Influence of the remanent polarisation on the liquid crystal alignment in composite films of ferroelectric poly(vinylidene fluoride-trifluoroethylene) and a cyanobiphenyl-based liquid crystal |
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| Authors: | Lars Holländer Wilhelm Kossack Matthias Kollosche Werner Wirges Friedrich Kremer Reimund Gerhard |
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| Institution: | 1. Institute of Physics and Astronomy, University of Potsdam, Potsdam, Germanylars.hollaender@uni-potsdam.de;3. Institute of Experimental Physics I, University of Leipzig, Leipzig, Germany;4. Institute of Physics and Astronomy, University of Potsdam, Potsdam, Germany |
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| Abstract: | Polymer-dispersed liquid crystals (PDLCs) of ferroelectric poly(vinylidene fluoride-trifluoroethylene) and nematic 4-cyano-4?-n-hexylbiphenyl (6CB) or 4-cyano-4?-n-pentylbiphenyl (5CB) were prepared to study the effect of the remanent polarisation of the polymer on the liquid crystal alignment. We measured the macroscopic alignment of the liquid crystal molecules in the thickness direction by means of Infrared Transition-Moment Orientational Analysis. Electrical poling at 100 V/µm caused an increased order parameter up to 0.15. After subsequent annealing above the nematic-to-isotropic phase-transition temperature, the order parameter was reduced to 0.02. Nevertheless, the order parameter was still higher than for non-poled film indicating a slight orientation in thickness direction. Both values are lower than those expected from model calculations. In agreement with dielectric measurements, we attribute this result to the shielding effect of mobile charge carriers within the liquid crystal inclusions. |
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| Keywords: | Polymer-dispersed liquid crystal ferroelectric polymer remanent polarisation liquid crystal alignment |
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