SMECTIC A TWIST GRAIN-BOUNDARY PHASE IN 3 NEW SERIES WITH CHIRAL (L) LACTIC-ACID DERIVATIVES

Three new series with a tolane core and a chiral L-lactic acid moiety have been synthesized. The theoretically predicted S(A)-TGB(A)-N* phase sequence is found in several compounds with short chains. The smectic A twist grain boundary phase (TGB(A)) obtained with a cholesteric texture, is characterized by different techniques. Helical pitch measurements were performed using Grandjean-Cano wedges or homeotropic drops. All pitch values are lower than those found in previously reported series exhibiting the TGB(A) phase. Ferroelectric smectic C (S(C)*) phases appear with long chains and have striated fan-shaped or pseudo-homeotropic textures. Electro-optical properties of the S(C)* phase were studied with the classical SSFLC geometry. We observed high polarization, slow response time and a saturated tilt angle of 20-degrees. These results are comparable with previous studies.