This study focuses on the synthesis and the structural characterization of various branched star-block copolymers (polyisoprene-block-polystyrene)(6)C-60 with a fullerene C-60 as a core. Well defined 6-arm stars (PI-b-PS)(6)C-60 with a low polydispersity and a precise control of the number of branches were prepared by grafting PI-b-PS diblock copolymers through the polystyrene block onto the C-60 core. The self-assembled structures formed in bulk were studied by Transmission Electron Microscopy (TEM) and Small Angle X-ray Scattering (SAXS) for both symmetric and asymmetric polystyrene-block-polyisoprene (PS-b-PI) diblock arms in the strong-segregation regime (65 <= chi N <= 115). Various microstructures including lamellae, hexagonal packings of PS and PI cylinders as well as a gyroid phase were obtained by varying the volume fraction of polystyrene (f(PS)) of the branches, leading to the formation of ordered, periodic and localized nanoscale dispersions of the C-60 in a polymer matrix including planes, threads and a 3D bicontinuous network of C-60. (C) 2008 Elsevier Ltd. All rights reserved.