Synthesis and thermotropic liquid-crystalline behaviour of novel main-chain poly(ether ether ketone ketone)s containing a lateral tert-butyl group

The synthesis of novel poly(ether ether ketone ketone)s containing a latera l group via the random copolymerization of 4,4'-biphenol, tert-butylhydroqu inone and 1,4-bis(p-fluorobenzoyl)benzene is described, The copolymers were characterized by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD) and polarized optical microscopy (POM) observation, The results showed that the thermotropic liquid-crystalline properties were ac hieved in the copolymers containing 30mol% and 50mol% tert-butylhydroquinon e, which have relatively lower melting temperatures due to the copolymeriza tion effect, Both the crystalline-liquid-crystalline transition (T-m) and t he liquid-crystalline-isotropic phase transition (T-i) were observable in t he DSC thermograms, while the biphenol-based poly(aryl ether ketone) has on ly one melting transition. The hydroquinone-based polymer was shown to be a morphous. Thermogravimetric analysis (TGA) results showed that these copoly mers are all high-temperature resistant with higher glass transition temper ature between 147 and 149 degreesC, and higher decomposition temperature Td in the range 480-520 degreesC, (C) 2000 Society of Chemical Industry.