Showing papers on "Liquid crystal published in 1993"

Observation of blue phases in chiral networks

Abstract: We report the first observation of cholesteric blue phases in chiral anisotropic polymer networks. In two-component mixtures of a chiral and a non-chiral diacrylate, we observed typical textures of BPI, BPII and BPIII phases. By photopolymerization of these materials at constant temperature we obtained blue phase networks. After polymerization, the blue phases were stored, which enabled us to further study them without any temperature control.

Electrooptic Effects in Liquid Crystal Materials

Abstract: 1 Liquid Crystalline State.- 1.1 Structure of Liquid Crystal Phases.- 1.1.1 Molecules.- 1.1.2 Thermotropic Mesophases Formed by Achiral Rod-Like Molecules.- 1.1.3 Thermotropic Chiral Mesophases.- 1.1.4 Mesophases of Disc-Like and Lath-Like Molecules.- 1.1.5 Polymer Liquid Crystals.- 1.1.6 Lyotropic Liquid Crystals.- 1.2 Mixtures.- 1.2.1 Nematic Eutectics.- 1.2.2 Reentrant Phases.- 1.2.3 Mixtures of Smectics.- 1.2.4 Nemato-Cholesteric Compositions.- 1.2.5 Ferroelectric Mixtures.- 1.3 Liquid Crystalline Materials.- 1.3.1 Chemical Classes.- 1.3.2 Chemical Structure and Transition Temperatures.- 1.3.3 Material.- 1.4 Direct Influence of an Electric Field on the Structure of Liquid Crystals.- 1.4.1 Field-Induced Shifts of the Phase Transition Temperatures.- 1.4.2 Influence of the Field on the Order Parameters.- 1.4.3 Field-Induced Changes in Symmetry.- References.- 2 Properties of the Materials.- 2.1 Dielectric Permittivity.- 2.1.1 Isotropic Liquids.- 2.1.2 Dielectric Anisotropy of Nematics.- 2.1.3 Nematic Mixtures.- 2.1.4 Other Phases.- 2.2 Electrical Conductivity.- 2.2.1 Dependence on Impurity Concentration.- 2.2.2 Conductivity Anisotropy.- 2.3 Optical Anisotropy and Dichroism.- 2.3.1 Optical Anisotropy.- 2.3.2 Dichroism.- 2.4 Viscoelastic Properties.- 2.4.1 Elasticity.- 2.4.2 Viscosity.- 2.4.3 Diffusion Coefficients.- References.- 3 Surface Phenomena.- 3.1 Structure of Surface Layers.- 3.1.1 Surface-Induced Changes in the Orientational Order Parameter.- 3.1.2 Surface-Induced Smectic Ordering.- 3.1.3 Polar Surface Order and Surface Polarization.- 3.2 Surface Energy.- 3.2.1 Wetting of a Solid Substrate.- 3.2.2 Surface Energy and Anchorage of a Nematic Liquid Crystal.- 3.2.3 Techniques for Measuring Anchoring Energies.- 3.3 Cells and Orientation.- 3.3.1 Electrooptical Cells.- 3.3.2 Liquid Crystal Orientation.- 3.3.3 Anchoring Transitions.- References.- 4 Electrooptical Effects Due to the Uniform Distortion of Nematic Liquid Crystals.- 4.1 Electrically Controlled Birefringence.- 4.1.1 Director Distribution.- 4.1.2 Tilted Directors at the Boundaries.- 4.1.3 Different Geometries. Simultaneous Action of Electric and Magnetic Fields.- 4.1.4 Effect of Electrical Conductivity.- 4.1.5 The Frederiks Transition for a Weak Anchoring at the Boundaries.- 4.1.6 Dynamics of the Frederiks Transition.- 4.1.7 The Frederiks Transition in Ferronematic Liquid Crystals.- 4.1.8 Optical Characteristics of the Electrically Controlled Birefringence Effect.- 4.2 Twist-Effect.- 4.2.1 Preparation of Twist Cells, Optical Properties at Zero Field.- 4.2.2 Transmission-Voltage Curve for Normal Light Incidence.- 4.2.3 Electrooptics of the Twist Cell for Oblique Incidence.- 4.2.4 Matrix Addressed Displays and Multiplexing Capability of Twist-Effect Materials.- 4.2.5 Dynamics of the Twist Effect.- 4.2.6 New Possibilities.- 4.3 Supertwist Effects.- 4.4 "Guest-Host" Effect.- 4.4.1 Change in Intensity of the Coloring.- 4.4.2 Colorimetry of "Guest-Host" Displays.- 4.4.3 Color Switching.- 4.4.4 Change in Fluorescence.- 4.5 The Flexoelectric Effect.- 4.5.1 Physical Reasons.- 4.5.2 Static Flexoelectric Distortion in Different Geometries Determination of Flexoelectric Moduli.- 4.5.3 Dynamics of the Flexoelectric Effect.- 4.5.4 Microscopic Approach to Determination of the Flexoelectric Coefficients.- 4.6 Reflectivity in an Electric Field.- 4.6.1 Optical Properties of Nontwisted Nematic Layers.- 4.6.2 Various Techniques.- 4.7 Field Behavior of the Isotropic Phase.- 4.7.1 The Kerr Effect in the Isotropic Phase.- 4.7.2 Reorientation of Surface Quasi-Nematic Layers.- 4.8 Electric Field Effects in Nematic Polymers.- 4.8.1 Thermotropic Mesophases.- 4.8.2 Lyotropic Polymers 212.- 4.9 Electrooptical Properties of Polymer Dispersed Liquid Crystal Films.