Supramolecular assembled nanocomposites were prepared through the solution casting of the complexing mixtures from the side chain (PDMS) with the 1-(4-methyl)-piperazinylfullerene (MPF). FT-IR and XPS analyses reveal that there are strong ionic interactions between the two components. Small-angle X-ray scattering study shows the formation of MPF fullerene nanodomains dispersed in the PDMS matrix, but no highly ordered structures, which is confirmed with TEM images. Compared to its polymeric precursor, the MPF crosslinked composites exhibit superior thermal mechanical stability and dramatic increase in the storage and loss moduli. Moreover, elastic response exceeds viscous response in the composites due to the formation of crosslinking structures. The increase of the MPF content in the composites leads to a denser packing of MPF nanodomains, resulting in better thermal, mechanical, and viscoelastic properties. The decrease in the carboxylic acid groups along the PDMS chains reduces the crosslinking density of the PDMS/MPF composites. The composites show a combined dielectric property from both PDMS and MPF components. (c) 2006 Elsevier Ltd. All rights reserved.