Sequential infiltration synthesis (SIS) provides an original strategy to grow inorganic materials by infiltrating gaseous precursors in polymeric films. Combined with microphase-separated nanostructures resulting from block copolymer (BCP) self-assembly, SIS selectively binds the precursors to only one domain, mimicking the morphology of the original BCP template. This methodology represents a smart solution for the fabrication of inorganic nanostructures starting from self-assembled BCP thin films, in view of advanced lithographic application and of functional nanostructure synthesis. The SIS process using trimethylaluminum (TMA) and H2O precursors in self-assembled PS-b-PMMA BCP thin films was established as a model system, where the PMMA phase is selectively infiltrated. However, the temperature range allowed by polymeric material restricts the available precursors to highly reactive reagents, such …