Preparation and Gas Separation Properties of Triptycene‐Based Microporous Polyimide

Abstract Polyimides with intrinsic microporosity (PIM‐PIs) are widely regarded as one of the most promising next‐generation membrane materials to simultaneously achieve high permeability and selectivity. Despite the fact that tremendous microporous polyimides have been synthesized, only cost‐efficient PIM‐PIs have the potential to be used in industrial applications. In this work, a PIM‐PI is prepared by using the commercial and inexpensive planar pyromellitic dianhydride (PMDA) as the dianhydride monomer, and 2,6‐diaminotriptycene as the diamine monomer. The CO 2 permeability of PMDA‐DAT is ≈23‐fold higher than that of Kapton, one of the commercially available polyimide membranes also made from PMDA, and with almost the same CO 2 /CH 4 selectivity. In addition, no plasticization phenomenon is observed for PMDA‐DAT membrane even at a CO 2 pressure up to 15 atm. The good plasticization resistance performance of PMDA‐DAT can be mainly attributed to the formation of pseudo‐physical crosslinking by interlocking and π–π interactions in triptycene moieties.