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Title: On some liquid crystalline phases exhibited by compounds made of bent-core molecules and their mixtures with rod-like molecules
Authors: Pratibha, R.
Madhusudana, N.V.
Sadashiva, B.K.
Keywords: Mixtures of rod-like and bent-core molecules
Biaxial smectic A
B-liquid crystals
Issue Date: Aug-2003
Publisher: Indian Academy of Sciences, Bangalore, India.
Citation: Pramana, 2003, Vol. 61, p405-415.
Abstract: In most homologous series of compounds made of bent-core (BC) molecules, the B2, B1 and B6 phases occur as the chain length decreases. We have studied binary mixtures of the compound 1,3-phenylene bis[4-(3-methylbenzoyloxy)]4'-n-dodecylbiphenyl 4'-carboxylate (BC12) which exhibits the B2 phase with the compound 4-biphenylyl 4''-n-undecyloxybenzoate (BO11) made of rod-like (R) molecules. We find the above sequence of occurrence of the B phases with increasing concentration of BO11. In this paper we describe the physical origin for the formation of these phases in both pure compounds and in the mixtures. We have also found the occurrence of the biaxial smectic A phase when the BO11 concentration is increased to 87–95.5 mol%. We also report on another binary system composed of BC12 and 4-n-octyloxy 4'- cyanobiphenyl (8OCB) made of R molecules. This system exhibits the biaxial smectic A phase down to 30oC. Using polarized infrared spectroscopy we find that the mutual orientation of the R and BC molecules in the SmAdb liquid crystal is such that the arrow axes of the BC molecules are along the layer normal of the partial bilayer smectic structure formed by the rods. We also describe unusual growth patterns obtained when the nematic phase transforms to the SmAdb phase in a mixture with 24 mol% of BC12.
Description: Proceedings of the international conference on liquid crystals and other soft materials held in 2002 at the Raman Research Institute, 2003.
ISSN: 0304-4289
Copyright: Indian Academy of Sciences, Bangalore, India.
Appears in Collections:Research Papers (SCM)

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