Download or read book Optical Characterization of Lyotropic Chromonic Liquid Crystals written by Hui Liu and published by . This book was released on 2006 with total page 87 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lyotropic chromonic liquid crystals (LCLCs) represent a special class of lyotropic mesophases markedly different from conventional amphiphilic mesogens. Materials forming LCLCs are composed of plank-like molecules with a polyaromatic central core and hydrophilic ionic groups at the periphery. The individual molecules tend to assemble into rodlike aggregates that form the N phase once the concentration exceeds about 0.1M. The LCLC materials show a tremendous potential for applications in optics as self-assembling polarizing and compensating films and in the area of real-time biological sensing. The emerging applications require an understanding of basic properties of LCLC. This work addresses these needs by providing the optical characterization of LCLC. We studied in detail the optical anisotropic properties of three different nematic LCLCs: disodium cromoglycate (DSCG), blue 27, and violet 20. We determined the birefringence of these three materials as the function of the temperature T and wavelength fÜ and the corresponding dependencies of the absorption coefficients for blue 27 and violet 20. The birefringence is negative and significantly lower in the absolute value as compared to the birefringence of typical thermotropic N materials. We determined the scalar order parameter of the nematic phase of blue 27 and its temperature dependence. The scalar order parameter is close to the one predicted by the classic Onsager theory for solutions of rigid rods. However, this similarity is not complete, as the measured scalar order parameter depends on temperature. The I-N pretransitional fluctuations in an aqueous solution of DSCG were studied by light scattering. We obtained the correlation length of the orientational order-parameter fluctuations of isotropic DSCG solution. The pretransitional behavior of light scattering does not completely follow the classic Landau-de Gennes model. This feature is explained by the variable length of DSCG aggregates as a function of temperature.
Download or read book Lyotropic Chromonic Liquid Crystals written by Shuang Zhou and published by Springer. This book was released on 2017-02-14 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis describes lyotropic chromonic liquid crystals (LCLCs) with exotic elastic and viscous properties. The first part of the thesis presents a thorough analysis of the elastic and viscous properties of LCLCs as functions of concentration, temperature and ionic contents, while the second part explores an active nematic system: living liquid crystals, which represent a combination of LCLC and living bacteria. LCLCs are an emerging class of liquid crystals that have shown profound connections to biological systems in two aspects. First, the assembly process of the chromonic aggregates is essentially the same as DNA oligomers and other super-molecular assemblies of biological origin. LCLCs thus provide an excellent model system for studying physical properties such as the elasticity and viscosity of these supramolecular assemblies. Second, LCLCs are biocompatible, thus serving as a unique anisotropic matrix to interface with living systems such as bacteria. This thesis deepens our understanding of both aspects. The noncovalent nature of chromonic aggregation produces the unique viscoelasticity to be found in LCLCs, which differs dramatically from that of traditional LCs. Anisotropic interactions between LCLCs and bacteria lead to fascinating phenomena such as the deformation of LCLCs with a characteristic wavelength determined by the elasticity of the LCLCs and the activity of the bacteria, orientationally controlled trajectories of bacteria and visualization of 24 nm flagella motion.
Download or read book Magneto optical and Imaging Studies of Chromonic and Thermotropic Liquid Crystals written by Tanya Ostapenko and published by . This book was released on 2011 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation addresses three experimental questions. First, the pretransitional behavior of lyotropic chromonic liquid crystals (LCLCs) is investigated in order to gain further insight into the aggregation mechanism and structure. In order to study the pretransitional behavior of LCLCs in the isotropic phase, a high magnetic field is applied perpendicular to the light propagation direction, which induces birefringence in the material; this is called the Cotton-Mouton effect. The aggregates align with the field, which makes it possible to study how the aggregates form in the isotropic phase. The results of this study indicate that multiple optical effects can be induced, which supports the possibility of a complex aggregate structure. The second part of this dissertation explores the possibility of a biaxial nematic phase (Nb). The geometry of the liquid crystal mesogen is important and it is thought that banana-shaped liquid crystals will have an Nb phase. However, contradicting reports on different bent-core materials have not determined whether this phase exists in them. Optical techniques usually rely on a sample cell rubbing treatment to homeotropically align the main director, n, but optical misidentification of Nb could occur if the material is in a tilted uniaxial phase, which appears the same as a homeotropically-aligned biaxial phase. Using a high magnetic field to completely align n and measuring the magnetic field-induced optical phase difference perpendicular to n gives a conclusive way to determine whether a material has non-zero biaxial order. None of the materials studied appear to have an Nb phase. The last part of this dissertation examines director fluctuations in calamitic and bent-core liquid crystals using dynamic imaging analysis. Dynamic image analysis is a relatively new technique where a measurement of nematic phase fluctuations is made in direct space. These measurements are done using a polarizing microscope, heat stage and CCD camera. The advantage of this technique is that it measures small values of q, making it a complementary technique to dynamic light scattering, where large values of q are easily obtained. Basic material properties may be related to the wave vector and decay time of the fluctuations.
