Electrospinning of nanofibers

One-dimensional (1-D) nano-composite fibers (i.e. long fibers with a nano-scale diameter) have attracted considerable attention, owing to their potential applications in sensors, as antibacterial materials, in gas separation, in lithium-ion batteries, and as photocatalysts. - Electrospinning technology has proved to be a simple, efficient, and versatile way to fabricate nano-composite fibers.  

CNTs are a prospective novel material for multi-component nano-composite fibers, as they have been widely applied as composites components because of their excellent optical, mechanical, and electrical properties. Cobalt ferrite (CoFe204) nanoparticles are an important magnetic material used in high-density data storage, ferrofluids, and electronic devices.  

with an average molecular weight of 150 000, was purchased from Aldrich Chemical Company, USA. Multi-walled CNTs with diameter of 20-30 nm were purchased from Wako Pure Chemical Industries, Ltd., Japan. All other reagents in this work were of analytical grade and used as received without further purification. 

Pristine CNTs (30 mg) were first dispersed into 60 mL nitric acid (10 M) by ultrasonication for 1 h. This CNT suspension was then transferred into a round-bottomed flask equipped with a magnetic stirring bar and a reflux condenser, and refluxed at 130°C for 12 h with vigorous stirring. The treated CNTs were washed repeatedly with deionized water and ethanol to remove any residual nitric acid. The CNTs were collected by filtration and dried in a vacuum drying oven. 

The synthesized CoFe204 particles were dispersed ultrasonicaUy in dimethyl formamide (DMF) for 1 h, and PAN was added into this solution. The PAN concentration was kept at 8 wt.%. After stirring, the solution was used to spin the nanofibers by electrospinning. As a comparison, nanofibers with several CoFe204 loadings were prepared. 

Nanotechnology literally means any technology performed on a nanoscale that has applications in the real world [1]. The electrospinning electrostatic spinning) method and its products are principally related to nanotechnology. The diameters of electrospun fibers are usually from several nanometers up to a few microns, but they are typically in the submicron range. These fibers are called nanofibers in the literature [38] because they have unique properties compared to microfibers. 

Electrospinning was developed from the electrospraying method which was first patented in 1902 by Morton [39] and Cooley [40] who both invented methods that were able to disperse fluids with the help of electrostatic forces. The other important step which led to the electrospinning technique as known today was the workmanship of Zeleny [41]. 

In 1934 Formhals developed a feasible method [42] to obtain yarns via electrospinning. Somehow the technology was less appreciated and did not have either scientific or industrial importance. As nanotechnology became a well-researched field, several scientists began to focus on electrospinning in the 1990s. 

Inasmuch as we focus on the composite applications of nanofibers, only the most important fields are introduced here, and even those only briefly. The first one is filtration, which is currently the primary utilization of electrospun nanofibers. Nanofibrous mats axe available in the market and can be applied in industrial filters, and in air and water cleaning systems. It is also an example for functionalized nanofibers because these nanomaterials contain activated carbon particles and therefore can fQter out different chemicals in addition to submicron particles [44]. 

The biomedical field is very wide but can principally be divided into three different groups  

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Yarin, A.L., Koombhongse, S., and Reneker. D.H., 2001b, Taylor cone and jetting from liquid droplets in electrospinning of nanofibers, J. Appl. Phys.. 9(90), pp. 4836-4845. 

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Haghi A. K., Electrospinning of Nanofibers in Textiles, Apple Academic Press, NJ, 2012. 

Yarin, A.L., Koombhongse, S. and Reneker, D.H. 2001. Bending instability in electrospinning of nanofibers. 

Wnek G, Carr M, Simpson D and Bowlin G, Electrospinning of nanofiber fibrinogen stmctures Nano Lett., 2003,3,213-216. 

Yarin, A, Koombhongse S and Reneker D, Bending instabihty in electrospinning of nanofibers ,/.App/. Phys., 2001,89,3018-3026. 

Kowalewski, T. A., Barral, S., and Kowalczyk, T. Modeling Electrospinning of Nanofibers. lUTAM Symposium on Modelling Nanomaterials and Nanosystems, 13, 219-29Z (2009). 

Haggenmueller R, Gommans H H, Rinzler A G, Fischer J E and Winey K I (2000) Aligned singlewall carbon nanotubes in composites by melt processing methods, Chem Phys Lett 330 219-225. Reneker D H, Yarin A L, Zussman E and Xu H (2007) Electrospinning of nanofibers from polymer... 

Electrospinning of nanofibers, measurement of birefringence and fiber dimensions in the mat, discussed. 

Polymer/surfactant interaction in Lin et al. (2004) electrospinning of nanofibers studied. Cationic surfactants additives reported to improve the solution conductivity, but with no effect on the viscosity. 

McCann, J. T., D. Li, and Y. N. Xia (2005). Electrospinning of nanofibers with core-sheath, hollow, or porous structures. Journal of Materials Chemistry 15(7) 735-738. 

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