Â鶹ÒùÔº

Scientists make water-repellent replacement for toxic 'forever chemicals'

A team of international scientists has invented a substitute for synthetic chemicals, called PFAS (perfluoroalkyl substances), which are widely used in everyday products despite being hazardous to health and the environment.

Until now, it was believed fluorine—the element in such products which forms a highly effective barrier between substances like air and water, making them water repellent—could not easily be replaced because of its unique properties.

But scientists from the University of Bristol in the US, Hirosaki University, Japan, and Université Côte d'Azur, France, have discovered that the unique "bulky" attribute of fluorine, which makes it especially good at filling space, can actually be replicated in a different, non-toxic form. The findings are in the Journal of Colloid and Interface Science.

Co-lead author Professor Julian Eastoe, from the University of Bristol's School of Chemistry, said, "From fire-fighting foam to furniture, food packaging and cookware, to make-up and toilet tissue, PFAS products are everywhere. Despite the risks to human health, and the fact they don't degrade, perfluoroalkyl substances persist in the environment, finding an alternative with comparable properties has proven elusive. But after many years of intensive research, we've made a great breakthrough."

The results of their discovery are published in a study which unpacks the chemical structure of PFAS and pinpoints the characteristic "bulkiness" they sought to replicate in a safer form. It also demonstrates how non-fluorinated components, containing only non-toxic carbon and hydrogen, could be equally effective replacements.

Prof Eastoe said, "Through extensive experimentation, it turns out these 'bulky' fragments feature in other common chemical systems like fats and fuels. So we took those principles and created modified chemicals which have these positive attributes and are also much safer.

"Using our specialized laboratories for chemical synthesis, we substituted the fluorine in PFAS with certain groups containing only carbon and hydrogen. The whole process has taken about 10 years and the implications are very significant not least because PFAS is used in so many different products and situations."

The researchers now plan on using these principles discovered in the lab to design commercially viable versions of PFAS substitutes.

Co-author Professor Frédéric Guittard, from the Université Côte d'Azur, Nice said, "These new results are of great interest for industrial and academic researchers. We are now working with companies in France and China to bring these ideas to market."