Inspired by nature

Water and dirt repellent garments are often criticised on the grounds of sustainability. Outdoor clothing especially often still derives its functionality from per- and polyfluorinated compounds (PFCs). An interdisciplinary research product undertaken by German textile research institutes addresses this specific issue and takes its inspiration from fungi.

Whether you are hiking, cycling or on the way to work – outdoor clothing protects from wind and weather and has now even become a fashion statement. The downside: the functionality of water and dirt repellent garments is often derived from per- and poly-fluorinated chemicals – PFCs in short. These retain their ability to repel rain droplets from the textile even after multiple washes. However, whilst fluorinated chemicals are very useful, they do pose an equally serious risk to human health and the natural world. Some are even considered to be cancerogenic, resulting in a call by environmentalists for a total ban.

This discussion has already been going on for some time, with industry yet to provide a solution that is as long lasting, universally applicable and as price competitive as the standard finishes. Now the Hohenstein Institute and the Straubing based BioCat branch of the Fraunhofer Institute for Interfacial Engineering and Biotechnology (IGB) has initiated an interdisciplinary research project. The idea is to develop a textile finish with water and dirt repellent properties that uses natural proteins and so is an alternative to the toxic hydrophobic finish based on per- and polyfluorinated chemicals.

The approach taken by the researchers is to only use hydrophobic proteins as they occur naturally in the cell walls of fungi. ‘’We manufacture the proteins artificially from microorganisms and then use a biotechnological process to provide them with an anchor that is able to bond to cellulose fibres”, explains Dr. Michael Hofer from BioCat. “Fungi use this same anchor in nature, when they break down cellulose to get to nutrients. To this end they create enzymes, so-called cellulases that also use these anchors.”

Furthermore, a feasibility study has already been conducted which shows that this anchor protein finish does work. “To demonstrate this more clearly we used green fluorescent proteins with a cellulose anchor enabling the creation of a strong bond between these proteins and different textiles,” explains Hofer.

“The current objective is to show that the process works and how effective it is. A cost estimation is also required,” says Hofer. After the BioCat branch of Fraunhofer Institute IGB has manufactured the proteins, they are applied to textiles by the Hohenstein Institutes. Subsequent tests are conducted to provide information about the durability, resistance to sunlight and the degradability of the materials.

This joint project is supported by representatives from the textile and biotechnology sector with a view to ensuring the industrial feasibility and economic viability of the new method. There is no shortage of application areas. Outdoor clothing would not be the only area to profit from this development. It would also be step forward for technical and surgical textiles.