The film specimens having the double gyroid network structure with la (3) over bard space group symmetry were prepared by solution casting of poly(2-vinylpyridine)-block-polyisoprene mixed with a small but varying amounts of polyisoprene with chloroform as a solvent. The network phase composed of poly(2-vinylpyridine) was first crosslinked with 1,4-diiodobutane and then the matrix phase composed of polyisoprene was degraded by ozonolysis to obtain "free-standing" double gyroid network texture in which the two sets of networks are interlaced without contacts with one another in vacant space via their grain boundary connections. The network structures before and after ozonolysis were investigated, respectively, by transmission electron microscopy and field-emission scanning electron microscopy with the aid of numerically calculated three-dimensional computer graphics (3d CG) of the structure. The results clarified a success of the nano-fabrication on the free-standing double gyroid structure. We propose that the 3d CG-SEM, as discussed in the text, on the morphology of the freeze-fractured surface is particularly useful for the identification of the structure. (c) 2006 Elsevier Ltd. All rights reserved.