Synthesis and characterization of halogen‐containing poly(ether ketone ketone)s

A series of novel poly(ether ketone ketone)s (PEKKs) were synthesized from diphenyl ether and isophthaloyl chloride derivatives such as 5‐halo‐ and 5‐tert‐butyl‐isophthaloyl chloride. The aromatic electrophilic substitution route to polyketones was a convenient route for the preparation of the polymers in high yields via precipitation polycondensation at a low temperature with aluminum trichloride as a catalyst. High molecular weight PEKKs were achieved with number‐average molecular weights of 15,000–100,000 g/mol for polymers that showed good solubility in organic solvents. The presence of substituents greatly modified the spectroscopic features in comparison with those of unsubstituted isophthaloyl poly(ether ketone ketone)s, particularly for the series containing halogens, for which significant variations of the chemical shifts in both ¹H and ¹³C NMR spectra were observed; these shifts could be related to the nature of the halogen. Thermal properties were also affected by the presence of pendent substituents, with clear enhancements of the glass‐transition temperatures, which could be ascribed to the nature and bulkiness of the substituents. Thermogravimetric analyses showed that the new polymers had good thermal resistance, although an important drop in thermal resistance was observed for polymers bearing large halogen atoms, such as bromine and iodine. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2601–2608, 2002