Helix twist inversion in the SmC phase of lactic acid derivatives

The helix twist inversion in the chiral smectic-C phase was studied in new homologue series of lactic acid derivatives. The temperature of inversion was found to increase with increasing molecular chiral tail. With all studied substances high values of spontaneous polarisation P s were found which did not reach a saturation on cooling, in spite of saturated tilt angle Θ s . Dielectric properties as well as the dielectric relaxation frequency exhibit anomalies around the helix twist inversion temperature. The helix twist inversion phenomena is qualitatively discussed on the basis of a competition between spatial conformers and a thermodynamic model of the SmC* phase.