Tailoring polyamideimide and polyetherimide membrane characteristics by experimental and mesoscale model approach for selective gas separation

Conventional gas separation techniques require substantial energy due to the complex molecular interactions involved. Polymer-derived carbon membranes stand out for their tunable pore structures and selective molecular sieving capabilities. This study investigates PAI/PEI-based membranes for gas separation, employing the Flory-Huggins model to analyze pore formation. PAI/PEI solutions were systematically varied from 0 to 100 wt.% to determine the optimal blend ratio. Subsequently, the pyrolysis behavior of these membranes was examined, with thermodynamic parameters χ = 2 and Np = 69, to target specific structures. Elemental analysis confirmed the presence of carbon, hydrogen, and nitrogen, which plays a crucial role in controlling membrane swelling and hydrophilicity. Contact angle measurements revealed a hydrophobic character, with a value of 75° for the carbon membrane pyrolyzed at 800°C. Notably, the 25/75 wt.% PAI/PEI blend, subjected to pyrolysis at 800°C, exhibited an asymmetric structure with a pore size of 3.7 Å, facilitating efficient gas permeation. This optimized membrane demonstrated promising performance for gas purification, further validated through mesoscale modeling. Additionally, this study explored the impact of pyrolysis parameters such as temperature, ramp rate, and blend concentration on the resulting membrane characteristics with modeling improving pore efficiency and saving resources. The top-surface morphology of the carbon membranes displayed a well-defined honeycomb structure with abundant pores, outperforming other blends and meeting industrial gas separation requirements through a strategically modeled membrane design. These findings provide a foundation for the scalable production of high-performance carbon membranes tailored for specific gas separation applications. The integration of experimental and modeling approaches offers a predictive framework for designing next-generation membrane systems.