Chirality effects in thermotropic and lyotropic nematic liquid crystals under confined geometries PDF Download
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Author: Clarissa Dietrich
Publisher: Cuvillier Verlag
ISBN: 3736961286
Category : Science
Languages : en
Pages : 190
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Book Description
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.
Author: Clarissa Dietrich
Publisher: Cuvillier Verlag
ISBN: 3736961286
Category : Science
Languages : en
Pages : 190
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Book Description
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.
Author: Heinz Kitzerow
Publisher: Springer Science & Business Media
ISBN: 0387216421
Category : Science
Languages : en
Pages : 513
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Book Description
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.
Author: Johanna. R Bruckner
Publisher: Springer
ISBN: 3319272039
Category : Science
Languages : en
Pages : 130
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Book Description
In this thesis Johanna Bruckner reports the discovery of the lyotropic counterpart of the thermotropic SmC* phase, which has become famous as the only spontaneously polarized, ferroelectric fluid in nature. By means of polarizing optical microscopy, X-ray diffraction and electro-optic experiments she firmly establishes aspects of the structure of the novel lyotropic liquid crystalline phase and elucidates its fascinating properties, among them a pronounced polar electro-optic effect, analogous to the ferroelectric switching of its thermotropic counterpart. The helical ground state of the mesophase raises the fundamental question of how chiral interactions are "communicated" across layers of more or less disordered and achiral solvent molecules which are located between adjacent bi-layers of the chiral amphiphile molecules. This thesis bridges an important gap between thermotropic and lyotropic liquid crystals and pioneers a new field of liquid crystal research.
Author: Lev M. Blinov
Publisher: Springer Science & Business Media
ISBN: 9048188296
Category : Science
Languages : en
Pages : 448
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Book Description
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.
Author: Cheng Long
Publisher:
ISBN:
Category :
Languages : en
Pages : 0
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Book Description
Liquid crystal is a state of matter where constituents show orientational order, despite lack of translational order. For regular nematic liquid crystals, the ground state of orientational distribution of mesogens is described by a single axis, known as the director. Due to effects such as surface anchoring or chiral nature of added liquid crystal molecules, the uniformity in an orientational order field can be broken. The short-range spatial correlation persisting in the orientational order field, as well as topological defects enabled by the uniaxial symmetry manifested from the local orientational order of a nematic liquid crystal, often gives rise to abundant intriguing and sophisticated pattern formation in nematic liquid crystals. Studying the pattern formation and the topological defects in those orientational order fields is essential for understanding rheological and optical properties of nematic liquid crystals. Employing analytical and numerical tools, this dissertation explores the implications of elasticity theory which is commonly used to characterize the deformation of a uniform orientational order field, and the motion of different topological defects in nematic liquid crystals. In the conventional Oseen-Frank elasticity theory, a uniform ground state is protected by the elastic constants satisfying Ericksen inequalities. To examine the scope of the elasticity theory beyond the Ericksen inequalities, we revisit the Oseen-Frank elasticity theory for nematic liquid crystals from the perspective of a reformulated form and find a new set of necessary inequalities for Frank elastic constants to ensure the existence of stable solutions, which is weaker than the Ericksen inequalities. We therefore identify a regime where the Ericksen inequalities are violated but the system is still stable. Remarkably, lyotropic chromonic liquid crystals are in that regime. We investigate the nonuniform structure of the director field in that regime, show that it depends sensitively on system geometry, and discuss the implications for lyotropic chromonic liquid crystals. Applying the same reformulated elasticity theory, we prove that geometric frustration exists in cholesteric liquid crystals. We explicitly demonstrate influences of geometric frustration in two models. First, we consider a chiral liquid crystal confined in a long cylinder with free boundaries. When the radius of the tube is sufficiently small, the director field forms a double-twist configuration, which is the ideal local structure. However, when the radius becomes large enough, due to the geometric frustration, the director field transforms into either a cholesteric phase with single twist, or a set of double-twist regions