Plasma Technology Explores PFAS-Free Water-Repellent Textile Coatings

Waterproof and stain-resistant performance textiles often rely on coatings containing PFAS. These fluorine-based chemicals offer excellent resistance to water, dirt and grease. However, they also persist in the environment and can contribute to long-term pollution. Researchers at Empa are therefore working with textile manufacturers to develop PFAS-free alternatives.

The Innosuisse-funded EC0Tex project focuses on water-repellent coatings for textile yarns. It combines fluorine-free substances with a specially developed plasma coating process. The project originated from Subitex, a long-term collaboration between Empa and companies associated with the Swiss Textiles Association.

Avoiding Regrettable Substitutes

The researchers follow the Safe and Sustainable by Design (SSbD) framework. This means that potential alternatives must meet requirements for performance, safety, sustainability and economic viability.

According to Empa researcher Dirk Hegemann, replacing PFAS should not lead to so-called “regrettable substitutes”. These are alternatives that later prove to be as harmful as the chemicals they replace. The research team therefore assesses potential materials and technologies early in the development process.

Coating Individual Fibres

Together with Swiss textile companies Bäumlin & Ernst AG, Lothos KLG and Seilfabrik Ullmann AG, Empa is developing the plasma process on an industrial scale.

Conventional coating methods can require large quantities of PFAS-free substances to achieve the required performance. This can reduce both their economic and environmental benefits. The new plasma system takes a different approach. It applies extremely thin coatings to individual fibres within a yarn. As a result, manufacturers can reduce the amount of chemicals while still treating the yarn throughout its structure.

The system generates plasma through an electric gas discharge. The energy causes the coating chemicals to form reactive species, which attach themselves to the fibres. While conventional plasma treatment mainly reaches the outer fibres, Empa’s process allows reactive species to penetrate deeper into the yarn.

The resulting yarns could be used for outdoor and sportswear as well as technical products such as ropes.

Organosilicon Compounds As An Alternative

The researchers are currently investigating organosilicon compounds as possible substitutes for PFAS. Initial studies show that these compounds can form highly cross-linked coatings with strong water-repellent and quick-drying properties. According to Empa, their durability can even exceed that of PFAS coatings.

However, the researchers still need to examine the safety of these compounds when abrasion or washing releases them into the environment.

Grease and dirt repellency also remain a challenge. This is particularly important for specialist textiles such as protective workwear. The wide range of organosilicon compounds offers possibilities for further development. By adjusting the starting materials and plasma coating conditions, the researchers aim to tailor textile properties while continuing to follow SSbD principles.

The EC0Tex project recently received the Innovation Award for sustainability and innovation at Techtextil in Frankfurt am Main.

Source & photos: Empa