The orientational behaviour of some aminoanthraquinone dyes in E8 and ZLI-1132 nematic solvents and effect of addition of carbon nanotubes

Abstract

Guest-host liquid crystal displays have been widely utilised because of their many advantages such as colour, wide viewing angle and high brightness. For practical guest-host applications, it is important to choose dyes with a high ability of orientation in the liquid crystal matrix. In this work, two different nematic liquid crystals (E8 and ZLI-1132) were separately doped with three different dyes (1,2-, 1,4- and 2,6-diaminoanthraquinone). Their solubilities, textures, phase transition temperatures and order parameters were determined. At the second stage, single-walled carbon nanotubes (CNTs) were added (0.05% m/m) to these solutions and the same parameters (except solubilities) were studied again. The highest solubility and order parameter values were attained with 1,4- diaminoanthraquinone dye in ZLI-1132 nematic host. When CNTs in a small amount were added to the dye mixtures as co-dopant, the further increases in order parameters (S) were observed in mixtures with low S values. These dyes and CNTs did not significantly destabilise the mesomorphic phase of nematic hosts. An appreciable change in textures was not observed with addition of dopant(s). © 2011 Taylor & Francis.