Hydrogen bonding-induced 6FDA-DABA/TB polymer blends for high performance gas separation membranes

To promote polyimide gas transport properties, we propose a facile technique through adjustable hydrogen bonding energy through blending polyimide (6FDA-DABA) containing –COOH groups and Tröger's base (TB) polymer without damaging polymer chemical structures. The hydrogen bonding strength between –OH groups in PI and the N atoms in TB (O–H⋯N) is well tailored via controlled thermal treatment which has been confirmed by molecular simulations. Hydrogen bonding amounts and strength reach maximum within membranes annealed at 120 °C for 16 h, and exhibit CO2/CH4 and H2/CH4 selectivities of 115.0 and 481.8 respectively, surpassing the 2008 upper bound. Contributed by the enhanced hydrogen bonding strength, the membranes annealed at 120 °C for 16 h display excellent CO2 plasticization resistance and physical aging in comparison with pristine PI and TB membranes. Such a approach potentially renders a synthetic membrane applicable for CO2 separation and hydrogen purification at high temperatures.