Self-Assembly of Metal–Organic Framework (MOF) Nanoparticle Monolayers and Free-Standing Multilayers

We report the first self-assembled porous monolayer and free-standing multilayer films composed of metal–organic framework (MOF) nanoparticles. Self-assembled MOF monolayers (SAMMs) were assembled at a liquid–air interface to produce films that are 87 wt % (89 vol %) MOF. Monolayer self-assembly was aided by growing a layer of poly(methyl methacrylate) (PMMA) on the particle surface using a histamine anchor. SAMMs could be stacked to obtain MOF multilayers, including alternating MOF/polymer heterostructures. SAMMs were coated on silicon microparticles, and a MOF film constructed of only five stacked layers could be manipulated as a free-standing, opalescent film. These monolayers are a significant advancement for obtaining highly functional porous membranes and coatings.