Magnetospinning instead of electrospinning
How to get nanofibers using a refrigerator magnet?
Alexander Tokarev, "Science and Life" based on the materials of the University of Georgia: "Magnetospinning" used to create new nanofibersResearchers from the University of Georgia (University of Georgia, GA, USA) in collaboration with colleagues from Princeton and Oxford have developed a new method for producing ultrathin polymer filaments – nanofibers.
The results are published in the journal Advanced Materials (Tokarev et al., Magnetospinning of Nano- and Microfibers), a patent application has been filed.
Figures a–d show the principle of magnetospinning. The e–f photographs taken with an electron microscope show the resulting nanofibers. The g–h photographs show ~2500 nanofibers obtained in 5 minutes at a magnet rotation speed of 500 rpm.
The new method, called magnetospining (from the English spinning – spinning, pulling the thread) is very easy to use and allows you to obtain large volumes of nanofibers thousands of times thinner than a hair, which can be used to create new materials. Nonwovens based on nanofibers have broad prospects, in particular, for the manufacture of filters, and in medicine for growing new organs, testing medicines and delivering medicines to foci of infections in the human body.
The essence of the method is that the polymer solution is mixed with magnetic particles, for example, iron oxide, and is fed through a syringe in drops to a magnet fixed on a rotating stand, the rotation frequency of which can be adjusted from 5 to 5000 revolutions per minute. At the time of the drop supply, the magnet is located at the maximum distance. When a magnet approaches a drop, it is attracted to it. The magnet continues to rotate, forming a liquid polymer bridge between the magnet and the needle. The diameter of the bridge gradually decreases to nanometer sizes, the solvent evaporates and a nanofiber is formed. With a magnet rotation speed of more than 1000 revolutions per minute, more than 50 kilometers of nanofiber can be produced in 5 minutes. This simple process makes it possible to obtain high-quality nanofibers.
Currently, the most popular method for obtaining nanofibers is electrospinning, in which fibers are pulled out of a polymer solution using high voltage. The main disadvantage of this method is that it does not allow working with solutions of polymers with low dielectric permittivity, for example, Teflon. In addition, it is quite expensive. The cost of an electrospinning device starts at $ 10,000, while a magnetospinning system can be built using a magnet for $5, a simple electric motor for $ 30 and a syringe.
"The method that we have developed makes it possible to obtain high–quality nanofibers without using expensive equipment," the authors of the article note. "This method not only reduces the cost of fiber production, but also makes it possible for universities and companies to experiment with nanofibers without spending a lot on research." Note also that working with high voltages always carries a danger.
The new method can be used for the manufacture of nanofibers and water-repellent surfaces made of Teflon, obtaining porous and composite nanofibers. In addition, it was found that nanofibers obtained by magnetospinning are not toxic to cells and can be used to grow artificial organs.
It is curious that electrospinning has been known for more than 100 years, since 1887, and the first patents for it were issued in the USA in 1902. However, then he was focused on the textile industry. Our country has also contributed to the development of this technology. In 1938, on its basis, the future academician I.V. Petryanov-Sokolov developed the so-called "Petryanov filters", which were used, in particular, in gas masks and in the nuclear industry. A new surge of work on this topic began in the early 1990s, when the applicability of the method to many organic polymers was shown and nanotechnology began to develop. Since then, the number of papers on this topic has been growing exponentially every year.
Portal "Eternal youth" http://vechnayamolodost.ru18.05.2015