The Elastic Constants of Nematic n-Hexylcyanobiphenyl Determined with the Capacitance Method

Abstract

Abstract The splay (K 11) and bend (K 33) elastic constants of n-hexylcyanobiphenyl (C6H13-Ph-Ph-C=N) were determined from the voltage (U) dependence of the capacitance (C) of the planar nematic cell with a small molecular pretilt angle. The capacitance changes are due to distortion of the director n driven by the applied electric field. K 11 was obtained from the Freedericksz threshold voltage (Uth) and K 33 from the C(U) dependence above the threshold voltage by means of the method proposed by Gruler et al. and Uchida et al. The significance of the pretilt angle in the determination of K 33 is discussed.