Tro?ger?s base-derived dianhydride as a promising contorted building block for polyimide-based membranes for gas separation

Tro center dot ger's base-derived dianhydride (TBDA) was prepared and used to synthesize two solution-processable pol-yimides using 2,3,5,6-tetramethyl-p-phenylenediamine (TMPD) and 1,7-diamino-6H,12H-5,11-methanodibenzo [1,5]diazocine-2,8-diol (HTB). The polyimides TBDA-TMPD and TBDA-HTB demonstrated excellent thermal stability with Td,5% exceeding 400 degrees C, and high gas separation performance. A freshly made TBDA-TMPD membrane displayed CO2 permeability of 1457 barrer and CO2/CH4 selectivity of 17. Physical aging over 50 days of TBDA-HTB membrane revealed CO2 permeability of 61 barrer and CO2/CH4 selectivity of 54. Aged TBDA-HTB exhibited notable performance that crossed 2008 upper bound for H2/CH4 separation with H2 permeability of 147 barrer and H2/CH4 selectivity of 129. Developing contorted dianhydride provides new scope for designing high-performance polyimide-bearing nitrogen groups in its backbone for different separation applications.

Automated summary

In this study, two solution-processable polyimides were successfully synthesized, displaying excellent thermal stability and gas separation performance. The TBDA-TMPD membrane showed a CO2 permeability of 1457 barrer and a CO2/CH4 selectivity of 17, while the TBDA-HTB membrane showed a CO2 permeability of 61 barrer and a CO2/CH4 selectivity of 54. The aged TBDA-HTB membrane exhibited outstanding performance, surpassing the 2008 upper bound for H2/CH4 separation with an H2 permeability of 147 barrer and an H2/CH4 selectivity of 129. These findings provide new possibilities for designing high-performance polyimides with nitrogen groups for various separation applications.