On some liquid crystalline phases exhibited by compounds made of bent-core molecules and their mixtures with rod-like molecules

Pratibha, R. ; Madhusudana, N. V. ; Sadashiva, B. K. (2003) On some liquid crystalline phases exhibited by compounds made of bent-core molecules and their mixtures with rod-like molecules Pramana - Journal of Physics, 61 (2). pp. 405-415. ISSN 0304-4289

[img]
Preview
PDF - Publisher Version
198kB

Official URL: http://www.ias.ac.in/pramana/v61/p405/fulltext.pdf

Related URL: http://dx.doi.org/10.1007/BF02708320

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 BOH. 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 30°C. 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.

Item Type:Article
Source:Copyright of this article belongs to Indian Academy of Sciences.
Keywords:Mixtures of Rod-like and Bent-core Molecules; Biaxial Smectic A; B-liquid Crystals
ID Code:76055
Deposited On:29 Dec 2011 07:38
Last Modified:18 May 2016 19:52

Repository Staff Only: item control page