Relaxation of the Induced Orientational Order in the Isotropic Phase of Nematic Polymer

Abstract

Orientational dynamics in the isotropic phase of a comb-shaped nematic polymer with mesogenic and functional side groups was studied using the Kerr effect and dielectric spectroscopy. For the first time, it was found that in a mesogenic polymer, in contrast to low-molecular-weight mesogens, the relaxation of the electric birefringence of a melt above the temperature of the nematic-isotropic phase transition can be presented by a sum of several exponential processes, two of which play a decisive role. These main processes replace each other in a temperature range of about fifty degrees. Dielectric spectroscopy also made it possible to distinguish two processes of orientational relaxation: the first is due to rotation of the side mesogenic groups, and the second is associated with motion of the main chain segments.