A team of researchers at the University of Toronto designs a solution to reduce the amount of microplastic fibers shed when washing synthetic fabrics. But University of Toronto researchers say the slippery solution to this problem could already be in household cabinets, a silicon-based organic polymer coating.
PDMS Brushes with Two-layer Coatings
When clothes made from synthetic fabrics go in the washing machine, the friction caused by cleaning cycles produces tiny tears that cause microplastic fibers, measuring less than 500 micrometers in length, to break off and make their way down laundry drains to enter waterways, where the particles can be difficult to remove and take decades or more to fully break down.
Kevin Golovin, an assistant professor of mechanical and industrial engineering in the Faculty of Applied Science & Engineering, and his team have created 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.
Experiments conducted by the team shows that this coating can significantly reduce microfiber shedding of nylon clothing after repeated laundering, according to findings published in Nature Sustainability.
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My lab has been working with this coating on other surfaces, including glass and metals, for a few years now,” said Golovin. “
One of the properties we have observed is that it is quite slippery, meaning it has very low friction.” PDMS is used in shampoos to make hair shiny and slippery and is also used as a food additive in oils to prevent liquids from foaming when bottled.
Sudip Kumar Lahiri, a post-doctoral researcher in Golovin’s lab and lead author of the study, reasons that reducing the friction that occurs during wash cycles with a PDMS-based fabric finish could prevent fibers from rubbing together and breaking off during laundering.
Molecular Primer Developed to Retain PDMS Brushes on the Fabric
One of the biggest challenges the researchers faced during their study was ensuring the PDMS brushes stayed on the fabric. Lahiri, who is a textile engineer by trade, developed a molecular primer based on his understanding of fabric dyes.
Lahiri figured the type of bonding responsible for keeping dyed apparel colorful after repeated washes would work for the PDMS coating as well.
Neither the primer nor the PDMS brushes work separately to decrease the microplastic-fiber shedding. But together, they created a strong finish that reduced the release of microfibers by more than 90 per cent after nine washes.
Researchers to Make Water-repellent Material Become Hydrophilic
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PDMS brushes are environmentally friendly because they are not derived from petroleum like many polymers used today. With the addition of Sudip’s primer, our coating is robust enough to remain on the garment and continue to reduce micro-fiber shedding over time,” continued Golovin.
Since PDMS is naturally a water-repellent material, the researchers are currently working on making the coating hydrophilic so that coated fabrics will be better able to wick away sweat.
The team has also expanded the research to look beyond nylon fabrics, including polyester and synthetic-fabric blends.
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Many textiles are made of multiple types of fibers,” added Golovin. “
We are working to formulate the correct polymer architecture so that our coating can durably adhere to all of those fibers simultaneously.”
Source: University of Toronto