X-ray Diffraction and Torsional Viscosity Investigations of Laterally Linked SC Liquid Crystal Dimers

The mechanism by which a tristable, laterally linked, SC* liquid crystal dimer reorients under the application of an electric field has been investigated by a combination of X-ray diffraction studies and torsional viscosity measurements. A new experimental liquid crystal cell has been developed that allows direct measurement of layer spacing as a function of applied field at controlled temperature. The distance between smectic layers is consistent with the dimer naturally arranging in a “U” conformation. No significant change in layer spacing of the dimer was observed upon the application of an electric field for all temperatures and field strengths accessible. The torsional viscosity of the tristable phase of the dimer is similar to previously characterized tristable compounds. These results are consistent with the hypothesis that electrically induced switching of the optically pure dimer occurs by conventional, conical Clark−Lagerwall-type switching seen in other ferroelectric and antiferroelectric materials.