We have prepared polystyrene/clay nanocomposites using an emulsion polymerization technique. The nanocomposites were exfoliated at 3 wt% content of pristine clay relative to the amount of polystyrene (PS). We employed two surfactants for the montmorillonite: cetylpyridinium chloride (CPC) and the CPC/alpha-CD inclusion complex. Prior to polymerization, each surfactant intercalates into the layers of the pristine clay dispersed in water. The inclusion complex was characterized by X-ray diffraction, C-13 CP/MAS NMR spectra, and H-1 NMR spectroscopy, and TGA. X-ray powder patterns of the CPC/alpha-CD complex indicate that the alpha-CDs units form channels. The C-13 CP/MAS NMR spectrum of the complex suggests that a CPC chain is included in the channel formed by the alpha-CDs. The H-1 NMR spectra of the complexes indicate that the stoichiometry of the complexes is 1:2 (i.e. one CPC molecule and two alpha-CD units). The TGA reveals that the inclusion complex has higher thermal stability relative to the virgin CPC. We employed both X-ray diffraction (XRD) and transmission electron microscopy (TEM) to characterize the structures of the nanocomposites. The value of T-g of the PS component in the nanocomposite is 6degreesC higher than that of the virgin PS and its thermal decomposition temperature is 33degreesC higher. The CPC/alpha-CD-treated clay is more effective than is virgin CPC-treated clay at enhancing the thermal stability of polystyrene. (C) 2004 Published by Elsevier Ltd.