Download or read book Lyotropic Liquid Crystals written by Ingo Dierking and published by Oxford University Press. This book was released on 2024-07-16 with total page 225 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book aims to review the field of lyotropic liquid crystals from amphiphilic to colloidal systems, bridging the gap between the two worlds of lyotropics and thermotropics by showing that many of the features observed in standard thermotropic liquid crystals may also be observed in lyotropic systems and vice versa. Indeed, for a long time, lyotropic liquid crystals have been overshadowed by their thermotropic counterparts, mainly due to the potential for application of the latter in the display industry. This picture has somewhat shifted over the last decade, with numerous novel lyotropic systems having been discovered and formulated, bringing to light their importance in wider scientific research. For example, the understanding of viruses forming self-assembled ordered phases has largely increased as mineral liquid crystals and clays have experienced a renaissance leading to fundamental research and work on structure formation in nanotechnology. Similarly, nano-rods, nano-wires, nanotubes and 2D materials like graphene oxide and others have been shown to exhibit liquid crystalline behaviour, which may be exploited in self-assembly, drug delivery or biosensors. Cellulose nanocrystals have become an important and popular field of research. The self-assembly of short chain DNA fragments has led to liquid crystal behaviour previously thought to be impossible. Chromonics were shown to exhibit fascinating physical properties, and the combination of active fluids with liquid crystals has opened a whole new field of research to be explored - 'living 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 Nonlinear Optical Properties of Liquid Crystals and Polymer Dispersed Liquid Crystals written by Francesco Simoni and published by World Scientific. This book was released on 1997 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt: This monograph is devoted to a detailed treatment of the nonlinear optical properties of liquid crystals. The basic concepts of director optical reorientation and thermal nonlinearities are presented showing the fundamental theoretical approaches and describing the main experimental observations. The presentation is self-consistent and tutorial although the subject matter is of current research interest.The last part of the book deals with more recent results on new composite materials: Polymer Dispersed Liquid Crystals (PDLC). A general presentation of the optical properties is given and the observations of several nonlinear optical effects are reported.
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 Optics and Nonlinear Optics of Liquid Crystals written by Iam-Choon Khoo and published by World Scientific. This book was released on 1993 with total page 442 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is a monograph/text devoted to a detailed treatment of the optical, electro-optical and nonlinear optical properties of all the mesophases of liquid crystals and related processes, phenomena and application principles. Quantitative data on material and optical parameters spanning the ultraviolet, visible, infrared as well as the microwave regimes are presented along with detailed theoretical treatments of basic liquid crystal physics, material properties and nonlinear optics.Starting with a discussion on the basic building blocks of liquid crystalline molecules, the authors proceed to present in a pedagogical manner current theories, experiments, and applications of these unique and important optical properties of liquid crystals. Numerous tables of hard-to-find liquid crystalline parameters, a self-contained chapter on general nonlinear optics, and comprehensive literature review are also included.
Download or read book Optical and Electro optical Properties of Liquid Crystals written by Minko Parvanov Petrov and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes the general properties of the most popular liquid crystal (LC) phases nematics (Ns) and smectics (Ss), and in addition, is directed to fill in a niche of the LC field. This book covers topics ranging from the types and classifications of liquid crystals to a detail description of the fundamental properties of nematics and smectics, including continuum theory, non-linearity, behaviour in electric field, surface alignment, phase transitions, defect and textures and provides a useful reference intended for advanced topics of the physics of liquid crystals.
Download or read book Electro optical and Magneto optical Properties of Liquid Crystals written by Lev Mikhaĭlovich Blinov and published by John Wiley & Sons. This book was released on 1983 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Introduction to Liquid Crystals for Optical Design and Engineering written by Sergio R. Restaino and published by . This book was released on 2015 with total page 119 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Electro Optical and Magneto Optical Properties of Liquid Crystals written by Lev Mihajlovič Blinov and published by . This book was released on 1983 with total page 363 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Physics of Lyotropic Liquid Crystals written by Antônio M. Figueiredo Neto and published by OUP Oxford. This book was released on 2005-01-27 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gives a comprehensive description of the physical properties of lyotropic liquid crystals. Structural features, phase transitions and phase diagrams are discussed in detail. The available experimental data on lyotropic mixtures is presented in the unifying context of the Landau theories. This phenomenological approach is used for establishing connections between structural properties and phase diagrams. The book is suitable for use as a pedagogical introduction to the subject.
