Covalent-Linking Enabled Superior Compatibility of ZIF-8 Hybrid Membrane for Efficient Propylene Separation.

The interface is a critical issue for metal organic frameworks hybrid membranes in propylene separation. Here, the covalent-linking strategy is reported for strikingly reinforcing the interfacial compatibility in a ZIF-8 based membrane. A functionalized ZIF-8 material named as ZIF-8-CN is firstly synthesized using the mixed-ligand approach. ZIF-8-CN owns identical crystalline structure to ZIF-8 and 4,5-dicyanoimidazole ligand available for further functionalization. Covalent linkage of ZIF-8-CN with PIM-1 is driven by thermal reaction of cyano groups on both entities, which strengthens the filler-polymer connection in the ZIF-8-CN@tPIM-1 membrane. ZIF-8-CN@tPIM-1 exhibits remarkably enhanced propylene permeation property with C3 H6 /C3 H8 selectivity of ∼28, which is 350% and 180% higher than those on non-treated ZIF-8-CN/PIM-1 and non-functionalized ZIF-8@tPIM-1, respectively. Additionally, ZIF-8-CN@tPIM-1 shows the highest C3 H6 permeability of ∼370 Barrer among all relevant ZIF-8 membranes. This strategy opens an avenue for precise interface engineering in membranes and resultant high performance is appealing in propylene separation industry. This article is protected by copyright. All rights reserved.