages":null},"PeriodicalIF":5.1,"publicationDate":"2013-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/21680396.2013.766410","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60429977","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chemical and biological sensing using liquid crystals.","authors":"Rebecca J Carlton, Jacob T Hunter, Daniel S Miller, Reza Abbasi, Peter C Mushenheim, Lie Na Tan, Nicholas L Abbott","doi":"10.1080/21680396.2013.769310","DOIUrl":"10.1080/21680396.2013.769310","url":null,"abstract":"<p><p>The liquid crystalline state of matter arises from orientation-dependent, non-covalent interaction between molecules within condensed phases. Because the balance of intermolecular forces that underlies formation of liquid crystals is delicate, this state of matter can, in general, be easily perturbed by external stimuli (such as an electric field in a display). In this review, we present an overview of recent efforts that have focused on exploiting the responsiveness of liquid crystals as the basis of chemical and biological sensors. In this application of liquid crystals, the challenge is to design liquid crystalline systems that undergo changes in organization when perturbed by targeted chemical and biological species of interest. The approaches described below revolve around the design of interfaces that selectively bind targeted species, thus leading to surface-driven changes in the organization of the liquid crystals. Because liquid crystals possess anisotropic optical and dielectric properties, a range of different methods can be used to read out the changes in organization of liquid crystals that are caused by targeted chemical and biological species. This review focuses on principles for liquid crystal-based sensors that provide an optical output.</p>","PeriodicalId":18087,"journal":{"name":"Liquid Crystals Reviews","volume":null,"pages":null},"PeriodicalIF":5.1,"publicationDate":"2013-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4005293/pdf/nihms-555473.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"32315914","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Chemistry of discotic liquid crystals: from monomers to polymers","authors":"Sandeep Kumar","doi":"10.1080/21680396.2014.950489","DOIUrl":"https://doi.org/10.1080/21680396.2014.950489","url":null,"abstract":"Introduction Self-Organization of Molecules and Liquid Crystals Brief History of Liquid Crystals Classification of Liquid Crystals Lyotropic Liquid Crystals Thermotropic Liquid Crystals Calamitic Liquid Crystals Bent-Core Liquid Crystals Discotic Liquid Crystals Structure of the Nematic Phases of Discotic Mesogens Smectic Phases of Discotic Mesogens Columnar Phases of Discotic Mesogens Cubic Phase Alignment of Discotic Liquid Crystals Monomeric Discotic Liquid Crystals Benzene Core Naphthalene Core Phenanthrene Core Anthraquinone Core Pyrene Core Triphenylene Core Perylene Core Dibenzo[g,p]chrysene Core Dibenzo[ fg,op]naphthacene Core Truxene Core Decacyclene Core Hexabenzocoronene Core Macrocyclic Cores Miscellaneous Aromatic Cores Triazine Core Phenazines Hexaazatriphenylene Core Heterotruxenes Tricycloquinazoline Core Porphyrin Core Porphyrazine Core Phthalocyanine Core Miscellaneous Discotic Metallomesogens Miscellaneous Heterocyclic Cores Non-Aromatic Cores Discotic Dimers Benzene-Based Discotic Dimers Scylloinositol Dimer Discotic Dimers Derived from Pyranose Sugars Rufigallol-Based Discotic Dimers Triphenylene-Based Discotic Dimers Cyclotetraveratrylene Dimer Phthalocyanine-Based Discotic Dimers Porphyrin Double-Deckers Hexabenzocoronene-Based Dimers Discotic Oligomers Discotic Trimers Discotic Tetramers Discotic Pentamers Discotic Hexamers Star-Shaped Discotic Heptamers Discotic Polymers Benzene-Based Discotic Polymers Alkynylbenzene-Based Discotic Polymers Rufigallol-Based Main-Chain Discotic Polymers Triphenylene-Based Polymers Cyclotetraveratrylene-Based Polymers Phthalocyanine-Based