Nematic future developments

Using self-assembly of a chiral nematic phase in a biopolymer liquid crystal of cellulose nanociystals, a well-controlled technique has been developed to create solid helicoidal architectures for structural colour and for further functionalisation. This section describes the self-assembly process and the control parameters of tuneable helicoidal cellulose films, and the prospects for future development. 

It can be safely predicted that applications of liquid crystals will expand in the future to more and more sophisticated areas of electronics. Potential applications of ferroelectric liquid crystals (e.g. fast shutters, complex multiplexed displays) are particularly exciting. The only LC that can show ferroelectric property is the chiral smectic C. Viable ferroelectric displays have however not yet materialized. Antifer-roelectric phases may also have good potential in display applications. Supertwisted nematic displays of twist artgles of around 240° and materials with low viscosity which respond relatively fast, have found considerable application. Another development is the polymer dispersed liquid crystal display in which small nematic droplets ( 2 gm in diameter) are formed in a polymer matrix. Liquid crystalline elastomers with novel physical properties would have many applications. 

We have presented EMD and NEMD simulation algorithms for the study of transport properties of liquid crystals. Their transport properties are richer than those of isotropic fluids. For example, in a uniaxially symmetric nematic liquid crystal the thermal conductivity has two independent components and the viscosity has seven. So far the different algorithms have been applied to various variants of the Gay-Beme fluid. This is a very simple model but the qualitative features resembles those of real liquid crystals and it is useful for the development of molecular dynamics algorithms for transport coefficients. These algorithms are completely general and can be applied to more realistic model systems. If the speed of electronic computers continues to increase at the present rate it will become possible to study such systems and to obtain agreement with experimental measurements in the near future. 

The liquid crystalline polymer has since developed far beyond imagination that a decade ago. The liquid crystalline polymer family has so far included the main chain-, side chain-, and crosslinked- (i.e. network or elastomer) types, and their solutions and gels. The liquid crystal phases cover nematic, cholesteric and smectics. Although the science of the liquid crystalline polymer is not fully mature, it has attracted significant research interests and has already made tremendous progress. As investments and human resources continue, the liquid crystalline polymer is expected to have an even brighter future. 

The present research and development on LC display technology is conducted primarily in industrial labs. Academic research focuses mainly on more exciting and explorative topics that can not only stimulate fundamental scientific interest, but offer tremendous potential for innovative applications beyond the realm of displays, for example, new materials and attractive properties, and new uses in optics, nano/micromanipulation, novel composites, and biotechnology [7]. Future applications depend on the increase of complexity and functionality in LC materials and phases. The past three decades have seen the discovery of complex LC molecules with a variety of new shapes for instance, disc shape (Fig. 6.1b) [8], bent-core shape (Fig. 6.1c) [9], H shape (Fig. 6.1d) [10-13], board shape (Fig. 6.1e) [14,15], T shape (Fig. 6.1f) [16], cone shape (Fig. 6.1g) [17], and semicircular shape (Fig. 6.1h) [18]. The shapes of the molecules are not exactly associated with the types of mesophases formed. Like rod-shaped molecules, each complex shape is likely to organize a nematic, Sm, Col, and 3D-ordered mesophases [19,20]. The incorporation of functionality, amphiphilicity, and nano-segregation into these molecular shapes offers different ways to increase the complexity of LC phases. 

There are several developments that could affect LCD technology in the near future. One example is the development of LEDs for use as backlighting for LCDs. By using LEDs rather than a fluorescent bulb, as LCD technology now uses, LCDs can manifest greater contrast in different areas of the screen. Other areas of LCD development include photoalignment and supertwisted nematic (STN) LCDs. 

The first half of the book deals with alignment technologies for nematic liquid crystals, and in the second half those for smectic liquid crystals are covered. Almost all commercially available LCDs use nematic liquid crystals, and so the first chapters provide information that is practical and useful. However, alignment of smectic liquid crystals with all their variations is a very fruitful area of study, and with developments that are possible in the future, a knowledge of smectic liquid crystal alignment could be even more important. It is therefore one of the key features of the book that the alignments for both smectic and nematic liquid crystals are presented. 

In conclusion, electric field effects in liquid crystals is a well-developed branch of condensed matter physics. The field behavior of nematic liquid crystals in the bulk is well understood. To a certain extent the same is true for the cholesteric mesophase, although the discovery of bistability phenomena and field effects in blue phases opened up new fundamental problems to be solved. Ferroelectric and antiferroelectric mesophases in chiral compounds are a subject of current study. The other ferroelectric substances, such as discotic and lyotropic chiral systems and some achiral (like polyphilic) meso-genes, should attract more attention in the near future. The same is true for a variety of polymer ferroelectric substances, including elastomers. 

Silver halide photosensitive materials for photographic purposes were the main products of FUJIFILM, and in the 1990s, future market projections did not hint any decline. Thus, silver hahde photosensitive materials were mainstream materials in our company. As a result, less than 1 % of researchers developed optical films for LCDs. Our team had developed and commercialized an optical compensation film for super twisted nematic (STN) LCDs since 1987, but we were greatly defeated by competitions that had products with better performance, but we were greatly defeated by competitors that had products with better performance. Thus, in 1992 we faced the closing down of our unit. 

For high-speed response, thinning the LC layer is one conceivable method. Thus it is necessary to increase the optical properties of the LC materials, which in turn necessitates future material development. Ferroelectric LCs use the interaction of the electric field with the spontaneous polarization of the LC molecules for highspeed switching, but the problems are the stable molecular alignment in thin-gap cells and the increase of the speed of the current supply of the drive elements because of the relatively high dielectric constant of ferroelectrics, as compared to a nematic LC. 

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