Gaseous flow focusing for spinning micro and nanofibers

Abstract We apply the gaseous flow focusing principle to produce fibers of polyvinylpyrrolidone down to the nanometer scale. The polymer solution is injected in front of a glass converging micronozzle through which a high-speed air stream flows. The air stream sucks and drags the liquid forming a meniscus whose tip emits a thin jet. The jet flies while whipping until it solidifies due to the solvent evaporation. The resulting fiber is deposited on a rotating drum collector. Gaseous Flow Focusing Spinning does not require any additional source of energy. It proves to be stable and robust, and produces fibers over hours with hardly any interruptions for wide ranges of gas pressures and liquid flow rates. Fibers with diameters of the order of 100 nm are produced for sufficiently low polymer concentrations. Their sections are circular and uniform in diameter. The standard deviation of the diameter distribution ranges from around 20%–40% of the corresponding mean value.