Esters of N-hydroxypyridine-2-thione (Barton esters, BE) were appended to a carboxylated poly(arylene ether sulfone), PSF-COOH, backbone. Irradiation of the polymer bound Barton ester in monomer/DMF solution initiated a free radical graft polymerization at 25 degrees C without promoting concomitant homopolymerization. The following monomers were grafted to PSF backbones using this technique: styrene, methyl methacrylate, vinyl pyridine and acrylamide. Since the grafts are attached to the backbone by an ester linkage, the graft segments were cleaved and subjected to independent characterization. Graft length is dependent upon the [BE]/[M], and the degree of BE substitution on the backbone. Treatment of BE modified PSF with styrene in the presence of TEMPO afforded the corresponding TEMPO adducts, which were used to promote the controlled radical graft polymerization of styrene. (C) 2000 Elsevier Science Ltd. All rights reserved.