Synthesis and Properties of Polythienylene Derivatives with Fluorine-Containing Chiral Liquid Crystalline Substituents (I)

Abstract

Chiral liquid crystalline (LC) substituent with fluorine-containing asymmetric moiety was introduced into the 3-position of thiophene ring. Polymerizations of 2,5-dibrominated thiophene derivatives were carried out through dehalogenative polycondensations. Polythienylene derivatives thus prepared were fusible and soluble in ordinary organic solvents. Phase transition behaviors of the polymers and monomers were examined by differential scanning calorimetry, polarizing optical microscope, and X-ray diffraction. The polymers and precursors showed several types of mesophases in the heating and cooling processes. Besides, one of the polymers exhibited a striated fan-shaped texture in polarizing optical microscope. This is attributed to a formation of chiral smectic C (S_C*) phase, which is indispensable for ferroelectricity.

Key Words:

• conjugated polymers
• polythienylene derivatives
• ferroelectricity
• chiral smectic C phase