- References.- 5 Modulated and Nonuniform Structures in Nematic Liquid Crystals.- 5.1 Orientational Modulated Structures.- 5.1.1 Flexoelectric Domains.- 5.1.2 Dielectric Two-Dimensional Structure in the Frederiks Transition.- 5.1.3 Other Types of Modulated Structures.- 5.2 Electrohydrodynamic Modulated Structures.- 5.2.1 Low-Frequency Limit The Kapustin-Williams Domains.- 5.2.2 Different Types of Low-Frequency Electrohydrodynamics.- 5.2.3 Electrohydrodynamic Instability in Nematics with Oblique Director Orientation at the Boundaries.- 5.2.4 Electrohydrodynamic Instability: "Chevron" Mode.- 5.2.5 Anisotropic Instabilities for Different Field and Cell Configurations.- 5.2.6 Allowance for Flexoelectricity in Anisotropic Domain Structures.- 5.2.7 High-Frequency Inertia Anisotropic Mode.- 5.2.8 Modulated Structures with Large Periods in Homeotropic Nematics.- 5.2.9 "Isotropic" Mechanism of the Excitation of Electrohydrodynamic Domains.- 5.2.10 Instabilities in Homeotropic Nematics with ?? >0.- 5.2.11 Classification of Threshold Conditions for Different Instabilities in Nematics.- 5.2.12 Electrohydrodynamic Instabilities in Polymer Nematics.- 5.2.13 The Instabilities above the Threshold Voltage. Dynamic Scattering of Light.- 5.3 Nematics in Spatially Nonuniform Fields.- 5.3.1 Homeotropic Orientation.- 5.3.2 Homogeneous Alignment.- 5.3.3 Twist Cells.- References.- 6 Electrooptical Properties of Cholesterics and Nonferroelectric Smectics.- 6.1 The Pitch of Helix and the Optical Properties of Cholesterics.- 6.1.1 Textures.- 6.1.2 Methods of Measuring the Pitch.- 6.1.3 Optical Properties of Planar Cholesteric Textures.- 6.1.4 Diffraction on the Focal-Conic Texture.- 6.1.5 Pitch Dependence on Cell Thickness.- 6.2 Field-Induced Dielectric Instabilities of Cholesterics.- 6.2.1 Texture Transitions.- 6.2.2 Instability of the Planar Cholesteric Texture.- 6.2.3 Field Untwisting of a Cholesteric Helix.- 6.2.4 Electrically Switched Bistable Structures.- 6.3 Electrohydrodynamic Instabilities in Cholesterics.- 6.4 Flexoelectric Effects.- 6.4.1 Fast Linear-in-Field Rotation of the Cholesteric Helix.- 6.4.2 Flexoelectric Domains.- 6.5 Electrooptical Effects in Blue Phases.- 6.5.1 Optical Features.- 6.5.2 Field Behavior.- 6.6 Electric Field Behavior of Nonferroelectric Smectics.- 6.6.1 The Frederiks Transition in a Smectic A.- 6.6.2 Dielectrically Induced Texture Transitions.- 6.6.3 The Frederiks Transition in a Smectic C.- 6.6.4 Electrohydrodynamic Instabilities in Smectics A and C.- References.- 7 Ferroelectric Liquid Crystals.- 7.1 The Physical Properties of Ferroelectric Liquid Crystals. Methods of Measurement.- 7.1.1 The Symmetry.- 7.1.2 The Microscopic Approach. Ferroelectric Mixtures.- 7.1.3 Physical Parameters.- 7.1.4 Tilt Angle.- 7.1.5 Spontaneous Polarization.- 7.1.6 Flexoelectric Polarization.- 7.1.7 Rotational Viscosity.- 7.1.8 Helix Pitch.- 7.1.9 Dielectric Properties.- 7.1.10 Optical Properties.- 7.1.11 Total Free Energy with Allowance for Anchoring.- 7.2 Electrooptical Effects in Ferroelectric Liquid Crystals.- 7.2.1 The Clark-Lagerwall Effect.- 7.2.2 Deformed Helix Ferroelectric Effect.- 7.2.3 Electroclinic Effect Near the Smectic A ? C* Phase Transition.- 7.2.4 Other Electrooptical Effects.- 7.2.5 Orientation of Samples.- 7.2.6 Problems of Bistability Realization.- 7.3 Ferroelectric Liquid Crystal Polymers.- 7.3.1 Introductory Remarks.- 7.3.2 Chemical Structures.- 7.3.3 Ferroelectricity.- 7.3.4 Electrooptical Switching.- References.- 8 Applications of Electrooptical Liquid Crystalline Materials.- 8.1 Displays.- 8.1.1 Active Matrix Addressed Displays.- 8.1.2 Supertwist Displays for Personal Computers.- 8.1.3 Projection Displays.- 8.1.4 Guest-Host Large Area Information Boards.- 8.1.5 General Trends in Display Applications.- 8.2 Optical Data Processing Devices.- 8.2.1 Light Valves.- 8.2.2 Modulators, Shutters.- 8.2.3 Deflectors of Light.- 8.2.4 Integrated Optical Devices.- 8.2.5 Matrix Spatial Light Modulators or Controlled Transparencies.- 8.2.6 Liquid Crystal Logic Elements.- 8.2.7 Optical Filtration.- 8.2.8 Application of Polymer Liquid Crystals in Optoelectronics.- 8.3 Other Applications.- 8.3.1 Storage Devices.- 8.3.2 Stereoscopic Liquid Crystal Sytems.- 8.3.3 Nondestructive Testing.- 8.3.4 Large Area Glass Light Shutters on Polymer Dispersed Liquid Crystal Films.- References.

