A new procedure is described for the formation of a hyperbranched poly(ether ketone) with carboxylic acid terminal groups. This preparation was based on the one-step synthesis of an AB2-type monomer 5-phenoxyisophthalic acid using phosphorus pentoxide/methanesulfonic acid as the condensing agent and solvent. The electrophilic aromatic substitution reaction led to the formation of the aryl ketone linkage. With the help of model compounds, 1H NMR studies revealed that the degree of branching of the poly(ether ketone) was about 55%. The terminated carboxylic acid groups were readily functionalized, yielding hyperbranched polymers with a variety of different functional chain ends. The nature of the chain ends was shown to dramatically affect physical properties of the hyperbranched macromolecules. The ammonium derivative was soluble in water and behaved as a unimolecular micelle.

In this paper the synthesis and characterization of a hyperbranched poly(aryl ether oxazole) with terminal phenolic groups are described. An ABB‘ monomer containing a pair of phenolic groups and an aryl fluoride which is activated toward displacement by the attached oxazole ring was prepared. The nucleophilic substitution of the fluoride with the phenolic group leads to the formation of ether linkage and subsequently the hyperbranched poly(aryl ether oxazole) P1. As determined by a combination of model compound studies and 1H NMR integration experiments, the degree of branching of P1 is approximately 50%. The polymer P1 is thermally stable and readily soluble in polar organic solvents. The terminal phenolic groups in P1 were easily functionalized, yielding hyperbranched polymers with a variety of functional chain ends. Physical properties, such as the glass transition temperature and the solubility of the hyperbranched poly(aryl ether oxazole)s, depended significantly on the nature of the chain ends.