In this study, we prepared organic-inorganic hybrid nanoparticies with a core-shell structure using a surface-initiated polymerization technique. Initiators for the atom transfer radical polymerization were anchored onto the surface of silica nanoparticies, and from there N-isopropylacrylamide and methylene bisacrylamide were polymerized to form cross-linked polymeric shell layers. The thickness of the polymer layers was controlled by varying the reaction time. The thermal phase transition of the surface polymer layer was characterized by dynamic light scattering analysis, which showed reversible swelling/deswelling behavior between $25^{circ}C$ and $40^{circ}C$. Compared to the silica nanoparticies with linear polymer layers, the swelling/deswelling behavior was of a smaller degree, but it consistently exhibited similar size changes after repeated processes. HF etching of the silica nanoparticies with surface cross-linked polymer layers removed the silica core to render a hollow structure.