Dipole polarization relaxation and molecular structure of main-and side-chain liquid-crystalline polymers

Molecular mobility in thermotropic polyesters and side-chain polymers with different structure of-mesogens and spacers has been studied by dielectrical method in dilute solutions. The results made it possible to establish the multiplicity. of dielectric relaxation transitions which reflects the small- and large-scale types of molecular motion. It was shown. that dielectric relaxation processes occurring in accordance with local mechanism (relaxation. times 10(-9)-10(-7)s. and the activation energy 10-50kJ/mol) are due to the mobility of kinetic chain elements of different length within a monomer units. It was found that the dielectric relaxation process connected with a large-scale form of molecular motion (relaxation times 10(-5)-10(-6)s. and the activation energy 100kJ/mol) did not depend on the molecular mass but was influenced by factors changing the conformational state of the macromolecule. It is established that the cooperative reorientation mobility of associated mesogenic fragments is the source of the large-scale process.