Dissolution of cellulose in the mixed solvent of [bmim]Cl–DMAc and its application

Abstract

A mixed solvent of 1-butyl-3-methylimidazolium chloride ([bmim]Cl) and dimethylacetamide (DMAc) was developed for various applications involving cellulose. By changing the ratio of DMAc, the mixed solvent could be used either for cellulose swelling (more than 65% DMAc), selective dissolution of the non-crystalline domains for extraction of the crystalline nanofibers of cellulose (35–60% DMAc), or complete dissolution (less than 30% DMAc). In the region of complete dissolution, the dissolution rate of cellulose increased drastically as the DMAc ratio increased. The cellulose nanofibers prepared in the mixed solvent of [bmim]Cl–DMAc (50% DMAc) had a diameter of 30 nm and maintained the crystalline structure of cellulose I. A model was proposed to describe the selective dissolution and fibrillation of cellulose nanofibers in the mixed solvent of [bmim]Cl–DMAc.