Dissolution of cellulose in novel carboxylate-based ionic liquids and dimethyl sulfoxide mixed solvents

A series of substituted piperazinium, piperidinium, and pyrrolidinium acetates were synthesized. Highly effective cellulose solvents have been designed by mixing an aprotic polar solvent, dimethyl sulfoxide (DMSO), with synthesized ionic liquids (Rs). Different weight ratios of corresponding IL/DMSO mixed solvents were prepared to investigate the effect of cosolvent on cellulose solubility. Cellulose solubility in IL/DMSO solvent systems was measured at 25, 50 and, 80 degrees C. The effect of factors such as solvent composition, process temperature, type of IL's cation, and alkyl chain length of IL's cation on cellulose solubility was investigated. Amongst all tested solvents, N,N'-dimethyl-N-ethylpiperazinium acetate ([DMEPpz][Ac]/DMSO) mixed solvent exhibits the best performance in the dissolution of cellulose, reaching up to 13.5 wt% at 80 degrees C. The dissolved cellulose was regenerated using water as an antisolvent. The structure and morphology of the regenerated cellulose material were characterized by SEM, XRD, and FTIR, respectively.