Rapid Sintering of Porous Organic Polymer Powders Into Mechanically Strong Monoliths for Efficient CO 2 Capture

Abstract Porous organic polymers (POPs) with high surface areas and tunable pore sizes show great potential for carbon capture, catalysis, and separation applications. However, their insolubility and infusibility pose challenges for processing them into functional shapes. This study reports the use of spark plasma sintering (SPS) to process cost‐effective imine/aminal‐linked POPs from fine powders into mechanically robust monoliths. SPS enables rapid and efficient sintering within minutes. The resulting POP monoliths exhibit high mechanical stability, with ultimate strength and Young's modulus of up to 85.12 and 378.35 MPa, respectively. Spectroscopic and microscopic analyses reveal that sintering induces further condensation of the POP nanospheres through polycondensation of residual surface amine and aldehyde groups, forming welded nanostructures. Although the specific surface area (measured by N 2 at 77 K) decreases significantly after sintering, the CO 2 adsorption capacity is largely retained. Notably, the POP monoliths display rapid CO 2 adsorption kinetics, high CO 2 /N 2 selectivity (up to 100), and excellent sorption cyclability. Furthermore, the sintered monoliths exhibit enhanced aging stability, with only a 3.5% decrease in CO 2 uptake after 18 months of ambient storage. This work presents an efficient, binder‐free approach for shaping porous organic materials, supporting their practical deployment in gas sorption applications.