Poly(styrene-b-4-vinylpyridine) (PS-b-P4VP) nanostructures with multiple morphologies were fabricated by immersing PS-b-P4VP nanotubes in ethylene glycol, a nonsolvent for PS and a good solvent for P4VP, at different temperatures. Mesoporous structures were generated from uniform nanoscopic wormlike micelles due to a solvent-induced reconstruction when the spherical micellar structures were heated above the glass transition temperature of the PS block. The mesoporous nanostructures can be converted into inorganic oxide structures, like SiO(2) and TiO(2), by well-known sol-gel methods. The mesoporous inorganic oxides can be produced with tunable porosity by controlling the molecular weight of the block copolymers. Confinement also plays an important role to create the nanostructures with unusual morphologies.