Unveiling the Potential: Core-Shell Nanoparticles Assembly of Metal-Organic Framework@poly(1,3-dioxolane) Methacrylate for Gutter-Layer-Free Ultrathin Film Composite Membranes

Increasing amounts of carbon dioxide (CO₂) emissions in the atmosphere are a leading cause of climate change. Ultrathin film composite (UTFC) membranes have the potential to effectively reduce CO₂ emissions from energy production and industrial processes. UTFC membranes typically require a gutter layer, to provide flat surfaces above the porous substrate for an ultrathin selective layer to be deposited. Removing the gutter layer, while maintaining compatibility with the support layer, can have substantial benefits of high gas permeation, cost-effectiveness, and fewer manufacturing steps. However, achieving this faces significant challenges, due to limitations on the geometric design of gas pathways and incompatibility between the substrate and selective layers. Herein, zeolitic imidazolate framework-8 (ZIF-8) is used as an initiating core, and arms of poly(1,3-dioxolane) dimethacrylate (PDXLMA), which possesses superior CO₂/N₂ selectivity, are used to create core-shell nanoparticles. These two-layered UTFC membranes are successfully produced from the nanoparticles via a simple drop-spreading method. The importance of designing core-shell structures is also investigated to achieve defect-free two-layered UTFC membranes and enable precision thickness control. The resulting membranes exhibit remarkable CO₂ permeance of 3969 – 6035 GPU with CO₂/N₂ selectivity of 28.0–20.4, demonstrating their considerable performance improvement compared to the current three-layered UTFC membranes.