Shear Deformation and Ferroelectricity in Chiral SmC* Main-chain Elastomers

Abstract

Ferroelectric smectic main-chain liquid crystalline elastomers were synthesized and subjected to simple shear deformation to achieve reorientation of the layer structure and the formation of a macroscopic spontaneous polarization. The phase behavior and structural parameters of these elastomers are investigated and discussed. A shear-induced splitting of the X-ray scattering intensity distribution is found. A splitting of the sample in domains of two director orientations that couple differently to the shear deformation is proposed. The smectic layers also move at different affinities depending on their initial orientation. The smectic layer spacing was found to be nearly constant even though the smectic tilt angle changes significantly. The realignment of the smectic layers indicates a migration process, where depending on their original orientation the layer normals are leaving or entering the X-ray scattering plane. The spontaneous polarization was found to be linearly dependent on the dopant concentra...