Polymeric liquid crystals, dielectric studies

In a majority of works on LC polymers, the main attention was paid to the synthesis and structural studies of such polymers. Significantly less information is available on physical properties of LC polymers, especially, when compared to low-molecular liquid crystals. In this chapter some rheological and dielectric properties of polymeric liquid crystals, characteristics of their dynamic properties and intramolecular mobility, are considered. 

A 0-jum polymerized film has been placed between two conductive glass plates. When the polymerization of such a layer is performed under orienting electric fields, the dielectric constant decreases from the high value of the liquid crystal to the classical value for the polymer. Mesomorphic order in the resulting polymer will be investigated by x-ray studies. 

Broadband dielectric spectroscopy enables one to analyse the dynamics of polar groups in polymeric systems. Due to its broad frequency range of more than 10 decades a manifold of different molecular fluctuations can be studied from the dynamic glass transition (spanning already more than 10 decades in times) to secondary relaxations. Additionally one finds in chiral liquid crystals cooperative processes like soft-and Goldstone modes. 

The pressure dependence of the dielectric constant has been reviewed for fluids and liquids, ionic crystals, semiconductors, ferroelectrics, vitreous materials," ice phases, polymeric systems, and plastic crystals. These studies are helpful to probe theories of dielectric polarization and intermoleeular forces. 

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