A novel oligochitosan/DMSO system as a green sorbent for CO₂capturing.

A series of micro/meso porous imidazolium poly(ionic liquid)s for CO₂ capture and utilization is reported. They show moderate sorption capacity under RTP conditions, and good catalytic activity towards the cycloaddition of CO₂ and epoxides to synthesize cyclic carbonates.

A new eco-friendly, isocyanate-free, energy-saving method for the production of [6]-oligourea, utilizing a green carbonylating agent, viz. propylene carbonate, is reported. It comprises an organocatalyzed, microwave-assisted, solvent-free synthesis. Two modes of microwave-assisted synthesis, viz. dynamic and fixed energy modes, were applied. Upon optimization, the dynamic mode gave 79% yields of [6]-oligourea. On the other hand, almost quantitative yields were obtained using the fixed mode, within 20 min, at 10 W and with the same catalyst loading. Combination of both organocatalysis and microwave energy input appears to be a key issue for the efficiency of the reaction, with the fixed energy mode being best suited. It should be noted that all data reported are reproducible (due to the homogeneous microwave technology used by CEM Discover S-Class of microwave reactors). To the best of our knowledge, this is the best eco-friendly synthetic approach for the preparation of the title oligomers. It paves the way for using more of the biorenewable and sustainable chemicals as a feedstock for the production of polyureas. The oligomer produced was analyzed by EA, ATR-FTIR, XRD, ¹H and ¹³CNMR. Furthermore, thermal properties of the resulting [6]-oligourea were analyzed using TGA and DSC.

Renewable materials, viz. cellulose, chitin, chitosan and cyclodextrins are promising alternatives to petroleum-based feedstocks for CO₂ sequestration.