Poly(2-(dimethylamino)ethyl methacrylate)-b-poly(gamma-methacryloxypropyl-trimethoxysilane) (PDMA-b-PMPS) was synthesized via consecutive reversible addition-fragmentation chain transfer (RAFT) polymerizations in 1,4-dioxane. Subsequent micellization of the obtained amphiphilic diblock polymer in aqueous solution led to the formation of nanoparticles consisting of hydrophobic PMPS cores and well-solvated PDMA shells. Containing tertiary amine residues, PDMA blocks in micelle coronas can spontaneously catalyze the sol-gel reactions of trimethoxysilyl groups within PMPS cores, leading to the formation of hybrid nanoparticles coated with PDMA brushes. Transmission electron microscopy (TEM) and laser light scattering (LLS) revealed the presence of monodisperse spherical hybrid nanoparticles, and the grafting density of PDMA chains at the surface of nanoparticle cores was estimated to be similar to 5.8 nm(2)/chain. PDMA brushes exhibit dual stimuli-responsiveness, and the swelling/collapse of them can be finely tuned with solution pH and temperatures. The obtained multi-responsive hybrid nanoparticles might find potential applications in fields such as smart devices, recyclable catalysts, and intelligent nanocarriers for drug delivery or gene transfection. (C) 2008 Wiley Periodicals, Inc.