New self-healing fabric can neutralise toxic chemicals

Scientists, including one of Indian origin, have created a new self-healing fabric which can break down toxic materials and may help make suits to protect soldiers from chemical or biological attacks.
"Fashion designers use natural fibres made of proteins like wool or silk that are expensive and they are not self-healing," said Melik C 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," said Demirel.
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 amenable to scale-up," according to the researchers, including Srinivas Tadigadapa, professor at Penn State.
Polyelectrolyte coatings are made up of positively and negatively charged polymers, in this case polymers like those in squid ring teeth proteins.

"We currently dip the whole garment to create the advanced material. But we could do the threads first, before manufacturing if we wanted to," said Demirel.
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 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 coatings are thin, less than a micron, so they wouldn't be noticed in everyday wear," said Demirel.
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 minimise infections for quick recovery.
The research appears in the journal ACS Applied Materials and Interfaces.