Insight into dissolution mechanism of cellulose in [C4mim][CH3COO]/DMSO solvent by 13C NMR spectra

• Dissolution mechanism of cellulose in [C4mim][CH3COO]/DMSO solvent was investigated.
• Anion [CH3COO]− in [C4mim][CH3COO]/DMSO solvent impacts cellulose dissolution.
• Cation [C4mim]+ in [C4mim][CH3COO]/DMSO solvent also impacts cellulose dissolution.
• DMSO serves to dissociate [C4mim][CH3COO] ion pairs into solvated cations and anions.

Recently, it has been reported that 1-butyl-3-methylimidazolium acetate/dimethyl sulfoxide ([C4mim][CH3COO]/DMSO) can efficiently dissolve cellulose at room temperature. In the present study, 13C NMR measurements of 1-butyl-3-methylimidazolium acetate [C4mim][CH3COO] and cellulose were carried out in [C4mim][CH3COO]/DMSO-d6 (Deuterated dimethyl sulfoxide)/cellulose solution to directly reveal the possible dissolution mechanism of cellulose in true [C4mim][CH3COO]/DMSO solvent. The results indicate that both cation and anion of [C4mim][CH3COO] in [C4mim][CH3COO]/DMSO solvent dominate cellulose dissolution, and DMSO mainly serves to dissociate the ion pairs in [C4mim][CH3COO] into solvated cations and anions. Moreover, the hydrogen bonding interaction of anion of [C4mim][CH3COO] with cellulose hydroxyl proton is much stronger than that of cation of [C4mim][CH3COO] with cellulose hydroxyl oxygen.

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