Liquid crystalline cyanobiphenyl homologues doped with gold nanoparticles

Abstract

The following paper reviews our study of the dispersion of gold nanoparticles (GNPs) in different homologues of cyanobiphenyl (CB) liquid crystals (nCB with n = 5, 6, 7). We show that doped GNPs dramatically affect the material, and consequently the display parameters and mesophase stability of these mainly room temperature nematics. We report several homologues at certain GNP percentages with their values a few times lower than that for pure nematics, switching voltages and times, and with a broader operational thermal range. These materials are good candidates for application in liquid crystal (LC) display devices. We show that the amount of carbon atoms n in the alkyl ‘tail’ of the homologues' constituent molecules and the concentration of dispersed GNPs critically affect the behaviour of the material parameters in the nanocomposites. We report a certain correlation of the material parameters behaviour with an odd−even−odd change in the number of CB homologues. We propose that the influence of GNPs on the material parameters and the thermal stability of the nematics is caused by the formation of different kinds of aggregations between nanoparticles and LC molecules. These clusters affect the local ordering of the LC molecules, consequently changing the material parameters and mesophase stability.