A combination of ring opening metathesis polymerization (ROMP) and click chemistry approach is first time utilized in the preparation of 3-miktoarm star terpolymer. The bromide end-functionality of monotelechelic poly(N-butyl oxanorbornene imide) (PNBONI-Br) is first transformed to azide and then reacted with polystyrene-b-poly(methyl methacrylate) copolymer with alkyne at the junction point (PS-b-PMMA-alkyne) via click chemistry strategy, producing PS-PMMA-PNBONI 3-miktoarm star terpolymer. PNBONI-Br was prepared by ROMP of N-butyl oxanorbornene imide (NBONI) 1 in the presence of (Z)-but-2-ene-1,4-diyl bis(2-bromopropanoate) 2 as terminating agent. PS-b-PMMA-alkyne copolymer was prepared successively via nitroxide-mediated radical polymerization (NMP) of St and atom transfer radical polymerization (ATRP) of MMA. (C) 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47:497-504, 2009