Viscoelastic properties of poly(ethylene oxide) solution

Area of Science:

• Polymer Science
• Rheology
• Materials Science

Background:

• Poly(ethylene oxide) (PEO) is a versatile polymer with applications requiring specific viscoelastic properties.
• Understanding PEO solution rheology is crucial for optimizing its performance in various formulations.

Purpose of the Study:

• To investigate the viscoelastic properties of poly(ethylene oxide) (PEO) solutions.
• To determine the influence of molecular weight, concentration, solvent composition, and salt on PEO rheology.

Main Methods:

• Dynamic oscillatory testing was employed to measure viscoelastic parameters.
• Measurements included storage modulus (G1), loss modulus (G2), complex viscosity (eta*), and loss tangent (tan delta).
• Experiments were conducted over a frequency range of 10(-3)-2.5 Hz at 30°C.

Main Results:

• High molecular weight PEO solutions demonstrated increased elasticity due to chain entanglement.
• Complex viscosity exhibited shear-thinning (power-law) behavior, consistent with the Cox-Merz rule.
• Increasing water content in mixed solvents and PEO concentration significantly enhanced both storage and loss moduli.
• NaCl addition (up to 2% w/w) did not adversely affect the viscoelasticity of a 10% PEO solution.

Conclusions:

• PEO viscoelasticity is highly tunable via molecular weight, concentration, and solvent composition.
• Entanglement effects dominate the rheological response of high molecular weight PEO.
• The findings provide valuable insights for formulating PEO-based materials with desired flow properties.