A versatile method was developed for the chain-end functionalization of the grafted polymer chains for surface modi. cation of nanoparticles with functionalized groups through a combination of surface-initiated atom-transfer radical polymerization (ATRP) and Huisgen [3 + 2] cycloaddition. First, the surface of SiO2 nanoparticles was modified with poly(methyl methacrylate) (PMMA) brushes via the "grafting from'' approach. The terminal bromides of PMMA-grafted SiO2 nanoparticles were then transformed into an azide function by nucleophilic substitution. These azido-terminated PMMA brushes on the nanoparticle surface were reacted with alkyne-terminated functional end group via Huisgen [3 + 2] cycloaddition. FTIR and H-1 NMR spectra indicated quantitative transformation of the chain ends of PMMA brushes onto SiO2 nanoparticles into the desired functional group. And, the dispersibility of the end-functional polymer-grafted SiO2 nanoparticles was investigated with a transmission electron microscope (TEM). (C) 2009 Elsevier B. V. All rights reserved.