A novel, simple geometry for high throughput electrospinning from a bowl edge is presented that utilizes a vessel filled with a polymer solution and a concentric cylindrical collector. Successful fiber formation is presented for two different polymer systems with differing solution viscosity and solvent volatility. The process of jet initiation, resultant fiber morphology and fiber production rate are discussed for this unconfined feed approach. Under high voltage initiation, the jets spontaneously form directly on the fluid surface and rearrange along the circumference of the bowl to provide approximately equal spacing between spinning sites. Nanofibers currently produced from bowl electrospinning are identical in quality to those fabricated by traditional needle electrospinning (TNE) with a demonstrated ∼ 40 times increase in the production rate for a single batch of solution due primarily to the presence of many simultaneous jets. In the bowl electrospinning geometry, the electric field pattern and subsequent effective feed rate are very similar to those parameters found under optimized TNE experiments. Consequently, the electrospinning process per jet is directly analogous to that in TNE and thereby results in the same quality of nanofibers.

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The process of edge electrospinning relies on forming electric-field-induced instabilities (i.e., jets) in a polymer solution bath which act as sources for nanofiber production. As such, it depends on the fundamental interactions between the fluid and the electric field, which are studied in this report as a function of solution parameters (viscosity, surface tension, and conductivity). Over a wide range of conditions, experimental observations including time required for initial jet formation, total number of jets, feed rate per jet, and resultant fiber diameter are reported and compared with theoretical predictions. The presently realized fiber throughput is 40× a single needle approach while maintaining similar high fiber quality. Two distinct voltage intervals are utilized to generate many fiber-forming instabilities: a high level for jet creation and then reduced amplitude for fiber production. This dual-stage approach relies on hysteresis in Taylor cone-jet formation, wherein a larger voltage is required to create a jet-emitting cone than to maintain it.

Superior mechanical and thermal properties in bulk polymers can be achieved by aligning the molecular chains through drawing-induced plastic deformation. Although highly aligned polymer films (HAPFs) are in demand, current fabrication methods are limited to manual, lab-scale batch processes. Here we report a continuous fabrication platform for HAPFs consisting of a three-step sol-gel extrusion, structure freezing and drying, and mechanical drawing process. First, a polymer-solvent solution is subjected to a high shear, high temperature, Couette flow extrusion into a thin film, resulting in initial chain disentanglement. Next, the extruded disentangled structure is frozen using a liquid N 2-cooled substrate, and then solvent is removed from polymer gel through ambient evaporation. Finally, dried films are mechanically drawn within a heated enclosure using a constant-force adaptive-thickness drawing system. The performance of this platform has been confirmed by fabricating polyethylene HAPFs with > 99% crystallinity and draw ratios up to 100× (creating continuous films > 15 m in length).