The packing of azobenzene dye moieties and mesogens in polysiloxane copolymers and its impact on the opto-dielectric effect

Abstract

Broadband dielectric spectroscopy (102-105Hz) is used to study the opto-dielectric effect in statistical polysiloxane copolymers with side groups containing chiral mesogenic units and others containing azobenzene moieties. Below 64 C, the unexposed copolymer is ferroelectric. UV-exposure induces a photoisomerization of the azobenzene to the cis -configuration, and the phase transition, ferroelectric/non-ferroelectric (SC*/SA), is shifted to lower temperatures. In the temperature interval between the phase transition temperatures ferroelectric/nonferroelectric 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.