The in situ grafting-from approach via atom transfer radical polymerization was successfully applied to polystyrene, poly(styrene-co-acrylonitrile), and polyacrylonitrile grafted onto the convex surfaces of multiwalled carbon nanotubes (MWCNTs) with (2-hydroxyethyl 2-bromoisobutyrate) as an initiator. Thermogravimetric analysis showed that effective functionalization was achieved with the grafting approach. The grafted polymers on the MWCNT surface were characterized and confirmed with Fourier transform infrared spectroscopy and nuclear magnetic resonance. Raman and near-infrared spectroscopy revealed that the grafting of polystyrene, poly(styrene-co-acrylonitrile), and polyacrylonitrile slightly affected the side-wall structures. Field emission scanning electron microscopy showed that the carbon nanotube surface became rough because of the grafting of the polymers. Differential scanning calorimetry results indicated that the polymers grafted onto MWCNTs showed higher glass-transition temperatures. The polymer-grafted MWCNTs exhibited relatively good dispersibility in an organic solvent such as tetrahydrofuran. (c) 2006 Wiley Periodicals, Inc.