![Self-repairing coated fabrics. From left to right: fabric with a hole in the center, wet fabric and patched with a drop of water, fabric after self-repair. [Courtesy: Demirel Lab / Penn State]](https://www.hayadan.org.il/images/content3/2016/08/3image_11-500x126.jpg)
[Translation by Dr. Nachmani Moshe]
In the near future, chemical protective suits made of fabric with a self-repairing coating will be able to protect farmers from exposure to organophosphorus pesticides, soldiers from chemical/biological warfare agents on the battlefield, and factory workers from accidental leakage of toxic substances, according to the researchers.
"Fashion designers use natural fabrics made of proteins, such as wool or silk, which are expensive and incapable of self-repair," said Melik C. Demirel, professor of engineering sciences. "We are looking for a way to produce fabrics that are able to repair themselves through routine weaving." The procedure is very simple - the material to be coated is immersed in a series of liquids to prepare layers of self-repairing material, in the process of coating layer by layer. The coating can be obtained "under mild conditions in safe solvents, such as water, at low cost, using simple equipment that also allows large-scale production", the researchers describe their findings in an article published in the scientific journal ACS Applied Materials & Interfaces.
Polyelectrolytic coatings are made of positively and negatively charged polymers, in this case - polymers similar to those found in the proteins that make up the attachment rings in squid legs. "We immerse the entire assembly in order to prepare the advanced material," said the chief researcher. While laying the layers one by one, enzymes can be incorporated into the coating. The researchers used the enzyme urease - the enzyme that breaks down urea into ammonia and carbon dioxide - but in commercial use, enzymes adapted to the target substance will be combined. "If you need to use enzymes for biological or chemical purposes, it will be possible to trap the enzyme in capsules with self-repairing properties so that they can break down the toxin before it reaches the skin," explains the lead researcher.
Many toxic substances can be absorbed through the skin layer. Organophosphorus substances, for example, used in pesticides and herbicides are absorbed through the skin and can be fatal to humans and animals. Some of these substances are also used in nerve gases (chemical warfare agents). Clothing that has been coated with a layer of self-repairing material that contains organo-phosphorus hydrolase, an enzyme that breaks down the toxic substance, will be able to prevent fatal exposure to the body. The self-repairing polymer does this in the presence of water, so washing can simply repair micro- and macro-defects in the coating, making the garment highly suitable for repeated use and wear. "The coating itself is extremely thin, less than one micron, so it will not be possible to see it with a normal eye," said the researcher. "Despite their small thickness, the coatings increase the overall strength of the material."
For production environments where it is necessary to use hazardous materials, coated clothing with the appropriate enzyme combination can protect against accidental leakage of such materials. Future use of these coatings in the field of medical clothing could also help hospitalized patients reduce their potential for infection and speed up recovery.
Self-repairing coated fabrics. From left to right: fabric with a hole in the center, wet fabric and patched with a drop of water, fabric after self-repair. [Courtesy: Demirel Lab / Penn State]
