Enhanced CO₂ separation performance of mixed-matrix membranes through PIM-1 based surface engineering using non-solvent induced surface deposition

Abstract

Carbon dioxide (CO₂), a major greenhouse gas, significantly contributes to global warming and negatively affects ecosystems. This necessitates the development of high-performance materials for CO₂ removal. Mixed-matrix membranes (MMMs) incorporating metal-organic frameworks (MOFs) are effective for CO₂ separation, but the poor interfacial compatibility between the polymer and filler often reduces membrane performance. In this study, the interfacial issue in MMMs was addressed by surface modification of ZIF-8 with polymers of intrinsic microporosity (PIM-1) using the non-solvent induced surface deposition method. The PIM-1 polymer on the ZIF-8 surface has a high surface area, which prevents pore blockage and overcomes the interfacial issue with the polymer matrix. The effect was studied using Pebax-1657 as a host polymer matrix. At 20 % loading, MMMs with surface-modified ZIF-8@PIM-1 exhibited enhanced CO₂/N₂ and CO₂/CH₄ selectivities, increasing from 44.4 to 15.1 to 45.6 and 18.8, respectively, compared to those of MMMs with unmodified ZIF-8. In addition, the CO₂ permeability increased by about 40 %, from 71 barrer to 105 barrer, compared to that of pure Pebax-1657. This study demonstrates that simple surface modification with PIM-1 can effectively address the interfacial issues between the polymer matrix and MOF in MMMs.