Enhanced Performance of Mixed-Matrix Membranes through a Graft Copolymer-Directed Interface and Interaction Tuning Approach

Herein, a high performance mixed-matrix membrane (MMM) is reported with simultaneously large improvements in the CO₂ permeability by 880% from 70.2 to 687.7 Barrer (1 Barrer=1×10^-10 cm³ cm cm^-2 s^-1 cmHg^-1) and CO₂/N₂ selectivity by 14.4% from 30.5 to 34.9. These findings represent one of the most dramatic improvements ever reported for MMMs. These improvements are obtained through an interface and interaction tuning approach based on an amphiphilic grafted copolymer. Poly(vinyl chloride)-g-poly(oxyethylene methacrylate) (PVC-g-POEM) graft copolymer plays a key role as a soft organic matrix to provide good permeation properties, uniform distribution of zeolite imidazole frameworks-8 (ZIF-8), and better interfacial contact with inorganic compounds. In particular, the CO₂/C₃H₈ and CO₂/C₃H₆ selectivities reached 10.5 and 42.7, respectively, for PVC-g-POEM/ZIF (40 %) MMMs; this indicates that it could be a promising membrane material for the purification of C₃ hydrocarbons.