Investigations of twist elastic constant K22 of new nematic liquid crystal materials using threshold IPS method

Abstract

The liquid crystal technology is one of the most popular at the present time. To the most important parameters of liquid crystals belong optical anisotropy, viscosity, and twist elastic constants. One of the most difficult and problematic to measure parameters is a twist elastic constant K22. For new liquid crystalline materials, we have to characterize their physical properties, also a twist elastic constant K22. As a final result of this work, a twist elastic constant of new nematic liquid crystal materials was investigated. In this paper, a transmission-voltage characteristic of the in-plane switching cell was observed to find Freedericksz threshold, and then twist elastic constants could have been calculated. The method was checked on well-characterized materials E7 and 6-CHBT and its accuracy was better than 20%. In addition, the temperature dependence of K22 was determined for all materials. © 2011 Versita Warsaw and Springer-Verlag Wien.