Rheology of cellulose nanocrystals dispersed in dimethyl sulfoxide

Cellulose nanocrystals (CNCs)/H₂O suspensions have attracted significant attention for their diverse applications, yet research on the physicochemical and rheological properties of CNCs in organic solvents is scarce. This work explored the dispersion behavior of CNCs in dimethyl sulfoxide (DMSO) through ultrasonication, and the physical state of the suspensions along with the viscosity, viscoelasticity, thixotropy, and yield stress were analyzed as a function of concentration. The results revealed that the CNC/DMSO suspension transitioned from isotropic to anisotropic at a concentration of 4.0 wt%. Both the viscosity and viscoelasticity exhibited a three-stage power-law relationship with concentration. The liquid-solid transition point of the CNC/DMSO suspensions, determined from rheology, was near the gel crowding factor of 14. The suspensions behaved as thixotropic yield stress fluids, with both thixotropy and yield stresses demonstrating a power-law dependence on concentration. The power-law exponent changed at a concentration of 6.0 wt%. Various perspectives on the yield stress of CNC suspensions were explored, with algebraic stress bifurcation providing a clearer representation of the yield process. This study provides a theoretical foundation for understanding the physical state of CNCs in organic solvents and for advancing the development of cellulose-based nanocomposites.