Treating soft furnishings with toxic flame-retardants could be avoided in the future thanks to a new non-flammable polymer developed by US scientists. 

Polyurethanes are used in a wide variety of common products, including upholstery and mattresses, in the form of flexible foams. However, they are naturally combustible and flame-retardants must be added to meet safety regulations, but these can bring further disadvantages. 

'Some fire-retardant additives, especially halogenated examples, have been shown to be toxic and bio-accumulative,' explains lead researcher Todd Emrick at the University of Massachusetts, Amherst. They can also adversely affect the physical properties of the polyurethane, he adds. 

Deoxybenzoin-based polymers have been found to have low heat release rates and high char formation - two key measures of low flammability materials, says Emrick. Charring insulates the polymer-air interface and reduces heat conduction. Emrick synthesised two novel deoxybenzoin-containing monomers, and explored their polymerisation chemistry with different diols, producing polyurethanes that were more flame resistant than conventional ones without the need for environmentally hazardous additives.

'Their approach is to develop some high char materials and they succeeded in that,' comments Charles Wilkie an expert on fire retardancy and polymer degradation at Marquette University, Milwaukee, US. 

Emrick says he hopes to scale up the synthesis for use in industry. 

Erica Wise 

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