Investigation of a novel urethane-inspired CO₂ chemisorbent: structure modifications and activation barriers

Polyurethane (PU) and its numerous fine-tuned derivatives are widely employed as CO₂ scavengers thanks to (1) physisorption and (2) functionalization of the PU backbone with other CO₂ sorbents. In the present work, it has been unraveled why PU cannot exhibit CO₂ chemisorption, despite possessing the nitrogen docking sites and exhibiting strong electrostatic sorbent-sorbate interactions. Furthermore, a few types of spatial separation of the active sorption sites have been proposed to unleash the chemisorption functionality of PU. By comparing various structural modifications of PU using the in silico methodology, we have identified that CO₂ chemisorption by PU takes place in the case of implementing methyl and ethyl fragments between the oxygen and nitrogen atoms of PU. Herewith, the introduction of the ethyl moiety even makes CO₂ chemisorption energetically favorable relative to physisorption. The reported specific progress on materials design represents an obvious practical value for chemical engineers developing inexpensive CO₂ scavengers.