Browsing by Author "Kuczynski, Wojciech"

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    Investigations of the structure of a cholesteric phase with a temperature induced helix inversion and of the succeeding S*C phase in thin liquid crystal cells
    (1993) Dierking, Ingo; Gießelmann, Frank; Zugenmaier, Peter; Kuczynski, Wojciech; Lagerwall, Sven T.; Stebler, Bengt
    Investigations of 4-[(S, S)-2, 3 epoxyhexyloxy]-phenyl-4-(decyloxy)-benzoate by polarizing microscopy, the Cano-Grandjean method, optical rotation dispersion and UV-VIS spectroscopy reveal a cholesteric phase with temperature induced reversal of the helical twist. Switching time experiments in the S*C phase show that the intrinsic helix can be unwound reversibly and irreveribly by application of electric fields of different strengths.
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    The origin of the helical twist inversion in single component cholesteric liquid crystals
    (1994) Dierking, Ingo; Gießelmann, Frank; Zugenmaier, Peter; Mohr, Kristina; Zaschke, Horst; Kuczynski, Wojciech
    The cholesteric twist inversion by temperature variation of a single component thermotropic liquid crystalline system was experimentally investigated and is explained by the partial twisting power model, evaluating the temperature dependent pitch of five different configurations of a benzoic acid biphenyl ester with two chiral centers. The temperature dependence of the twisting power and the cholesteric pitch for several stereoisomeric compounds can in first approximation be predicted by the partial twisting powers of the individual chiral centers determined from the partially racemic configurations.