3,5-bis(4-aminophenoxy)phenyl phenylearbamate-a novel AB(2)-type blocked isocyanate monomer and 3,5-bislethyleneoxy(4-aminophenoxy)}phenyl carbonyl azide - a novel AB(2)-type azide monomer were synthesized in high yield. Step-growth polymerization of these monomers were found to give a first example of hyperbranched poly (aryl-ether-urea) and poly(aryl-alkyl-ether-urea). Molecular weights (M-w) of the polymer were found to vary from 1,858 to 52,432 depending upon the monomer and experimental conditions used. The polydispersity indexes were relatively narrow due to the controlled regeneration of isocyanate functional groups for the polymerization reaction. The degree of branching (DB) was determined using H-1-NMR spectroscopy and the values ranged from 87 to 54%. All the polymers underwent two-stage decomposition and were stable up to 300 degrees C. Functionalized end-capping of poly(aryl-ether-urea) using phenylchloroformate and di-t-butyl dicarbonate (Boc)(2)O changed the thermal properties and solubility of the polymers. Copolymerization of AB(2)-type blocked isocyante monomer with functionally similar AB monomer were also carried out. The molecular weights of copolymers were found to be in the order of 6 X 10(5) with narrow dispersity. It was found that the T-g's of poly(aryl-alkyl-ether-urea)s were significantly less (46-49 degrees C) compared to poly(aryl-ether-urea)s. Moreover the former showed melting transition at 154 degrees C, which was not observed in the latter case. (c) 2007 Wiley Periodicals, Inc.