Manipulation of the ferroelectricity in LC polymers via photomechanical isomerization of azobenzene moieties

Abstract

Abstract We report the synthesis and characterization of a new ferroelectric liquid crystalline side chain copolymer containing photoisomerizable chromophores and non‐photoisomerizable mesogenic units. On illumination with 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 disrupted by the cis ‐isomer of the chromophore. After illumination with VIS‐light only the major part of P s is restored. The photochemical cis‐trans back‐isomerization (restoration of the phase) leads to a different stationary state than the dark state of the material. The thermal reisomerization ( cis‐trans ) in the liquid‐crystalline phase was observed to be faster than in solution by one order of magnitude.