Rheological behaviors of cellulose in 1-ethyl-3-methylimidazolium chloride/dimethylsulfoxide

• The rheology of cellulose/[Emim]Cl/DMSO solutions was investigated.
• The cellulose solutions are classified into three regimes as dilute, semidilute unentangled and semidilute entangled regimes with slopes of 1.1, 2.1 and 4.7.
• [Emim]Cl/DMSO appears to be a θ solvent for cellulose at 25 °C.
• No significant change of the rheological conformation and the entanglement network structure occurred with varying cDMSO in the solvent.

Dynamic rheological behaviors of α-cellulose 1-ethyl-3-methylimidazolium chloride ([Emim]Cl)/dimethylsulfoxide (DMSO) solutions were investigated in a large range of cellulose concentrations (0.1–10 wt%) at 25 °C. The overlap concentration c* and the entanglement concentration ce for cellulose in [Emim]Cl/DMSO were determined to be 0.5 wt% and 2.0 wt% respectively, and the exponents of the specific viscosity ηsp versus cellulose concentration c were determined as 1.1, 2.1 and 4.7 for dilute, semidilute unentangled and entangled regimes respectively, which were in accordance with the scaling prediction for neutral polymer in θ solvent. Under the same cellulose concentration, the complex viscosity η*, the reptation time τrep and the relaxation time of a segment between entanglements τe all decreased with increasing DMSO content in the solvent, while the number of entanglements of cellulose chains and the molar mass of an entanglement strand Me both remained unchanged.