Molecular Imprinting as a Tool for Exceptionally Selective Gas Separation in Nanoporous Polymers

The alarming rise in atmospheric CO₂ levels, primarily driven by fossil fuel combustion and industrial processes, has become a major contributor to global climate change. Effective CO₂ capture technologies are urgently needed, particularly for the selective removal of CO₂ from industrial gas streams, such as flue gas and biogas, which often contain impurities like N₂ and CH₄. In this study, we report the design and synthesis of novel molecularly imprinted polymers (MIPs) using 4-vinylpyridine (4VP) and methacrylic acid (MAA) as functional monomers, and thiophene (Th) and formaldehyde (HC) as molecular templates. The MIPs were specifically engineered to create selective molecular cavities within a nanoporous polymer matrix for the efficient capture of CO₂. By adjusting the molar ratios of the template to functional monomers, we optimized the molecular imprinting process to enhance CO₂ selectivity over N₂ and CH₄. The resulting MIPs exhibited outstanding performance, with a maximum CO₂/N₂ selectivity of 153 at 25 bar and CO₂/CH₄ selectivity of 25.3 at 1 bar, significantly surpassing previously reported porous polymers and metal-organic frameworks (MOFs) under similar conditions. Furthermore, we conducted heat of adsorption studies, which revealed the strong and selective interaction of CO₂ with the imprinted cavities, confirming the superior adsorption properties of the synthesized MIPs. The study demonstrates that molecular imprinting can effectively enhance both CO₂ capture capacity and selectivity, providing a cost-efficient and scalable solution for industrial CO₂ separation and purification processes.