The nitroxide-mediated radical polymerization of styrene was carried out on the surfaces of multiwalled carbon nanotubes (MWNTs) initiated by an MWNT-supported initiator multiwalled carbon nanotube-2",2",6",6"-tetramethylpiperidinyloxy (MWNT-Tempo). The content of polystyrene grafted from the surface was controlled by changes in the polymerization conditions, such as the reaction times or the ratios of monomers to initiators. The obtained polystyrene-grafted multiwalled carbon nanotubes (MWNT-PSs) were further used to initiate the polymerization of 4-vinyl-pyridine to get polystyrene-b-poly(4-vinylpyridine)-grafted multiwalled carbon nanotubes (MWNT-PS-b-P4VPs). In contrast to unmodified MWNTs, MWNT-PSs had relatively good dispersibility in various organic solvents, such as tetrahydrofuran, CHCL3, and o-dichlorobenzene. The structures and properties of MWNT-PSs and MWNT-PS-b-P4VPs were characterized and studied with several methods, including thermogravimetric analysis, Fourier transform infrared, ultraviolet-visible, and transmission electron microscopy. (c) 2006 Wiley Periodicals, Inc.