A hierarchically structured platform was obtained from directed self-assembly of a poly(styrene)-b-poly(4-vinylbenzylchloride) (PS-b-PVBC) block copolymer (BCP) during breath figure (BF) templating. The BF process using a water/ethanol atmosphere gave a unique double porosity in which hexagonally arranged micron-sized pores were encircled by a secondary population of smaller, nano-sized pores. A third level of structuration was simultaneously introduced between the pores by BCP self-assembly to form out-of-the-plane nano-cylinders, offering a film with an unprecedented triple structure, which could be used as a reactive platform. Indeed the surface nano-domains of VBC were exploited as reactive nano-patterns for site-specific chemical functionalization.