Synthesis and Mesomorphic Properties of Main-Chain Polymers Containing V-Shaped Bent-Core Mesogens with Acute-Subtended Angle

Abstract

Four achiral polymers with V-shaped bent-core mesogens in the main chain have been synthesized by polycondensation, and the effect of acute-angled central cores (Ar = 1,2-phenylene or 2,3-naphthylene) and lateral halogen substituents (X = For Cl) was studied. All polymers were only soluble in strong acids such as H(2)SO(4) and CF(3)CO(2)H. The solution viscosities were in the range of 0.31-0.81 dL/g. Although polymers contained a V-shaped bent-core mesogen with acute-angled configuration in their main chain, in general they were semicrystalline in the solid state and could form smectic C phases in the melt state. However, polymer with Ar/X = 1,2-phenylene/Cl was almost amorphous. Especially, polymer with Ar/X = 2,3-naphthylene/F formed a ferroelectric smectic C phase (SmCP(F)), possibly B7 phase: on ground state the spontaneous polarization was not zero (P(s) = 140 nC cm(-2)), and on applying tin triangular electric field a switching occurred by a collective rotation of the mesogens around the main chain axis.