A novel approach to synthesizing Trimesoylchloride-branched 6FDA-based polyimide membranes with superior stability for high-performance gas separation

Hyperbranched polyimide (HBPI) membranes have emerged as promising materials for gas separation due to their loose interchain structure and large free volume. However, their widespread application is hindered by challenges such as complex synthesis procedures, high-cost monomers, and poor resistance to plasticization. In this study, a series of Trimesoylchloride (TMC)-branched 6FDA-based PI membranes were successfully synthesized using different contents of TMC as a branching agent to regulate the pore distribution. The molecular structure and degree of branching (DB) of HBPI were characterized using FTIR and 1 H NMR. The incorporation of TMC into the HBPI structure effectively enhanced the permeability and selectivity of the acyl chloride-branched PI membranes while improving thermal stability. The optimized membrane (A5-TMC content is 5%), exhibits the improving O 2 and CO 2 permeabilities of 176.52 and 930.94 Barrer combined with the O 2 /N 2 , CO 2 /N 2 and CO 2 /CH 4 selectivities of 4.68, 24.65 and 23.85, respectively. Particularly, the A5 HBPI membrane, with a DB value of 85.71%, demonstrated superior anti-aging properties compared to linear 6FDA-DAM membrane over 365 days. Most importantly, the 6FDA-DAM-TMC HBPI membranes significantly enhanced the resistance to plasticization at elevated CO 2 feed pressures, maintaining stability up to 300 psi and significantly outperforming the linear 6FDA-DAM membrane. This study provides an effective method for the fabrication of high-performance gas-separated polymer membranes with enhanced plasticization resistance and long-term durability for advanced gas separation applications.