Building ternary mixed matrix membranes with ionic liquid-functional COF fillers for efficient CO2 separation

Developing novel mixed matrix membranes (MMMs) with high CO2 permeability and selectivity, while overcoming the limitations of traditional MMMs, presents a significant challenge. Herein, we reported a simple and straightforward method to develop ternary mixed matrix membranes (TMMMs) featuring excellent matrix-filler compatibility for CO2 separation through the modification of the covalent organic framework (COF) using ionic liquid (IL) additives. A novel IL ([Bmim][Tf2N]) encapsulated COF filler (IL@TpTta-COF) was facilely prepared, and incorporated into the PIM-1 matrix to develop a series of TMMMs.The incorporation of ILs with high affinity towards CO2 within the TpTta-COF improves the molecular sieving effect of the functional filler, and helps to enhance polymer-filler interfacial compatibility, and mitigates particle agglomeration during the preparation of TMMMs. Notably, the resultant TMMMs demonstrate remarkable stability, and achieve an impressive CO2 permeability of 10,035 Barrer and an excellent selectivity of 30.2 for CO2/N2 mixtures, exceeding the Robeson upper bound in 2019. This research underscores the potential of integrating functional additives to produce novel COF-based MMMs with enhanced CO2 separation efficiency for industrial applications.