Synthesis of Quaternary Ammonium Room-Temperature Ionic Liquids and their Application in the Dissolution of Cellulose

In this work, several kinds of quaternary ammonium-based room-temperature ionic liquids (QA RTILs) are synthesized by alkylation and ion-exchange reactions for the rapid dissolution of cellulose. The applications of cellulose materials have been limited due to their poor solubility in conventional organic solvents, because of a high degree of structural regularity and a large number of hydrogen bonds. The prepared ionic liquids were identified by nuclear magnetic resonance, elemental analysis, and liquid chromatography-mass spectrometry. The results indicated that N,N,N-triethylhexan-1-aminium acetate (N6222OAc), tetrahexylammonium acetate (N6666OAc), and N,N,N,N,N,N-hexaethyldecane-1,10-diaminium acetate (C-10(N222OAc)(2)) exhibited good cellulose-dissolution without any pretreatment. The regenerated cellulose films with a low degree of crystallization of the cellulose II phase were also prepared easily in this process using N6222OAc due to its polar and small cation. These QA RTILs can be used as non-derivatizing solvents for cellulose and can also be easily recycled because of their thermostable and nonvolatile properties.