For the preparation of core-shell nanoparticles containing functional nanomaterials, a photo-cross-linkable amphiphilic ABC triblock copolymer, poly(ethylene glycol)-b-poly(2-cinnamoyloxyethyl methacrylate)-b-poly(methyl methacrylate) (PEG-PCEMA-PMMA), was synthesized. This triblock copolymer was then used to encapsulate Au nanoparticles or pyrene. The triblock copolymer of PEG-b-poly(2-hydroxyethyl methacrylate)-b-PMMA (PEG-PHEMA-PMMA) (M-n = 15,800 g/mol, M-w/M-n = 1.58) was first synthesized by activators generated by electron transfer atom transfer radical polymerization. Its middle block was then functionalized with cinnamoyl chloride. The degrees of polymerization of the PEG, PHEMA, and PMMA blocks were 45, 13, and 98, respectively. PMMA-tethered Au nanoparticles (with an average diameter of 3.0 nm) or pyrene was successfully encapsulated within the PEG-PCEMA-PMMA micelles. The intermediary layers of the micelles were then cross-linked by UV irradiation. The spherical structures of the PEG-PCEMA-PMMA micelles containing Au nanoparticles or pyrene were not changed by the photo-cross-linking process and they showed excellent colloidal stability. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4963-4970, 2009