Aim of this research is the development of a fundamental understanding about the mechanisms of dispersion and localization of carbon nanotubes (CNTs) in block copolymers (BCPs), which have been hardly scientifically investigated so far. On the basis of the already known structure-property correlations in BCPs the influence of an anisotropic shaped nanofiller on the phase behaviour of BCPs and on the interactions at the interfaces and their effect on the morphological, mechanical and electrical behavior is studied. The exceptional nanostructured morphology of BCPs will be used for a defined localization of the CNTs in one phase or at the interface of both phases via melt mixing. By blending the BCP/CNT composites with one of the homopolymers, of which the copolymer blocks consist of, it will be possible to specifically increase the domain thickness of the corresponding phase [1, 2]. With this kind of blend processing it is aimed to facilitate the localization of the CNTs in the expanded phase. Within this study a styrene-b-styrene-co-butadiene-b-styrene block copolymer with lamellar morphology is melt compounded with various concentrations of CNTs. Selected BCP/CNT nanocomposites are subsequently blended with a polystyrene homopolymer via melt processing. The influence of blending on the nanocomposite morphology and particularly on the domain thickness of the PS-rich phase is investigated. The localization behavior of the CNTs and additionally the mechanical and electrical properties are studied. References: [1] R. Lach, R. Weidisch, A. Janke, K. Knoll, Macromolecular Rapid Communications, 2004, 25, 2019-24. [2] B. K. Satapathy, R. Lach, R. Weidisch, K. Schneider, A. Janke, K. Knoll, Engineering Fracture Mechanics, 2006, 73, 2399-412. Acknowledgements: We thank the German Research Foundation for financial support of this research.