Shear dependent viscosity of poly(ethylene oxide) in two protic ionic liquids

• Viscosity measurements have been performed on 100 kDa PEO in EAN, PAN and water.
• There are solvent conditions: good (water), good-theta (EAN) and theta (PAN).
• EAN and PAN solvent nanostructure effects viscoelastic properties.

Steady shear viscosity measurements have been performed on 100 kDa poly(ethylene oxide) (PEO) dissolved in the protic ionic liquids ethylammonium nitrate (EAN) and propylammonium nitrate (PAN) and in water. The zero shear viscosity in all three solvents increases with polymer concentration, falling into three concentration regimes corresponding to dilute, semi-dilute and network solutions. Huggins plots reveal three distinct solvent conditions: good (water), good-theta (EAN) and theta (PAN). However, differences in the transition concentrations, power law behaviour of the viscosities, and relaxation times arising from shear thinning in the two ILs can be directly related to the effects of solvent nanostructure.

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