Dynamic effects of electric fields near the nematic and cholesteric to isotropic phase transitions

ABSTRACTWe investigate the effects of external electric fields on the macroscopic dynamics close to the nematic and cholesteric to isotropic transitions. We find as the most novel feature a non-linear reversible cross-coupling between an applied electric field and the stress tensor leading to flow phenomena close to the cholesteric to isotropic, but not in the vicinity of the nematic-isotropic transition. The existence of several dissipative cross couplings is pointed out and their order of magnitude is estimated.