After horrific fires involving home furnishings and clothing, manufacturers began adding flame retardants to fabric. It was effective at reducing fires, but there was just one problem: the chemicals used to prevent material from catching fire were often toxic.
Some of the earliest flame retardants, polychlorinated biphenyls (PCBs), were outlawed in the U.S. in 1977. Some of the chemical compounds that took their place are now getting close scientific scrutiny.
Naturally occurring material
Scientists at the University of Texas (UT) have developed a flame retardant from naturally occurring material found in some marine mussels. They believe the material could give manufacturers a way to prevent fires while keeping toxic chemicals out of the environment.
Flame retardants are widely used in manufacturing, especially in furniture. These chemicals are added to foams found in mattresses, sofas, car upholstery, and many other consumer products.
Scientists have found that once the flame retardant chemicals are embedded into the foam, they don't stay there. Over time they can be released into the air and environment.
In some states environmental activists are putting pressure on legislature to ban some flame retardants, especially the ones containing brominated compounds (BRFs), a mix of human-made chemicals thought to pose a risk to public health.
A team of UT researchers, led by engineering associate professor Christopher Ellison, found that a synthetic coating of polydopamine — made from the natural compound dopamine — is highly effective when used as a water-applied flame retardant for polyurethane foam.
Dopamine is found in humans and animals and facilitates signals in the brain and other parts of the body. The researchers believe their dopamine-based nanocoating would work just as well as the chemicals that activists find objectionable.
“Since polydopamine is natural and already present in animals, this question of toxicity immediately goes away,” Ellison said. “We believe polydopamine could cheaply and easily replace the flame retardants found in many of the products that we use every day, making these products safer for both children and adults.”
67% reduction in peak heat
The scientists say a smaller amount of polydopamine works just as well, or better, than current flame retardants. It leads to a 67% reduction in peak heat release rate, a measure of fire intensity and imminent danger to building occupants or firefighters.
In fact, they say the natural flame retardant’s ability to reduce a fire’s intensity is about 20% better than existing chemical-based flame retardants commonly used today.
As many discoveries are, this one came about by accident. The UT researchers were experimenting with synthetic polydopamaine for health purposes, including as a cancer drug delivery system, when they observed its flame reduction properties.
To the team members' surprise, they didn't even have to change the structure of the polydopamine from its natural form to use it as a flame retardant. The substance was coated onto the interior and exterior surfaces of the polyurethane foam by simply dipping it into a water solution of dopamine for several days.