A new technology to coat fabric in self-healing, thin films may one day lead to chemically protective suits that may prevent farmers from exposure to pesticides, soldiers from chemical or biological attacks in the field and factory workers from accidental releases of toxic materials, say researchers. “Fashion designers use natural fibres made of proteins like wool or silk that are expensive and they are not self-healing,” said Melik Demirel, Professor at Pennsylvania State University in the US.
“We were looking for a way to make fabrics self-healing using conventional textiles. So we came up with this coating technology,” Demirel said. The procedure is simple. The material to be coated is dipped in a series of liquids to create layers of material to form a self-healing, polyelectrolyte layer-by-layer coating. Polyelectrolyte coatings are made up of positively and negatively charged polymers.
This coating is deposited “under ambient conditions in safe solvents, such as water, at low cost using simple equipment amenable to scale-up,” the researchers reported online in the journal ACS Applied Materials & Interfaces. “We currently dip the whole garment to create the advanced material,” Demirel said. “But we could do the threads first, before manufacturing if we wanted to,” he noted.
During the layering, enzymes can be incorporated into the coating. The researchers used urease — the enzyme that breaks urea into ammonia and carbon dioxide — but in commercial use, the coating would be tailored with enzymes matched to the chemical being targeted. “If you need to use enzymes for biological or chemical effects, you can have an encapsulated enzyme with self-healing properties degrade the toxin before it reaches the skin,” Demirel explained.
“The coatings are thin, less than a micron, so they wouldn’t be noticed in everyday wear,” Demirel said. For manufacturing environments where hazardous chemicals are necessary, clothing coated with the proper enzyme combination could protect against accidental chemical releases. The researchers believe that future use of these coatings in medical meshes could also help patients minimise infections for quick recovery.