Sustainable Electrospinning of Nanoscale Fibres

Abstract

Electrospinning is an effective technology for the preparation of nano and micro scale fibres for diverse application in oil recovery, medical devices, and filters. It is achieved by injecting a charged solution of polymeric material through a needle into a region of high electric field. Under these conditions, the expelled jet follows a chaotic, whip-like trajectory towards a grounded collection plate. At low polymer concentrations, the high forces experienced by the jet prior to becoming grounded on the collection plate, result in the formation of undesirable discrete droplets of material, rather than fibres. At higher concentrations, above the critical entanglement limit for the polymer, the polymer chains are stretched and orientated whilst the solvent rapidly evaporates, delivering high aspect ratio fibres. The resulting mesh of overlapping fibres frequently has useful properties such as high surface area and porosity, which has led to their investigation for a range of applications including filtration membranes and tissue scaffolds. One of the major challenges in the development of electrospinning as a manufacturing technology is the use of organic solvents. Typically, fibres are spun from relatively dilute solutions containing 95% solvent. It is clear that systems which use water as a solvent offer many advantages in terms of safety, cost and sustainability. In this work we optimise the conditions for effectively preparing nano/micro fibres of polyethylene oxide from aqueous solutions. We contrast the fibres produced with those prepared using volatile organic solvents.