Reference : A study of a bistereogenic mesogen for the development of orthoconic antiferroelectri...
Scientific journals : Article
Physical, chemical, mathematical & earth Sciences : Chemistry
A study of a bistereogenic mesogen for the development of orthoconic antiferroelectric liquid crystal materials
Lagerwall, Jan mailto [University of Stuttgart]
Yates, Chris [> >]
Rauch, Sebastian [> >]
Heppke, Gerd [> >]
Taylor & Francis Ltd
Yes (verified by ORBilu)
[en] The first orthoconic antiferroetectric liquid crystals (OAFLCs), i.e. smectics where the optical director changes direction by 90 degrees between neighboring layers, were mixtures of partially fluorinated monostereogenic compounds. They have successfully demonstrated the orthoconic properties (orientation-independent dark state between crossed polarizers) but suffer from too high polarization and too short helical pitch, necessitating very thin samples. Using an (S,R) bistereogenic OAFLC we have obtained the orientation-independent dark state in rather thick samples, but several other problems arise with this compound. The strongly first-order SmA-SmCa transition produces defects leading to light leakage. In order to be switchable the sample must furthermore be mixed with chiral dopants, generally reducing the tilt angle as well as a shortening the helical pitch. Finally, a SmC phase often appears in the phase sequence of the mixture, strongly dominating over the desired SmCa phase in thin cells.
Dublin, Ireland

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