PIEZOELECTRICITY OF CHOLESTERIC ELASTOMERS

We consider theoretically the properties of piezoelectricity in choles teric elastomers. We deduce using symmetry considerations the piezoele ctric contributions to the free energy in the context of a coarse-grai ned description of the material. In contrast to previous work we find that compressions or elongations of the material along the pitch axis do not produce a piezoelectric response, in agreement with fundamental symmetry considerations. Rather only suitable shear strains or local rotations produce a polarization. We propose some molecular mechanisms to explain these effects.