Phase Transitions and Soft Elasticity of Smectic Elastomers

Abstract

Smectic-$C$ elastomers can be prepared by cross-linking, e.g., liquid crystal polymers, in the smectic-$A$ phase followed by a cooling through the smectic-$A$ to smectic-$C$ phase transition. This transition from $D_{\infty h}$ to $C_{2h}$ symmetry spontaneously breaks rotational symmetry in the smectic plane as does the transition from a smectic-$A$ to a biaxial smectic phase with $D_{2h}$ symmetry. We study these transitions and the emergent elasticity of the smectic-$C$ and biaxial phases in three related models and show that these phases exhibit soft elasticity analogous to that of nematic elastomers.