Flux melting of UiO-67 family metal-organic frameworks: the thin film processing and nanofiltration property

Metal-Organic Frameworks (MOFs) have been demonstrated to be the perfect candidates of function materials for special specie separation. Although numerous MOFs, nearly 100,000 unique ones, have been explored, only several MOF-based membranes are reported because their lack of processability and grain boundary effects seriously limit their fabrication into thin film. This work discusses a strategy of flux melting, ‘borrowed from inorganic domain’, to prepare a MOF thin film via a simple heat-pressing process by using one meltable MOF and a non-meltable MOF. We observed the flux melting of the non-meltable Zr-MOFs and its meltable derivative modified by the binary ionic liquids, the proportion effect of each part on the melting, processability and film nanofiltration for dye molecules. The melt-quenched glass thin film possesses the network inherited from the pristine MOF via the melt, linker exchange and vitrification mechanism. The interesting pore recovery of MOF upon a solvent stimulation endows the film with pore size control (∼1.2 nm) on the dye molecule separation. A 99.88% rejection rate and a permeability of 27.7 L/m 2 ·h·bar for Congo red dye solution is observed, which is much better than that of analogous MOF membranes generally obtained through complicate processes.