Optics and Nonlinear Optics of Liquid Crystals

Abstract: Optical properties of liquid crystals electro-optical properties of liquid crystals nonlinear optical properties of liquid crystals nonlinear optics.

Recent Developments in Aromatic Azo Polymers Research

Abstract: : The photochemical and thermal cis to trans isomerization of aromatic azo groups covalently bonded within polymers and its practical consequences as well as some other recent applications are reviewed. The kinetics and mechanism of the isomerization of azo polymers are briefly presented and then several recent developments in azo polymers research are discussed. They include liquid crystallinity, nonlinear optical properties, monolayer assemblies and the light induced birefringence and dichroism. Some of the phase transitions of liquid crystalline azo polymers can be induced photochemically by the azo groups isomerization. Second order optical nonlinearity can be obtained in polymers with donor and acceptor substituted azo groups. Using the Langmuir-Blodgett technique, azo polymer monolayers can be built and used as 'command surfaces' of liquid crystal films. The light induced birefringence is a reorientation phenonmenon which is a consequence of the trans-cis-trans isomerization. Future possible applications for a variety of practical devices, such as display devices, optical modulators, optical waveguides, holography, and reversible optical storage are mentioned. Azo polymers, Review, Optoelectronic and photonic applications

Molecular dynamics simulation of a bilayer of 200 lipids in the gel and in the liquid crystal phase

