Optimization of pyroelectricity in the smectic-C* phase of a liquid-crystalline terpolymer

The dynamic pyroelectric response in the smectic-C* (SmC*) phase of a novel class of polysiloxane terpolymers is reported. In these terpolymers methyl groups and two distinct types of mesogenic side chains are attached to the siloxane backbone. Our investigations reveal that the magnitude and temperature dependence of the pyroelectric signal, as well as the temperature range of the SmC* phase, can be controlled by varying the relative side-chain composition. This permits optimization of the pyroelectric properties over a temperature range extending to subambient. Specifically, the pyroelectric coefficient p can be made very nearly temperature independent, and the ratio p/epsilon' extremely high, making these materials suitable for uncooled infrared detectors. (C) 1996 American Institute of Physics.