Rotational damping and the spontaneous polarization in ferroelectric liquid crystals.

The electro-optic behavior and spontaneous polarization in ferroelectric liquid crystals is caused by a breaking of the C sub (2h) symmetry of the phase by the inclusion of a chiral atom in the structures of the constituent molecules. The magnitude of the spontaneous polarization is markedly affected by the local dipolar environment of the asymmetric center and its relative rotational disorder about the long axis of the molecule. The reorientational viscosity of the mesophase is also related to the hindering of the rotation of the chiral center. In applications of these phases, the response time is found to be proportional to the viscosity, but inversely proportional to the polarization.