A NONCHIRAL SWALLOW-TAILED LIQUID-CRYSTAL EXHIBITING A SMECTIC-C PHASE THAT HAS AN ANTIFERROELECTRIC STRUCTURE

Antiferroelectric smectic liquid-crystalline materials have recently been shown to be of use in display devices where they show tristable switching behaviour. Most liquid-crystalline materials that exhibit antiferroelectric properties are, however, highly chiral and therefore have helical macrostructures. Unfortunately, this helical ordering is undesirable in the construction of display devices. In this article we report on the liquid-crystalline properties of a non-chiral material which apparently exhibits a smectic phase that has antiferroelectric-like layer ordering. As the material is non-chiral, it does not possess a helical macrostructure, and therefore could be of value as a suitable host for antiferroelectric mixtures. We suggest that the formation of an antiferroelectric structure is due to the presence of dimeric molecular species. This possibility allows us to speculate on other structures for mesophases that might be found in chiral liquid-crystalline systems.