Interfacially engineered MOC-1@HOF-based mixed matrix membranes toward efficient CO2 separation in hyperpermeable polymer

Hybridization of porous fillers has emerged as an effective strategy for improving the structural and transport properties of mixed matrix membranes (MMMs). In this study, a novel metal-organic cage/hydrogen-bonded organic framework composite (MOC-1@HOF) was synthesized via an in-situ functionalization method and incorporated into a Poly(4-methyl-1-pentene) (PMP) matrix to fabricate advanced MMMs for CO 2 separation. The membranes were characterized using FTIR, XRD, FESEM, EDX, TGA, and DSC analyses to evaluate their chemical structure, morphology, and thermal behavior. The results confirmed good interfacial compatibility and uniform dispersion of the MOC-1@HOF filler within the PMP matrix. Incorporation of the filler improved membrane crystallinity and thermal stability, while the glass transition temperature increased with filler loading, indicating restricted polymer chain mobility due to enhanced polymer-filler interactions. Gas permeation measurements demonstrated a significant enhancement in separation performance at the optimal loading of 20 wt.% MOC-1@HOF. Under 30 °C and 10 bar, CO 2 permeability increased from 143.7 Barrer for pure PMP to 370.6 Barrer, corresponding to a 158% improvement. In addition, the CO 2 /N 2 and CO 2 /CH 4 selectivities increased by 134% and 116%, respectively, compared with the pure PMP membrane. Long-term stability tests showed that approximately 85% of the initial CO 2 permeability was retained after 30 days, confirming good membrane durability. Overall, the results demonstrate the strong potential of MOC-based hybrid fillers for tuning membrane microstructure and enhancing CO 2 separation performance.