Effect of dimethylsulfoxide on the viscoelastic properties and sol–gel transition of cellulose/ionic liquid solutions

Viscoelastic properties of cellulose solutions with 1-butyl-3-methylimidazolium chloride ([BMIM] Cl) and dimethylsulfoxide (DMSO) as solvents were studied by rheological experiments. From the results of rheological behaviors, the non-monotonous decrease of viscosity with DMSO content was observed. When the content of DMSO in [BMIM] Cl/DMSO is lower than 5 wt% in [BMIM] Cl/DMSO, the viscosity and gelation temperature (T-gel) decreased with the increase of DMSO. However, the values of viscosity and T-gel showed a nonlinear change with the further increase of DMSO. It could be understood that DMSO acted as the diluent when the content of DMSO is below 5 wt%. The local micro-aggregation or micro-phase separation of cellulose could happen when the content of DMSO further increased due to the weak action between cellulose and DMSO.