A UT research team has developed an all-natural, highly effective flame retardant. 

Cockrell School of Engineering associate professor Christopher Ellison and Amanda Jones, a postdoctoral fellow working in Ellison’s lab, have found that the chemical polydopamine performs two fire-reducing processes: producing char and capturing free radicals. Polydopamine also sticks to surfaces, which means it won’t leach out like most flame retardants.

“It’s like if you’ve taken a marshmallow and you’ve gotten it too close to the fire, and it starts on fire, it’ll burn until it generates this porous carbon on the outside — but the inside’s still good,” Ellison said. “The fire will actually self-extinguish as it makes that char on the outside.” 

Scientists derive polydopamine from dopamine. Dopamine is a natural compound that animals use as a neurotransmitter — it’s usually associated with the brain’s pleasure system. 

Polydopamine can capture free radicals, small molecules that form when a material catches fire. Free radicals attack other materials and make them more likely to catch fire. 

Most flame retardants currently on the market have only one flame protecting property, and are not as effective as polydopamine. In addition, researchers have found that many flame retardants are toxic and accumulate in the body.

For example, the EU banned the flame retardant polybrominated diphenylether because of toxicity concerns — it accumulates in the bodies of ringed seals and in human breast milk, according to Ellison. After Sweden banned it, the amount in Swedish breast milk began to drop.

“In Europe, you almost unequivocally have to prove that this chemical is not damaging to living organisms,” Ellison said. “In the United States, they’re usually allowed to manufacture until something is discovered.”

Ellison said this scientific discovery was unusually struggle-free.

“This is one of the few rare instances where I would say the hypothesis was almost exactly as we thought it might be,” Ellison said. “It worked the first time, and research almost never goes this way. 98, 99 percent of the time your experiment fails.”

However, their work isn’t done. Jones is now picking up the project from a doctoral student who has since graduated. She said she plans to investigate similar natural compounds to see if they are also flame retardant. 

“If dopamine works so well, there might be other ones that work really well,” Jones said. “We’re thinking about issues like scalability, biocompatibility and color — the dopamine does turn it brownish-black. It’s something that might be important for clothing or consumer products that are visible.”

Jones said the team has a lot of work to do — they are hopeful that they’ll make functional improvements and increase their work’s marketability. 

“We’re really just starting in this area,” Jones said.