Polymers Hexabenzocoronene-Based Polymers Perspectives Discotics for Wide Viewing Displays Discotics for High-Quality Carbon Products Discotic Liquid Crystals as Materials for a New Generation of Organic Electronics Discotic Solar Cells Discotic Liquid Crystals as Organic Light-Emitting Diode Materials Discotic Field Effect Transistors","PeriodicalId":18087,"journal":{"name":"Liquid Crystals Reviews","volume":null,"pages":null},"PeriodicalIF":5.1,"publicationDate":"2010-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/21680396.2014.950489","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60430698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Adsorption phenomena and anchoring energy in nematic liquid crystals","authors":"G. Barbero, L. R. Evangelista","doi":"10.1080/21680396.2014.937081","DOIUrl":"https://doi.org/10.1080/21680396.2014.937081","url":null,"abstract":"NEMATIC LIQUID CRYSTALS: FUNDAMENTALS AND BULK PROPERTIES Nematic Order Parameters Maier-Saupe Approach for the Nematic-Isotropic Phase Transition Continuum Description of the Nematic Phase External Field Contribution to the Elastic Energy Density Equilbrium Configuration in Strong and Weak Anchoring Situations NEMATIC LIQUID CRYSTALS: SURFACE PROPERTIES Anchoring The Anchoring Energy Function Periodic Deformations in Nematic Liquid Crystals Spontaneous Periodic Distortions in Nematic Liquid Crystals: Dependence on the Tilt Angle Theoretical Models for the Surface Free Energy Stochastic Contribution to the Anchoring Energy: Deviation from the Rapini-Papolar Expression Validity of the Elastic Model for Nematic Surface Anchoring Energy Contribution of the Smectic-Nematic to the Surface Energy TEMPERATURE DEPENDENCE OF THE SURFACE FREE ENERGY Thermal Relaxation Model of Surface Director Gliding in Lyotropic Liquid Crystals Thermal Renormalization of the Anchoring Energy Temperature Induced Surface Transition in Nematic Liquid Crystals Oriented by Evaporated SiOx A Local Self-Consistent Approach to the Phase Transition at the Nematic Liquid Crystal - Wall Interface SURFACE ADSORPTION OF PARTICLES: GENERAL CHARACTERISTICS Introduction Statement of the Problem: Langmuir's Isotherm Surface Adsorption and Anchoring Transition Photo-Manipulation of the Anchoring Strength of Photochromic Nematic Liquid Crystal Adsorption of Magnetic Grains in Magnetic Fluids Selective Ionic Adsorption in Liquid Crystals SURFACE ELECTRIC FIELD-INDUCED INSTABILITIES IN NEMATIC LIQUID CRYSTALS SAMPLE The General Electrostatic Model Analysis I: Variation Solution of the Eigenvalue Problem Analysis II: Series Solution of the Eigenvalue Problem Role of the Elastic Term Linear in the Spatial Derivatives of the Nematic Director in a 1D Geometry Conclusions IONS AND NEMATIC SURFACE ENERGY: BEYOND THE EXPONENTIAL APPROXIMATION FOR THE ELECTRIC FIELD OF IONIC ORIGIN Introduction Theoretical Model: Non-Linear Poisson-Boltzman Equation External Electric Field Effect in the Nematic Anchoring Energy Contribution to the Surface Energy of Dielectric Origin Conclusions ADSORPTION PHENOMENON AND EXTERNAL FIELD EFFECT ON AN ISOTROPIC LIQUID CONTAINING IMPURITIES Introduction The Model The Charge and Field Distributions Ionic Adsorption in the Absence of External Equilibrium Distribution of Charges Extensions of the Model Influence of the Adsorption Energy in the Dieletric Contribution to the Anchoring Energy FERMILIKE DESCRIPTION OF THE ADSORPTION PHENOMENON Introduction The Fermi-Like Model Application: Ion Adsorption in Isotropic Fluids Limits Numerical Results Conclusions","PeriodicalId":18087,"journal":{"name":"Liquid Crystals Reviews","volume":null,"pages":null},"PeriodicalIF":5.1,"publicationDate":"2005-07-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1080/21680396.2014.937081","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"60430250","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"材料科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}