Canadian researchers have come up with a way to reduce the amount of microfibers that synthetic fabrics shed during the laundry cycle.
The problem, a team from the University of Toronto said, is the same friction meant to shake loose dirt and grime also creates tiny tears in clothing, liberating fibers less than 5 millimeters in length that end up escaping down drains and into waterways, where they can pose a threat to the broader ecosystem.
But the “slippery solution” could lie in a silicon-based organic polymer coating found in many household products, said Kevin Golovin, an assistant professor of mechanical and industrial engineering in the Faculty of Applied Science & Engineering. More specifically, a two-layer coating made of polydimethylsiloxane (PDMS) brushes, which are linear, single polymer chains grown from a substrate to form a nanoscale surface layer.
PDMS is already used in shampoos to give hair shine. It’s also a food additive in oils that prevents liquids from bubbling over when bottled.
“My lab has been working with this coating on other surfaces, including glass and metals, for a few years now,” Golovin said. “One of the properties we have observed is that it is quite slippery, meaning it has very low friction.”
Sudip Kumar Lahiri, a postdoctoral researcher in Golovin’s lab and lead author of the study, said that a PDMS-based finish could keep fibers from rubbing together and breaking off in the wash.
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To ensure that the PDMS brushes actually stayed on the fabric, Lahiri and his colleagues developed a molecular primer similar to the type that keeps dyes from washing out. While neither the PDMS brushes nor the primer worked separately to reduce microplastic shedding, together they were able to slash fiber generation from nylon clothing by more than 90 percent after nine washes.
“PDMS brushes are environmentally friendly because they are not derived from petroleum like many polymers used today,” said Golovin, who was awarded a Connaught New Researcher award from the school for this breakthrough.
Since PDMS is naturally water-repellent, the University of Toronto team is now working on making the coating hydrophilic—that is, water-attracting—so that the fabrics it imbues can better wick away sweat.
The researchers are also expanding their research beyond nylon to look at polyester and synthetic-fabric blends so commonly found in popular athleisure and activewear garments.
“Many textiles are made of multiple types of fibers,” Golovin said. “We are working to formulate the correct polymer architecture so that our coating can durably adhere to all of those fibers simultaneously.”
Many have proposed microfiber filters as one way out of the morass. Patagonia and Samsung, for instance, have created a washing machine with a Less Microfiber Filter that they have dubbed a “breakthrough in the fight against microplastics.” Legislators are paying attention: France will require microfiber catchers in all new laundry appliances by 2025. In Ontario, where the University of Toronto is based, legislative members have introduced a bill that would do the same. Lawmakers in the United Kingdom have been urging a similar requirement, as have members of California’s state legislature. There have also been efforts brewing to recycle and repurpose the collected waste.
“And yet, when we look at what governments around the world are doing, there is no trend towards preventing the creation of microplastic fibers in the first place,” Golovin said. “Our research is pushing in a different direction, where we actually solve the problem rather than putting a Band-Aid on the issue.”