Mesomorphic and structural properties of liquid crystal possessing a chiral lactate unit

The mesomorphic and structural properties of the chiral lactic acid derivative 4′-(1-(octyloxy)-1-oxopropan-2-yloxy) biphenyl-4-yl 4-(decyloxy)benzoate have been studied. The compound shows the blue phase (BPII), the cholesteric (N*), the TGBA and the paraelectric SmA* phases over a broad temperature range. Polarising optical microscopy, differential scanning calorimetry, optical transmission, X-ray diffraction and dielectric spectroscopy studies have been performed. In the SmA* phase the layer spacing (d) values are found to be slightly temperature dependent and suggest that there is no bi-layer association present in the mesophase. In the TGBA phase, the d values show strong temperature dependence near SmA*–TGBA phase transition, indicating pre-transitional effect. The temperature dependence of scattered X-ray intensities indicate the appearance of long range smectic ordering at the N*–TGBA phase transition. Near the TGBA–SmA* phase boundary strong SmA* fluctuations predominate. This behaviour is also observed from the temperature dependence of the d values. The transverse correlation lengths, ξ⊥, diverge near the N*–TGBA phase transition indicating second order phase transition.