Tuning the Surface Polarity of Microporous Organic Polymers for CO₂ Capture

CO₂ capture is very important to reduce the CO₂ concentration in atmosphere. Herein, we report the preparation of microporous polymers with tunable surface polarity for CO₂ capture. Porous polymers functionalized with -NH₂ , -SO₃ H, and -SO₃ Li have been successfully prepared by using a post-synthesis modification of microporous polymers (P-PhPh₃ prepared with 1,3,5-triphenylbenzene as the monomer and AlCl₃ as the catalyst) by chemical transformations, such as nitration-reduction, sulfonation, and cationic exchange. The CO₂ adsorption selectivity (CO₂ /N₂ and CO₂ /H₂ ) and isosteric heats of the microporous polymers increase markedly after modification, P-PhPh₃ -NH₂ and P-PhPh₃ -SO₃ Li afford higher CO₂ uptake capacity than P-PhPh₃ at pressures of less than 0.15 bar due to the enhanced interaction between CO₂ and the -NH₂ and -SO₃ Li functional groups. Moreover, functionalized porous polymers could be stably used for CO₂ capture. Surface modification is an efficient approach to tune the CO₂ capture properties of porous polymers.