Circular fashion: fluorine-free water-repellent textile coating with natural chitosan
German Pavilion, Circular Fashion exhibition area
“Designing Future Society for Our Lives“ – under this motto, the countries of the world will meet at the Expo in Osaka from April 13 to October 13, 2025, to discuss how the United Nations' sustainability goals can be achieved. As a “People's Living Lab,” the Expo will serve as a test laboratory for new systems and technologies to stimulate innovation and demonstrate pathways to a sustainable future.
The theme of the German Pavilion at Expo 2025 is Circular Economy. Its title “Wa! Germany” sums it up, because “Wa” has three meanings in Japanese:
The German Pavilion itself is an exhibit of circular and sustainable construction. It brings together architecture, landscape, and exhibition into a single whole and and, through a unique visitor experience, showcases pathways to a circular future.
The circular economy is at the center of this, which aims to close material cycles holistically and radically reduce the consumption of resources. The goal is a zero-waste economy. This topic is central to several UN sustainability goals. The German Pavilion invites you to think about circular solutions together.
The tour through the pavilion is circular: it begins in the Biosphere Intro, leads through immersive spaces to Circular Living, Circular Economy and Circular Me, and ends in the Biosphere Outro.
At the end of the tour, visitors return to the Biosphere, the space they could only vaguely make out at the beginning. Dense plant growth and harmoniously integrated exhibits symbolize the connection between the biosphere and the technosphere. However, this harmony is only possible if material cycles are consistently closed – the central goal of a circular economy. Achieving this goal requires efforts at the individual, corporate and societal levels.
Interactive exhibits playfully demonstrate how today's innovations can enable a functioning circular economy of tomorrow. Six interactive stations invite visitors to explore circular solutions from the sections of construction, fashion, food production and energy generation.
The exhibit is dedicated to the transformation from fast to circular fashion. It shows how sustainable textiles, new production methods, upcycling concepts and environmentally friendly materials enable a more ecologically and socially responsible future for the fashion industry. The selection includes 12 textile innovations from Germany – from scientific materials research to artistic experiments and circular collections.
For the Expo, we have implemented our development of bio-based water-repellent coatings in an exhibit for the Circular Fashion theme area of the German Pavilion. The key feature: The water-repellent properties of textiles are achieved by coating them with the natural raw material chitosan, which our researchers extract from waste streams in the food industry. In this way, we use natural raw materials, avoid harmful chemicals and thus contribute to sustainability and a circular economy in the textile industry.
Water-repellent properties of textiles are often achieved by chemicals that are harmful to health and the environment. A sustainable alternative is offered by a coating based on chitosan. We obtain it from chitin, a natural polymer found in insects, fungi and crustaceans.
Chitosan is a sugar molecule with various binding sites for other chemical functions. We use these for a fluorine-free water-repellent treatment of cotton, polyester and blended fabrics. For this purpose, we equip chitosan with natural substances that have the desired water-repellent properties. This way, chitosan serves as a kind of anchor to bind the finish to the textile fabric using chemical or bio-based cross-linking agents.
For many textiles, such as sleeping bags, the water-repellent coating made of modified chitosan can already replace conventional fluorine-containing chemical finishes. One of its special features is its resistance to washing: the treatment retains its water-repellent effect even after multiple wash cycles. The chitosan-based coating also increases the fabric's resistance to abrasion. This also adds to its sustainability.
Expo 2025 Osaka takes place in Japan from April 13 to October 13, 2025, on Yumeshima, an artificial island in the Osaka harbor area.
This Expo will be the second time that Osaka has hosted the event, following Expo '70, which marked the first time that either Japan or Asia had ever hosted an Expo. Expo organizers hope that Expo 2025 will once again bring the international community to Japan and provide a space where the latest technologies and innovations can help achieve global sustainability goals.
With the theme “Designing Future Society for Our Lives,” the Expo aims to encourage everyone to think about how they want to live and how each and every one of us can contribute to a better world. The Expo serves the goal of encouraging the international community to help shape a sustainable society.
The theme of the Expo is underpinned by the three interlinked sub-themes “Saving Lives”, “Empowering Lives” and “Connecting Lives”.
In addition to each sub-theme, each pavilion is also assigned goals from the United Nations Sustainable Development Goals, and the country pavilions are intended to provide ideas and solutions for achieving them.
Fraunhofer Institute for Interfacial Engineering and Biotechnology IGB