Hyperbranched poly(ether ketone) with carboxylic acid terminal groups: Synthesis, characterization, and derivatization

A new procedure is described for the formation of a hyperbranched poly(ethe r ketone) with carboxylic acid terminal groups. This preparation was based on the one-step synthesis of an AB(2)-type monomer 5-phenoxyisophthalic aci d using phosphorus pentoxide/methanesulfonic acid as the condensing agent a nd solvent. The electrophilic aromatic substitution reaction led to the for mation of the al yl ketone linkage. With the help of model compounds, H-1 N MR studies revealed that the degree of branching of the poly(ether ketone) was about 55%. The terminated carboxylic acid groups were readily functiona lized, yielding hyperbranched polymers with a variety of different function al chain ends. The nature of the chain ends was shown to dramatically affec t physical properties of the hyperbranched macromolecules. The ammonium der ivative was soluble in water and behaved as a unimolecular micelle.