Synthesis and Characterization of New Thermotropic Side-Chain Liquid Crystal Polymers Containing 1,6-Heptadiyne Backbone

Abstract

Abstract Poly(1,6-heptadiyne) derivatives with side-group liquid crystalline mesogens are prepared by ring-forming metathesis polymerization with transition metal catalysts. MoCl5-based catalyst systems are more effective for the polymerization of 1,6-heptadiyne monomers with various mesogenic groups than are WCl6-based catalyst systems. The resulting polymers exhibit good solubility in common organic solvents such as chloroform and THF, and they can be easily spin-coated on ITO glass. The weight-average molecular weights of the polymers are in the 3.5 to 26 × 104 range relative to polystyrene standards by GPC. The 1H-, 13C-NMR, and IR spectra of the resulting polymers indicate that sidechain liquid crystal polymers with a 1,6-heptadiyne backbone possess a polyene structure, presumably with cyclic recurring units in the polymer backbone. Thermal behaviors, morphology, and electrical conductivities are investigated by using differential scanning calorimetry, crosspolarized optical microscopy, and an LCR me...