Flexoelectric behavior of bimesogenic liquid crystals in the nematic phase – observation of a new self-assembly pattern at the twist-bend nematic and the nematic interface

Abstract

Flexoelectric properties – the effective flexoelectric coefficient and flexoelectric polarization – are investigated for a bimesogenic liquid crystal CBC11CB with a twist bend nematic phase (N_tb). Results show that the effective flexoelectric coefficient is at least two times higher than that for bimesogens that do not exhibit the N_tb phase. The flexoelectric polarization for the N_tb phase is also two times greater than that in the nematic phase. In a temperature gradient cell, we observe surprisingly a new phenomenon, in the bimesogens CBC7CB and CBC9CB and their mixtures with 5CB, of periodic self-assembly in the N phase close to the N–N_tb phase transition temperature. This phenomenon is reminiscent of the self-deformation and spontaneous chirality that appear in the system.