Abstract: We have constructed and simulated a membrane-water system which consists of 200 molecules of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylcholine forming a rectangular patch of a bilayer and of 5483 water molecules covering the head groups on each side of the bilayer. The total number of atoms is approximately 27 000. The lateral dimensions of the bilayer are 85 A×100 A, and the distance between the bilayer surfaces as given by the average phosphorus to phosphorus distance is 35 A. The thickness of each water layer is up to 15 A. In all, we simulated 263 ps of the dynamics of the system. To prevent system disintegration, atoms within 5 A from the surface were harmonically restrained and treated by Langevin dynamics, forming a stochastic boundary

Liquid crystalline polymers

Abstract: Not much more than a decade ago, the plastics industry viewed itself as a mature branch of the heavy chemical industry. Its raison d'etre was the mass production of four or five main-line polymers, and profits were equated to tonnage output, plant efficiency, and clever downstream processing such as film blowing. The chemistry was essentially simple and the monomer, of course, cheap. There was, however, a spark of new thinking. A trend was developing toward the design and manufacture of more complex, more expensive polymers, with special properties which could command a special price. Such products would sell advanced scientific know-how, not just engineering expertise which could all too easily be exported to the major oil producers in the form of a polymer plant. Designing particular molecules to achieve desired properties is now a major theme of polymer producers. There is a move toward increasing the aromatic content of polymer backbones to achieve greater levels of chemical and thermal stability, while the development of new cross-linking systems remains as chemically intensive as ever. It is, however, the introduction of liquid crystalline polymers which, above all, has exploited the principles of molecular design, while at the same time challenging our understanding in a new area of polymer science. A polymer is “liquid crystalline” where the chains are sufficiently rigid to remain mutually aligned in the liquid phase although the perfect positional periodicity of a crystal is no longer present. In other words there is a long-range orientational order without long-range positional order (Figure 1). Structurally, therefore, the phase is intermediate between a crystal and a liquid leading to the use of the term mesophase . Where the liquid crystalline phase forms on melting the polymer, it is known as thermotropic , but where it is achieved by solvent addition it is called Inotropic. Increasing temperature, or solvent concentration, will eventually lead to the reversion of the liquid crystal phase to the normal isotropic polymer melt.

Effect of shear on a lyotropic lamellar phase

Abstract: We present a series of experiments, using different techniques such as light scattering, conoscopy, neutron scattering and microscopic observations, to determine the orientation of lyotropic lamellar phases under shear. Three states of orientation are observed, depending upon both the shear rate and the inter-membrane separation. These steady states are separated by dynamic transitions. Among the states described, we focus our attention on a state made of monodisperse close-packed multilayered vesicles whose size is precisely fixed by the shear rate.

Electrooptical liquid crystal system

Abstract: The invention relates to an electrooptical system which between two electrode layers contains a PDLC film comprising a liquid crystal mixture forming microdroplets in an optically isotropic, transparent polymer matrix, characterized in that the precursor of the PDLC film comprises: a) 50-90 wt.% of a liquid crystal mixture, b) 15-49.5 wt.% of the precursor of the polymer matrix at least comprising a component A containing between 40-95 wt.% of one or more monofunctional monomers of the ene-type, a component B containing between 1-13 wt.% of one or more at least difunctional monomers of the ene-type, a component C containing between 1-30 wt.% of one or more mono-, di- or multifunctional oligomers of the ene-type, c) 0.01-5 wt.% of a radical photoinitiator.

Photochemical switching of polarization in ferroelectric liquid-crystal films

Abstract: LIQUID crystals have been used extensively as active media in display devices such as full-colour television screens These devices are generally based on changes in the arrangement of the liquidcrystal molecules induced by electric fields, which change their optical properties1 Ferroelectric liquid crystals2,3 exhibit spontaneous polarization and therefore show a faster response to changes in the applied field Switching of this field causes a reversal in the direction of polarization2–;5 Here we report polarization switching in ferroelectric liquid crystals driven by a photochemical process The liquid-crystal films are doped with a photochromic compound which undergoes trans–cis isomerization on irradiation Photoisomerization induces a change in the switching potential of the host liquid-crystal film, and thereby causes switching at the irradiated sites The process is fast, stable, reversible and repeatable, and should be exploitable in device applications

