Liquid Crystalline Materials for Polymers with Anisotropic Ultrastructures

1989 ◽  
Vol 175 ◽  
Author(s):  
George S. Attard
Keyword(s):  
Liquid Crystals ◽  
Liquid Crystalline ◽  
Lyotropic Liquid Crystals ◽  
Crystalline Materials ◽  
Liquid Crystalline Materials

AbstractThe in-situ polymerisation of reactive thermotropic and lyotropic liquid crystals affords a method of processing new polymers with anisotropic ultrastructures.

scholarly journals Artificial colloidal liquid metacrystals by shearing microlithography

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Yanqiu Jiang ◽  
Fan Guo ◽  
Zhen Xu ◽  
Weiwei Gao ◽  
Chao Gao
Keyword(s):  
Liquid Crystals ◽  
Liquid Crystalline ◽  
Molecular Size ◽  
Digital Design ◽  
Lyotropic Liquid Crystals ◽  
Colloidal Systems ◽  
Extended Form ◽  
Crystalline Materials ◽  
Liquid Crystalline Materials ◽  
External Stimuli

Abstract Meta-periodicity beyond intrinsic atomic and molecular order, such as metacrystalline and quasicrystalline lattices, exists in solids, but is usually elusive in lyotropic liquid crystals for its energetic instability. The stable meta-periodicity in lyotropic liquid crystals in the absence of external stimuli remains unexplored, and how to achieve it keeps a great challenge. Here we create lyotropic liquid crystals with stable meta-periodicity in a free state, coined as liquid metacrystals, in colloidal systems by an invented shearing microlithography. The meta-periodicity is dynamically stabilized by the giant molecular size and strong excluded volume repulsion. Liquid metacrystals are designed to completely cover a library of symmetries, including five Bravais and six quasicrystalline lattices. Liquid metacrystal promises an extended form of liquid crystals with rich meta-periodicity and the shearing microlithography emerges as a facile technology to fabricate liquid meta-structures and metamaterials, enabling the digital design of structures and functionalities of liquid crystalline materials.

scholarly journals Light Propagation in Confined Nematic Liquid Crystals and Device Applications

2021 ◽  
Vol 11 (18) ◽  
pp. 8713
Author(s):  
Antonio d’Alessandro ◽  
Rita Asquini
Keyword(s):  
Liquid Crystals ◽  
Optical Switching ◽  
Liquid Crystalline ◽  
Light Propagation ◽  
Soda Lime ◽  
Significant Feature ◽  
Molecular Reorientation ◽  
Crystalline Materials ◽  
Integrated Optic Devices ◽  
Liquid Crystalline Materials

Liquid crystals are interesting linear and nonlinear optical materials used to make a wide variety of devices beyond flat panel displays. Liquid crystalline materials can be used either as core or as cladding of switchable/reconfigurable waveguides with either an electrical or an optical control or both. In this paper, materials and main device structures of liquid crystals confined in different waveguide geometries are presented using different substrate materials, such as silicon, soda lime or borosilicate glass and polydimethylsiloxane. Modelling of the behaviour of liquid crystal nanometric molecular reorientation and related refractive index distribution under both low-frequency electric and intense optical fields is reported considering optical anisotropy of liquid crystals. A few examples of integrated optic devices based on waveguides using liquid crystalline materials as core for optical switching and filtering are reviewed. Reported results indicate that low-power control signals represent a significant feature of photonic devices based on light propagation in liquid crystals, with performance, which are competitive with analogous integrated optic devices based on other materials for optical communications and optical sensing systems.

scholarly journals Inexpensive, operationally simple flow reactor for rapid, chromatography free synthesis of siloxane based liquid crystals

2018 ◽  
Vol 3 (4) ◽  
pp. 515-519 ◽  
Author(s):  
Richard J. Mandle ◽  
John W. Goodby
Keyword(s):  
Liquid Crystals ◽  
Liquid Crystalline ◽  
Flow Reactor ◽  
Crystalline Materials ◽  
Terminal Alkenes ◽  
Liquid Crystalline Materials ◽  
Simple Flow

We report on the hydrosilylation of terminal alkenes in flow using a “Karstedt-like” platinum-on-silica catalyst to afford liquid-crystalline materials.

scholarly journals In Situ and Ex Situ Syntheses of Magnetic Liquid Crystalline Materials: A Comparison

Polymers ◽  
2012 ◽  
Vol 4 (1) ◽  
pp. 448-462 ◽  
Author(s):  
Ophelie Riou ◽  
Lacramioara Zadoina ◽  
Barbara Lonetti ◽  
Katerina Soulantica ◽  
Anne-Françoise Mingotaud ◽  
...  
Keyword(s):  
Liquid Crystalline ◽  
Ex Situ ◽  
Magnetic Liquid ◽  
Crystalline Materials ◽  
Liquid Crystalline Materials

scholarly journals Exploration of immobilization conditions of cellulosic lyotropic liquid crystals in monomeric solvents by in situ polymerization and achievement of dual mechanochromism at room temperature

RSC Advances ◽  
2018 ◽  
Vol 8 (44) ◽  
pp. 24724-24730 ◽  
Author(s):  
K. Miyagi ◽  
Y. Teramoto
Keyword(s):  
Liquid Crystals ◽  
Polymer Composites ◽  
Liquid Crystalline ◽  
Room Temperature ◽  
In Situ Polymerization ◽  
Synthetic Polymer ◽  
Lyotropic Liquid Crystals ◽  
Liquid Crystalline Structure ◽  
Cholesteric Liquid Crystalline

We obtained cellulosic/synthetic polymer composites incorporating a cholesteric liquid crystalline structure by in situ polymerization and accomplished dual mechanochromism at room temperature.

