High-performance ester-crosslinked polymers of intrinsic microporosity membranes with enhanced CO2 selectivity and plasticization resistance

Ester-crosslinking has proven to be an effective strategy for enhancing gas selectivity and CO2-induced plasticization resistance. However, achieving ester-crosslinked membranes that surpass the 2019 CO2/N2 upper bound remains a significant challenge. To address this, we used polymer of intrinsic microporosity (PIM-1) as a precursor, followed by hydrolysis to prepare PIM-COOH. Subsequently, 1,4-butylene glycol was employed as a crosslinker to react with PIM-COOH, forming M-PIM, which is then thermally crosslinked at different conditions. The ester-crosslinked membrane treated at 250 degrees C for 8 h demonstrated a CO2 permeability of 7184 Barrer, with a selectivity of 36.7 for CO2/N2 and 30.4 for CO2/CH4, both surpassing the 2019 upper bounds. Additionally, the ester-crosslinked membrane demonstrated resistance to CO2-induced plasticization even at a test pressure of 35 bar. These results suggest that esterification and crosslinking modification significantly enhance both the gas separation performance and plasticization resistance of PIM-1 membranes. The approach presented in this work provides a promising pathway for designing high-performance membranes that exceed the 2019 CO2 separation upper bounds and improve resistance to CO2 plasticization, with potential applications in natural gas purification and CO2 capture.