A new chiral LC acrylate that exhibits pyroelectricity

The new material (R)-4-(5-acryloyloxy-4-methylpentanoyloxy)-4'-octanoyloxy biphenyl has been synthesised and characterised by POM, DSC, X-ray diffract ion, IR dichroism, pyro- and piezoelectric techniques. The acrylate was sho wn to exhibit direct isotropic to smectic H* phase transition. The natural texture of the H* phase separates from the isotropic phase in the form of b atonnets and rounded domains, the latter develop into a mosaic. The mesopha se was found to align in a thin cell of KBr plates with homeotropic anchori ng independently of the type of surface treatment. The molecular organisati on in the H* phase strongly favours fast and efficient polymerisation when the initial orientation retains upon the reaction. The structure of the cry stal and H* phases is mono-layer, the molecules pack monoclinic in antipara llel fashion with long-range polar ordering. The pyroelectric coefficient W as found to be very high in the crystal (gamma = 2.0 divided by 2.9 nC/cm(2 ).K) and H* (gamma = 2.9 divided by 1.0 nC/cm(2).K) phases. The direction o f the macroscopic polarisation was not shown to be controlled by an externa l voltage. The piezocoefficient is stable and constant within the crystal p hase (d(31) = 0.41 nC/N).