Electrospinning: A whipping fluid jet generates submicron polymer fibers
Wiki Entry by Daniel Rubin, AP225, 9/24/2012
Authors: Y. M Shin, M. M. Hohman, M. P. Brenner, G. C. Rutledge.
Publication: Y. M. Shin, et al. Electrospinning: A whipping fluid jet generates submicron polymer fibers. Appl. Phys. Lett., Vol. 78, No. 8, 19 February 2001
Key Words: Electrospinning, linear instability
Electrospinning (electrostatic fiber spinning) is a material fabrication technique used to generate sub-micrometer fibers from polymers and proteins. By extruding a viscous polymer solution from a needle, into an electric field, one is able to form large amounts of very fine, solid fibers at a collection plate. Due to their extremely high surface area, fine porosity, and small diameter, electrospun fibrous mats have been constructed for many different applications including bioengineered tissue scaffolds and water filtration membranes. Figure 1 depicts an electrospun fibrous mat composed of poly-ethylene oxide (PEO).
Despite the broad interest in both single nanofibers and nanofibrous mats, there is litte known about the fundamental physics and process engineering that determines fiber diameter and homogeneity. Specifically, what physical parameters are resopnsible for converting a millimeter scale column of polymer solution to a sub micron fiber, and how might we control it better? To begin, consider Figure 2, a series of images taken of the polymer solution undergoing the transition to a nanofiber. Moving from the needle tip of the syringe to the collecting plate, you first encounter the Taylor cone, followed by the straight jet (2.A), the bending region (2.B(, and finally the whipping jet (2.C).
As the polymer solution approaches the bending region, it rapidly becomes unstable, resulting in the aforementioned whipping instability.
Y. M. Shin, et al. Electrospinning: A whipping fluid jet generates submicron polymer fibers. Appl. Phys. Lett., Vol. 78, No. 8, 19 February 2001