Researchers at the University of Texas are testing nanocoatings of polydopamine, based on the nervous system messenger molecule dopamine, as a flame retardant for polyurethane foams. The idea was inspired by marine mussels which use the compound to adhere strongly to surfaces.
The foam was simply immersed in aqueous dopamine solution at pH 8.5 for 1-3 days, compressing the foam several times to ensure solution uptake into pores and with vigorous stirring, followed by rinsing in water and drying. This resulted in a 240 nm layer of polydopamine on the foam surface. This treatment reduced peak heat release rate from foam samples by up to 2/3 and prevented melt-dripping. The researchers suggest that the polydopamine acts against fire both by forming a strong char surface on the foam and by releasing the amine group which neutralises free radicals in fire gases.
“Bioinspired Catecholic Flame Retardant Nanocoating for Flexible Polyurethane Foams”, J. Cho et al., Chemistry of Materials (ACS) DOI: 10.1021/acs.chemmater.5b03013 www.pubs.acs.org/cm