THE PACKING OF AZOBENZENE DYE MOIETIES AND MESOGENS IN POLYSILOXANE COPOLYMERS AND ITS IMPACT ON THE OPTO-DIELECTRIC EFFECT

Broadband dielectric spectroscopy (10(-2)-10(5) Hz) is used to study t he opto-dielectric effect in statistical polysiloxane copolymers with side groups containing chiral mesogenic units and others containing az obenzene moieties. Below 64 degrees C, the unexposed copolymer is ferr oelectric. UV-exposure induces a photoisomerization of the azobenzene to the cis-configuration, and the phase transition, ferroelectric/non- ferroelectric (S-C()/S-A), is shifted to lower temperatures. In the t emperature interval between the phase transition temperatures ferroele ctric/non-ferroelectric of the exposed and unexposed samples, an opto- dielectric effect is observed. The efficiency of this opto-dielectric switching depends on the packing of the chromophore within the smectic layers.