Azidopropyl-heptaisobutyl-substituted polyhedral oligomeric silsesquioxane (POSS-N-3) was reacted with 1,1,1-tris[4-(2-propynyloxy)phenyl]-ethane (1) and poly(ethylene glycol) (PEG)-b-poly(methyl methacrylate) (PMMA) copolymer with alkyne at its center (PEG-PMMA-alkyne) affording the first time synthesis of 3-arm star POSS and PEG-PMMA-POSS 3-miktoarm star terpolymer, respectively, in the presence of CuBr/N,N,N',N '',N '',N ''-pentamethyldiethylenetriamine as catalyst and N,N-dimethylformamide/tetrahydrofuran as solvent at room temperature. The precursors and the target star polymers were characterized comprehensively by H-1 NMR, GPC, and DSC. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5947-5953, 2009