Liquid crystalline binary mixtures at the air–water interface

The interaction behaviour of the binary mixtures composed of the liquid crystals 4-octyl-4′-cyanobiphenyl (8CB) and 4-pentyl-4′-cyanoterphenyl (5CT) as well as biphenyl (BP) and terphenyl (TP) at different molar ratios has been studied using Langmuir technique. The surface pressure-mean molecular area isotherms have been recorded. The miscibility of the components in Langmuir films has been determined by using the additivity rule and collapse surface pressure criterion. It has been found, that 8CB is partially miscible with BP and TP. 5CT is miscible with TP, whereas the mixtures of two liquid crystals, 8CB and 5CT reveal the phase separation over a whole range of composition.