Smart spatial light modulators using liquid crystals on silicon

Abstract: Smart pixels are discussed in terms of the following neurally inspired functions: memory, sensors, intrapixel circuitry, interpixel communication, and optical outputs. The types of liquid crystals and electronic circuits used in VLSI/liquid crystal arrays, and their electrooptic properties are reviewed. Examples of electrically addressed and optically addressed liquid crystal smart pixels, and results from a 128*128 VLSI/FLC SLM are presented. This device has a response time of 150 mu s, a contrast ratio of 8:1 measured on a row containing more than 50 pixels, and a frame rate of 4.7 kHz. Improvements of these devices are discussed in terms of what the silicon technology can yield in the future. A few examples in which the liquid crystal on silicon technology has been applied are presented. >

Conjugated liquid crystalline polymers-soluble and fusible poly(phenylenevinylene) by the Heck coupling reaction

Abstract: The Heck coupling reaction between organic halides and vinylbenzene compounds was utilized to synthesize soluble and fusible conjugated polymers. Compared to other approaches, the Heck reaction offers an easier way to prepare processible poly(phenylenevinylenes). The fusibility of the alkoxy subatituted poly(phenylenevinylene) enables us to observe the nematic liquid crystalline phase above the melting temperature

Electron microscopic study of supramolecular liquid crystalline polymers formed by molecular-recognition-directed self-assembly from complementary chiral components.

Abstract: Electron microscopic observation provides insight into the nature of the polymeric supramolecular liquid crystalline species (TP2, TU2)n formed by polyassociation of the complementary components TP2 and TU2 derived from D-, L-, or meso-tartaric acid (where T is any form of tartaric acid, D is the D species, and L is the L species) and from pyridine (P) and uracil (U) derivatives. Increasing the concentration of equimolecular solutions of (LP2 + LU2) mixtures leads to the progressive assembly of very long supramolecular-polymolecular entities. The process involves successively nucleation to give small nuclei, growth to filaments, and lateral association to tree-like species, strings, and fibers. The species formed are helical; their helicity is right-handed, induced by the chirality of the components and transferred to the larger entities. The data agree with the formulation of the primary filament as a triple-helical species formed by three helically wound supramolecular strands. (DP2 + DU2) mixtures yield left-handed helical species. The helicity of the materials obtained from complementary components having different chirality is imposed by the U component, being, respectively, right- and left-handed for (DP2 + LU2) and (LP2 + DU2). No helicity is found for the meso compounds. The racemic mixture of all four L and D components yields long superhelices of opposite handedness that coexist in the same sample. This points to the occurrence of spontaneous racemate resolution by chiral selection of the components in the self-assembly of these supramolecular liquid crystalline species. The present results illustrate how extended supramolecular-polymolecular entities build up through molecular-recognition-directed polyassociation of complementary components. They also show that molecular chirality is translated into supramolecular helicity that is expressed at the level of the material on nanometric and micrometric scales.

Synthesis of Two-Dimensional Polymers

Abstract: A synthetic pathway is described to construct "in bulk" two-dimensional (2D) polymers shaped as molecular sheets. A chiral oligomeric precursor is used that contains two reactive sites, a polymerizable group at one terminus and a reactive stereogenic center near the middle of the molecule. The bulk reaction yields bilayer 2D polymers of molecular weight in the order of millions and a monodisperse thickness of 50.2 angstroms. The 2D molecular objects form through molecular recognition by the oligomers, which self-organize into layers that place the reactive groups within specific planes. The oligomers become catenated by two different stitching reactions involving the reactive sites. At room temperature, stacks of these molecular objects can organize as single crystals and at higher temperatures melt into smectic liquid crystals. Nonlinear optical experiments reveal that solid films containing the 2D polymers form structures that are thermally and temporally more stable than those containing analogous 1D polymers. This observation suggests that the transformation of common polymers from a 1D to a 2D architecture may produce generations of organic materials with improved properties.

Mechanism of quasi‐one‐dimensional electronic conductivity in discotic liquid crystals

Abstract: Recently, it has been shown that a new class of quasi‐one‐dimensional conductors can be created by doping discotic liquid crystals with appropriate oxidants. This paper reports the elucidation of the mechanism of conduction in these new materials. In particular, the ac conductivity of 2,3,6,7,10,11‐hexahexyloxytriphenylene (HAT6) doped with the Lewis acid AlCl3, has been measured as a function of frequency (10−3–107 Hz), and temperature in its crystalline solid (K), hexagonal discotic liquid crystal (Dho), and isotropic liquid (I) phases. In all three phases the conductivity is independent of frequency at low frequencies, but shows a power law dependence on frequency [σ(ω)∼ωs, s∼0.7–0.8] at higher frequencies. This behavior is characteristic of charge carrier transport by a hopping mechanism. The conductivity data have been analyzed in terms of the Scher and Lax theory to obtain the parameters describing this process. In macroscopically aligned K and Dho phases, the conductivity measured along the column ...

