Download or read book Chirality in Liquid Crystals from Bent cores to Chromonics written by Leah Elaine Bergquist and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chirality is a central scientific concept but its superstructural and nanoscale manifestation are not well understood, severely limiting the potential of materials in a range of emerging applications. In the first part of this dissertation, we examine a lyotropic chromonic liquid crystal (LCLC) forming a nematic phase for its more intense response to gold nanoparticles capped with chiral L-cysteine ligand molecules than to their free molecular counterparts. We show that such nanoparticles induce a tighter chiral twist within, and similar among, the stacks of nematic LCLCs but with several orders of magnitude fewer chiral molecules. The second part of this dissertation focuses on the SmCP phase and the development of an optically isotropic antiferroelectric liquid crystal (OI-AFLC) display mode. This report describes in detail the synthesis and characterization of a series bent-core liquid crystal (LC) systems. Multi-component mixtures of these compounds achieved room temperature switching between optically isotropic and birefringent states; several mixtures displayed a modulated SmCaPA phase extending from below -40 °C up to about 100 °C. Requiring high fields and showing slow switching speeds, their utility is found in non-video-rate switching applications requiring high contrast.
Download or read book Introduction to Liquid Crystals written by Peter J. Collings and published by CRC Press. This book was released on 2019-10-23 with total page 397 pages. Available in PDF, EPUB and Kindle. Book excerpt: Introduction to Liquid Crystals: Chemistry and Physics, Second Edition relies on only introductory level chemistry and physics as the foundation for understanding liquid crystal science. Liquid crystals combine the material properties of solids with the flow properties of fluids. As such they have provided the foundation for a revolution in low-power, flat-panel display technology (LCDs). In this book, the essential elements of liquid crystal science are introduced and explained from the perspectives of both the chemist and physicist. This new edition relies on only introductory level physics and chemistry as the foundation for understanding liquid crystal science and is, therefore, ideal for students and recent graduates. Features Introduces and explains the essential elements of liquid crystal science, including discussion of how liquid crystals have been utilized for innovative and important applications. New to this edition are over 300 figures, 90 end-of chapter exercises, and an increased scope that includes recent developments. Combines the knowledge of two eminent scientists in the field; they have fully updated and expanded the text to cover undergraduate/graduate course work as well as current research in what is now a billion-dollar industry. Immerses the reader in the vocabulary, structures, data, and kinetic models, rapidly building up an understanding of the theories and models in current use. Begins with a historical account of the discovery of liquid crystals and continues with a description of how different phases are generated and how different molecular architectures affect liquid crystal properties.
Download or read book Chirality in Liquid Crystals written by Heinz Kitzerow and published by Springer Science & Business Media. This book was released on 2006-04-28 with total page 513 pages. Available in PDF, EPUB and Kindle. Book excerpt: Describes the main aspects of chirality in liquid crystals, and points out some of the open questions of current research. The chapters review the highlights of the important topics and questions.
Download or read book Bent Shaped Liquid Crystals written by Hideo Takezoe and published by CRC Press. This book was released on 2017-07-20 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bent-Shaped Liquid Crystals: Structures and Physical Properties provides insight into the latest developments in the research on liquid crystals formed by bent-shaped mesogens. After a historical introduction, the expert authors discuss different kinds of mesophase structures formed by bent-shaped molecules. This book devotes the majority of its pages to physical properties such as polar switching, optics and non-linear optics, and behavior in restricted geometries. However, as chemistry is often highly relevant to the emergence of new phases, particularly with reflection symmetry breaking, it also involves a broad spectrum of interesting chemistry viewpoints.
Download or read book Liquid Crystals Beyond Displays written by Quan Li and published by John Wiley & Sons. This book was released on 2012-05-29 with total page 598 pages. Available in PDF, EPUB and Kindle. Book excerpt: The chemistry, physics, and applications of liquid crystals beyond LCDs Liquid Crystals (LCs) combine order and mobility on a molecular and supramolecular level. But while these remarkable states of matter are most commonly associated with visual display technologies, they have important applications for a variety of other fields as well. Liquid Crystals Beyond Displays: Chemistry, Physics, and Applications considers these, bringing together cutting-edge research from some of the most promising areas of LC science. Featuring contributions from respected researchers from around the globe, this edited volume emphasizes the chemistry, physics, and applications of LCs in areas such as photovoltaics, light-emitting diodes, filed-effect transistors, lasers, molecular motors, nanophotonics and biosensors. Specific chapters look at magnetic LCs, lyotropic chromonic LCs, LC-based chemical sensors, LCs in metamaterials, and much more. Introducing readers to the fundamentals of LC science through the use of illustrative examples, Liquid Crystals Beyond Displays covers not only the most recent research in the myriad areas in which LCs are being utilized, but also looks ahead, addressing potential future developments. Designed for physicists, chemists, engineers, and biologists working in academia or industry, as well as graduate students specializing in LC technology, this is the first book to consider LC applications across a wide range of fields.
