A Rigid and Planar Aza-Based Ternary Anhydride for the Preparation of Cross-Linked Polyimide Membrane Displaying High CO/CH Separation Performance.

In this study, based on the preparation of hexaazatriphenylene-ternary-anhydride (HAT-T), polyimide membranes were prepared by reaction of 4,4'-(hexafluoroisopropylidene)diphthalic anhydride (6FDA), 4,4'-diaminodiphenyl sulfide (SDA), 2,2'-bis (trifluoromethyl)diaminobiphenyl (TFDB) and 5-amino-2-(4-aminophenyl) benzimidazole (PABZ). Polyimide films with a hexazobenzo structure have good film-forming properties, high molecular weight ( = 0.79-11.79 × 10, = 1.03-16.60 × 10) and narrow molecular weight distribution (polymer dispersity index = 1.17-1.54). With the introduction of rigid HAT-T, the tensile strength and elongation at break of polyimide films are 195.63-510.37 MPa and 4.00-9.70%, respectively, with excellent mechanical properties. The gas separation performance test shows that hexaazatriphenylene-containing polyimide films have good gas selectivity for CO/CH. In particular, the separation performance of PIc-t (6FDA/PABZ/HAT-T) surpasses the "2008 Robeson Upper Bound". The selectivity of 188.43 for CO/CH gas reveals its potential value in the separation and purification of methane gas.