Highly Selective Capture of the Greenhouse Gas CO2 in Polymers

Owing to their high physicochemical stability and low skeleton density, polymers are highly promising for capturing the greenhouse gas CO2. However, complicated monomers, expensive catalysts, and/or severe conditions are usually required for their synthesis, which makes the process costly, tedious, and hard to scale up. In this paper, a facile nucleophilic substitution reaction is developed to synthesize polymers from low-cost monomers, namely chloromethylbenzene and various diamines. Due to the appropriate reactivity of monomers, the polymerization takes place at a low temperature of about 60 °C in the absence of any catalysts. A series of polymers containing plentiful secondary amines are successfully fabricated; these secondary amines provide a proper adsorbate–adsorbent interaction from the viewpoints of selective capture of CO2 and energy-efficient regeneration of adsorbents. Moreover, the materials possess well-defined micropores with the dimension close to the size of adsorbate molecules and subsequently, exhibit the molecule sieving effect. As a result, these materials are active in selective adsorption of CO2 and show high CO2/N2 and CO2/CH4 selectivities. More importantly, the adsorbents can be completely regenerated under mild conditions, and no loss in activity is detected after eight cycles.