Chemical ManagementNews & UpdatesSustainability

Empa Develops Eco-Friendly Water Repellent Textile Finishing Solution

For decades, per- and polyfluoroalkyl substances (PFAS) have been the workhorses of water repellency in textiles. From rain jackets to ski pants, PFAS coatings have kept us dry, but at a hidden cost. These “forever chemicals” accumulate in the environment and human body, posing potential health risks. Now, a team of researchers at the Swiss Federal Laboratories for Materials Science and Technology (Empa) has developed a promising alternative – an eco-friendly water-repellent solution free of PFAS.

Figure: Textile fibers (blue) can be given a uniform water-repellent finish using plasma coating. Even more demanding elastic fibers (red) remain permanently impregnated thanks to the new process. (Scanning electron microscopy, colored) Image: Empa

The Problem with PFAS

PFAS are a group of man-made chemicals known for their ability to repel water, oil, and grease. This property has made them ubiquitous in a wide range of products, including textiles, non-stick cookware, firefighting foams, and even food packaging. However, their persistence in the environment and potential health effects have raised serious concerns.

PFAS chemicals are highly stable and don’t break down easily.They build up in the environment and can enter our bodies through contaminated water, food, or even dust.

Dr. Dirk Hegemann, lead researcher at Empa’s Advanced Fibers Laboratory

Studies have linked PFAS exposure to various health problems, including cancer, thyroid issues, and developmental delays in children. As a result, public pressure and growing regulations are pushing for alternatives.

Figure: Plasma cloud: The plasma system atomizes environmentally friendly siloxanes into a cloud that can coat textile fibers with nanometer precision. Image: Empa

A New Hope: Siloxanes to the Rescue

Empa’s researchers, working in collaboration with Swiss textile companies, have developed a novel approach using “highly cross-linked siloxanes” to impart water repellency to textile fibers. Siloxanes are a class of organic compounds containing silicon and oxygen. Unlike PFAS, siloxanes are considered safe and readily degrade in the environment.

Here’s the science behind the solution:

  • Precise Application: The siloxanes are first atomized (broken down into tiny particles) and then activated in a reactive gas environment. This activation process ensures they retain their water-repellent properties.
  • Plasma Power: The activated siloxanes are then applied to the textile fibers using a plasma coating technique. This method utilizes a highly ionized gas (plasma) to precisely coat the fibers with a thin (around 30 nanometers) layer of the siloxane material.
  • Uniform Coverage: One of the key advantages of plasma coating is its ability to create an even distribution of the coating material, even on complex structured textiles. This ensures consistent water repellency throughout the fabric.

Beyond Safety: Performance Benefits

Initial lab tests reveal promising results. Textiles treated with the new siloxane coating exhibit better water repellency and faster drying times compared to their PFAS-coated counterparts. However, the true advantage emerges after multiple washes.

PFAS coatings tend to lose their effectiveness after repeated washing cycles, especially in stretchy fabrics.Our siloxane-based solution, on the other hand, maintains its water repellency even after several washes.

Dr. Dirk Hegemann, lead researcher at Empa’s Advanced Fibers Laboratory

This superior durability offers a significant benefit for garments that require frequent washing, such as sportswear and outdoor gear.

Figure: Where water cannot penetrate: Even stretched fibers allow the water droplet (blue) to roll off. (Microscopy, 30x magnification) Image: Cilander/Empa

Scaling Up for Sustainability

While the lab results are encouraging, the next step is to translate this technology into an economically viable industrial process. Dr. Hegemann and his team are working on scaling up the process to meet the demands of large-scale textile production.

Our goal is to develop an efficient and cost-effective solution that can be readily adopted by the textile industry,” he says.

The project has received funding from Innosuisse, the Swiss Innovation Agency, highlighting the importance of sustainable innovation in the textile sector.

Collaboration for a Greener Future

The development of this new water-repellent solution is a testament to the power of collaboration. The partnership between Empa researchers and Swiss textile companies demonstrates a shared commitment to sustainability and innovation.

Several Swiss textile companies, including Lothos KLG, beag Bäumlin & Ernst AG, and AG Cilander, are already on board, recognizing the potential of this new technology.

This project exemplifies successful collaboration between materials science, fiber technology, and plasma coating. It leads to an innovative, sustainable, and effective solution.

Dominik Pregger from Lothos KLG

The development of this eco-friendly water-repellent solution represents a significant step towards a more sustainable future for the textile industry. By eliminating harmful PFAS chemicals, it aims to protect the environment and potentially improve our health. The success of this project could pave the way for the development of other sustainable solutions in the textile sector and beyond. As consumers, we can also play a role by supporting brands that embrace sustainable practices and advocate for stricter regulations on harmful chemicals in textiles. Together, we can create a future where raincoats

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