Polyurethane-Inspired CO2 Chemisorbent: Ab Initio Reaction Profiles

TL;DR

This study investigates why polyurethane cannot normally chemisorb CO2 and proposes structural modifications, such as adding methyl and ethyl groups, to enable chemisorption, which could lead to more effective CO2 scavengers.

Contribution

The paper reveals the reasons behind polyurethane's inability to chemisorb CO2 and demonstrates through ab initio calculations that specific structural modifications can enable chemisorption.

Findings

Ethyl groups make CO2 chemisorption energetically favorable.

Structural modifications can convert PU into an effective chemisorbing material.

In-silico methods identify key molecular features for CO2 chemisorption.

Abstract

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 by 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.