MANIPULATION OF THE FERROELECTRICITY IN LC POLYMERS VIA PHOTOMECHANICAL ISOMERIZATION OF AZOBENZENE MOIETIES

We report the synthesis and characterization of a new ferroelectric li quid crystalline side chain copolymer containing photoisomerizable chr omophores and non-photoisomerizable mesogenic units. On illumination w ith UV-light a suppression of the polar order is obtained as indicated by a substantial drop of the spontaneous polarization (P-s) compared to the dark state. We interpret this as the phase order being disrupte d by the cis-isomer of the chromophore. After illumination with VIS-li ght only the major part of P, is restored. The photochemical cis-trans back-isomerization (restoration of the phase) leads to a different st ationary state than the dark state of the material. The thermal reisom erization (cis-trans) in the liquid-crystalline phase was observed to be faster than in solution by one order of magnitude.