Liquid crystals textures

Gray GW, Goodby JWG (1984) Smectic Liquid Crystals, Textures and Structures. Blackie, Glasgow... 

Figure 7.1. Categories of smectic liquid crystals. From Smectic Liquid Crystals, Textures and Structures, Gray, G.W. and Goodby, J.W.G. 1984 (Leonard Hill, Glasgow). (Reproduced by kind permission of the authors and publishers.) Side elevation and plan representation of molecular ordering in each of the smectic modifications. Triangles or arrows are used to represent tilt direction.

G. W. Gray and J. W. G. Goodby, Smectic Liquid Crystals—Textures and Structures, Leonard Hill, Glasgow and London, 1984. 

Figure 3. Liquid-crystal textures of the methyl-substituted model ester viewed through crossed polarizers, a, Smectic C-to-nematic transitional phase and b, smectic mosaic texture at 160 °C. Original magnification, 320x.

Gray GW, Goodby JW (1984) Smectic liquid crystals - textures and structures. Leonard Hill,... 

Gabriel, J.C.P., Sanchez, C. and Davidson, P. (1996) Observation of Nematic Liquid-Crystal Textures in Aqueous Gels of Smectite Clays. The Journal of Physical Chemistry 100, 11139-11143... 

Liquid crystal textures were observed by optical microscopy between crossed polars. The instrument used was an Olympus BH-2 polarizing microscope equipped with a Linkam TH-600RH hot stage. 

For comprehensive descriptions of the structure and properties of liquid crystals and leading references, see (a) F. D. Saeva (Ed.), Liquid Crystals. The Fourth State of Matter, Marcel Dekker, Inc., New York, 1979 (b) H. Kelker and R. Hatz, Handbook of Liquid Crystals, Verlag Chemie, Weinheim, 1980 (c) G. W. Gray and J. W. Goodby, Smectic Liquid Crystals. Textures and Structures, Leonard Hill, Glasgow, 1984. 

Polarizing optical microscopy is often the method of first choice. It was with POM that the textures of liquid crystals were observed and the classification of liquid crystals was first made according to these observations. In this field, two books are recommended The Textures of Liquid Crystals by Demus and Richter (1978) and Smectic Liquid Crystals — Textures and Structures by Gray and Goodby (1984). While the latter provides readers with a practical and useful experimental guideline to the textures and classification of smectic liquid crystals of different polymorphic types together with as many as 124 reference photographs of typical textures, the former... 

Gray G W and Gccdby J G W1984 Smectic Liquid Crystals Textures and Structures (Glasgow Hill)... 

Gray, G. W. Goodby, J. W. Smectic Liquid Crystals Textures and Structures Leonard Hill Glasgow, 1984. 

Outside of alluding to the importance of PLCs in the fabrication of ultra-high strength organic materials, I have not addressed the applications of PLCs, a major source of the intensive interest in PLCs. The slower time scales for mesophase reorientation will limit the use of PLCs in dynamic electro-optical devices, but the possibility of locking in liquid crystal textures into stable solid polymer films renders PLCs attractive alternatives in static optical devices, e.g., as polarizers, notch filters and non centro-symmetric matrices for non-linear optical phenomena. 

In the following sections some of the more common liquid crystal textures utilized in the classification of thermotropic calamitic mesophases are described. It should be noted that similar examinations of defects are used to classify discotic, polymeric, and lyotropic phases. 

Figure 5 Photomicrographs of liquid crystal textures seen in the polarizing microscope. (A) The Schlieren texture of a smectic I phase. (B) The focal conic texture of a chiral smectic C phase, which has a helical structure, forming at a transition from the liquid. The pitch of the helix shows up as parallel lines that are parallel to the molecule layers (each line corresponds to about a thousand molecular layers). The pitch lines reflect accurately the layer structure in the focal-conic domain. (A) Courtesy of JW Goodby, University of Hull, UK, with permission. (B) Reproduced with permission from Gordon and Breach, Switzerland.)...

C. L. Yang, Electro-optics of a transflective hquid crystal display with hybrid-aligned liquid crystal texture, Jpn. J. AppL Phys., part 1, 43, 4273 (2004). 

G.W. Gray, J.W. G. Goodby Smectic Liquid Crystals - Textures and Structures (Hill, Glasgow 1984)... 

FIGURE 13 Lines of constant phase for a planar cholesteric liquid crystal texture between two substrates (shown in cross section). The ripple arises in response to an applied field when the anisotropy is positive. 

McArdle, C. B., ed.. Side Chain Liquid Crystal Polymers, Blackie, Glasgow, 1989. Ciferri, A ed.. Liquid Crystallinity in Polymers, VCH Publishers, New York, 1991. Gray, G. W., and Goodby, J. W., Smectic Liquid Crystals—Textures and Structures, Heyden Son, Philadelphia, 1984. 

Figure 7 Liquid-crystal textures observed for PyAG-l 8 under the polarizing microscope as a function of temperature (a) and (b) wormlike textures found in the 60°C to 110°C range (c) the pseudofocal conic texture observed at 110°C (d) the transition phase occurring at 130°C, and (e) the cholesteric fingerprint texture observed at 180°C. (Taken from J. Watanabe and Y. Takashina. Polym. J. 24 709, 1992. With permission.)...

See, for example, G. W. Gray, J. W. Goodby, Smectic Liquid Crystals Textures and Structures, Leonard Hill, Glasgow and London, 1984 A. W. Hall, J. Hollingshurst, J. W. Goodby in Handbook of Liquid Crystal Research (Eds. P. J. Collings, J. S. Patel), Oxford University Press, New York and Oxford, 1997, pp. 17-70. 

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