New practical broad range FLC-mixtures for display application

Abstract

Two new broad range FLC-mixtures for practical use are presented. The qualification for display application imposes various requirements on the mixtures. Accordingly all compounds incorporated in the mixtures are thermally and photochemically stable. To facilitate easy and good orientation the mixtures exhibit the phase sequence X-S_C*-S_A*-N*-I with a long pitch in the N* phase. We present their most important physical characteristics as a function of temperature. This includes the rotational viscosity Which first of all requires a proper and unequivocal definition. Therefore emphasis is put on some fundamental aspects of rotational viscosity coefficients. Finally a new way of measuring the rotational viscosity γ_ϕ by means of the Sawyer-Tower bridge is presented.