Fabrication of Carboxylic Acid and Imidazolium Ionic Liquid Functionalized Porous Cellulosic Materials for the Efficient Conversion of Carbon Dioxide into Cyclic Carbonates
Yunlong Yang, Yuanlong Guo, Chengtao Gao, Michael North, Jili Yuan, Haibo Xie, Qiang Zheng
Abstract
Cellulosic poly(ionic liquid)s ([Cellmim][Br]) with a degree of substitution (DS) in the range of 0.32–0.89 were synthesized successfully via the homogeneous transesterification reaction of cellulose with 1-(2-methoxyacetyl)-3-methyl imidazole bromide IL ([Mmim][Br]) in a DBU/DMSO/CO 2 solvent system. The structure and properties of these novel materials have been fully characterized. Cellulosic poly(ionic liquid) POF polymers (POF-[Cellmim][Br]) were then obtained by an in situ crosslinking reaction without adding an exterior catalyst. The porosity and properties of the POF-[Cellmim][Br] materials can be modulated. The POF-[Cellmim][Br] materials functioned as green, efficient, and highly active catalysts for cycloaddition reactions of epoxides and carbon dioxide under solvent-free and co-catalyst-free conditions. These reactions gave high yields (up to 97%), and the catalyst can be easily separated with excellent reusability and no significant change to its structure. A plausible reaction mechanism for the cycloaddition reaction of epoxide and carbon dioxide by the POF-[Cellmim][Br] catalyst is proposed based on the experimental results. This work provided a new strategy to prepare cellulosic-PIL POF materials and offered a platform to understand the cooperative effects of porous properties and nucleophilic anions on the cycloaddition reaction of carbon dioxide and epoxides.