Controlled stretching of the first spiral in electrospinning whipping jet via surface charge

Abstract Generally, the first spiral of whipping jet (FSWJ) has the maximum motion velocity in the stretching and thinning of electrospinning jet. Accurate control of the stretching of FSWJ is vital to generate nanofibers with expected diameter and property, but it is still a technical bottleneck. Herein, a theoretical model has been established to quantitatively predict the diameter of FSWJ. It shows that the variation of radius with axial distance follows a power law with an exponent −1/4 for a fully charged jet, while the exponent increases for a partly charged jet. In addition, the stretching of FSWJ has been predicted by a scaling model of relation between stretch rate and axial distance, whose exponent gradually increases to −1/2 as the surface charge tends to saturation. Meanwhile, the experimental results achieved by a novel characterization method agreed well with the theoretical values calculated from the derived models. This work provides a new insight on controlling the jet stretching as well as the fiber diameter, which can promote the morphological and functional design of electrospun nanofibers.