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Synthesis and thermotropic liquid-crystalline behavior of novel main-chain poly(aryl ether ketones)

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Abstract

Novel aromatic poly(ether ketones) containing bulky lateral groups were synthesized via nucleophilic substitution reactions of 4,4′-biphenol and (4-chloro-3-trifluoromethyl)phenylhydroquinone (CF-PH) with 1,4-bis(p-fluorobenzoyl)benzene. The copolymers were characterized by differential scanning calorimetry (DSC), wide-angle X-ray diffraction, and polarized light microscopy observation. Thermotropic liquid-crystalline behavior was observed in the copolymers containing 40, 50, 60, and 70 mol % CF-PH. The crystalline–liquid-crystalline transition [melting temperature (Tm)] and the liquid-crystalline–isotropic phase transition appeared in the DSC thermograms, whereas the biphenol-based homopolymer had only a melting transition. The novel poly(aryl ether ketones) had glass-transition temperatures that ranged from 143 to 151°C and lower Tm's that ranged from 279 to 291°C, due to the copolymerization. The polymers showed high thermal stability, and some exhibited a large range in mesophase stability. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1347–1350, 2003

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