Functional Polymer Catalysts for CO2 Capture and Conversion: Design Principles, Applications, and Future Perspectives

Functional polymer catalysts have emerged as a transformative class of materials for CO2 capture and conversion, offering exceptional tunability, high CO2 affinity, and excellent recyclability. This review provides a comprehensive polymer-centric analysis of four major classes of functional polymer catalysts—linear and soluble polymers, crosslinked networks and resins, porous organic polymers (POPs), and polymer–metal hybrids—with a unified focus on their roles in CO2 capture, CO2 cycloaddition to epoxides, CO2 hydrogenation, and integrated carbon capture and utilization (CCU) strategies. We discuss how the polymer backbone chemistry, active site density, microenvironmental effects, hydrophilic–hydrophobic balance, and pore confinement collectively govern the CO2 uptake capacity, activation, conversion, and selectivity of these materials. The stability, recyclability, and green metrics of the polymer catalysts were critically assessed, and their performance was benchmarked against that of inorganic supports, metal–organic frameworks (MOFs), and covalent-organic frameworks (COFs). Current challenges, including structure–activity gaps, operando characterization, standardized performance reporting, processability, and scale-up, are also discussed.