Synthesis and Dielectric Property of a Ferroelectric Liquid Crystalline Polythiophene Derivative

Chiral liquid crystalline substituent containing asymmetric group was introduced into the thiophene monomer. The monomer with ferroelectric liquid crystalline substituent was polymerized by the chemical reaction with the aid of Ni(0) catalyst to afford linear ferroelectric liquid crystalline conductive polymer. The ferroelectric polythiophene derivatives thus prepared were good processability because the polymer is fusible and soluble in ordinary organic solvents. Absorption band was observed in the range from 400 to 415 nm due to the electronic transition (π − π* transition) of conjugated main chain. Phase transition behavior of the polymer was examined by differential scanning calorimetry, polarizing optical microscopy, and X-ray diffraction analysis. The polymers exhibited a striated fan-shaped texture under the polarizing optical microscopy observations. This is attributed to a formation of chiral smectic C (SmC*) phase with ferroelectricity. The ferroelectric behavior was also confirmed by examining the temperature dependence of dielectric constant of the polymer.