Solvent Effects on the Elasticity of Electrospinnable Polymer Solutions

Area of Science:

• Materials Science
• Polymer Science
• Rheology

Background:

• Electrospinning ultrafine fibers holds great promise for advanced applications.
• Commercialization requires a deeper understanding of polymer solution behavior during electrospinning.
• Complex fluid dynamics, including viscoelastic stresses, impact fiber formation but are not always captured by shear rheology.

Purpose of the Study:

• To characterize the extensional rheological properties of common electrospinning polymer solutions.
• To correlate electrospinnability with extensional rheology and solvent properties.
• To establish a framework for designing improved electrospinning dopes.

Main Methods:

• Utilized dripping-onto-substrate rheometry to measure extensional viscosities.
• Investigated four polymer solutions: polyvinylpyrrolidone (PVP) and poly(vinyl alcohol) (PVA) in various solvents.
• Characterized fiber morphology to assess electrospinnability.

Main Results:

• Established a link between electrospinnability and extensional rheological properties for semidilute and entangled polymer solutions.
• Demonstrated that higher surface tension solvents necessitate greater extensional viscosity and relaxation times for smooth fiber formation.
• Identified Deborah and Ohnesorge numbers as predictive metrics for electrospinnability.

Conclusions:

• Extensional rheology is crucial for understanding and optimizing the electrospinning process.
• Solvent characteristics significantly influence the required viscoelastic properties for successful fiber formation.
• This research enables the rational design of electrospinning dopes for applications in wearable electronics and pharmaceuticals.