Low dielectric constant nanocomposites of polyintides with grafted methacrylate side chains containing polyhedral oligomeric silsesquioxane (POSS) were successfully synthesized by thermally initiated free-radical graft copolymerization of methacrylcyclopentyl-POSS (MA-POSS) with the ozone-preactivated poly(arnic acid), followed by thermal imidization. The dielectric constant of the film can be tuned by varying the molar ratio of the grafted MA-POSS side chains in the copolymer. (C) 2004 Elsevier B.V. All rights reserved.