Hyperbranched poly(aryl ether oxazole)s: Synthesis, characterization, and modification

In this paper the synthesis and characterization of a hyperbranched poly(ar yl ether oxazoIe) with terminal phenolic groups are described. An ABB' mono mer containing a pair of phenolic groups and an aryl fluoride which is acti vated toward displacement by the attached oxazole ring was prepared. The nu cleophilic substitution of the fluoride with the phenolic group leads to th e formation of ether linkage and subsequently the hyperbranched poly(aryl e ther oxazole) P1. As determined by a combination of model compound studies and H-1 NMR integration experiments, the degree of branching of PI is appro ximately 50%. The polymer P1 is thermally stable and readily soluble in pol ar organic solvents. The terminal phenolic groups in P1 were easily functio nalized, yielding hyperbranched polymers with a variety of functional chain ends. Physical properties, such as the glass transition temperature and th e solubility of the hyperbranched poly(aryl ether oxazole)s, depended signi ficantly on the nature of the chain ends.