LOCAL ROTATIONAL DEGREES OF FREEDOM IN NEMATIC LIQUID-CRYSTALLINE SIDE-CHAIN POLYMERS

In nematic side-chain polymers the side chains are oriented in the mean along a certain direction (the director). Rotations of backbone segments relative to the director are degrees of freedom characteristic for such polymeric nematic systems. We investigate theoretically the influence of these relative rotations on the linear mode spectrum. We discuss longitudinal and transverse sound excitations and propose experiments, in which qualitatively new features due to these relative rotations are to be expected. We show that recent unexpected findings in director relaxation experiments can be explained with the help of these new degrees of freedom as well as by elasticity.