Intermediate State of Matter

Castieman A W Jr and Bowen K H Jr 1996 Ciusters structure, energetics, and dynamics of intermediate states of matter J. Phys. Chem. 100 12 911 -44... 

One type of material that has transformed electronic displays is neither a solid nor a liquid, but something intermediate between the two. Liquid crystals are substances that flow like viscous liquids, but their molecules lie in a moderately orderly array, like those in a crystal. They are examples of a mesophase, an intermediate state of matter with the fluidity of a liquid and some of the molecular order of a solid. Liquid crystalline materials are finding many applications in the electronics industry because they are responsive to changes in temperature and electric fields. 

Liquid crystals are substances that flow like viscous liquids, but their molecules lie in a moderately orderly array, like those in a crystal. They The word mesopbase comes from are examples of a mesophase, an intermediate state of matter with the... 

The very fascination of clusters, that they present us with an intermediate state of matter, conforming to neither the bulk nor the small molecule model, means that determining the electronic structure is not going to be quite simple. On the other hand, the very fact that one can speak of the evolution of cluster properties with size means that there are regularities. Some of those regularities do not depend on the specific size and must therefore appear also in more approximate theories. We will therefore proceed from the simpler points of view to the more elaborate ones. It is however, to be expected that the simpler models must be tailored to the bonding type in the cluster and that what will work for clusters held together by van der Waals forces will not do for metallic clusters, and so forth. 

An exposition of the physics of liquid crystals involves many disciplines continuum mechanics, optics of anisotropic media, statistical physics, crystallography etc. In covering such a wide field it is difficult to define what precisely the reader is expected to know already. An attempt is made to present as far as possible a self-contained treatment of each of these different aspects of the subject. Naturally, discussion of some topics has had to be curtailed for reasons of space. For example, we have not dealt with lyotropic systems, whose complex structures are only just beginning to be elucidated or the special applications of magnetic resonance techniques, as these have been adequately reviewed elsewhere or the very recent results of neutron scattering experiments. The primary aim of this monograph is to provide an insight into the variety of new phenomena exhibited by these intermediate states of matter. 

Liquid crystals represent an intermediate state of matter between a crystalline solid and an isotropic liquid phase [57]. Generally, most solids when heated directly transform to a liquid state. However, some solids do not change directly to a liquid state on heating but instead pass through a phase that has properties of both solids and liquids. This phase is known as liquid crystalline phase and the molecules comprised of them are known as liquid crystals. 

Liquid crystals are intermediate states of matter or mesophases, halfway between an isotropic liquid and a solid crystal. In nature, some substances, or even mixtures of substances, present these mesomorphic states. These liquid crystalline phases exhibit a local disorder ( liquid-like behavior) and are dynamic at a molecular level, but a long-range order exists, which endows it with unique rheological, mass transport, and optical properties. Liquid crystals offer a number of useful properties for the drug delivery. Solubilization of drug in the liquid crystalline is similar to the solubilization of drug in micelles. Simultaneously, increase in viscosity of the system helps to provide more... 

Liquid crystals (LCs) represent an intermediate state of matter between the solid and liquid phases, often referred to as the fourth state of matter, and exhibit the regularity of crystalline solid and the fluidity of isotropic liquid [1-4], The unique thermal, mechanical, optical, and electrical properties of LCs originate from the molecular self-organization facilitated by weak intermolecular interactions, which is sensitive to external stimuli. Stimuli-responsive LCs are at the forefront in the development of electro-optic devices such as LC displays (LCDs) and continue to attract great interest in view of both fundamental research and practical applications. 

The study of colloidal systems is a large field with many facets applications of these systems include optoelectronics, thin film growth, and catalysis. This is due to their exotic physiochemical properties lending credibility to the claim that these systems are an intermediate state of matter [115]. Colloidal metal clusters have also been examined as materials suitable for quantum confinement and quantum dots which may serve as models for studying single electron tunneling (SET) and... 

Fig. 10.8. (a) A perfect crystalline state of matter. Molecules preserve both positional and orientation order, (b) An intermediate state of matter. Molecules preserve orientation order but no positional order, and the matters preserve fluidity. A state of anisotropic liquid. (c) A totally disordered state of matter, for example, an isotropic liquid. The molecules preserve neither orientation nor positional order... 

Between the crystalline state (characterized by a long-range three-dimensional order), and the amorphous isotropic state, there is an intermediate state of matter referred to as liquid crystal. It is specific to certain molecules, which simultaneously exhibit order like crystals and flow like fluids. Reinitzer, who observed that cholesteric esters form opaque liquids that become transparent upon raising the temperature, is considered as the precursor of this field. In addition to the term liquid crystal, mesomorphic or mesophase can also be used (from Greek mesos meaning median ) to name this intermediate state between an isotropic liquid state and the three-dimensional crystalline order as first proposed by Friedel. Molecules that adopt a preferential orientation and result in an anisotropy are called mesogens. 

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