We have developed a facile method to prepare polyacrylonitrile/montmorillonite (PAN/MMT) nanocomposites using the surface-initiated redox polymerization of acrylonitrile (AN) in the aqueous phase. The MMT silicate surfaces were first treated with diethanolamine, and the modified MMT (DEA-MMT) was subsequently used together with the Ce(IV) salt to serve as a redox system. The PAN chains growing on a surface-tethered DEA expand the interlayer space, and thus lead to intercalated/exfoliated nanocomposites. The nano-morphology of the prepared nanocomposites depends on the AN/OH molar ratio in feed. An exfoliated PAN/MMT nanocomposite was obtained when the feeding AN/OH in the nanocomposites prepared by the present method is also dependent on the AN/OH molar ratio in feed and can be up to ca. 160,000 g/mol. The differential scanning calorimeter (DSC) and thermogravimetric analysis (TGA) analyses show that the increasing fraction of exfoliated silicate structures should enhance the contact interface between the silicate and polymer, resulting in the higher glass transition temperature and thermal stability. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 115: 416-423, 2010