Liquid crystal materials photoalignment

The photoalignment process is particularly useful at the mesoscopic level in the context of liquid crystals, the alignment of which can be controlled with azobenzene command surfaces [24, 25]. Alternatively, a small portion of master azobenzene molecules can be doped into a liquid crystal material where they control the orientation of passive slave molecules through collaborative movements. In an extreme case, the azobenzene dopants can induce order-disorder transitions of the hquid crystal material, as illustrated in Fig. Ic [20]. 

K. Ichimura, K. Photoalignment of Liquid-Crystal Systems. Chem. Rev. 100, 1847 (2000). Ichimura, K., Seki, T, Kawanishi, Y., Suzuki, Y., Sakuragi, M., and Tamaki, T. Photocontrol of Liquid Crystal Alignment by Command Surfaces , in Photoreactive Materials for Ultrahigh Density Optical Memory. M. Irie, Ed., Elsevier Amsterdam, (1994), p. 55. 

V. Strehmel, B. Stiller, B. Strehmel, A. M. Sarker, and D. C. Neckers, Fluorinated Distyrylbenzenes Containing Copolymers for Photoinduced Formation of Anisotropic Materials as Photoalignment Layers for Liquid Crystals. In Photoinitiated Polymerization, Vol. 847, K. D. Belfield and J. V. Crivello, Eds., American Chemical Society, Washington, DC, 2003, p. 482. 

B. Umanskii, N. Novoseletskii, S. Torgova, and G. Dorozhkina, Azo-dyes as photoalignment materials for liquid crystals. Molecular Crystals and Liquid Crystals 412,... 

O. Yaroshchuk, J. Ho, V. Chigrinov, and H.-S. Kwok, Azo-dyes as photoalignment materials for polymerizable liquid crystals. Japanese Journal of Applied Physics 46, 2995 (2007). 

To the best of our knowledge, a bibliographical review of US patents devoted to photoalignment has never been published despite a number of review articles (see e.g. [7-11] in Chapter 1). Such a review is very important because (i) 70-90% of patent data is never published in other sources and (ii) web analysis of the patent documents is complicated, since a person of ordinary skills has to make a selection from the enormous amount of a weakly structured information. This chapter is a bibliography of US patents (December 2007 included) on materials and processes for the photoalignment of liquid crystals, liquid crystal displays, optical liquid crystal devices and anisotropic optical elements, and other nondisplay applications. We restricted our attention to US patents only, since the majority of European, Asian, or other world patents are duplicated in the USA. 

Polyamideimide photoalignment materials having a photosensitive diamine derivative compound with side branches, and liquid crystal display devices using such a photoalignment material, beneficially as an alignment film. 

An aromatic polyamide photoalignment material prepared by a reaction from a diamine compound with a side branch and a photosensitive dicar-boxylic acid. Furthermore, liquid crystal display devices using such photoalignment materials in an alignment film on at least one substrate. 

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