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

Abstract

Novel side-chain type liquid crystalline (LC) polythienylene derivatives were synthesized by introducing fluorine-containing chiral LC substituents into the 3-position of thiophene rings, to achieve a quick response to electric field by virtue of ferroelectric liquid crystallinity (FLC). The polymers synthesized were fusible and soluble in ordinary organic solvents. UV-Vis absorption bands were observed in the region from 350 to 400 nm. Measurements of differential scanning calorimetry (DSC), polarizing optical microscope (POM), and X-ray diffraction (XRD) indicated that the polymers have various LC phases. Particularly, one of the polymer showed chiral smectic C (Sc*) phase, that is characteristic of the FLC mesophase. It was found that the effective conjugation length of main chain increased after the spontaneous orientation of the LC side chains. The polymer showed a drastic increase of dielectric constant in the temperature region of S_C* phase, which can be regarded as typical FLC behavior.

Key Words:

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