Synthesis of Hollow Metal Oxide Nanospheres by Templating Polymeric Micelles with Core―Shell―Corona Architecture

Hollow metal oxide nanospheres, such as niobium pentoxide, cerium oxide, and vanadia, have been successfully synthesized, for the first time, by templating a polymeric micelle of poly-(styrene-b-2-vinyl-1-methylpyridinium iodide-b-ethylene oxide) (PS-PVMP-PEO). PS-PVMP-PEO forms a micelle with a PS core, a PVMP shell, and a PEO corona in aqueous solutions. The significance of the present method is that each block of the copolymer has its unique function in the synthesis of hollow metal oxide nanospheres; the PS core plays the role of a template of the cavity, while the cationic PVMP shell works as a reservoir and nanoreactor for the precursors of the metal oxides and the PEO corona stabilizes the polymer/inorganic hybrid to prevent secondary aggregate formation.