Polymer-blend thin-film composite membranes with semi-IPN architecture for enhanced CO2 separation and mechanical robustness

Scalable thin-film composite (TFC) membranes with high CO₂ separation performance and robust mechanical durability are essential for industrial carbon capture. In this study, we present the design and fabrication of fully polymeric, high-performance TFC membranes based on a semi-interpenetrating polymer network (semi-IPN) architecture. A self-crosslinkable, comb-shaped copolymer—poly(glycidyl methacrylate-g-polypropylene glycol)-co-poly(oxyethylene methacrylate) (PGP-POEM)—was synthesized as a CO₂-selective matrix. To mitigate tackiness and improve mechanical strength, a small amount of commercial Polyactive was blended, forming a miscible semi-IPN with strong compatibility and synergistic interactions. Molecular dynamics (MD) simulations were employed to analyze free volume, thermodynamic miscibility, CO₂ affinity, diffusivity, and solubility. The optimized membrane containing 25 wt% Polyactive exhibited a CO₂ permeance of 1482 GPU and a CO₂/N₂ selectivity of 36.3, meeting benchmarks for post-combustion capture. Additionally, the membranes demonstrated excellent mechanical properties, with a tensile modulus of 1.15 MPa and an elongation at break of 161 %, while maintaining a non-tacky surface. These results highlight the potential of the semi-IPN approach as a scalable and cost-effective strategy for advanced gas separation membranes.