Static and dynamic electro-optic properties of a SmC* phase in surface stabilized geometry and dispersed in the polymer matrix
Laboratoire de Thermophysique de la Matiére Condensée - Équipe de l’UMR CNRS 8024, Université du Littoral Côte d’Opale, MREID, 59140, Dunkerque, France
2 Laboratoire d’Étude des Matériaux et Composants pour l’Électronique - EA 2601, Université du Littoral Côte d’Opale, MRBP, 62228, Calais, France
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Comparative electro-optical measurements have been made on a ferroelectric liquid crystal (FLC) in surface stabilized geometry and confined to an ellipsoidal cavity within a polymer matrix. The static and dynamic electro-optical characteristics were measured for both systems and show qualitatively similar behaviours. A fast switching and important bistability were observed and characterized as a function of the applied electric field strength. The switching time between the two stable states of the surface stabilized cell was found to be longer than that found for the composite films. We argue that the faster switching dynamic of the FLC in cavities is due to the enhance of the rotational mobility of the molecules, probably (and partly) because of the “soft” anchoring character of the molecules at the cavity walls. Using a collective switching model in the high field regime, which assume a linear coupling between the spontaneous polarization and the local cavity electric field, we give an estimate of the rotational viscosity of the FLC molecules in the droplets.
© EDP Sciences, Società Italiana di Fisica, and Springer-Verlag, 2003