ORDERING AND ORDERING TRANSITIONS IN CONFINED LIQUID CRYSTALS

1993 ◽  
Vol 07 (28) ◽  
pp. 1785-1808 ◽  
Author(s):  
G.P. CRAWFORD ◽  
J.W. DOANE
Keyword(s):  
Liquid Crystals ◽  
Liquid Crystalline ◽  
Finite Size ◽  
Finite Size Effects ◽  
Crystalline Materials ◽  
The Past ◽  
Ordering Transitions ◽  
The Subject ◽  
Liquid Crystalline Materials ◽  
Confined Liquid Crystals

A resurgence of interest in confined liquid crystals has taken place over the past few years because of the availability of well-defined and random-type matrices that can be used to constrain liquid crystalline materials to submicrometer spaces. The main driving force behind many of the studies on confined liquid crystals is their relevance to electrically controllable light-scattering devices. Apart from their electrooptic importance, confined liquid crystals introduce many fascinating surface and finite-size effects which are the subject of this review.

The Dynamical Theory of Liquid Crystals

1994 ◽  
Author(s):  
Antony N. Beris ◽  
Brian J. Edwards
Keyword(s):  
Liquid Crystals ◽  
Liquid Crystalline ◽  
Flow Behavior ◽  
Intermolecular Forces ◽  
Dynamical Theory ◽  
Shear Stresses ◽  
Crystalline Materials ◽  
Conformation Tensor ◽  
The Many ◽  
Liquid Crystalline Materials

Liquid crystals (LCs) present a state of matter with properties—as the name suggests—intermediate between those of liquids and crystalline solids. Liquid-crystalline materials, as all liquids, cannot support shear stresses at static equilibrium. Their molecules are characterized by an anisotropy in the shape and/or intermolecular forces. Thus, there is the potential for the formation of a separate phase(s), called a “mesophase(s),” where a partial order arises in the molecular orientation and/or location, which extends over macroscopic distances. This partial long-range molecular order, reminiscent of (but not equivalent to) the perfect order of solid crystals, in addition to the material fluidity, is primarily responsible for the many properties which are inherent characteristics of liquid-crystalline phases, such as a rapid response to electric and magnetic fields, anisotropic optical and rheological properties, etc.—see, for examples, the reviews by Stephen and Straley [1974] and Jackson and Shaw [1991], the monographs by de Gennes [1974], Chandrasekhar [1977], and Vertogen and de Jeu [1988], and the edited volumes by Ciferri et al. [1982] and Ciferri [1991]. The variety of the liquid-crystalline macroscopic properties is such that trying to derive a theory capable of describing the principal liquid-crystalline dynamic characteristics can be a very frustrating task if one does not approach the issue in a systematic fashion. Characteristically, the main two theories that have been advanced over the last thirty years for the description of the liquid-crystalline flow behavior—the Leslie/ Ericksen (LE) theory and the Doi theory—are essentially models developed from a set theoretical frame work—continuum mechanics and molecular theory, respectively. Nevertheless, each one of these theories has a limited domain of application. The description of the dynamic liquid-crystalline behavior through the bracket formalism, as seen in this chapter, leads naturally to a single conformation tensor theory with an extended domain of validity. This conformation theory consistently generalizes both previous theories, which can be recovered from it as particular cases. This offers additional evidence that the wealth of inherent information in LCs can only be appropriately handled when pursued in a systematic, fundamental manner.

scholarly journals PHASE TRANSITION STUDIES OF CHOLESTERYL PALMITATE, CHOLESTERYL DECANOATE AND THEIR MIXTURES USING DIELECTRIC, EPR AND DTA TECHNIQUES

2021 ◽  
Vol 9 (11) ◽  
pp. 210-223
Author(s):  
Sanjai Misra ◽  
Keyword(s):  
Phase Transition ◽  
Liquid Crystals ◽  
Order Parameter ◽  
Liquid Crystalline ◽  
Paramagnetic Resonance ◽  
Crystalline Materials ◽  
Phase Transition Temperatures ◽  
Cholesteryl Palmitate ◽  
Liquid Crystalline Materials ◽  
Electron Paramagnetic

The phase transition of two liquid crystalline materials, namely cholesteryl palmitate and cholesteryl decanoate and their mixtures (by weight)are studied using dielectric, Electron paramagnetic resonance (EPR) and differential thermal analysis (DTA) techniques. From the dielectric measurements, the phase transition temperatures were determined from the discontinuities in the curve between dielectric constant and temperatures for all the samples investigated. Further, since mixing of two liquid crystals modifies the transition of phases, the measurements were carried out on the mixtures of the two liquid crystals. Order parameter for each sample was calculated at varying temperatures by measuring the hyperfine splitting of three line EPR spectrums. The discontinuities in the curve between order parameter and the temperature again indicated the phase transition of the liquid crystals and their mixtures. A DTA study on these samples was also carried out in order to probe further their transitional behaviour. The DTA records of both the liquid crystals and their mixtures support the transition behaviour observed from the dielectric and EPR measurements.

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