Method of manufacture of liquid crystal display panel

Abstract: A method of manufacture of a liquid crystal display panel is described whereby a fixed number of drops of liquid crystal, or a mixture of liquid crystal and spacers, are dropped at various positions on an electrode face of at least one of a pair of substrates, with the amount of liquid crystal in each of the drops being predetermined to a very high degree of accuracy. One of the substrates is then superposed on the other, under a condition of reduced air pressure, then under a condition of normal atmospheric pressure, mutual lateral position adjustment of the substrates is performed to a high degree of precision.

Supramolecular chemistry : an introduction

Abstract: Supramolecular, bio-organic and bio-inorganic chemistry - supramolecular, bio-organic, bio-inorganic and bio-mometic chemistry, from molecular materials to supramolecular structures host-guest chemistry with cations and anions - bipyridine, crown ethers, cryptands, podands, spherands, the siderophores, the spherands bio-inorganic model compounds bio-organic model compounds - the selective complexation of topologically complementary organic molecules, the cyclodextrins, bio-organic molecular complexes clathrate inclusion compounds - the clathrates direct crystal formation with tailored additives - historical aspects, enantiospecific synthesis in crystals, the separation of enantiomers by crystallization in the presence of additives, the directed effect on the crystal habit, tailored etching additives for organic crystals, the "resorcinol" problem, concluding remarks and outlook photo-responsive host/guest systems - organic switches on the basis of azobenzene - azobenzene as a photo-switch, photo-controlled host systems based on azobenzene, concluding remarks liquid crystals - molecular order - and the consequences, chemical structure elements in liquid crystals, the application of liquid crystals, recent developments tensides, micelles, vesicles - preorganization of interface-active compounds - the effect of tensides on interfaces, micelles, layers, vesicles and other ordered aggregates, the cloud point organic semi-conductors, conductors and super-conductors - conducting charge-transfer complexes, the metal-to-insulator transition, super-conducting charge-transfer complexes, polymeric conductors, conducting polymeric metal/macrocycle complexes, information storage on a molecular level molecular wires, molecular rectifiers and molecular transistors - molecular wires, molecular rectifiers light-induced cleavage of water.

Monte Carlo investigations of a Gay—Berne liquid crystal

Abstract: We report extensive Monte Carlo simulations of two systems with 512 and 1000 particles interacting with a Gay–Berne potential with strength parameters (µ= 1, ν= 3) that enhance the side-by-side and end-to-end interactions between the particles. We show that the system has a smectic, nematic and isotropic phase and we calculate the order parameters 〈P2〉, 〈P4〉, the intermolecular vector distribution and other relevant observables as a function of temperature at a scaled density ρ*= 0.30.

Discotic liquid crystals. A brief review

Abstract: Progress in the field of discotic liquid crystals is summarized, with emphasis on experimental results rather than theoretical developments. Examples are given of discotic mesogens (including metallo-mesogens) and discotic polymers, and the structures of the mesophases identified to date are described.

Transitions and instabilities in liquid crystal elastomers

Abstract: Solid nematic liquids, formed by cross-linking polymer liquid crystals into elastomers, are shown to display novel and complex elasticity. The internal (nematic) direction suffers a barrier to its rotation and this couples to standard elasticity. By considering imposed strains we illuminate this elasticity and also demonstrate an entirely new nematic phase transition. At a critical strain there is a discontinuity of director rotation.