Download or read book Chirality effects in thermotropic and lyotropic nematic liquid crystals under confined geometries written by Clarissa Dietrich and published by Cuvillier Verlag. This book was released on 2019-12-09 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chirality is a phenomenon in nature that appears across all disciplines of natural science, from biology to mathematics. The spontaneous formation of chiral structures in a system of achiral components is known as spontaneous mirror symmetry breaking and is by itself of fundamental interest leading also towards the question of the origin of homochirality in nature in general. In this work, we show that by means of the topology imposed by the confining geometry and by interfacial boundary conditions – in combination with the physical properties of a liquid crystal – spontaneous mirror symmetry broken structures can be obtained. They are analyzed, inter alia, with respect to the types of geometrical confinements used, e.g. how the confinement amplifies, induces, and influences the detection of chirality effects in order to facilitate the measurement of tiny amounts of chiral additives qualitatively and quantitatively.
Download or read book The Synthesis and Properties of Achiral and Chiral Bent core Liquid Crystals written by Kenneth Matthew Fergusson and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The area of liquid crystals has received substantial research effort over the last century, particularly when the beneficial applications such as Liquid Crystal Displays (LCDs) were realised and developed. For the majority of this time, it has been considered that a linear molecular shape is required in order to generate a mesomorphic phase. It was therefore of particular interest and excitement when, in 1996, it was shown that a 'banana-shaped' molecular architecture could exhibit a new class of liquid crystalline phase. Additionally it was found that these new mesophases exhibited chiral domains, leading to electrooptical switching properties, despite the constituent molecules being achiral. Unsurprisingly, these observations have led to a vast frontier of research in the area of 'banana-shaped' and 'bentcore' systems over the past decade and many interesting properties relating to such systems have been reported. The work contained within this thesis investigates two areas of bent-core liquid crystals. Firstly, the introduction of fluoro-substituents to the bent-core of an achiral banana-shaped system has been assessed, in terms of both position, and number of substituents. The resultant mesomorphic properties of these compounds have shown that there is a very delicate boundary between banana, and 'conventional' mesomorphism, relating to subtle changes in molecular structure. Appropriately positioned fluoro-substituents upon the bent-core generate a more linear conformation, facilitating the generation of nematic phases. Possible reasoning for this observation has been discussed. Secondly, the effect of introducing a bent-core to a conventional calamitic structure, and the addition of fluoro-substituents, has been examined. Whilst a variation of this nature to the majority of calamitic molecular structures would have a severely detrimental effect upon the resultant mesophase morphology, it has been shown that this is not always the case and indeed the addition of fluoro-substituents is shown to enhance the mesomorphic stability of the smectic A phase.
Download or read book Bent core Liquid Crystals written by Hideo Takezoe and published by CRC Press. This book was released on 2015-12-26 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides insight into the latest developments in the research on liquid crystals formed by bent-core mesogens. After a short historical introduction, the authors discuss different kinds of mesophase structures formed by bent-core molecules. A majority of this book is devoted to physical properties such as elasticity, optics and non-linear optics, and behavior in restricted geometries. As chemistry is often relevant to the emergence of new phases, particularly with chiral symmetry breaking, chemistry viewpoints are broadly involved in this book.
