Continuum theory of ferroelectric smectic C* elastomers

(Received 15 October 1993, received in final form 21 December 1993, accepted 2 February 1994)

Abstract
The continuum free energy is derived for a crosslinked network of smectic C and chiral smectic C* liquid crystal polymers under small strain and orientational distortions. The coupling between elastic strain, the smectic C order parameter and the polarization (induced or spontaneous in C* phase) is examined and several new orientational and polarizational effects are predicted. Using group representation theory we obtain all relevant invariants, describing the coupling terms in the free energy. It is shown, on the other hand, that some effects in. conventional smectic C liquid crystals, for example the bistability and switching in ferroelectric C*, no longer exist in corresponding elastomers. Possible experimental configurations to observe some of the predicted effects are briefly discussed.