R. V. Talroze

Thermotropic liquid-crystalline polymers. XXVII. Reentrant nematic phase of side chain liquid-crystalline polymers and their optical properties

Abstract The phase diagrams of side chain liquid-crystalline acrylic copolymers with cyanobiphenyl mesogenic groups are described. These copolymers are shown to form a reentrant nematic phase. The main regularities of the reentrant behaviour of polymer systems are studied. Certain peculiarities of the electric field induced orientation phenomena are discussed.

Cholesteric polymers in electric fields

Abstract The main peculiarities of electric field-induced structural transformations in cholesterol containing comb-shaped polymers are discussed. As for low molar mass cholesterics both the changes in the texture and the untwisting of the helix can be observed. In cholesteric copolymers with a layered order of the side chains the untwisting of the helix results in the formation of a smectic-like structure. The dynamics of the helix untwisting is shown to be controlled by the mobility of the backbone.

Some electro-optical phenomena in comb-like liquid crystalline polymeric azomethines

The ability to orient in an electric field, a wellknown property of liquid crystals, is the basis of their numerous technical applications. This is why interest is expressed in electro-optical phenomena in liquid crystalline (LC) polymers. Comb-like LC polymers with nitrile groups in mesogenic moieties can be oriented in an alternating electric field1,2,3. In most cases the ability to quench this orientation in polymers below the glass transition temperature has been proven. The similarity in structure and properties of LC polymers and low molecular mass liquid crystals lead to the study of the electrooptical effects in polymers.

Influence of the structure of mesogenic groups on the structure and dielectric properties of the comb-like liquid crystalline azomethyne-containing polymers

The synthesis, structure and properties of some mesogenic monomer and polymer benzylideneaniline-derivatives are described. The anisotropy of dielectric constant of the polymers is measured. The CN-containing polymers are shown to be characterized by the high positive values of δe. The texture of polymer film is noticed to be dependent on the intensity of electric field. The influence of the electric field on the polymer structure is demonstrated.