New ferroelectric liquid crystals with cyclic and non-cyclic chiral groups

Abstract

New liquid crystalline materials with cyclic proline alkyl ester, fenchyl, bornyl, verbenyl and 2-decalinyl and non-cyclic 1-methyl-alkyl and ethyl-lactate chiral terminal groups were studied. Ferroelectric and antiferroelectric smectic phases were found for compounds with the semi-flexible chiral group while derivatives with the ring chiral moieties form exclusively ferroelectric smectics. The Ps values as high as 270 nC/cm² in the hexatic SmI* phase were detected for the 1-methyl-alkyl derivatives. Generally, a lower spontaneous polarisation was detected for the materials with cyclic groups. This is either due to large size of the bulky groups causing less hindered rotation of molecules or due to admixture of conformers with opposite Ps sign.