Blair Brettmann - Expansion of Electrospinnable Materials Beyond High Molecular Weight Polymers
From Katie Gentilello on October 7th, 2019
Electrospinning is a valuable production method for nanoscale polymeric fibers. However, a major limitation of the technology is the requirement for the use of high molecular weight polymers as a major part of the matrix. Many applications would benefit from a more expansive range in the materials able to be electrospun, including pharmaceuticals, wearable devices and diagnostics, and active filtration. In order to realize these more advanced functional materials, composites of polymers and particles must be developed and a strong understanding of how particle inclusion affects the electrospinning process and mat properties is essential. In this work, we examine material systems containing various polymers and active particles, focusing on how inclusion of particles affects electrospinnability and functionality of the fibrous mat. We have found that polymer solutions with high conductivity, hence narrow fiber diameters, tend to trap particles in a web-like structure, rather than within individual fibers. Other polymer-particle systems exhibit a ‘bunches of grapes’ morphology where the particles agglomerate yet the polymer matrix still surrounds them and connects the bunches with fibers. These interesting morphologies can be explained by conductivity, rheology, and particle interactions in the polymer solution. We also examine how particle inclusion affects the viscoelasticity of the solutions and tie this to the electrospinning process window; showing that a finite window of viscoelasticity yields optimal electrospinnability. We use these fundamental results to electrospin materials for advanced functional applications such as pharmaceuticals and conducting polymers and provide outlook for further work in increasing the range of materials that are electrospinnable.