New hybrid poly(hydroxyethyl methacrylate-co-methyl methacrylate)-g-polyhedral oligosilsesquioxane [poly(HEMA-co-MMA)-g-POSS] nanocomposites were synthesized by the combination of reversible addition fragmentation chain transfer (RAFT) polymerization and click chemistry using a grafting to protocol. Initially, the random copolymer poly(HEMA-co-MMA) was prepared by RAFT polymerization of HEMA and MMA. Alkynyl side groups were introduced onto the polymeric backbones by esterification reaction between 4-pentynoic acid and the hydroxyl groups on poly(HEMA-co-MMA). Azide-substituted POSS (POSS-N-3) was prepared by the reaction of chloropropyl-heptaisobutyl-substituted POSS with NaN3. The click reaction of poly(HEMA-co-MMA)-alkyne and POSS-N-3 using CuBr/PMDEATA as a catalyst afforded poly(HEMA-co-MMA)-g-POSS. The structure of the organic/inorganic hybrid material was investigated by Fourier transformed infrared, H-1-NMR, and Si-29-NMR. The elemental mapping analysis of the hybrid using X-ray photoelectron spectroscopy and EDX also suggest the formation of poly(HEMA-co-MMA)-anchored POSS nanocomposites. The XRD spectrum of the nanocomposites gives evidence that the incorporation of POSS moiety leads to a hybrid physical structure. The morphological feature of the hybrid nanocomposites as captured by field emission scanning electron microscopy and transmission electron microscopic analyses indicate that a thick layer of polymer brushes was immobilized on the POSS cubic nanostructures. The gel permeation chromatography analysis of poly(HEMA-co-MMA) and poly(HEMA-co-MMA)-g-POSS further suggests the preparation of nanocomposites by the combination of RAFT and click chemistry. The thermogravimetric analysis revealed that the thermal property of the poly(HEMA-co-MMA) copolymer was significantly improved by the inclusion of POSS in the copolymer matrix. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 127: 1569-1577, 2013