Needleless Electrospinning of Uniform Nanofibers Using Spiral Coil Spinnerets

Xin Wang,Tong Lin,Haitao Niu,Xungai Wang

doi:10.1155/2012/785920

Abstract

Polyvinyl alcohol nanofibers were prepared by a needleless electrospinning technique using a rotating spiral wire coil as spinneret. The influences of coil dimension (e.g., coil length, coil diameter, spiral distance, and wire diameter) and operating parameters (e.g., applied voltage and spinning distance) on electrospinning process, nanofiber diameter, and fiber productivity were examined. It was found that the coil dimension had a considerable influence on the nanofiber production rate, but minor effect on the fiber diameter. The fiber production rate increased with the increased coil length or coil diameter, or the reduced spiral distance or wire diameter. Higher applied voltage or shorter collecting distance also improved the fiber production rate but had little influence on the fiber diameter. Compared with the conventional needle electrospinning, the coil electrospinning produced finer fibers with a narrower diameter distribution. A finite element method was used to analyze the electric field on the coil surface and in electrospinning zone. It was revealed that the high electric field intensity was concentrated on the coil surface, and the intensity was highly dependent on the coil dimension, which can be used to explain the electrospinning performances of coils. In addition, PAN nanofibers were prepared using the same needleless electrospinning technique to verify the improvement in productivity.

Highlights

Electrospinning is a simple but effective method to produce polymer nanofibers [1], and electrospun nanofibers have shown enormous application potential in diverse areas [2, 3]
We found that the spiral coil produced finer nanofibers with a narrower diameter distribution than the needle electrospinning
The nanofibers produced from coil spinneret were much thinner with a narrower fiber diameter distribution compared to those from needle electrospinning, especially when the polyvinyl alcohol (PVA) concentration was higher than 9%

Summary

Introduction

Electrospinning is a simple but effective method to produce polymer nanofibers [1], and electrospun nanofibers have shown enormous application potential in diverse areas [2, 3]. Needleless electrospinning setups have been reported to increase nanofiber production rate [4,5,6,7,8]. Instead of being generated from a needle tip or small opening, jets in needleless electrospinning are formed from a widely open liquid surface. It clearly shows that the jet formation in needleless electrospinning is highly influenced by the external electric field strength. For a three-dimensional setup, the geometry of the spinneret greatly influences the distribution of the electric field intensity affecting the electrospinning process and fiber properties. It was interesting to find that the conical coil setup produced finer nanofibers with a higher productivity compared to the conventional needle electrospinning. We found that the spiral coil produced finer nanofibers with a narrower diameter distribution than the needle electrospinning. A finite element method was used to understand the electric field intensity profile around the coil surface and the influences of coil dimension on the electric field intensity profile and electrospinning performance

Experimental

Results and Discussion

Conclusions