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, -SO3H, and -SO3Li 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/N-2 and CO2/H-2) and isosteric heats of the microporous polymers increase markedly after modification, P-PhPh3-NH2 and P-PhPh3-SO3Li afford higher CO2 uptake capacity than P-PhPh3 at pressures of less than 0.15bar due to the enhanced interaction between CO2 and the -NH2 and -SO3Li 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.