Postsynthetic Imidation of Conjugated Porous Polymers: Enhanced CO2 Capture and Selectivity

Developing porous materials for efficient and selective capture of CO2 is necessary to fight climate change. Although amine scrubbing is widely utilized for CO2 capture, it is energy-intensive and not eco-friendly. In this context, utilizing solid adsorbents for postcombustion carbon capture presents a promising method for reducing carbon emissions. Here, we report the postsynthetic imidation strategy for synthesizing robust N-functionalized porous conjugated polymers (CPPs), <bold>NH-CPP</bold>, <bold>NH</bold>(<bold>2</bold>)<bold>-CPP</bold>, and <bold>EDA-CPP</bold> which provides CO2-philic groups. Postsynthetic imidation significantly improves the uptake of CO2, up to 53% for <bold>NH</bold>(<bold>2</bold>)<bold>-CPP</bold> and 48% for <bold>NH-CPP</bold> at 1 bar and 273 K. The uptake capacity for CO2 was evaluated at high pressures up to 30 bar and ambient temperature of 298 K, demonstrating a notable increase after postimidation, with the highest uptake reaching 4.5 mmol/g for <bold>NH</bold>(<bold>2</bold>)<bold>-CPP</bold>. More importantly, increased CO2 uptake leads to a 200% increase in the CO2/N-2 selectivity under typical flue gas conditions at 273 K (1 bar and 15% CO2, 85% N-2). These findings carry significant implications for their potential application in postcombustion carbon capture.