Bulg. J. Phys. vol.31 no.1-2 (2004), pp. 39-48

Flexoelectric Study of Cyanobiphenyl Liquid Crystals Dispersed in Various Polymer Matrices

L. Todorova, S. Naydenova, T. Angelov, Y. Marinov, A.G. Petrov
Institute of Solid State Physics, Bulgarian Academy of Sciences, Biomolecular Layers Laboratory, 72, Tzarigradsko Chaussee Blvd., 1784 Sofia, Bulgaria
Abstract. The linear electro-optic response of polymer dispersed liquid crystal films (PDLC) has been studied. Micrometer sized droplets of cyanobiphenyl mixtures were formed in a Norland Optical Adhesive 65 photopolymer by photopolymerization induced phase separation and in polymethylmetacrylate by solvent induced phase separation. Samples with various average nematic droplet size were systematically investigated. The temperature dependence of the first harmonic electrooptic spectra was obtained. Peculiar picks and double peaks in the spectra were found at temperatures close to the clearing point, especially in samples with narrow distributions of droplet size. A flexoelectric origin of the first harmonic spectra in confined nematic systems is discussed.

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