Thin films of block copolymers have been used as templated and scaffolds for the fabrication of arrays of nanostructured materials. In general, a chemical modification of the film or the removal of one of the components by photodegradative methods to required to produce a nanoporous film that serves as a template or scaffold. Here, however, the preferential interaction of one of the components with a solvent is shown to produce a reconstruction of the block copolymer film that, upon drying leads to the generation of a nanoporous template. The area density of the pores is identical to that of the original copolymer thin film. Since no chemical reactions occur, the process is fully reversible. Upon heating the copolymer film above its glass transition temperatures, mobility is imparted to the copolymer and the original copolymer film with orientated domains is recovered. The film reconstruction significantly simplifies the generation of nanoporous templates.