Unconfined, melt edge electrospinning from multiple, spontaneous, self-organized polymer jets

Abstract

Commercial grade polyethylene is melt electrospun from a thin film of unconfined molten polymer on a heated, electrically-grounded plate. Under the influence of an applied electric field, the melt spontaneously forms fingering perturbations at the plate edge which then evolve into emitting fiber-forming jets. Jet-to-jet spacing (∼5 mm), which is dependent on the applied voltage amplitude, is in agreement with estimates from a simple theoretical treatment. The broad applicability of the approach is verified by spinning a second polymer-polycaprolactone. In both cases, the fabricated fibers are similar in quality to those obtained under needle melt electrospinning; however for this method, there are no nozzles to clog and an enhanced production rate up to 80 mg min −1 is achieved from approximately 20-25 simultaneous parallel jets. The process of jet formation, effective flow rates, cone-jet diameters, as well as limits on jet density and differences with polymer type are compared with theoretical models. This particular approach allows facile, high throughput micro-and nano-fiber formation from a wide variety of thermoplastics and other high viscosity fluids without the use of solvents or the persistent issues of clogging and pumping that hamper traditional methods, resulting in mechanically strong meso-scale fibers highly desirable for industrial applications.

Mechanical Properties of Electrospun Fibers—A Critical Review

“…[ 32 ] One example of such a system is plate‐edge electrospinning from a thin sheet of polymer fluid on some solid surface (Figure 1B). [32a,33] This approach is particularly powerful as the process spontaneously generates and organizes any fiber‐forming jets, resulting in significant gains in material throughput while maintaining high fiber quality controlling the polymer solution feed rate. Moreover, there are no nozzles to clog or complex moving parts, and the system can be indefinitely refreshed as well as enables continuous tuning of the flow rate and the limit of feed to a range where high‐quality fiber formation is possible.…”

Modeling of downstream heating in melt electrospinning of polymers

“…This is due to the high viscosity and low charge density of the polymer melt. The former lowers the stretchability of the jet, while the latter results in a low electrostatic force on the jet . In addition, rapid heat exchange between the jet and the environment often solidifies the jet in the vicinity of the Taylor cone which prevents major jet drawing by the electric field …”

Melt-Blown and Electrospun Drug-Loaded Polymer Fiber Mats for Dissolution Enhancement: A Comparative Study

“…Despite the advantageous properties, both SES and MES have their own limitations. Although there have been attempts for process scale‐up, both for MES and particularly for SES applying a needleless (free surface) configuration, the achievable productivity is moderate compared with other fiber production techniques, and the use of volatile solvents seems to complicate the intensification because of the undesired drying of the free solution surface. Although MES can eliminate all the technological problems related to solvents mentioned above, only fibers of several tens of micrometers are achievable owing to the high‐melt viscosity …”