Self-healing textiles can also neutralise chemicals

SRT coated fabric self-heals. From left, fabric with hole, wet fabric and patch in a drop of water, self-healed fabric
A team of researchers from Penn State University have created a self-healing, thin film coating that could be applied to clothes to prevent soldiers from chemical or biological attacks in the field or factory workers from accidental releases of toxic materials.

Melik Demirel, professor of engineering science and mechanics, said: “We were looking for a way to make fabrics self-healing using conventional textiles. So we came up with this coating technology.”

The researchers explained that 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. This coating is deposited under ambient conditions in safe solvents, such as water, at low cost using simple equipment that the team hopes to scale-up.

Polyelectrolyte coatings are made up of positively and negatively charged polymers, in this case polymers like those in squid ring teeth proteins.

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,” said prof Demirel.

Many toxic substances can be absorbed through the skin. Organophosphates, for example, which are used as herbicides and insecticides are absorbed through the skin and can be lethal. Some of these chemicals have also been used as nerve agents. A garment coated with a self-healing film containing an organophosphate hydrolase, an enzyme that breaks down the toxic material, could limit exposure. The squid ring teeth polymer is self-healing in the presence of water, so laundering would repair micro and macro defects in the coating, making the garments rewearable and reusable.

The researchers say that the coating is less than a micron thin, so it wouldn't be noticed in everyday wear, plus it also increases the overall strength of the material.

For manufacturing environments where hazardous chemicals are necessary, clothing coated with the proper enzyme combination could protect against accidental chemical releases. Future use of these coatings in medical meshes could also help patients minimize infections for quick recovery.

Author
Tom Austin-Morgan

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