DIELECTRIC-RELAXATION SPECTROSCOPY STUDIES ON A POLYMER WITH MESOGENIC SIDE-CHAINS

The dielectric relaxations and the optical transmission of a carefully purified liquid crystalline side chain polysiloxane have been measured in the isotropic and the nematic phases, and an apparent hysteresis has been found in the biphasic region during cooling and warming cycles. In the biphasic region the rate of mesophase formation during cooling was found to be accelerated by an aligning field. Planar alignment was achieved, and the pure α process observed. The sample formed a gel upon lengthy heating, but it remained a liquid crystal. In the mesophase of the gel the α relaxation process was restricted in amplitude and the δ process was absent. © 1990.