Isotropic-nematic phase separation of a dispersion of organophilic boehmite rods

Abstract: An isotropic-nematic phase separation is observed in dispersions of sterically stabilized rodlike boehmite particle. The phase separation process is studied with polarization microscopy. Also, the phase volumes and particle concentrations in the coexisting phases are determined. The dependence of these quantities on the total concentration of the dispersion is analyzed in terms of the Onsager theory for the isotropic-nematic phase transition extended to bidisperse mixture of rodlike particles. Qualitative agreement between theory and experiment is obtained. The triphasic isotropic-nematic-nematic equilibrium as predicted by the theory is observed after 6 months

Synthesis and processing of heterocyclic polymers as electronic, optoelectronic, and nonlinear optical materials. 2. New series of conjugated rigid-rod polyquinolines and polyanthrazolines

Abstract: A series of 13 new homopolymers and three new copolymers along with six previously known polymers were synthesized and characterized in the class of conjugated polyquinolines and polyanthrazolines. The polymers were designed to systematically vary the π-electron delocalization along the conjugated polymer backbhone and, thereby, to tune the electronic structure and properties in a controlled fashion. The solid polymers, which exhibit a range of light yellow to deep red color in transmitted light, were obtained in high yield, with high intrinsic viscosity and high thermal stability

High efficiency chiral nematic liquid crystal rear polarizer for liquid crystal displays having a notch polarization bandwidth of 100 nm to 250 nm

Abstract: The efficiency of LC displays is improved by the use of a polymeric chiral nematic liquid crystal rear polarizer and reflective backlight housing which increases the net transmission of light and, at the same time, reduces the weight of the assemblage and increases battery life by utilizing lower levels of illumination The polymeric chiral nematic liquid crystal can be a freestanding film or films, or can be supported by a single glass substrate The liquid crystal polarizer can have a bandwidth sufficient to transmit electromagnetic radiation across the entire visible spectrum

Manufacture of liquid crystal display element

Abstract: PURPOSE: To manufacture a liquid crystal display element taking no long time for sealing liquid crystal, causing no pollution of liquid crystal and no mixing of refuse, and not requiring the precision of the liquid crystal drip quantity. CONSTITUTION: A seal material 3 provided with a liquid crystal discharge port 5 in advance is arranged at least on one of electrode substrates 1, 2 facing each other, a required quantity or above of liquid crystal 6 is dripped on the electrode substrate 1, then two electrode substrates 1, 2 are stuck together in vacuum, excess liquid crystal is discharged, and a sealing agent 7 is applied. The liquid crystal injection and sealing can be performed in a short time, the pollution of the liquid crystal 6 and the mixing of refuse are prevented, the precision of the drip quantity of the liquid crystal 6 is not required, and a liquid crystal display element can be easily manufactured. COPYRIGHT: (C)1994,JPO&Japio

Production of liquid crystal display element

Abstract: PROBLEM TO BE SOLVED: To provide a process for producing a liquid crystal display element capable of producing the liquid crystal display element having high display uniformity in spite of use of such liquid crystals that are deteriorated and decomposed by UV rays at the time of producing the liquid crystal display element by using a liquid crystal dropping method and liquid crystal injection method SOLUTION: A UV curing sealing material 3 is first formed to prescribed patterns on a first electrode substrate 1 The liquid crystals 4 are then dropped to the region enclosed by the sealing material 3 of the first electrode substrate 1 and spacers 5 for controlling a gap are sprayed on a second electrode substrate 2 facing the first electrode substrate 1 A color filter 14 covered with a transparent protective layer 15 on its surface is formed on the second electrode substrate 2 so as to exist on the surface on the inner side of the sealing the 3 The first and second electrode substrates 1 and 2 are then stuck to each other in vacuum to form the entire part of substrate 9 Finally the stuck entire part of substrate 9 is irradiated with the UV rays of a UV lamp 8 via a mask 6 having the prescribed patterns to allow the transmission of light and the second electrode substrate 2

An enhanced odd-even effect of liquid crystal dimers Orientational order in the α,ω-bis(4′-cyanobiphenyl-4-yl)alkanes

Abstract: The odd-even behaviour observed for liquid crystal dimers has been predicted to be a sensitive function of the geometry of the link joining the mesogenic groups to the flexible spacer. Here we report the synthesis of two cyanobiphenyl dimers with methylene links, together with a determination of their transitional properties. In particular we have probed their orientational order via the major and biaxial orientational order parameters of a solute molecule, anthracene-d 10, using NMR spectroscopy. For comparison we have also determined the corresponding quantities for the cyanobiphenyl dimers with ether links. The enhanced odd-even effect observed for the methylene linked dimers relative to those with ether links is in good accord with theory.