Homoporous hybrid membranes containing metal-organic cages for gas separation

Abstract Hybridization of porous fillers and polymers is an effective strategy for fabricating composite membranes, affording synergic properties contributed by every single component. However, it has high requirements on the dispersivity of porous fillers and compatibility between porous fillers and the polymeric matrix. Herein, we report the fabrication of homoporous hybrid membranes (HHMs) by chemically cross-linking polymerizable metal-organic cages (MOCs) with polymeric precursors via UV-induced polymerization. The polymerizable MOC molecules, synthesized by heterogeneous postassembly modification, are soluble in polymeric precursors and can be cross-linked with in-situ formed polymeric matrix at a molecular-level dispersivity. The cross-linking between MOCs and polymeric matrix can improve the interfacial compatibility and enhance the thermal stability of the membranes. Compared with the pristine polymeric membrane, the HHM with 1 wt% of MOC loading shows an enhanced CO2 permeability (338 Barrer) and a comparable CO2/CH4 selectivity (16.7) due to the increased CO2 solubility and diffusivity with the addition of MOCs. This strategy inspires the design of hybrid membranes with uniform yet tunable pore sizes for efficient molecular separations.