Polymer electrospinning is a process over a hundred years old. However, it was not until the mid-1990s that it began to gain relevance, thanks to its rediscovery by the group of Dr. Darrell H. Reneker, distinguished professor of Polymer Sciences at the University of Akron in the USA. By a piece of electrospinning equipment for professional use, it is possible to manufacture fibers with diameters from microns (one-millionth of a meter, 1X10-6 m) to nanometers (which is equivalent to one billionth of a meter, 1X10-9 m).
With these dimensions, researchers around the world soon realized the enormous potential of these nanofibers, due to the relationship that exists between the surface area and volume of these materials, a thousand times greater than that of a human hair.
With these properties, electrospun nanofibers have been suggested as structures to improve existing technologies today, as well as to develop novel applications in other areas, including chemical catalysis, gas, and liquid filtration processes, electronics, protective clothing,
controlled release of drugs, supports or scaffolds for the growth of cells or tissues, in addition to many applications that have been emerging as the knowledge of this manufacturing process advances. There are other methods for creating nanofibers, but very few (if not none) match electrospinning, which is very versatile due to the flexibility and ease it offers to produce the fibers.
How electrospinning works
Electrospinning is a process of creating nanofibers using an electrically charged jet of a polymer in solution or molten. Although electrospinning setup is simple and inexpensive, it is an intricate process that depends on various molecular and processing parameters.
On a laboratory scale, a typical electrospinning setup requires a high voltage power source (~ 30 kV) that provides the electrical charge (positive pole) to a solution of a polymer contained in a syringe with a metal needle connected to the source of power. At the other end, there is a metallic collector (negative pole) connected to the ground (aluminum, copper, etc.), where the nanofibers are deposited.
Electrospinning begins when voltage is applied to the tip of the needle where a drop (cone-shaped) of polymer solution forms as a result of its electrostatic polarization. When the electric field strength is greater than the surface tension, the polymer solution is expelled towards the collector in the form of a wire. On the way to the collector, the solvent evaporates to give rise to the formation of a nanofiber that is deposited in the collector, forming a non-woven membrane.
Electrospinning applications
Electronic and energetic applications
The fibers have great potential in the creation of polymeric and lithium batteries. And, likewise, with the manufacturing of this kind of battery, mechanical properties could be utilized to create flexible batteries.
Textile applications
By integrating advanced manufacturing, electrospinning has the potential to produce seamless non-woven garments introducing multi-functionality to textiles. Due to their unique chemical and physical properties, these particles can be applied in creating textiles with self-cleaning, antibacterial, and protection against ultraviolet ray agents.
Another textile application is achieved by adding nanofibers through the electrospinning technique to the garments increasing their endurance.
Medical and pharmaceutical applications
One of the main applications of this technology has been oriented towards the manufacture of biomaterials for use in medicine.
Due to the number of polymers that can be electrospun with different architectures, in recent years research has been carried out to use nanofibers in regenerative medicine (nerves, connective tissue, tendons, insertion of tendons with bone, etc.). It has also been used in the controlled release of drugs that allow reducing doses and increasing the effectiveness of the active compound, as well as in the release of bioactive compounds such as hormones, proteins, enzymes, compounds with insulin resistance properties, and others.
Research is also carried out with the purpose of using these polymeric membranes as scaffolds or supports for the growth of cells and tissues. The incorporation of antibiotics or certain metallic nanoparticles of silver, copper, or zinc has allowed the preparation of electrospun membranes with antimicrobial properties that prevent or impede the growth of microorganisms.
In 2006, the Biopolymers group of the Department of Advanced Materials at CIQA began a line of scientific research (Electrospinning of polymeric nanofibers for biomedical applications), whose purpose is to contribute, to the medium term, to the manufacture of devices and other biomaterials for use in medicine.
Finally, there have been studies carried out for the incorporation of antibiotics, and metallic silver and gold nanoparticles; other compounds, which are used on a daily basis in the treatment of common diseases, as well as chronic degenerative diseases (cancer and diabetes). All these studies have been published in prestigious international scientific journals in the discipline of polymers.
CIQA continues with these investigations in order to contribute to the advancement of the knowledge and application of electrospinning technology in the world.
