Engineering the ultrathin polyamide nanofilm featuring high free volume via interfacial polymerization for efficient CO2 capture

Interfacial polymerization (IP) has been received as an indispensable technology to fabricate thin-film composite (TFC) membranes for gas separation because of the simple and designable process. However, achieving the highly permeable polyamide (PA) TFC membrane for CO₂ capture via the IP technique remains challenging. Herein, a highly CO₂-permeable PA TFC membrane was synthesized by the polycondensation of N, N-Bis [3-(methylamino) propyl]methylamine (BMAPAm) and trimesoyl chloride (TMC). The ultrathin (∼47 nm) PA TFC membrane featuring with high free volume exhibited excellent CO₂ permeance with moderate CO₂/N₂ selectivity. The causes of this desired structure were systematically investigated from the aspects of monomer supply and molecular structure, in which the 3,3′-diamino-N-methyldipropylamine (DNMDAm) was used as a comparison. The results illustrated the underlying monomer-structure-performance relationships of IP-made membranes, demonstrating the solid potential of the IP technology specifically toward high-performance CO₂ capture membranes. Finally, a pilot-scale continuous membrane fabrication process was demonstrated.