Hydrophobic treatment of textiles with biobased chitosan

In the HydroFichi and ExpandChi projects, which were funded by the German Federal Ministry of Education and Research, we at Fraunhofer IGB and our partners from the textile industry were able to develop chitosan-based, water-repellent finishes. The chitosan-based hydrophobic equipment can replace PFAS in applications with low to medium requirements. The technology used is based on a modification of the chitosan backbone with activated structures or molecules that exhibit the desired hydrophobic properties. Chitosan acts in this case as a matrix. The cross-linking on the textile is then carried out either chemically or with biobased cross-linkers. When possible, the cross-linkers were functionalized biotechnologically.

In addition to the water repellant effect of the coated textile, which lasts even after several washes, the finish also improves the abrasion resistance of the textile fabric. The all-in-one formulation can be applied to the fabrics using processes common in textile technology, even on a larger scale. A large textile sample will be presented at the 2025 World Expo in Osaka. Research shows few incompatibilities with other formulation ingredients. This allows the combination of water repellency with other finishes.

We have already successfully adapted the water-repellent, chitosan-based finish to other materials (paper and cardboard), which is very interesting for the packaging industry. With appropriate research, we can produce customized derivatives of chitosan for other applications, such as adhesive coatings or biobased binders for the wood processing industry. In addition, the chemical and biotechnological modifications developed in the ExpandChi project can also be transferred to other polysaccharides for the production of further functionalities. We are happy to investigate further applications and utilization strategies on behalf of our customer or in a funded project.