Nanoparticle Templating of Ultrathin and High Density 6 nm Pore Arrays*

Active layers for next-generation water filtration membranes require large area and uniform arrays of nanometer-sized pores. We demonstrate an alignment-free method to transform freely suspended nanoparticle (NP) monolayer sheets into mechanically robust, high density 6 nm pore arrays using electron beam irradiation and subsequent wet chemical etching. As the secondary electrons responsible for ligand crosslinking originate from the NPs themselves, our substrate-free approach benefits from a variable crosslink density throughout the ~10 nm film thickness. We apply this general strategy to two NP systems—gold NPs with alkanethiol ligands and Fe₃O₄ NPs coated with oleic acid—to fabricate nanostructured polymer films with either thiol or carboxylate pore chemical functionalities.