Gas separation polymer membranes play a pivotal role in various industrial processes including carbon capture and hydrogen production. However, the inherent trade-off between permeability and selectivity coupled with challenges in membrane manufacturing has hindered their widespread industrial deployment. To address the permselectivity challenges, researchers have explored increasingly complex polymers, composite systems, and other materials. In this study, we introduce a novel membrane manufacturing technique called "electro-casting" that not only enables efficient membrane fabrication but also enhances the trade-off of traditional polymer-based membranes. We fabricated cellulose acetate (CA) membranes embedded with 1-ethyl-3-methyl imidazolium via electro-casting and performed a comparative analysis of structural, morphological, and gas transport characteristics against membranes made via conventional casting techniques. We discovered that electro-casted membranes exhibited a unique crystalline structure, surface topology that induced a remarkable 200% improvement in CO2/N2 selectivity and a 110% increase in CO2/CH4 selectivity. The electric field generated during the manufacturing process played a crucial role in altering the supramolecular structure of the polymer, thereby increasing the separation properties of the membranes as well as their thermal and mechanical features. Electro-casting induced a polymer crystallization effect that disrupted the permeability-selectivity trade-off observed in conventional membranes, while producing highly stable membranes. Moreover, the simplicity of this manufacturing method and its significant impact on membrane properties have the potential to accelerate the deployment of gas separation membranes, facilitating the transition toward a NetZero chemical industry.
Keywords: carbon capture; composite membrane; electric field crystallization; electro-casting; gas separation membranes; ionic liquids.