Production of core/shell fibers by electrospinning from a free surface

Electrostatic fiber formation (“electrospinning”) is the leading technology for production of continuous fibers with submicron diameter. Applications such as drug delivery and sensors benefit from the ability to produce submicron fibers with a core/shell morphology from electrified coaxial jets of two liquids. However, low productivity of the conventional needle-based coaxial process is a barrier for commercialization. We present a novel technology that overcomes this limitation by the development of coaxial jets directly from compound droplets of immiscible liquids entrained on wires, and control of mass transfer processes to produce uniform, core/shell fibers. The enabling feature of controlled evaporation by design of solution properties is verified by a simple mass transport model. Electron micrographs confirm the formation of fibers with the desired morphology. The proposed technology creates the opportunity to produce nanofibers with core/shell morphology on an industrial scale for a wide variety of applications.