Download or read book Statistical Mechanics of Polar Biaxial and Chiral Order in Liquid Crystals written by Subas Dhakal and published by . This book was released on 2010 with total page 118 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation addresses three distinct problems in liquid crystal: phase transitions among different SmCP phases of bent-core liquid crystal, flexoelectric effect in nematic liquid crystal and interplay between chirality and biaxiality in cholesteric liquid crystal. These problems are studied with computer simulations and analytical calculations. The first part of this dissertation is about chiral switching in smectic phases of bent-core liquid crystals. The phenomenon is investigated with a lattice Monte Carlo simulation and a phenomenological theory. Both methods show that the antiferroelectric (AFE) ground state switches into a ferroelectric state (FE) at sufficiently large electric field. In this transition, the chirality of the phase could change or not. In the case of weak inter-layer chiral coupling, anticlinic order of molecules from layer to layer could remain through the transition -thus changing the chirality of the phase. However, for a large value of chiral coupling, the anticlinic state could change to a synclinic state in the transition -thus preserving the chirality of the phase. Another area of focus is on flexoelectric effect in nematic liquid crystal. Recent experiments have shown that bent-core liquid crystals have a surprisingly large bend flexoelectric coefficient, up to 35 nC/m, roughly three orders of magnitude larger than the typical value. With this large bend flexoelectric coefficient, bent-core liquid crystals may be practical materials for converting mechanical into electrical energy. One of the focal points of this dissertation is to explain the large flexoelectric effect found in bent-core liquid crystals. Theoretical models of splay and bend flexoelectric effect are developed that incorporates the coupling between the director distortion (either splay or bend) and polarization. Through these models the flexoelectric response as a function of interaction parameters, temperature, and applied electric field is studied. Simulations and analytical calculations show that there is a large flexoelectric effect in the nematic phase, which diverges as the system approaches the transition to the polar phase. This observation demonstrated that flexoelectricity is not just a molecular effect but could be a statistical phenomenon associated with the response of correlated volumes of molecules, which increases as one approaches the polar phase. Finally, we investigate the statistical mechanics of chirality and biaxiality in liquid crystals through a variety of theoretical approaches, including Monte Carlo simulations, lattice mean-field theory, and Landau theory. All of these calculations show that there is an important interaction between cholesteric twist and biaxial order: The twist acts as a field on the biaxial order, and conversely, the biaxial order increases the twist, i.e. reduces the pitch. We model the behavior of chiral biaxial liquid crystals as a function of temperature, and discuss how the predictions can be tested in experiments.
Download or read book Unconventional Liquid Crystals and Their Applications written by Wei Lee and published by Walter de Gruyter GmbH & Co KG. This book was released on 2021-07-19 with total page 581 pages. Available in PDF, EPUB and Kindle. Book excerpt: The work focuses on recent developments of the rapidly evolving field of Non-conventional Liquid Crystals. After a concise introduction it discusses the most promising research such as biosensing, elastomers, polymer films , photoresponsive properties and energy harvesting. Besides future applications it discusses as well potential frontiers in LC science and technology.
Download or read book Liquid Crystals Fundamentals written by Shri Singh and published by World Scientific. This book was released on 2002-11-05 with total page 549 pages. Available in PDF, EPUB and Kindle. Book excerpt: Liquid crystals are partially ordered systems without a rigid, long-range structure. The study of these materials covers a wide area: chemical structure, physical properties and technical applications. Due to their dual nature — anisotropic physical properties of solids and rheological behavior of liquids — and easy response to externally applied electric, magnetic, optical and surface fields liquid crystals are of greatest potential for scientific and technological applications. The subject has come of age and has achieved the status of being a very exciting interdisciplinary field of scientific and industrial research.This book is an outgrowth of the enormous advances made during the last three decades in both our understanding of liquid crystals and our ability to use them in applications. It presents a systematic, self-contained and up-to-date overview of the structure and properties of liquid crystals. It will be of great value to graduates and research workers in condensed matter physics, chemical physics, biology, materials science, chemical and electrical engineering, and technology from a materials science and physics viewpoint of liquid crystals.
Download or read book Structure and Properties of Liquid Crystals written by Lev M. Blinov and published by Springer Science & Business Media. This book was released on 2010-10-26 with total page 448 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book by Lev M. Blinov is ideal to guide researchers from their very first encounter with liquid crystals to the level where they can perform independent experiments on liquid crystals with a thorough understanding of their behaviour also in relation to the theoretical framework. Liquid crystals can be found everywhere around us. They are used in virtually every display device, whether it is for domestic appliances of for specialized technological instruments. Their finely tunable optical properties make them suitable also for thermo-sensing and laser technologies. There are many monographs written by prominent scholars on the subject of liquid crystals. The majority of them presents the subject in great depth, sometimes focusing on a particular research aspect, and in general they require a significant level of prior knowledge. In contrast, this books aims at an audience of advanced undergraduate and graduate students in physics, chemistry and materials science. The book consists of three parts: the first part, on structure, starts from the fundamental principles underlying the structure of liquid crystals, their rich phase behaviour and the methods used to study them; the second part, on physical properties, emphasizes the influence of anisotropy on all aspects of liquid crystals behaviour; the third, focuses on electro-optics, the most important properties from the applications standpoint. This part covers only the main effects and illustrates the underlying principles in greater detail. Professor Lev M. Blinov has had a long carrier as an experimentalist. He made major contributions in the field of ferroelectric mesophases. In 1985 he received the USSR state prize for investigations of electro-optical effects in liquid crystals for spatial light modulators. In 1999 he was awarded the Frederiks medal of the Soviet Liquid Crystal Society and in 2000 he was honoured with the G. Gray silver medal of the British Liquid Crystal Society. He has held many visiting academic positions in universities and laboratories across Europe and in Japan.
