U of T researchers develop safer different to non-stick coatings

A brand new materials developed by University of Toronto researchers might provide a safer different to the non-stick chemical substances generally utilized in cookware and different functions. 

The substance is able to repelling water and grease about in addition to normal non-stick coatings; it additionally accommodates far decrease quantities of per- and polyfluoroalkyl substances (PFAS), a household of chemical substances – that features Teflon – which have raised environmental and well being considerations.

It was developed within the Durable Repellent Engineered Advanced Materials (DREAM) laboratory at U of T’s Faculty of Applied Science & Engineering utilizing a novel chemistry method described in Nature Communications.

“The research community has been trying to develop safer alternatives to PFAS for a long time,” says Kevin Golovin, an affiliate professor within the division of mechanical and industrial engineering who heads the DREAM lab. “The challenge is that while it’s easy to create a substance that will repel water, it’s hard to make one that will also repel oil and grease to the same degree. Scientists had hit an upper limit to the performance of these alternative materials.” 

Since its invention within the late Nineteen Thirties, Teflon – also called polytetrafluoroethylene or PTFE – has been prized for its skill to repel water, oil and grease alike.

Its non-stick properties are the results of the inertness of carbon-fluorine bonds, with PFAS molecules consisting of chains of carbon atoms, every bonded to a number of fluorine atoms.

However, this chemical inertness additionally causes PFAS to withstand the conventional processes that may break down different natural molecules over time. For this purpose, they’re generally known as ‘forever chemicals.’ 

In addition to their persistence, PFAS are identified to build up in organic tissues, and their concentrations can change into amplified as they journey up the meals chain. 

Various research have linked publicity to excessive ranges of PFAS to sure forms of most cancers, beginning defects and different well being issues, with longer-chain PFAS typically thought of extra dangerous than the shorter-chain selection.

Despite the dangers, the dearth of options implies that PFAS stay ubiquitous in shopper merchandise: along with cookware, they’re utilized in rain-resistant materials, meals packaging and cosmetics.

The materials Golovin’s staff have been working with is a substitute for PFAS known as polydimethylsiloxane (PDMS).

“PDMS is often sold under the name silicone, and depending on how it’s formulated, it can be very biocompatible – in fact it’s often used in devices that are meant to be implanted into the body,” says Golovin. “But until now, we couldn’t get PDMS to perform quite as well as PFAS.” 

To overcome this drawback, PhD pupil Samuel Au developed a brand new method known as nanoscale fletching which entails bonding brief chains of PDMS to a base materials – which Au likens to bristles on a brush.

“To improve their ability to repel oil, we have now added in the shortest possible PFAS molecule, consisting of a single carbon with three fluorines on it. We were able to bond about seven of those to the end of each PDMS bristle,” says Au.

“If you were able to shrink down to the nanometre scale, it would look a bit like the feathers that you see around the back end of an arrow, where it notches to the bow. That’s called fletching, so this is nanoscale fletching.” 

The staff coated the brand new materials on a chunk of material, earlier than inserting drops of varied oils on it to check its repellency.

The coating achieved a grade of 6 on an American Association of Textile Chemists and Colorists scale – inserting it on par with many normal PFAS-based coatings.

“While we did use a PFAS molecule in this process, it is the shortest possible one and therefore does not bioaccumulate,” says Golovin. 

“What we’ve seen in the literature, and even in the regulations, is that it’s the longest-chain PFAS that are getting banned first, with the shorter ones considered much less harmful. Our hybrid material provides the same performance as what had been achieved with long-chain PFAS, but with greatly reduced risk.” 

Golovin says the staff is open to collaborating with producers of non-stick coatings who may want to scale up and commercialize the method. In the meantime, they are going to proceed engaged on much more options. 

“The holy grail of this field would be a substance that outperforms Teflon, but with no PFAS at all,” says Golovin. “We’re not quite there yet, but this is an important step in the right direction.”