Influence of Anions of Imidazole Ionic Liquids on Dissolution of Cellulose

H.R. Liu*, H.W. Yu, E.P. Zhou, X.H. Zhang and X.C. Zhang

College of Chemical and Engineering, Shijiazhuang University, Shijiazhuang, P.R. China

*Corresponding author: Fax: +86 311 66617326; Tel: +86 311 66617320; E-mail:


[Bmim]Cl, [Bmim]Br, [Bmim]HSO4, [Bmim]BF4 and [Bmim]PF6 were synthesized to study the influence of anions on the dissolution of cellulose. Experimental studies showed that the dissolution of cellulose was related to the formation of hydrogen bonds between the anions and cellulose, which is attributed to the charge density on the anion. The sequence of solubility of cellulose in six ionic liquids tested was [Bmim]Cl > [Bmim]Br > [Bmim]HSO4 > [Bmim]BF4, [Bmim]PF6. Thermogravimetric method was employed to investigate the stability of ionic liquids. The dissolution process was monitored with polarizing microscope. The results showed that dissolution of cellulose was related to stability of the ionic liquids. For similar ionic liquids, poorer stability led to higher solubility. Both the original and regenerated cellulose samples were characterized with wide-angle X-ray diffraction and FTIR. It was shown that the structures of original cellulose and regenerated cellulose were similar; however, the crystalline structure of cellulose was converted to cellulose II from cellulose I of the original cellulose.


Cellulose, Dissolution, Ionic liquid.

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