Polymer nanocomposites can exhibit superior multi-functional properties if they possess phase separated morphology at the nanoscale. Despite the huge potential of these materials, there are several fundamental issues including the ultimate microstructures which need to be resolved to tailor different, physical and mechanical properties required for specific applications. A 'ternary nanocomposites' approach is adopted to prepare electrically conductive and super-tough(1) (in terms of notched impact energy) hybrid polymer nanocomposites (polyamide 6/carbon nanotube/elastomer) that possess better properties than either of the constituent binary polymer nanocomposites (polyamide 6/carbon nanotubes and polyamide 6/elastomer). The individual roles of the nano-fillers involved in achieving multi-functionality are emphasized. The level of property enhancements of ternary nanocomposites depends essentially on the microstructure inducing a volume exclusion effect and the capability of fillers to activate the plastic deformation mechanisms in the matrix. (C) 2009 Elsevier Ltd. All rights reserved.