Postsynthetic Imidation\nof Conjugated Porous Polymers:\nEnhanced CO<sub>2</sub> Capture and Selectivity

Developing porous materials for efficient and selective\ncapture\nof CO<sub>2</sub> is necessary to fight climate change. Although amine\nscrubbing is widely utilized for CO<sub>2</sub> capture, it is energy-intensive\nand not eco-friendly. In this context, utilizing solid adsorbents\nfor postcombustion carbon capture presents a promising method for\nreducing carbon emissions. Here, we report the postsynthetic imidation\nstrategy for synthesizing robust N-functionalized porous conjugated\npolymers (CPPs), <b>NH-CPP</b>, <b>NH</b><sub><b>2</b></sub><b>-CPP</b>, and <b>EDA-CPP</b> which provides\nCO<sub>2</sub>-philic groups. Postsynthetic imidation significantly\nimproves the uptake of CO<sub>2</sub>, up to 53% for <b>NH</b><sub><b>2</b></sub><b>-CPP</b> and 48% for <b>NH-CPP</b> at 1 bar and 273 K. The uptake capacity for CO<sub>2</sub> was evaluated\nat high pressures up to 30 bar and ambient temperature of 298 K, demonstrating\na notable increase after postimidation, with the highest uptake reaching\n4.5 mmol/g for <b>NH</b><sub><b>2</b></sub><b>-CPP</b>. More importantly, increased CO<sub>2</sub> uptake leads to a 200%\nincrease in the CO<sub>2</sub>/N<sub>2</sub> selectivity under typical\nflue gas conditions at 273 K (1 bar and 15% CO<sub>2</sub>, 85% N<sub>2</sub>). These findings carry significant implications for their\npotential application in postcombustion carbon capture.