Design of Liquid Crystalline Materials

An extended, structurally rigid, highly anisotropic shape seems to be the main criterion for liquid 

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Although the dielectric and optical anisotropies Ae and An are properties of the condensed nematic phase, they can be related to the physical properties of single molecules. This is of great importance for the targeted, rational design of liquid crystalline materials. 

C. Tschierske, Micro-segregation, molecular shape and molecular topology partners for the design of liquid crystalline materials with complex mesophase morphologies, J. Mater. Chem. 11(11), 2647-2671, (2001). 

Fig. 1 Templates for the design of liquid-crystalline supermolecular materials. The meso-genic units are shown as various shapes, however, the materials may be constructed with mesogenic units of the same type. In this case, many of the constructions shown are essentially dendritic...

In Chapters 1, 2, and 3 unconventional liquid crystalline molecules with complex structures based on covalent bonding are described. In Chapter 4, Rowan and Mather demonstrate that non-covalent bonding such as hydrogen bonds may be used for the design and construction of liquid crystalline materials. 

Chemistry and physics of liquid-crystalline polymers are discussed in Chapter 1.10 by Valery P. Shibaev. The main attention is paid to the design of liquid-crystalline polymer materials with usefid photochromic, electrooptical, and optoelectronic properties. 

First, we will consider the design of polyphosphazenes as side-chain liquid-crystalline materials.241 248 Side-chain liquid-crystalline polymers are a subclass of species described earlier as structure 3.72. Liquid crystallinity occurs when the rigid side groups become organized, usually in the semi-liquid state. The organization may be nematic (oriented but unlayered) or smectic (layered) as illustrated in Figure 3.25. 

The optically active aryl-methylene cycloalkanes and related compounds, shown in Figure 4, were designed by Schuster et al. as chiral, photobistable materials to be used in particular as chiroptical triggers for the control of liquid crystalline phases (see Section 5.5).[22]... 

For foods and pharmaceutical products, the handling of slurries and solids at industrial scale presents problems where the product is exposed on filters and in dryers, rather than being enclosed within a pipe or vessel as a liquid. Contamination of the crystalline material can occur, and the product itself or the solvent phase it must be removed from might be toxic. Various types of equipment have therefore been developed to enable wet crystalline cakes and dry powders to be handled in a contained manner, using specially designed booths, isolators, and pack off systems to protect the product from its environment (and vice versa for highly potent materials). 

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