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Mesophase

About: Mesophase is a research topic. Over the lifetime, 8671 publications have been published within this topic receiving 185077 citations.


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Journal ArticleDOI
TL;DR: In this article, the molecular shapes of covalent organosilanes, quaternary ammonium surfactants, and mixed surfactant in various reaction conditions can be used to synthesize silica-based mesophase configurations.
Abstract: The low-temperature formation of liquid-crystal-like arrays made up of molecular complexes formed between molecular inorganic species and amphiphilic organic molecules is a convenient approach for the synthesis of mesostructure materials. This paper examines how the molecular shapes of covalent organosilanes, quaternary ammonium surfactants, and mixed surfactants in various reaction conditions can be used to synthesize silica-based mesophase configurations, MCM-41 (2d hexagonal, p6m), MCM-48 (cubic Ia3d), MCM-50 (lamellar), SBA-1 (cubic Pm3n), SBA-2 (3d hexagonal P63/mmc), and SBA-3 (hexagonal p6m from acidic synthesis media). The structural function of surfactants in mesophase formation can to a first approximation be related to that of classical surfactants in water or other solvents with parallel roles for organic additives. The effective surfactant ion pair packing parameter, g = V/a0l, remains a useful molecular structure-directing index to characterize the geometry of the mesophase products, and pha...

1,428 citations

Journal ArticleDOI
TL;DR: In this article, 1-alkyl-3-methylimidazolium tetrafluoroborate (TFLB) is described as an isotropic ionic liquid with an enantiotropic smectic A mesophase.
Abstract: Air- and water-stable 1-alkyl-3-methylimidazolium tetrafluoroborate salts with the general formula [Cn-mim][BF4] (n = 0–18) have been prepared by metathesis from the corresponding chloride or bromide salts. The salts have been characterised by 1H NMR and IR spectroscopy, microanalysis, polarising optical microscopy and differential scanning calorimetry. Those with short alkyl chains (n = 2–10) are isotropic ionic liquids at room temperature and exhibit a wide liquid range, whereas the longer chain analogues are low melting mesomorphic crystalline solids which display an enantiotropic smectic A mesophase. The thermal range of the mesophase increases with increasing chain length and in the case of the longest chain salt prepared, [C18-mim][BF4], the mesophase range is ca. 150 °C.

1,169 citations

Journal ArticleDOI
TL;DR: This Review will focus on the major classes of columnar mesogens rather than presenting a library of columner liquid crystals, and emphasis will be given to efficient synthetic procedures, and relevant mesomorphic and physical properties.
Abstract: Most associate liquid crystals with their everyday use in laptop computers, mobile phones, digital cameras, and other electronic devices. However, in contrast to their rodlike (calamitic) counterparts, first described in 1907 by Vorlander, disklike (discotic, columnar) liquid crystals, which were discovered in 1977 by Chandrasekhar et al., offer further applications as a result of their orientation in the columnar mesophase, making them ideal candidates for molecular wires in various optical and electronic devices such as photocopiers, laser printers, photovoltaic cells, light-emitting diodes, field-effect transistors, and holographic data storage. Beginning with an overview of the various mesophases and characterization methods, this Review will focus on the major classes of columnar mesogens rather than presenting a library of columnar liquid crystals. Emphasis will be given to efficient synthetic procedures, and relevant mesomorphic and physical properties. Finally, some applications and perspectives in materials science and molecular electronics will be discussed.

1,056 citations

Journal ArticleDOI
23 Nov 1995-Nature
TL;DR: In this paper, the authors report the templating of silica mesostructures from ordered liquid-crystalline mesophases: the resulting silica phase, with pores of ∼3 nm diameter, is a cast of the organic mesophase.
Abstract: THE synthesis of inorganic mesoporous materials using ionic surfactant template molecules was first reported in 19921,2, and surfactant-mediated synthesis has since been used to form a variety of mesoporous materials3–8. Such materials could find application in catalysis, membrane and separation technology, and molecular engineering. Previous syntheses have used low surfactant concen-trations, and the templating mechanism (which is still controversial) is thought to be a cooperative process involving the interaction of inorganic ions with discrete surfactant aggregates1,2,5,9. Here we report the templating of silica mesostructures from ordered liquid-crystalline mesophases: the resulting silica phase, with pores of ∼3 nm diameter, is a cast of the organic mesophase. As the phase diagram of the surfactant/silica/water system at high surfactant concentration is similar to the (known) phase diagram of surfactant/water alone, this approach should introduce an element of predictability into the synthesis of mesoporous materials.

