Transformation of Helically Structured Nanofibers into Linearly Oriented Nanofibers
- PDF / 504,188 Bytes
- 5 Pages / 612 x 792 pts (letter) Page_size
- 49 Downloads / 217 Views
0888-V05-03.1
Transformation of Helically Structured Nanofibers into Linearly Oriented Nanofibers M. K. Shin, S. J. Park, S. K. Yoon, M. S. Kim, B. K. Gu, I. Y. Kim, S. I. Kim, and S. J. Kim Dept. of Biomedical Engineering, Hanyang University, Seoul, Korea ABSTRACT Helical structures have been fabricated from a solution of poly(2-acrylamido-2-methyl-1propane sulfonic acid) (PAMPS) in water and ethanol by the whipping instability of a jet in a conventional electrospinning system. The simple modification of the electrospinning system involved introducing two parallel subelectrodes, which enabled the transformation of helical nanofibers into linearly oriented nanofibers due to the tensional forces caused by the modified electric field. This means that the tensional forces caused by the modified electric field had an important effect on linearizing the helical structures. Therefore, a technique using modified electric fields can play a significant role as an intermediary between helical structures and onedimensional linear structures. INTRODUCTION In addition to the fabrication of well-aligned nanowires [1] or nanofibers [2], micro- and nanoscale helical structures have attracted much attention recently because of their potential applications, such as nanoscale sensors, transducers, and resonators; helically coiled carbon fibers [3, 4] and metal-oxide helical nanostructures [5–7] have been produced for these purposes. However, for the successful construction of micro- and nanoscale assemblies that possess both structures, it is necessary to investigate the formation of a helical structure and its conversion into a linearly oriented structure. Electrospinning is a good candidate for fabricating and transforming helical structures because of its unique processing capability. The electrospinning technique is an electrostatic process that uses high voltages to induce the formation of a liquid jet. When a high voltage is applied to a syringe tip containing a polymer solution, a conical object known as the Taylor cone is formed. Once the electrostatic force overcomes the surface tension of the polymer solution, a liquid jet is ejected from the syringe tip, and then undergoes a whipping (or bending) instability, leading to the formation of long and thin fibers [8]. Although the whipping instability generates unstable behavior in the jet [9], it has the advantage of producing helically structured nanofibers. Reneker et al. proved that coiled nanofibers collected on hard surfaces were similar in shape to the whipping instability of a jet photographed using a high-speed camera [10]. In addition, electrospinning has the ability to fabricate oriented nanostructures using an electrospinning system with a modified electric field. Li et al. have fabricated axially aligned polymeric and ceramic nanofibers using a collector consisting of two metal strips separated by an insulating gap [2], and Katta et al. have aligned nanofibers by rotating a copper-wire framed drum [11]. In this work, helically structured nanofibers were fabricated f
Data Loading...
