Styrene–butadiene–styrene/montmorillonite nanocomposites synthesized by anionic polymerization

We successfully synthesized an exfoliated styrene–butadiene–styrene triblock copolymer (SBS)/montmorillonite nanocomposite by anionic polymerization. Gel permeation chromatography showed that the introduction of organophilic montmorillonite (OMMT) resulted in a small high‐molecular‐weight fraction of SBS in the composites, leading to a slight increase in the weight‐average and number‐average molecular weights as well as the polydispersity index. The results from 1 H‐NMR revealed that the introduction of OMMT almost did not affect the microstructure of the copolymer when the OMMT concentration was lower than 4 wt %. Transmission electron microscopy and X‐ray diffraction showed a completely exfoliated nanocomposite, in which both polystyrene and polybutadiene blocks entered the OMMT galleries, leading to the dispersion of OMMT layers on a nanoscale. The exfoliated nanocomposite exhibited higher thermal stability, glass‐transition temperature, elongation at break, and storage modulus than pure SBS. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci, 2006