Download or read book Chirality in Liquid Crystals written by Heinz Kitzerow and published by Springer. This book was released on 2013-03-26 with total page 502 pages. Available in PDF, EPUB and Kindle. Book excerpt: Describes the main aspects of chirality in liquid crystals, and points out some of the open questions of current research. The chapters review the highlights of the important topics and questions.
Download or read book Chemistry of Discotic Liquid Crystals written by Sandeep Kumar and published by CRC Press. This book was released on 2016-04-19 with total page 512 pages. Available in PDF, EPUB and Kindle. Book excerpt: The self-contained properties of discotic liquid crystals (DLCs) render them powerful functional materials for many semiconducting device applications and models for energy and charge migration in self-organized dynamic functional soft materials. The past three decades have seen tremendous interest in this area, fueled primarily by the possibility
Download or read book Liquid Crystals written by Peter J. Collings and published by Princeton University Press. This book was released on 2002 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt: Publisher Description
Download or read book X ray Study of Mesomorphism of Bent core and Chromonic Mesogens written by Leela Pradhan Joshi and published by . This book was released on 2009 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: The discovery of thermotropic biaxial nematic phase in bent-core mesogens, have engendered interest in these systems. Also, it undergoes optical switching about 100 times faster than conventional uniaxial nematic liquid crystal. Azo-substituted bent-core compounds, A131 and A103, were investigated as both offer an opportunity to observe their structures and phase transitions from the uniaxial nematic (Nu) to biaxial nematic (Nb) phase and from Nb to the underlying smectic-C (SmC) phase. Plank-like molecular systems are also expected to form Nb phase. Chromonic liquid crystals formed by aqueous solutions of plank-like dye molecules are interesting for their unique self-assembly and structural evolution. They have applications in optical element, coloring in food and textiles, and etc. Both systems were investigated with synchrotron x-ray scattering, polarizing optical microscopy, and differential scanning calorimetry. Temperature dependence of d-spacing and positional order correlations along the director clearly mark the phase boundaries where Nu-Nb transition was approximately 27o below the clearing point. Positional order correlation length of A131 increased from 1.5 in Nu to 3.3 molecular lengths in Nb phase, before it jumps by a factor of at least 5 in SmC phase. The lack of large discontinuous changes in the structural parameters and the subtle signatures in heat capacity establish the second order nature of Nu-Nb and Nb-SmC phase transitions. The chromonic system investigation results provide quantitative information of structural properties in nematic and columnar mesophases. We studied water solutions of (achiral) sunset yellow dye and (chiral and achiral) dihydrochloride salts of perylenebis-dicarboxydiimide. Positional order correlation lengths' measurements, parallel and perpendicular to the aggregate axis, revealed that they increase with concentration and decrease with temperature. Temperature dependence of correlation lengths yielded the scission energy to be 1.8 ("0.1) x10-20J and 1.5 ("0.08) x10-20J in the nematic and columnar phases. The aggregates' small aspect ratio (2.5) is inconsistent with the Onsager model for the formation of an orientationally ordered phase, which strongly suggests more complicated aggregate-shape than simple cylindrical objects as postulated by Laventovich, et al.
Download or read book Advances in Cholesteric Liquid Crystals written by Michel Mitov and published by MDPI. This book was released on 2020-02-05 with total page 122 pages. Available in PDF, EPUB and Kindle. Book excerpt: With their helical structure, cholesteric liquid crystals figure prominently in liquid crystal science. The selective reflection of light is their flagship property, and they offer a myriad of applications as advanced optical materials with multiscale properties. The cholesteric structure is also a ubiquitous design in the animal and plant kingdoms. This book contains eight contributions on fundamental investigations about defects, textures and structures of cholesteric materials, and experimental studies aimed at applications such as temperature sensors, head-up displays for improving automobile driving safety, or smart windows.
