Together with Swiss textile businesses, researchers at the Swiss Federal Laboratories for Materials Testing and Research (Empa) have created an environmentally acceptable method for applying a water-repellent coating to fibers.
“We employ what are known as highly cross-linked siloxanes, which form silicone-like layers and are safe—unlike PFAS containing fluorine,” stated Dirk Hegemann of Empa’s Advanced Fibres Laboratory in St. Gallen in an Empa press release. Siloxanes are organic compounds that have two silicon atoms linked to an oxygen atom as a functional group.
The siloxanes are atomized and activated in a reactive gas for coating textile fibers. In doing so, they preserve their functional characteristics and cover the textile fibers with a thin, 30-nanometer-thick layer of water-repellent material.
After being coated in this manner, the fibers can be treated to create textiles that repel water, which can be utilized for upholstery and clothing. The Swiss innovation agency Innosuisse is providing funding for the initiative.
There are benefits to the novel method over traditional wet-chemical methods. The hydrophobic materials are assured to be evenly distributed throughout all of the twists in the entwined fibers, even in intricately constructed textiles.
This is important because, in a pair of swimming trunks, even a tiny wet area could allow water to seep in and keep the material from drying rapidly. “We have even succeeded in permanently impregnating more demanding, elastic fibres with the new process, which was previously not possible,” Hegemann stated.
Textiles made of the novel fibers are already outperforming traditional PFAS-coated fabrics, according to preliminary laboratory assessments. They dry more quickly and absorb less water.
But only after multiple washings can the fabrics’ amazing qualities of the fluorine-free coating truly shine through: According to the release, the fluorine-free fibers maintain their water-repellent qualities even after repeated washing cycles, whereas the performance of traditional PFAS coatings in stretchable textiles significantly decreases.
The current task for Hegemann and his group is to scale up the procedure into productive and profitable industrial processes. Because they repel oil, grease, and water, per- and polyfluorinated alkyl compounds, or PFAS, are a class of synthetic chemicals with a wide range of uses.
They have been used since the 1970s, for instance, in the manufacturing of frying pans, fire extinguishers, and practical apparel.
Carbon-fluorine compounds are called “forever chemicals” because they do not break down but instead build up in the environment and eventually in the human body.
The compounds may be responsible for a number of illnesses, including cancer, heart disease, obesity, and developmental abnormalities, in both people and animals. A few PFAS are already prohibited.
