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clay nanocomposites by emulsion polymerization in aqueous and in supercritical carbon dioxide medium I.R. Kamrupi and S.K. Dolui In this article, the synthesis of polystyrene/bentonite clay nanocomposites by emulsion polymerization in aqueous and supercritical carbon dioxide (sc-CO2) media using organically modified bentonite clay is reported. The modified clay is dispersed within the monomer via ultrasonication and the mixture is allowed to undergo in situ emulsion polymerization, resulting in the formation of polymer/clay nanocomposites. A comparative study of the properties of the nanocompo-sites synthesized in the two media was carried out. The effects of clay concentration on polymer conversion, molecular weight, morphology, and mechanical properties have been investigated. Sodium dodecylbenzene sulfonate was used as a stabilizer in aqueous medium and polydimethylsiloxane in sc-CO2 medium. The nanocomposites were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, gel permeation chromatography, and thermogravimetric analysis