Fabric repels both oil and water thanks to clever silicone coating

By Layal Liverpool

A new method of making fabric that repels oil and water could help clothing become more environmentally friendly and sustainable.

Coating fabrics with chemicals called perfluorinated compounds is a common way in which clothing and other textiles are made oil and water-repellent. However, there has been growing concern about the use of these chemicals because they contain toxins that harm the environment and don’t degrade easily.

Kevin Golovin at the University of British Columbia, Canada, and his colleagues came up with a set of chemical equations that relate a fabric’s structure and surface chemistry to its ability to repel oils. Using their equations, a particular weave pattern can be matched with a carefully designed form of silicone, which is then used to coat the fibres. The silicone coating makes the fabric repellent to oil and water and it is more environmentally friendly than perfluorinated compounds.

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“The coating for a specific woven fabric should be designed with that fabric in mind,” says Golovin. “It isn’t a one-size-fits-all solution anymore, like perfluorinated compound coatings were. Different fabrics may require different coating formulations to achieve the same level of oil repellency.”

Golovin and his team tested this on a nylon jacket. Based on its underlying weave pattern, they predicted that coating the surface of every fibre in the fabric with an extremely thin layer of a particular form of silicone should make it repellent to oil – without the need for perfluorinated compound coating.

They found that the treatment worked in practice too. It was sufficient to change the overall chemical properties of the jacket’s fabric such that it was able to repel rapeseed, olive and castor oils during laboratory tests. It also repelled water and synthetic sweat.

“Silicone-based finishes have been around for decades, but changing the surface chemistry alone is insufficient to make a fabric oil-repellent,” says Golovin. The key was to consider both surface chemistry and textile structure together, he says.

“Perfluorinated compounds are toxic, environmentally persistent and accumulate in the bodies of living organisms. However, prior to our work, they were the only compounds that had shown oil repellency on textiles,” says Golovin.

There is no good reason to harm the environment for the sake of keeping our clothes dry, says Clara Barker at the University of Oxford, who wasn’t involved with the work. Barker says durability tests will now be important to make sure fabric with the silicone finish can still handle wear and tear.

Journal reference: Nature Sustainability, DOI: 10.1038/s41893-020-0591-9