Click-based porous cationic polymers for enhanced carbon dioxide capture

TL;DR

This study presents a new click chemistry-based method to synthesize porous cationic polymers with high CO2 capture capacity, especially with acetate anions, and explores their chemisorption mechanisms involving N-heterocyclic carbenes.

Contribution

It introduces an innovative, facile synthesis approach for porous imidazolium-based polymers with hierarchical porosity and high CO2 uptake, including carbene modifications for enhanced interaction understanding.

Findings

Polymers exhibit hierarchical porosity and high surface area.

CO2 uptake reaches 2 mmol/g at 1 bar and 273 K, among the highest for similar materials.

Carbene modification alters the interaction mechanism, evidenced by chemisorption phenomena.

Abstract

Imidazolium based porous cationic polymers were synthesized using an innovative and facile approach, which takes advantage of the Debus Radziszewski reaction to obtain meso- and microporous polymers following click chemistry principles. In the obtained set of materials, click based porous cationic polymers have the same cationic backbone, whereas they bear the commonly used anions of imidazolium poly(ionic liquid)s. These materials show hierarchical porosity and a good specific surface area. Furthermore, their chemical structure was extensively characterized using ATR FTIR and SS NMR spectroscopies, and HR MS. These polymers show good performance towards carbon dioxide sorption, especially those possessing the acetate anion. This polymer has an uptake of 2 mmol per g of CO2 at 1 bar and 273 K, a value which is among the highest recorded for imidazolium poly(ionic liquid)s. These polymers were also modified in order to introduce N-heterocyclic carbenes along the backbone. Carbon dioxide loading in the carbene-containing polymer is in the same range as that of the non-modified versions, but the nature of the interaction is substantially different. The combined use of in situ FTIR spectroscopy and microcalorimetry evidenced a chemisorption phenomenon that brings about the formation of an imidazolium carboxylate zwitterion.