Activated CO2 Sorption in Mesoporous Imidazolium-Type Poly(ionic liquid)-Based Polyampholytes

In this contribution, we present the formation of mesoporous polyampholyte networks via self-complexation (inter- and intrapolyelectrolyte complexation) of copolymers bearing both the imidazolium cations and the carboxylic acid units. The copolymers were prepared via straightforward free radical copolymerization of acrylic acid and vinylimidazolium-based ionic liquid monomers possessing different alkyl substituents in DMSO at 80 degrees C. Nitrogen adsorption measurements and electron microscopy were used to examine the porous structures. The Brunauer-Emmett-Teller (BET) specific surface areas of the resulting mesoporous complexes were measured to be up to 260 m(2)/g and varied in terms of the complexation solvent quality, the copolymer composition, and the precipitation concentration of copolymers as well as the chemical structure of the employed ionic liquid monomers. The CO2 sorption behavior of a selected mesoporous polyampholyte was studied in detail. It could be shown that two processes are effective: adsorption at the external surface and absorption into the polymer matrix. Fourier transform infrared (FTIR) spectroscopy gave hints that the absorption process comes along with the formation of imidazolium-carboxylates, presumably via a transient N-heterocydic carbene intermediate.