Penn State University researchers have developed a polyelectrolyte coating that, when applied to conventional fabrics, allows them to self-heal.

The technology could help pave the way for the development of chemically protective suits made of fabric coated in self-healing films that protect soldiers from chemical or biological attacks or factory workers from accidental releases of toxic materials. Polyelectrolyte coatings are made up of positively and negatively charged polymers, in this case polymers like those in squid ring teeth proteins. The polymer is self-healing in the presence of water, so laundering would repair micro and macro defects in the coating, making such garments rewearable and reusable.

Fabric with hole (left), wet fabric and patch in a drop of water (center) and self-healed fabric (right). Image credit: Demirel Lab/Penn State.Fabric with hole (left), wet fabric and patch in a drop of water (center) and self-healed fabric (right). Image credit: Demirel Lab/Penn State. The procedure for applying it to textiles is simple: the fabric is dipped in a series of liquids to create layers of material to form a self-healing, polyelectrolyte layer-by-layer coating. The coating is deposited under ambient conditions in safe solvents, such as water, at low cost using simple equipment amenable to scale-up.

"We currently dip the whole garment to create the advanced material," says Melik Demirel, professor of engineering science and mechanics. "But we could do the threads first, before manufacturing, if we wanted to."

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.

Many toxic substances can be absorbed through the skin. Organophosphates, for example, which are used as herbicides and insecticides, can be lethal. A garment coated with a self-healing film containing an organophosphate hydrolase, an enzyme that breaks down the toxic material, could limit exposure.

Future use of these coatings in medical meshes could also help patients minimize infections for quick recovery, according to the researchers.

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