Hydrodynamic and electrohydrodynamic properties of the smectic phase in liquid crystals

(Received 3 June 1991, revised 22 July 1991, accepted 16 September 1991)

Abstract
We present the hydrodynamic and electrohydrodynamic equations for the liquid crystalline smectic phase. This phase, which is fluid in the layers, orthogonal and optically biaxial, has recently been found experimentally in polymeric liquid crystals. We compare the macroscopic properties of the phase with those of the classical fluid smectic phases, namely smectic A, which is uniaxial, and the classical smectic C phase, that is tilted and biaxial. We predict that the in-plane director in the phase can show flow alignment. We point out that the chiralized version of smectic , , has electromechanical properties, that are qualitatively different from those of chiral smectic , but rather similar to those of a classical cholosteric phase. In contrast to , is not helielectric and thus does not show a linear response to an externally applied spatially homogeneous electric field, except for an electroclinic effect near phase transitions to a tilted phase. But similarly to and cholesterics it is predicted to show piezoelectricity.