The thermally stimulated current technique applied to side-chain liquid-crystal polymers

The thermally stimulated current (t.s.c.) technique is applied to three side-chain liquid-crystal polymers (LCP) and an LCP that contains a highly dipolar dye. The t.s.c. trace is shown to be very sensitive to a number of LCP properties including glass transition, degree of mesogenic alignment and the amount of polarization that can be stored. A strong correlation between such properties and the results of high-frequency dielectric spectra is established. These parameters are directly relevant for the application of these materials as optical storage media and in non-linear optics. In particular, the technique is able to define the optimum conditions for poling these LCP systems. The technique can also be used to determine a number of fundamental molecular properties such as activation energy, molecular relaxation distribution and polymer flexibility and, as such, allows fundamental examination of the relationships between main-chain and mesogenic motions.