Interfacial void induced low selectivity is a critical drawback for mixed matrix membranes (MMMs) applied to gas separation. In this study, post-synthetic functionalization of fabricated MMMs by TAEA vapor-induced covalently interconnecting polymeric networks (CIPNs) technology has been employed to molecularly tune the 6FDA-Durene-ZIF-71 MMMs from CO2-selective into H2-selective via enhancement of the molecular-sieving properties. The new selective layer comprise of polyamide-based matrix and ZIF-71, interfacial void was refilled by vaporous TAEA treatment.
Both X-ray Photoelectron Spectroscopy (XPS) and Doppler Broadening Energy Spectroscopy (DBES) results reveal that non-selective interfacial voids between particle-particle and particle-polymer have been mitigated by construction of vapor-induced based CIPNs inside the ZIF-71 based MMMs. TGA-IR demonstrated the high thermal stability of resultant membranes and the feasibility of applying the fabricated membranes in a high temperature H2/CO2 separation application. Embedding 10 wt% of ZIF-71 nano-particles with size of less than 100 nm inside the TAEA-treated 6FDA-Durene membrane further enhances the pure H2 permeability by 80% (from 300 Barrer to 540 Barrer) and the ideal H2/CO2 selectivity by 34% (from 46.8 to 62.5). The newly developed technology of tripodal amine-based vapor induced CIPNs may solve the most challenging issue in MMMs fabrication and may molecularly tune the MMMs to fit in a specific industrial gas separation application.
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