0000000000637061

AUTHOR

Tanja ÖGe

showing 3 related works from this author

Optical suppression of ferroelectricity in polysiloxane copolymers with chiral and photochromic side groups

1998

The ferroelectricity of surface-stabilized aligned films of polysiloxane copolymers containing chiral esters and photochromic azobenzene moieties within the side groups is suppressed on UV irradiation and is rebuilt on visible irradiation. The liquid crystalline polymer (Sc* 64 SA 80 i) shows ferroelectric behavior below 64°C. The photoinduced modification of supramolecular order and the corresponding changes in its dynamics are studied by polarized UV/vis spectroscopy and broad band dielectric spectroscopy (10−2–105 Hz). The dielectric measurements show that UV irradiation causes a loss of ferroelectricity within an interval of 10 K below the phase transition temperature. The photochemical…

Photochromismchemistry.chemical_compoundMaterials sciencePolymers and PlasticsAbsorption spectroscopyPhotoisomerizationAzobenzenechemistryMesophaseDielectricPhotochemistrySpectroscopyFerroelectricityPolymers for Advanced Technologies
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Fourier-transform infrared study of the switching process in a ferroelectric liquid crystalline polymer

1995

The implementation of the step-scan technique on our spectrometer enabled us to follow the electric field induced reorientation dynamics of different molecular segments of the ferroelectric liquid crystalline polymer [Si(Me)(R)O/Si(Me)(R')O/Si(Me) 2 O] n (R= (CH 2 ) 11 OPhCOOPhOCO * CHCl * CH(Me)(Et); R'= (CH 2 ) 11 OPhN=NPhO * CH(Me)(Hex)) on a sub-millisecond time scale. It was detected that not only the mesogen but also the spacer and at least part of the backbone take part in the reorientation process

Azo compoundMaterials sciencePolymers and PlasticsInfraredMesogenOrganic ChemistryFerroelectricityCrystallographychemistry.chemical_compoundsymbols.namesakeFourier transformchemistryLiquid crystalElectric fieldPolymer chemistryMaterials ChemistrySide chainsymbolsMacromolecular Rapid Communications
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Manipulation of the ferroelectricity in LC polymers via photomechanical isomerization of azobenzene moieties

1996

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 (Ps) 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 Ps 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 reisom…

Polymers and PlasticsChemistryMesogenOrganic ChemistryChromophoreCondensed Matter PhysicsFerroelectricityCis trans isomerizationchemistry.chemical_compoundDark stateAzobenzeneLiquid crystalPolymer chemistryMaterials ChemistrySide chainPhysical and Theoretical ChemistryMacromolecular Chemistry and Physics
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