Boosting CO2/N2 separation in PIM-1/CSU-1 mixed matrix membranes by interfacial H-bonding and CO2-philic fillers

Polymers of intrinsic microporosity (PIM) have attracted considerable attention in the development of mixed matrix membranes (MMMs) for CO 2 separation. A prominent challenge lies in engineering the spacing of the polymer matrix chains while eliminating non-selective interfacial defects. In this study, a CO 2 -philic triazine-based porous polymer, featuring robust hydrogen bond donating groups, was employed to fabricate a series of interfacial defect-free PIM-1 based MMMs (denoted as PIM-1/CSU-1). The interfacial adhesion and compatibility have been greatly improved due to the strengthened hydrogen bond interaction, which was systematically validated through variable-temperature infrared spectroscopy. Additionally, the formation of hydrogen bonds allowed for the regulation of the polymer matrix chain spacing, making the chain distance loose. Remarkably, the resulting membrane exhibited a CO 2 permeability of 13,429 Barrer and CO 2 /N 2 selectivity of 33.1—246.6% and 70.2% higher than pristine PIM-1, respectively, surpassing the latest Jansen/McKeown upper bound established in 2019, but also significantly exceed the performance of previously reported MMMs for CO 2 separation. The strategy of mitigating interfacial defects through the formation of hydrogen bonds between fillers and the polymer matrix emerges as a viable and effective method for fabricating gas separation membranes with exceptional separation capabilities.