MECHANICAL FIELD ORIENTATION OF CHIRAL SMECTIC-C POLYMER NETWORKS

Deformation experiments on chiral smectic C elastomers show a signific ant influence of the layer structure. In contrast to nematic systems a deformation of the smectic polydomain does not lead to a uniform dire ctor orientation. Obviously, the smectic layers lock in the polydomain structure in a transient network. Therefore, on experimental time sca le, no equilibrium conditions can be achieved during the deformation p rocess in the smectic state. Reducing the influence of the smectic lay ers by swelling the sample with toluene offers the possibility to prep are samples with uniform director orientation. In these samples the sm ectic layers are distributed on a cone around the director, preventing ferroelectric properties. Further deformation experiments on these al igned samples show a strong interaction of the layer orientation with the mechanical field in the smectic state. Layers which enclose large angles with the mechanical field realign to layer orientations with sm all angles to the deformation direction. This orientation behaviour le ads to an anisotropic distribution of the layers on the cone causing a non-centrosymmetric phase structure. This anisotropic alignment can b e locked in by chemical crosslinking, leading to a highly transparent non-centrosymmetric bulk material.