Initial Jet Before the Onset of Effective Electrospinning of Polymeric Nanofibers

Lei Xu,Dezhi Wu,Wen Han,Xiang Wang,Gaofeng Zheng,Daoheng Sun

doi:10.2174/1874155x01509010666

Abstract

Initial jet usually has a large primary droplet hanging at flying end before the onset of effective electrospinning. The primary droplet is undesired as its diameter is several orders of magnitude higher than that of electrospun nanofibres. A new method is used to derive micro-scaled initial jet and fine primary droplet under applied small-aperture needle by utilizing low solution flow rate and pre-applied electric potential before the extrusion of polymeric solution out of the needle. Small-aperture needle reduces the base of conical pendant, while low solution flow rate prevents a fluidic inrush into conical pendant. The pre-applied electric potential preforms a miniature liquid cone, as an origin of initial jet, within the needle. The conic preformation reduces the formation time of Taylor cone in order to escape from a swollen Taylor cone under a continuous inflow of polymeric solution. The miniature conical pendant grows so acute that it emits fine primary droplet rapidly from its tip with accumulated ions. Carrying primary droplet, thin initial jet experiences axial elongation and circumferential rotation in the space.

Highlights

Electrospinning has promising applications in filtering [1,2,3], sensing [4, 5], and biomedical [6, 7] fields owing to its excellent ability to produce nanofibers with high surface-tovolume ratio
Fig. (1) characterizes three transitional stages for the formation of thin initial jet, which was photographed at the frame rate of 2500 fps, under applied polymeric solution flow rate of 10 μL/hr
The primary droplet flies so straightly that a thin initial jet connects conical pendant with flying primary droplet owing to the viscoelasticity of polymeric solution as shown in Fig. (1a)

Summary

INTRODUCTION

Electrospinning has promising applications in filtering [1,2,3], sensing [4, 5], and biomedical [6, 7] fields owing to its excellent ability to produce nanofibers with high surface-tovolume ratio. Sun et al [19] developed near-field electrospinning to paint a fine pattern by collecting the quasilinear jet; Yang et al [20] observed a swing of quasilinear segment that enlarges the deposition region of nanofibers on substrate. The primary droplet is large and undesired as its diameter is usually several orders of magnitude higher than that of electrospun nanofibres. It might play an important role in pulsated electrohydrodynamic printing [23]. A new method is used to generate thin initial jet and fine primary droplet under applied small-aperture needle and low solution flow rate by utilizing pre-applied electric potential prior to the extrusion of PEO solution out of the needle

EXPERIMENT

RESULTS AND DISCUSSION

CONCLUSION