Effect of Enantiomeric Excess on Electro-Optical Properties of Antiferroelectric Liquid Crystal: 4-(1-Trifluoromethyl-6-ethoxyheptyl-oxycarbonyl)phenyl-4'-nonyloxybiphenyl-4-carboxylate (TFMEOHPNBC)

Abstract

The mesomorphic and electro-optical properties of the (R)- and (S)-mixture of 4-(1-trifluoromethyl-6-ethoxy- heptyloxycarbonyl) phenyl-4'-nonyloxybiphenyl-4-carboxylate (TFMEOHPNBC) have been studied as a function of enantiomeric excess. Optically pure compound exhibits the SmA*-SmX*-SmC A * phase sequence. The SmX* phase is shown to be thresholdless and hysteresis-free V-shaped switching. On the other hand, in enantiomeric mixtures (R=0∼60ee%), the phase sequence exhibits the SmA*-SmC*-SmC A * phase sequence and does not show a SmX* phase. When the enantiomeric concentration range was R=20ee% below 75°C and R=0ee% below 80°C, no electro-optical change in the high electric field (1Hz, - 70V) was observed. Moreover, the spontaneous polarizations gradually increased and response times slowly decreased with increasing enantiomeric excess. On the other hand, the apparent tilt angles for the pure and racemization mixtures are fairly the same.