The magnitude of the spontaneous polarization in two ferroelectric liquid crystals.

The spontaneous polarization was measured for two chemically isomeric ferroelectric smectogens which have different phase sequences. The two compounds S-4-(3,7-dimethyloctyloxy)phenyl 4-n-decycloxybenzoate and S-4-n-decycloxyphenyl 4-(3,7-dimethyloctyloxy)benz oate differ only in the direction of the central ester linkage. Thus both materials have similar dipolar characters. The first material exhibits a smectic A to smectic C* phase transition, but the second exhibits a cholesteric to smectic C* phase change. The first compound has a low value for its optical tilt angle, close to 22 degrees at saturation in the smectic C* phase, whereas the second has a relatively large value of approximately 45 degrees.