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

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 Ntb phase. The flexoelectric polarization for the Ntb 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-Ntb phase transition temperature. This phenomenon is reminiscent of the self-deformation and spontaneous chirality that appear in the system.