Synthesis and characterization of thermotropic liquid crystalline poly(aryl ether ketone) copolymers with pendant 3-(trifluoromethyl) phenyl groups

Novel poly(aryl ether ketone) copolymers with pendant 3-(trifluoromethyl)phenyl groups were synthesized by the reaction of a crystal-disrupting monomer, 3-(trifluoromethyl)phenylhydroquinone (FH) and a mesogenic monomer, 4,4'-biphenol (BP) with 1,4-bis(p-fluorobenzoyl)benzene (BF). Thermotropic liquid crystalline behavior of the copolymers was investigated by means of differential scanning calorimetry, polarized optical microscope and wide-angle X-ray diffraction. As a result, the copolymers with the respective molar ratios of FH/BP/BF of 0/100/100-10/90/100 and 80/20/100-100/0/100 were semi-crystalline without liquid crystalline properties, and amorphous polymers, respectively. In contrast, copolymers with the molar ratio of FH/BP/BF of 20/801100-70/30/100 had liquid crystalline characteristics. Interestingly, the formation of a highly ordered smectic phase was confirmed for copolymers with the molar ratio of FHMP/BF of 20/80/100-50/50/100, respectively. All the liquid crystalline copolymers had a wide liquid crystalline temperature range (57-75 degrees C). (c) 2006 Society of Chemical Industry.