Scission of electrospun polymer fibres by ultrasonication

In this work we show that sonication alone can be used to scission bulk electrospun membranes into short fibres. The mechanism of such scission events is bubble cavitation stimulated by the ultrasonic probe, followed by bubble implosion. The tendency of polymer nanofibres to undergo failure by such a scission process appears to primarily depend on the ductility of the polymer, with brittle, electrospun polymer membranes such as poly(styrene) and poly(methyl methacrylate) readily producing short fibres of approximately 10 μm length. More ductile polymers such as poly(l-lactide) or poly(acrylonitrile) require additional processing after electrospinning and before sonication, to make them conducive to such sonication-based scission. Both the initial diameter of the fibres and the degree of nanofibre alignment of the electrospun membrane influence the final length of the resultant short fibres. It was found that the chemical and physical properties of the short nanofibres were unaltered by the sonication process. We are thus able to demonstrate that sonication is a promising method to produce significant quantities of short fibres of nanometre diameter and microns in length.