Synthesis and characterization of substituted poly(arylene ether ketone)s through nitro displacement reaction

Abstract

New amorphous poly(arylene ether ketone)s containing three kinds of substituent groups, trifluoromethyl, piperidylcarbonyl, and diphenylamide, with relatively high molecular weight were prepared through nucleophilic nitro displacement reaction from novel AA or AB type monomers. The nitromonomers activated by two electron withdrawing groups (carbonyl and pendent groups), 1,4-bis-(3-trifluoromethyl-4-nitrobenzoyl)benzene, 1,4-bis[4-nitro-3-(1-piperidylcarbonyl)benzoyl]benzene, 1,4-bis(3-N,N-diphenylcarbamoyl-4-nitrobenzoyl)benzene, 1,4-bis[3-(2-benzoxazoyl)-4-nitrobenzoyl]benzene, 1,4-bis[3-(2-phenyl-1,3,4-oxadiazoyl)-4-nitrobenzoyl]benzene, 4-hydroxy-4`-nitro-3`-trifluoromethylbenzophenone, and 4-(4-hydroxyphenoxy)3`-trifluoro-methyl-4`-nitrobenzophenone, were synthesized with a-aminoacetonitrile derivative, masked acylanion equivalent. This synthetic method may be useful for introducing various pendent groups on poly(arylene ether ketones) backbone. In order to demonstrate whether doubly activated monomers would undergo facile nucleophilic aromatic substitution and whether polymerization is feasible, the model reaction was studied with m-cresol. The model reaction revealed that nucleophilic aromatic substitution of the nitro groups began to occur at room temperature and was completed at 80℃ and the model compound was obtained in high isolated yield. Polymerizations of nitromonomers with several dihydroxy comonomers were carried out in a polar aprotic solvent with potassium carbonate as a base. The polymerizations of nitromonomers proceeded successfully, except heterocyclic ring containing monomers and 4-hydroxy-4`-nitro-3`-trifluoromethylbenzophenone monomer at mild condition. The concept of double activation with carbonyl and other electron withdrawing pendent group for facile expulsion of nitro leaving group was successfully applied to step polymerization at relatively mild condition. The thermal properties and solubilities of the polymers were investigated. ...