1,038 citations

BookDOI
01 Jan 1970
TL;DR: In this paper, the authors present a NMR study of the transition of a mixture of two Isomeric Cyano-Ester homologous series, showing that the phase transition of one of the two isomeric versions of this series is a transition of the other.
Abstract: Some Novel Ferroelectric Smectic Liquid Crystals.- Liquid Crystalline Esters of Phenylhydroquinone and 3-Phenyl 4-Hydroxybenzoic Acid.- The Synthesis and Characterization of Some Perylene and Anthraquinoic Dichroic Dyes for Liquid Crystal Display Applications.- Some New Thermotropic Discogens.- Syntheses and Properties of Liquid Crystalline Heterocycloalkanes.- Characterization of Two Isomeric Cyano-Ester Homologous Series -I.- Effects of Molecular Length on Nematic Mixtures - IV: Structure Effects on Viscosity of Ester Mixtures.- Orientational Disorder in Smectic Liquid Crystals: An Aspect of Structure that has to be Included.- Effect of Molecular Structure of Rigid - Flexible Polyesters on Their Thermotropic Liquid Crystalline Properties.- Relationships Between Molecular Structure and the Incidence of Crystal B and Hexatic B Phases.- Characterization of the Phases of Two Isomeric Cyano-Ester Homologous Series - II.- Unusual Glass Transition of Smectic Liquid Crystal in p-n-Hexyloxybenzylidene-p'-Butylaniline.- Some High Electric Field Effects in Nematic Liquid Crystals.- Application of Generalized Van Der Waals Theory of Homologous Nematogens - Part 1: Trans-4-Ethoxy-4'-N-Alkanoyloxyazobenzenes..- Application of Regular Solution Theory to Discotic Mesophases: Calculation of Phase Diagrams Exhibiting Minima.- Extension of McMillan's Model to Liquid Crystals of Disc-Like Molecules.- Thermotropic Liquid-Crystalline Polymers with Mesogenic Groups and Flexible Spacers in the Main Chain.- Effect of Mesogenic Unit and Spacer Structures on the Thermotropic Properties of Main Chain Liquid Crystal Polyesters.- The Role of Sequence Distribution on Liquid Crystalline Properties of Aromatic Copolyesters.- Diffusion of Rigid Polyamides Through Swollen Gel of Same.- The Molecular Weight Dependence of the Splay and Bend Elastic Constants of a Polymer Liquid Crystal.- DSC, Miscibility and X-ray Studies of the Thermotropic Liquid Crystalline Polyesters with Aromatic Moieties and Flexible Spacers in the Main Chain.- Influence of the Leprosy Drug, Dapsone, on the Phase Transitions of the Lyotropic, Dipalmitoy1 Phosphatidylcholine (DPPC).- Nonaqueous Lyotropic Liquid Crystals of Lecithin and Oligomers of Polyethylene Glycols.- The Diamagnetic Anisotropy of Lyotropic Nematic Mesophases.- Physical Models of Lipid Membranes in Latent Cancer Cells: Ordering Effects of Petroleum Hydrocarbons.- Adiabatic Compression: A New Method to Measure Latent Heats in Phospholipid Bilayers.- Anisotropy of the Electric Conductivity in Amphiphilic Liquid Crystals.- Phase Transition Properties of Bilayers of Mixed Lipids and Their Covalent Analogs.- On The Orientation of Liquid Crystals by Monolayers of Amphiphilic Molecules.- Refractive Index Measurements Using a Double Arm Converging Beam Interferometer.- A Pulsed NMR Study of Transient and Persistent Molecular Order in Nematic Liquid Crystals.- The Effect of Twist on Biaxial Ordering in the Cholesteric Phase.- Deuteron Magnetic Relaxation and Molecular Dynamics in Thermotropic Liquid Crystals.- An Effective Proton Hyperfine Tensor for Di-Tertbutylnitroxide.- Alkyl Chain Flexibility in Liquid Crystals.- Orientational Order in Binary Mixtures of Nematic Liquid Crystals.- The Effect of the Tricritical Region on the Smectic A - Smectic C Transition.- Spatial Correlations in Nematic Liquid Crystals.- Molecular Structure and Ordering in Liquid Crystals.- New Liquid Crystals, Polymeric and Monomeric, Derived From Binaphthyl.- Ioneneomeric Liquid Crystals.- Mesomorphic Properties of an Homologous Series of Alkyl-Terminated Enamine-Ketone Containing Liquid Crystals.- Liquid Crystalline Polymers with Amphiphilic and Non Amphiphilic Side Chains - Effect of the Main Chain on the Phase Behaviour.- The Fluid Mesophases of Polar Rods.- The Nematogeneity of Some Hydrocarbons.- Some Heterocyclic Analogues of Biphenyl Mesogens.- Alignment of Liquid Crystal Molecules on Various Surfaces: Myths, Theories, Facts.- Development of Dual-Frequency Addressable Liquid Crystals.- Dielectric Studies of Monoester and Diester Nematogens.- Intermolecular Guest-Host Interactions and the Optical Order Parameter of Pleochroic Dyes.- Liquid Crystal Alignment on Substrate Surfaces, A Collective Phenomenon.- Alignment of Liquid Crystals in the Vicinity of the SmA-N Transition.- Nematic-Substrate Interaction and the Boundary Layer Phase Transition.- Optical Properties of the Blue Phase of Cholesteric Liquid Crystals.- Lattice Parameters in Blue Phase Mixtures.- Blue Phase Structure Analysis by Optical Bragg Diffractions.- Mesomorphic Polymers as Three Component Systems.- Colloidal Crystals and Glasses.- Self Diffusion Constant and Viscosity of Charged Polystyrene Colloids.- Influence of Molecular Conformation on the Helical Twisting Power of Terpenes in Nematic Liquid Crystals.- Vibrational Spectra of Liquid Crystals XIII: Crystallization Kinetics Study of 4, Octyloxy, 4', Cyano Biphenyl by Rapid Raman Spectroscopy..- Nuclear Spin-Lattice Relaxation Due to Orientational Fluctuation in Smectic Liquid Crystals.- NMR Studies of Molecules Oriented in Mixed Thermotropic Liquid Crystals of Opposite Diamagnetic Anisotropies.- Discotic Mesophase: A Complementary Review.- Identification of the Structure of Mesomorphic Polymers by Means of their Miscibility.- Effect of Molecular Structure on Mesomorphism: Difluorinated Siamese Twin Mesogens.- Anisotropy Induced in a Semi-Flexible Polymer by a Liquid-Crystalline Solvent.- Electrooptical Behaviour of a Novel Strong-Weak Anchored Nematic Layer: First Measurements of MBBA Flexoelectric Coefficient of Splay elz.- On Thermotropic Disc-Like Mesogens.- On The Nature of the Smectic-C Phase.- Contributors.

1,036 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023113
2022217
2021140
2020183
2019199
2018171