Preparation and Gas Separation Properties of Triptycene-Based Microporous Polyimide

摘要

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 costefficient 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.