Polystyrene/organoclay nanocomposites were prepared by melt intercalation in the presence of elastomeric impact modifiers. Three different types of organically modified montmorillonites; Cloisite(R) 30B, 15A, and 25A, were used as reinforcement, whereas poly [styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS-g-MA) and poly(ethylene-b-butyl acrylate-b-glycidyl methacrylate) (E-BA-GMA) elastomeric materials were introduced to act as impact modifier. Owing to its single aliphatic tail on its modifier and absence of hydroxyl groups, Cloisite(R) 25A displayed the best dispersion in the polystyrene matrix, and mostly delaminated silicate layers were obtained in the presence of SEBS-g-MA. This was attributed to the higher viscosity of SEBS-g-MA compared with both E-BA-GMA and poly(styrene-co-vinyloxazolin) (PS). In addition, the compatibility between SEBS-g-MA and PS was found to be better in comparison to the compatibility between E-BA-GMA and PS owing to the soluble part of SEBS-g-MA in PS. The clay particles were observed to be located mostly in the dispersed phase leading to larger elastomeric domains compared with binary PS/elastomer blends. The enlargement of the elastomeric domains resulted in higher impact strength values in the presence of organoclay. Good dispersion of Cloisite(R) 25A in PS/SEBS-g-MA blends enhanced the tensile properties of this nanocomposite produced. It was observed that the change in the strength and stiffness of the ternary nanocomposites mostly depend on the type of the elastomeric material. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013