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).

Keywords:

• guest–host systems
• nematic liquid crystal
• aminoanthraquinone dye
• carbon nanotube
• order parameter
• phase transition