Scaling Laws in Polysaccharide Rheology: Comparative Analysis of Water and Ionic Liquid Systems
Roshan Akdar Mohamed Yunus, Daniele Parisi
Abstract
High Resolution Image Download MS PowerPoint Slide This study investigates the rheological behavior of two plant-based polysaccharides, with different degrees of hydrophilicity, agar (highly hydrophilic) and guar gum (hydrophilic), in water and 1-ethyl-3-methylimidazolium acetate (EMImAc). The rheological response of these polymers is highly dependent on the solvent’s ability to disrupt intermolecular associations. In water, agar forms hydrogels, while guar gum behaves as a viscoelastic liquid with slow modes. The plateau modulus ( G N 0 ) scales with polymer concentration ( c ) as G N 0 ∼ c 3, consistent with other natural polymers. In EMImAc, both polysaccharides form viscoelastic liquids, exhibiting G N 0 ∼ c 2.3, as expected for semiflexible polymer solutions. However, the terminal relaxation time, τ D, and the specific viscosity, η sp, scale as τ D ∼ c 5.3 and η sp ∼ c 7.6, indicative of intermolecular chain–chain associations. Despite the solvent or polysaccharide, the fractional viscosity overshoot and the shear strain at the maximum stress show a terminal Weissenberg number dependence similar to other synthetic polymers.