High Birefringence Lateral Difluoro Phenyl Tolane Liquid Crystals

Four laterally difluorinated phenyl tolane liquid crystals were synthesised and their physical properties evaluated. These compounds exhibit a fairly small heat fusion enthalpy (ΔH ~ 12.56 kJ mol-1), which is favourable for mixture formulations. For comparison, four lateral difluoro cyclohexane tolane homologues are also studied. We doped 10 wt% of each compound into a commercial negativemixture N1 andmeasured the birefringence, visco-elastic coefficient and figure of merit. Birefringence varies very little between homologues, but the visco-elastic coefficient increases as alkyl chain length increases. The refractive indices of these guest - host mixtures at 1550 nm are also measured. © 2010 Taylor & Francis