Angew. Chem. Int. Ed. http://doi.org/f26btc (2015)

The processing of metal–organic framework (MOF) powders into specific macroscopic shapes can be achieved by applying mechanical pressure, by using extrusion methods or by the inclusion of additives and binders. Now, Xiao Feng, Bo Wang and colleagues report the formation of elastic, stand-alone membranes of MOF crystalline powders in which polymeric chains covalently join the crystals together. Nanoscale crystals of a MOF — UiO-66-NH2 — are modified with methacrylamide groups, and then mixed with the monomer butyl methacrylate and a photoinitiator to form a suspension that is dropped into a Teflon mould. Irradiation of the mixture with ultraviolet light induces polymerization resulting in a MOF–polymer hybrid membrane, which is flexible and can be easily peeled away from the mould. The mild conditions of the photopolymerization step allow the MOF nanoparticles to retain their crystallinity producing homogeneous, crack-free membranes that have good abilities to separate heavy-metal ions, such as CrVI, from water. This method could be used for a range of MOF crystals and to prepare many differently shaped hybrid materials.