— By Dede Williams — 

Efforts by researchers at the University of Toronto in Canada to find safer alternatives to the conventionally used polytetrafluoroethylene (PTFE) in non-stick coatings for cookware appear to be paying off.

Used since the 1940s and best known under its commercial trademark Teflon, PTFE is efficient in repelling both grease and water but contains what today is considered to be excessive levels of per- and polyfluoroalkyl substances (PFAS), the so-called “forever chemicals”.

Up to now, finding a less toxic substance that could perform as well as a PFAS-based solution has proved elusive. The one currently being tested, polydimethylsiloxane (PDMS, or in simpler terms, silicone), is said to have many advantages, however.

Following initial trials, the team led by Kevin Golovin, head of the Durable Repellent Engineered Advanced Materials (DREAM) laboratory at the university’s engineering school, known by its acronym MIE, hopes that its new material will offer the same protective properties as Teflon but have a greatly reduced level of PFAS and therefore fewer negative effects on health and the environment.

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Depending on how it is formulated, PDMS – which is often used in devices designed to be implanted into the body – can be very biocompatible, Golovin says. However, until recently, “we couldn’t get it to perform quite as well as PFAS”.

The breakthrough came when PhD student Samuel Au developed a new chemical technique that the team has dubbed nanoscale fletching – the process is explained in a paper published in the journal Nature Communications. To overcome the performance problems, says Au, the team bonded short chains of PDMS to a base material.

As he explains, PFAS molecules are made of chains of carbon atoms, each of which is bonded to several fluorine atoms. While the inertness of the bonds creates the desired non-stick properties, the same chemical inertia also keeps the substances from breaking down.

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But not only are PFAS persistent in the environment, the molecules can also accumulate in biological tissue in concentrations that can become amplified as they travel up the food chain in such ubiquitous applications as non-stick coatings, for example. Chronic exposure to even low levels has been linked to liver damage, high cholesterol, reduced immune responses, low birth weights, and several kinds of cancer. Long-chain molecules are usually seen as more harmful than the shorter ones.

To improve the new coating’s ability to repel oil, the Canadian scientists have added to the formula the shortest possible PFAS molecule, consisting of a single carbon with three fluorines attached to it. Like bristles on a brush, “we were able to bond about seven of those to the end of each PDMS bristle”, Au says.

On a scale developed by the American Association of Textile Chemists and Colorists, the new coating is said to have achieved a performance grade of 6, on par with that of many standard PFAS-based coatings.

Golovin says the team is open to collaborating with manufacturers of non-stick coatings who may be interested in scaling up and commercialising the process. In the meantime, it will continue working on further alternatives.

“The holy grail of this field would be a substance that outperforms Teflon, but with no PFAS at all,” the professor concludes.

Many countries and political blocs are still struggling to get PFAS exposure under control. This past spring, Canada proposed phasing out forever chemicals in many products. Restrictions coming into force from 2027 would first target firefighting foam, followed by cosmetics, food packaging, and textiles, before being extended to prescription drugs and medical devices.

The ban, however, would at first exclude fluoropolymers as research continues. Guidelines for PFAS in drinking water were issued in 2024.

Under administrator Lee Zeldin, the US Environmental Protection Agency (EPA, Washington, DC; www.epa.gov) is working on an adapted plan to combat PFAS, while the EU is slowly moving ahead with its research amid little fanfare. Separately, France in February this year banned the production of some products containing PFAS, including water-repellent clothing and ski wax.