Structure-property relationships in dopant-induced ferroelectric liquid crystals

Measurements are reported of the ferroelectric polarization P s induced in a non-chiral smectic C phase by a variety of chiral dopants having different molecular structural features. Using molecular calculations of contributing dipole moments, ferroelectric order parameters are determined from the experimental results. The relationships between the P s and various other molecular properties are discussed, and it is shown that restricted rotation of the molecule due to its shape and internal energy barriers to rotation can result in relatively high values of P s. In contrast dipolar groups flexibly attached to a chiral centre may have their contribution to P s greatly reduced through internal rotation.