separated by disclinations, depending on the ratio of disclination energy density to elastic energy density. Second, we study a cholesteric liquid crystal confined between two infinite parallel plates with free boundaries, and we find that geometric frustration induces buckled helical cholesteric structure close to the free boundaries, reminiscent of the Helfrich-Hurault instability. Inspired by the experimental observation that skyrmions in cholesteric liquid crystals can move like particles under applied electric fields, we propose a general theoretical methodology for studying the motion of localized topological objects in liquid crystals, based on collective coordinate method. In our method, the continuum field of a topological soliton is represented by a few macroscopic degrees of freedom, including the position of the excitation and the orientation of the background field, and the motion of the topological soliton is thus derived from the equations of motion for those macroscopic degrees of freedom. Using the coarse-grained method, we elucidate the mechanism of moving solitons and skyrmions in a toggling field. Finally, to understand disclinations, an important class of topological defects in liquid crystals, we build a simple nematic order tensor model for a disclination in a nematic liquid crystal clarifying an analytical relation between the properties of the tensor field close to a disclination and the rotation axis of the nematic orientation around the disclination, which turns out to be an important quantity for the behaviors of a disclination. Analogous to a dislocation in a solid, we find that a Peach-Koehler force can be induced to drive a disclination to move by applying an effective external stress, and that the force is closely related to the rotation axis of the nematic orientation. With the help of the Peach-Koehler force, we further develop a theoretical model for explaining the Frank- Read mechanism in nematic liquid crystals, where a pinned disclination can be multiplied under an effective external stress.
Author: Ning Lin
Publisher: Springer Nature
ISBN: 9811509131
Category : Technology & Engineering
Languages : en
Pages : 414
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Book Description
This book describes the latest research on nanopolysaccharides in the development of functional materials, from their preparation, properties and functional modifications to the architecture of diverse functional materials. Polysaccharide-based nanoparticles, including nanocellulose, nanochitin, and nanostarch have attracted interest in the field of nanoscience, nanotechnology, and materials science that encompasses various industrial sectors, such as biomedicine, catalyst, coating, energy, optical materials, environmental materials, construction materials, and antibacterial materials. This book establishes a fundamental framework, highlighting the architecture strategies of typical functional systems based on nanopolysaccharides and integrated analysis of their significant influence and properties to various functional behaviors of materials, to help readers to fully understand the fundamental features of nanopolysaccharides and functional materials. Addressing the potential for practical applications, the book also covers the related industrial interests and reports on highly valued products from nanopolysaccharides, providing ideas for future studies in the area. Intended both for academics and professionals who are interested in nanopolysaccharides, it is also a valuable resource for postgraduate students, researchers, and engineers involved in R&D of natural polymers, nanotechnology, and functional materials.
Author: Antônio M. Figueiredo Neto
Publisher: Oxford University Press, USA
ISBN: 0198525508
Category : Science
Languages : en
Pages : 317
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Book Description
This book presents a comprehensive review of structural properties and phase transition phenomena in lyotropic mixtures. It includes a wealth of experimental results, in addition to the main theoretical models and a number of technological applications, such as cosmetics, detergents and techniques of oil recovery. It is suitable for use as a pedagogical introduction to the subject.
Author: L.M. Blinov
Publisher: Springer Science & Business Media
ISBN: 1461226929
Category : Science
Languages : en
Pages : 477
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Book Description
Electrooptic effects provide the basis for much liquid-crystal display technology. This book, by two of the leaders in liquid-crystal research in Russia, presents a complete and accessible treatment of virtually all known phenomena occurring in liquid crystals under the influence of electric fields.
Author: Glenn Halstead Brown
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 106
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Book Description
Author: Ingo Dierking
Publisher: Oxford University Press
ISBN: 0192653822
Category : Science
Languages : en
Pages : 225
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Book Description
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'.
