Synthesis and Properties of High Tilted Antiferroelectric Esters with Partially Fluorinated Alkoxyalkoxy Terminal Chains

Novel chiral esters with partially fluorinated alkoxyalkoxy terminal chains are described. Their phase transition temperatures, enthalpies, and electrooptical properties are reported. A helical pitch in pure compounds and their mixtures based on selective reflection of light is also characterized

Liquid Crystalline Materials With High Birefringence

The mesogenic, optical, and dielectric properties of the new mixtures of high-birefringence nematic liquid crystals based on isothiocyȧnatotolanes are investigated, and examples of multicomponent mixtures with low viscosity and optical anisotropy Δn≈0.4 are presented. © 2005 Optical Society of America

Studies on the Utilisation of Spent Palladium–Activated Carbon (Pd/AC) Catalysts

The present paper offers an assessment of using wastes such as palladium–activated carbon (Pd/AC) catalysts through their regeneration or metal recovery. In order to regenerate a catalyst it has been found necessary to clean up its surface completely and restore the original form of the metal. Supercritical fluid extraction can be useful in removing organic substances from the surface of a spent catalyst whereas microwave mineralisation can be used to recover palladium from the mass of a spent catalyst

Synthesis And Mesomorphic Properties Of Isothiocyanatotolanes

The synthesis, mesomorphic properties and visible spectra of 4′-substtituted alkyl-, alkoxy-, alkylcyclohexyl and alkylcyclohexylethyl-4-isothiocyanatotolanes have been described. Multicomponent mixtures with birefringence higher than 0.4 and low viscosity have been formulated. © 2002 SPIE · 0277-786X/02/$15.00

Mesomorphic And Dielectric Properties Of Esters Useful For Formulation Of Nematic Mixtures For Dual Frequency Addressing System

Mesomorphic and dielectric properties of three homologous series of two and three ring fluorosubstituted esters are described. They are 4-cyano-3-fluorophenyl 4-alkyloxy-2-fluorobenzoates, 4-cyano-3-fluorophenyl 4-(4-alkylbenzoyloxy)-2-fluorobenzoates and 3-fluoro-4-cyanophenyl, or 3-fluoro-4-isothiocyanatophenyl or 3,4-difluorophenyl 4\u27-alkyl-2,3-difluoro- biphenyl-4-carboxylates. The compounds exhibit the nematic mesophase accompanied by the smectic A or smectic C mesophase in some cases. Most of them show strong dependence of the dielectric anisotropy Δε upon frequency, at low frequencies Δε reaches a value ∼200, while at high frequencies a small negative dielectric anisotropy appears. © 2009 © Versita Warsaw and Springer-Verlag Berlin Heidelberg

Low Viscosity, High Birefringence Liquid Crystalline Compounds And Mixtures

Two types of fast switching mixtures with high positive dielectric anisotropy were described. The first type, with a birefringence below 0.3, was designed for devices operating at room or lower temperatures and the second one, with a birefringence higher than 0.3 for devices operating at elevated temperatures

Synthesis And Mesogenic Properties Of Three- And Four-Ring Compounds With A Fluoroisothiocyanatobiphenyl Moiety

The syntheses and mesomorphic properties of 4-alkylcyclohexyl- and 4-alkylcyclohexylethyl and 4-alkylbicyclo-hexyl-3-fluoro- and 3,5-difluorobiphenyl-4-isothiocyanates are described. The compounds are low melting, very broad range nematic liquid crystals and are very useful for the formulation of nematic mixtures of low viscosity and with a moderately high birefringence (0.3-0.35). The refractive indices, bulk viscosity and dielectric anisotropy extrapolated from Demus\u27 ester mixture for the prepared compounds are presented. © 2010 Taylor & Francis

Syntheses And Mesomorphic Properties Of Laterally Fluorinatedphenyl Isothiocyanatotolanes And Their High Birefringent Mixtures

Syntheses and mesomorphic properties of di-, tri- and tetrafluorosubstituted 4\u27-(4-alkylphenyl)-4-isothiocyanatotolanes are described. Four fluorine substituted compounds in the position 2\u27, 3\u27, 3, and 5 show stronger nematic character than difluorosubstituted ones in the position 3, 5 or 2\u27, 3\u27. Example of high birefringence nematic mixture and its properties are given. © 2009 © Versita Warsaw and Springer-Verlag Berlin Heidelberg