Construction of Vapor-Induced Covalently Interconnecting Polymeric Network (CIPN): A Potential Method to Mitigate Non-Selective Interfacial Voids in Mixed Matrix Membranes with Enhanced Molecular-Sieving Properties

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.