Syndiotactic polystyrene (sPS)/montmorillonite nanocomposites were prepared via in situ intercalative coordination polymerization using mono-(eta(5)-pentamethylcyclopenta- dienyl) tribenzyloxy titanium [Cp*Ti(OBZ)(3)] complex activated by methylaluminoxanes. (MAO) and triisobutylaluminum (TIBA). The influences of polymerization conditions, such as the weight ratio of montmorillonite and styrene, temperature, and monomer concentration, on the preparation of sPS/montmorillonite nanocomposites was investigated. The intercalation spacing in the nanocomposites, as well as the exfoliation of the montmorillonite interlayers, was characterized with wide angle X-ray diffraction (WAXD) and transmission electron microscopy (TEM). The dispersibitity of the nanoscale elements depended on the polymerization conditions and the surfactant treatment. The crystallizability and thermal properties of these nanocomposites were determined by differential scanning calorimetry (DSC) analysis and thermogravimetric analysis (TGA). Experimental results indicated that the degree of crystallinity of the sPS nanocomposite increased with increasing montmorillonite content and with higher T. and thermal decomposition temperature than pure sPS. (C) 2005 Wiley Periodicals, Inc.