Inorganic polymer liquid crystals

This chapter is concerned with a discussion of completely inorganic polymers that display liquid crystalline character. Until recently there was no description of such material in the literature. Part of the problem lies in the fact that most inorganic materials when prepared in the form of polymeric chains, tend to be very water sensitive which tends to inhibit further study. Furthermore, to prepare such materials in the form necessary to achieve liquid crystalline character greatly complicates the process for designing synthetic methodologies necessary to produce rod-like or discotic shapes. 

There have been reports of rod-like inorganic structures such as (SiS ) which is usually depicted as an extended chain polymer [I]. Also, polythiazyl, (SN), has been observed to display highly anisotropic character exhibiting pseudo-metallic behavior [2]. However, these materials do not melt, and the close proximity of the rods suggests that they are better classified as three-dimensional inorganic structures than as polymers. 

There are some interesting allusions in earlier literature to the potential for liquid crystalline character in inorganic materials. Bragg demonstrated in 1960 that he could stretch graphite rod at temperatures 

Mechanical and Thermophysical Properties of Polymer Liquid Crystals Edited by W. Brostow 

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The basic modem data describing the atomic stmcture of matter have been obtained by the using of diffraction methods - X-ray, neutron and electron diffraction. All three radiations are used not only for the stmcture analysis of various natural and synthetic crystals - inorganic, metallic, organic, biological crystals but also for the analysis of other condensed states of matter - quasicrystals, incommensurate phases, and partly disordered system, namely, for high-molecular polymers, liquid crystals, amorphous substances and liquids, and isolated molecules in vapours or gases. This tremendous... 

Thermal analysis has been used to study a wide range of phenomena occurring on a large number of materials, e.g., catalysts, polymers, liquid crystals, metals and alloys, organic materials, inorganic compounds, ceramics and glasses, etc. There is such a variety of applications for thermal analysis fliat it is not possible to include every aspect here. This section presents a representative range of applications of the three most widely used techniques (i.e., TG, DTA, and DSC) in fliermal analysis. 

Soft matter is nowadays used to describe an inaeasingly important class of materials that encompasses polymers, liquid crystals, molecular assemblies building hierarchical structures, organic-inorganic hybrids, and the whole area of colloidal science. Common to all is that fluctuations, and thus the thermal energy ksT and entropy, play an important role. Soft then means that these materials are in a state of matter that is neither a simple liquid nor a hard sohd of the type studied in hard condensed matter, hence sometimes many types of soft matter are also named complex fluids. ... 

The majority of studies using PR-TRMC in recent years have involved complex organic materials such as conjugated polymers or discotic liquid crystals. Inorganic semiconductor materials have however also received attention over the years. The first of these was a study of the radiation-induced conductivity in a powder sample of the high-Tc superconductor DyBajCujOj,. The superconductivity transition at 88 K on cooling was found to be accompanied by a dramatic, sudden increase in the radiation-induced conductivity an effect which... 

Polyphosphazenes represent a new approach to the design and synthesis of side-chain liquid crystal polymers. Polyphosphazenes are inorganic main-chain polymers consisting of alternating phosphorus-nitrogen atoms in the main chain with two substituents attached to each phosphorus atom. The top of Figure 1 shows the general structure for a side chain liquid crystal polymer a polymer... 

Polyphosphazene synthesis provides additional possibilities for preparing liquid crystal polymers with different properties. As noted above, the substitution process (Figure 2) enables one to synthesize a wide variety of polymers. The phosphazene inorganic backbone Is a highly flexible polymer chain glass transition temperatures can... 

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