Building interfacial compatible PIM-1-based mixed-matrix membranes with β-ketoenamine-linked COF fillers for effective CO2/N2 separation

Mixed matrix membranes (MMMs) with easy scale-up architectures have shown great potential to achieve superior CO2 permeance, while their performances are often restricted by the poor interfacial compatibility between fillers and the matrix, and also by blocking of the original channel for gas transmission. Here, a rational design and facile construction of highly permeable MMMs is presented by dispersing triphenyltriazine-based β-ketoenamine-linked covalent organic framework (TpTta-COF) within solution-processable polymer of intrinsic microporosity (PIM-1). An intimate mixing was achieved by improved compatibility of the components induced by the hydrogen bond interaction between -N-H in TpTta-COF and CN of PIM-1. The good adhesion avoids the formation of interface defects, preserving the original gas transmission channel. TpTta-COF particles with strong CO2 affinity are evenly distributed in the matrix, forming a fast and continuous channel for CO2 transmission. The physical properties of MMMs were easily tuned, and the as-prepared PIM-1/TpTta–COF–6wt% demonstrates extraordinary stability, high CO2 permeability and CO2/N2 selectivity, surpassing the β-ketoenamine-free MMM counterparts. This study provides a feasibly pathway for the development of efficient and high performances separation membranes.