The Synthesis and Mesomorphic Properties of Some Novel Antiferroelectric Liquid Crystals

Abstract

Several esters have been synthesised that exhibit the antiferroelectric smectic C phase. The core structures, like virtually all antiferroelectric materials, are very similar to that of MHPOBC. Lateral fluoro substituents have been used to reduce melting points and to investigate their effect on mesomorphic properties, spontaneous polarisation and tilt angle. A new device format reported by Lagerwall requires antiferroelectric liquid crystals with a 45° tilt angle. Novel antiferroelectric materials were prepared with fluoro substituents in lateral positions and in a terminal chain to provide low melting points, high antiferroelectric phase stability, high spontaneous polarisation and tilt angles of up to 45°. The synthetic routes to the novel materials are discussed, and the transition temperatures, tilt angles and spontaneous polarisations are compared to those of known materials.