Tröger’s Base Polyimide Hybrid Membranes by Incorporating UiO-66-NH2 Nanoparticles for Gas Separation

Hybrid membranes based on the Tröger's base polyimide (PI-TB) as a rigid microporous polymer matrix containing a kinked N-heterocycle and a kind of CO2-philic porous UiO-66-NH2 nano-filler were successfully fabricated for gas separation. This new hybrid membrane exhibits good interfacial compatibility through hydrogen bonds and charge transfer interactions between the PI-TB matrix and the UiO-66-NH2 nano-filler, thus enabling a relatively high loading and well dispersion of nano-filler. Meanwhile, the as-synthesized UiO-66-NH2 nanoparticles increase the average inter-chain spacing distance of PI-TB by interfering with the packing of polymer chains and thus providing additional transport pathways in the membranes. The pure gas permeabilities and ideal selectivities for CO2/CH4, CO2/N2, and O2/N2 systems were investigated at 35 °C and a feed pressure of 1 bar. Among them, the hybrid membrane containing 30 wt % UiO-66-NH2 exhibits the optimal gas separation performance with enhanced permeabilities of CO2 and O2 increased by ∼166% (415 and 92.3 Barrer, respectively) while maintaining comparable CO2/CH4, CO2/N2, and O2/N2 gas pair selectivities (25.0, 18.9, and 4.2, respectively) with the pristine PI-TB membrane. This work enriched the studies on the post-modification of PI-TB as a potential candidate membrane material for gas separation.