Abstract
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 (C10(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.
Highlights
Cellulose is the most abundant regenerative material in the world, and it has been widely used in many fields such as in medicine, food, packaging, and industrial materials due to its good physical properties [1]
Its structure bears a high degree of regularity and exhibits a large number of hydrogen bonds; this renders cellulose insoluble in water and other common organic solvents, resulting in its limited application
The successful synthesis of three ionic liquids was established by the similarity between the estimated values and the obtained 1 H nuclear magnetic resonance (NMR), elemental analysis (EA), and liquid chromatography-mass spectrometry (LC/MS) data
Summary
Cellulose is the most abundant regenerative material in the world, and it has been widely used in many fields such as in medicine, food, packaging, and industrial materials due to its good physical properties [1] It is a linear polysaccharide composed of d-glucose monomers linked by β-(1,4) glycosidic bonds. In comparison to the traditional method (Viscose process) [4], NMMO is a more environmentally friendly, non-derivatizing solvent It still has some disadvantages, such as the requirement of high temperature to dissolve the cellulose, degradation of cellulose, side reactions of the solvent itself, which are caused without any antioxidant, and large investments in safety [5]
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