Synthesis and thermotropic liquid crystalline behaviour of novel poly(arylether ketone)s with a lateral methoxy group

Novel poly(aryl ether ketone)s containing a lateral methoxy group were synt hesized by nucleophilic substitution reactions of 4,4'-biphenol and methoxy hydroquinone with 1,4-bis(4-fluorobenzoyl)benzene in a sulfolane solvent in the presence of anhydrous potassium carbonate. Their thermotropic liquid c rystalline properties were characterized by a variety of experimental techn iques, e.g. differential scanning calorimetry (DSC), polarized light micros copy and temperature-dependent FTIR. Thermotropic liquid crystalline behavi our was observed in the copolymers containing 30-80 mol-% mexthoxyhydroquin one. Both melting (T-m) and isotropization (T-i) transitions appeared in th e DSC curves. The polarized light microscopy study of the liquid crystallin e copolymers suggested their ordered smectic structures. As expected, the c opolymers had lower melting transitions than the biphenol-based homopoly(ar yl ether ketone)s because of the copolymerization effect of the crystal-dis rupting monomer methoxyhydroquinone.