Download or read book Optical Applications of Liquid Crystals written by L Vicari and published by CRC Press. This book was released on 2016-04-19 with total page 284 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, there has been increasing activity in the research and design of optical systems based on liquid crystal (LC) science. Bringing together contributions from leading figures in industry and academia, Optical Applications of Liquid Crystals covers the range of existing applications as well as those in development. Unique in its thorou
Download or read book New Trends in Lyotropic Liquid Crystals written by Ingo Dierking and published by MDPI. This book was released on 2020-11-02 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: Liquid crystals (LCs) were discovered more than a century ago, and were, for a long time, treated as a physical curiosity, until the development of flat panel screens and display devices caused a revolution in the information display industry, and in fact in society. There would be no mobile phones without liquid crystals, no flat screen TVs or computer monitors, no virtual reality, just to name a few of the applications that have changed our whole world of vision and perception. All of these inventions are based on liquid crystals that are formed through a change in temperature, thermotropic LCs. However, there is another form of liquid crystals, described even earlier, yet much less talked about; the lyotropic liquid crystals that occur through the change of concentration of some molecules in a solvent. These are found in abundance in nature, making up the cell membranes, and are used extensively in the food, detergents and cosmetics industries. In this collection of articles by experts in their respective research areas, we bring together some of the most recent and innovative aspects of lyotropic liquid crystals, which we believe will drive future research and set novel trends in this field.
Download or read book Studies on Lyotropic Chromonic Liquid Crystals in Nematic and Biphasic Regions written by Xuxia Yao and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Chromonic liquid crystals are a relatively new class of lyotropic liquid crystals. In an effort to understand this lyotropic phase better, studies on the phase behavior, defects formed in these systems and characterization of the order were performed. We studied three chromonic liquid crystal materials in nematic and biphasic regions: Sunset Yellow FCF (SSY, a food dye), a cationic perylene diimide derivative (PDI, a conducting dye) and cromolyn sodium (DSCG, a drug). For SSY chromonics in the nematic region, order parameters (and) were obtained by polarized Raman measurements. Using the order parameters the flow behavior was predicted and was found to be non-flow aligning. A comprehensive viscoelastic property set of SSY chromonics was obtained by studying the statics and dynamics of defects during the formation of planar aligned monodomain. Applications of PDI thin films as vapor sensors were explored; anisotropic electronic properties of oriented PDI films show good conductivity along the columns presumably arising from the overlap between the? systems. In the biphasic region, growth and fluctuation of SSY tactoids and interesting patterns of biphasic DSCG under capillary geometry were observed; elastic properties and surface tension were estimated based on the shape of DSCG tactoids. Polymer dispersed lyotropic chromonic liquid crystals with different drop shapes and director configurations were also fabricated using various water-soluble polymers.
Download or read book Opticals Effects in Liquid Crystals written by I. Jánossy and published by Springer Science & Business Media. This book was released on 2013-11-11 with total page 242 pages. Available in PDF, EPUB and Kindle. Book excerpt: In 1988 physicists and chemists commemorated the centenary of the discovery of the first liquid crystals. Fora long period after this discovery, although many significant results were found, liquid crystal research remained a marginal topic of condensed matter physics. The situation changed in the sixties. At that time the remarkable electro-optical properties of liquid crystals were recognized and found soon widespread application in numeric displays. From a more fundamental point of view, the interest in disordered systems. increased in general at the same time. Liquid crystals represented an important dass of such systems. Among others, phase transitions, hydrodynamics and topological defects occurring in them attracted considerable attention. The connection between the liquid-crystalline state and the structure of biological membranes stimulated a Iot of works also. In the present volume we discuss a relatively new and rapidly developing branch of the fi. eld, namely nonlinear optical effects in liquid crystals. Optical studies have always played a signifi. cant role in liquid crystal science. Research of optical nonlinearities in liquid crystals began at the end of the sixties. Since then it became a powerful tool in the investigation of symmetry properties, interfacial phenomena or dynamic behaviour. Furthermore, several new aspects of nonlinear processes were demonstrated and studied extensively in liquid crystals. The subject covered in this book is therefore of importance both for liquid crystal research and for nonlinear optics itself. The term "nonlinear optics" is used here in a broad sense.
