Liquid crystalline with cholesteric side groups

Liquid Crystalline Order in Polymers and Copolymers with Cholesteric Side Groups... 

The article covers synthesis, structure and properties of thermotropic liquid-crystalline (LC) polymers with mesogenic side groups. Approaches towards the synthesis of such systems and the conditions for their realization in the LC state are presented, as well as the data revealing the relationship between the molecular structure of an LC polymer and the type of mesophase formed. Specific features of thermotropic LC polymers and copolymers of nematic, smectic and cholesteric types are considered. 

A large number of azobenzene-based amorphous and liquid crystalline polymers, particularly polyacrylates and polymethacrylates with chiral azobenzene pendants, have been prepared for the development of data storage and photonic devices [1-3,11-14]. For instance, the introduction of optically active mesogenic azobenzene residues into the side groups of the polymers produces chiral nematic and cholesteric phases, which are regulated by photoisomerization of the azobenzene units [10,14]. In most cases, however, the optical activity and chiroptical... 

There have been many papers concerning liquid-crystalline polymers having azobenzenes in their side chains (Figure 14) because of the mesogenic nature of the azo chromophore. Liquid-crystalline polymers incorporating azobenzene moieties in their main chains (30) have also been prepared.102 A family of poly(acrylates) substituted with azobenzenes having chiral alkyl groups (31) showed smectic A as well as cholesteric phases.103 The photochromic behavior... 

Polymers may exhibit liquid crystalline, ordered structures similar to those of small molecular liquid crystals. As polymer chains are very long, containing about 10 -10 monomer units, only parts of them or side groups can be ordered in oeir tic. cholesteric, and different kinds of smectic structures. As in small-molecular nematic liquid crystals, in nematic polymer structures groups of cylindrical-like symmetry are arranged statistically with their long axes along a certain direction. 

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