Cyanobiphenyls optical properties

Boamfa et al. investigated macroscopic orientation of disubstituted cyano-biphenyl poly(norbornene) IV-n (n=3,5) using different magnetic fields of up to 20 T. Both the degree of orientation and optical properties were compared with a cyanobiphenyl-substituted acrylate polymer with a spacer of four methylene units [49,50]. 

P. Karat and N. Madhusudana, Elastic and optical properties of some 4 -n-alkyl-4-cyanobiphenyls, part 11, Moi. Cryst Liq. Cryst, 40, 2 39 (197 73. 

Terunuma and coworkers reported the properties of a different type of carbosilane dendrimer (Nq = 3, Wb = 3) bearing either cyanobiphenyl species or an optically active unit derived from 2-phenylpyrimidine at the periphery (Fig. 15). Only three branches emanated from the central silicon atom, the fourth valency being blocked by a phenyl group leading to 3 (GO), 9 (Gl), and 27 (G2) terminal functional units. 

Static force [45,50,51,57] and friction properties [45,46,51,57-59] have been extensively studied in thermotropic nematics. The surface anchoring conditions were symmetric, with both mica sheets inducing either planar or homeotropic alignment. Bare mica naturally induces planar anchoring on cyanobiphenyls such as 5CB the liquid crystal optical axis orients at abont 7t/6 with respect to the slow optical direction of a (birefringent) freshly cleaved mica sheet [60]. A homeotropic ahgnment can be obtained by adsorbing a mono-layer of surfactant [45,50] on mica. 

Since the cyanobiphenyl derivatives had proved to be excellent materials for electro-optic displays, equivalent homopolymer poly-siloxane liquid crystals, based on these low molar mass mesogens, were synthesized. Their properties are summarized in Table 1. Since the homopolymers only exhibited smectic phases, copolymers were prepared using destabilizing 2-methyl-substituted ester side-groups. As shown in Table 2, at sufficiently high ester-group concentrations, a... 

Merck E7TM is the liquid crystal host used in the LCPDI device. E7 is a nematic liquid crystal mixture.with a mesophase between -10°C and 60.5°C. The R-group substituents on the nickel dithiolene dye need to be selected for maximum solubility in the E7 host without compromising other important properties (absorption wavelength, optical density or thermal stability). Merck E7 is a room temperature eutectic mixture of cyanobiphenyl and cyanoterphenyl liquid crystal compounds its components are shown in Figure 4. 

---