Ester-crosslinked polymers of intrinsic microporosity membranes with enhanced plasticization resistance for CO2 separation

Polymers of intrinsic microporosity (PIMs) have seen a growing role in gas separation membranes. Further exploitation of gas separation performance of PIM membranes and overcoming their persistent challenge of plasticization are urgently demanded. To address these issues, exemplified PIM-1 is synthesized and hydrolyzed to form carboxylated PIM-COOH polymers, followed by esterification using propylene glycol to prepare monoesterified PIM, which is finally thermally ester-crosslinked at various temperatures and time. The 300 °C-8 h treated membranes exhibit a CO2 permeability of 7421 Barrer, with a CO2/CH4 and CO2/N2 selectivity of 11.5 and 19.2, respectively, considerably exceeding the 2008 Robeson upper bounds. Furthermore, the crosslinked membranes demonstrate significantly enhanced CO2 plasticization resistance up to 42 bar, compared with uncrosslinked ones. It is the first time of reporting ester-crosslinking of carboxylated PIM-1 with both higher gas permeability and selectivity than PIM-1, using a much milder crosslinking temperature than other techniques, such as decarboxylated crosslinking. The design principle of this work paves the way for preparing high-performance and plasticization-resistant PIM membranes with promises for energy-efficient gas separations.