Thirty-minute preparation of microporous polyimides with large surface areas for ammonia adsorption

Toxic solvents and catalysts, tedious monomer synthesis, and long reaction time significantly limit the sustainable and large-scale preparation and practical application of microporous polyimides (MPIs). In this work, three kinds of MPIs were successfully prepared through thermal polycondensation in the diphenyl sulfone (DPS) solvent using 1,4,5,8-naphthalenetetracarboxylic dianhydride and triamines as building blocks. The polymerization can be completed in 30 min, and the resultant MPIs exhibit large surface areas up to 1825 m2 g−1. Owing to their abundant microporous structures and plenty of imide rings, MPIs demonstrate excellent ammonia adsorption performance (21.10 wt%, at 303 K and 1.0 bar) and favorable regeneration ability. DPS as a non-volatile solvent can be recovered and recycled three times. In comparison with previous reports, this strategy is more time efficient, environmentally friendly and potentially scalable.