The ketone functionalized N-alkoxyamine, a derivative of 4-oxo-2,2,6,6-tetramethylpiperidin-1-oxyl (4-oxo-TEMPO) was synthesized and applied as an initiator in the nitroxide mediated polymerization of styrene in bulk at 120 degrees C. In the presence of the prepared initiator: 1-phenyl-1-(4-oxo-2,2,6,6-tetramethylpiperidinoxy)propanone polymers with well-defined molecular weight were obtained. By contrast, when an accelerator such as acetic anhydride (10%) was added to the system, lower control of polymerization was observed. Additionally, the functionality of polymers was evaluated on the basis of a quantitative investigation of UVvisible spectra of 2,4-dinitrophenylhydrazone formed from the polymers and the synthesized initiator. The UVvis spectra of the hydrazone derivatives obtained from polymers by means of 2,4-dinitrophenylhydrazone made it possible to confirm that the polymers prepared in the presence of the ketone functionalized N-alkoxyamine retain the ketone functionality on the polymer chain. The functionality for the obtained polymers exceeded 1 significantly. The obtained (a, ?) telechelic polymers are of great importance in the synthesis of new biohybrid materials such as bioconjugates with proteins or peptides as well as new polymer nanostructures. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013