David Coates

Synthesis and properties of liquid crystalline materials with high optical anisotropy

Liquid crystalline materials with high optical anisotropy are of great interest for many electrooptical devices, such as STN and 2-Mithmum Active Matrix Displays. Use of these materials leads to improved response times by using smaller cell gaps as well as enhanced contrast. As standard materials for achieving high optical anisotropy cyanobiphenyls and cyanoterphenyls are used at present. The demand for materials with lower viscosity as well as improved stability and resistivity has led us to develop new materials to meet these requirements. Introduction offluorine and fluorine containing substituents (CF3, OCF3, OCHF2) in terminal position ofhigh nstructures leads to new liquid crystals with high positive dielectiic anisotropy and good stability. Also liquid crystals with negative dielectñ anisotropy can be obtained by the incorporation of an 2,3-difluoro-l,4-phenylene moiety.