纤维素在1-丁基-3-甲基咪唑系列离子液体中的溶解性能研究

Dissolution of cellulose in 1-butyl-3-methylimidazolium ionic liquids

合成了1-丁基-3-甲基咪唑的乙酸盐([bmim][Ac])、乳酸盐([bmim][La])、乙醇酸盐([bmim][Ga])以及二氰胺盐([bmim][Dca])4种离子液体.测定了70℃时纤维素在这些离子液体中的溶解度,并利用1 HNMR核磁研究了其溶解规律.借助傅里叶转换红外光谱(FT-IR)、热重分析(TGA),对从[bmim][Ac]/纤维素溶液中再生纤维素的结构和热稳定性进行了表征.结果表明,4种离子液体中,乙酸根的氢键形成能力最强,离子液体[bmim][Ac]对纤维素的溶解效果最佳,而且在纤维素的溶解以及再生过程中,纤维素与[bmim][Ac]溶剂没有发生化学反应,与原料纤维素相比,再生纤维素大分子结构没有被破坏,热稳定性稍有降低.

The four ionic liquids （ILs） including 1-butyl-3-methylimidazolium acetate （[bmim] [-Ac]）, lactate （[bmim][La]）, glycollate （[bmim][Ga]）, dicyanamide （[bmim]EDca]） have been synthesized. Solubilities of mi crocrystalline cellulose （MCC） in these ionic liquids have been determined at 70 ℃. The effect of anionic structure on solubility of the cellulose has been estimated, and investigated by HNMR. Furthermore, the structure and ther mal stability for the cellulose regenerated from Ebmim][Ac]/cellnlose solution were characterized by Fourier trans form infrared spectroscopy （FT-IR） and thermogravimetric analysis （TGA）. The results indicate that, among the four ionic liquids, the acetate anion has the strongest hydrogen bond accepting capability, the highest solubility of cellulose can be attained. Moreover, no chemical reaction takes place between cellulose and IL during the cellulose dissolution and regeneration processes. Additionally, compared to the original cellulose, the molecular structure of the regenerated cellulose is not destroyed, and the thermal stability slightly decreases.