• Date 2024-08-12

The water-repellent properties of many surface coatings are based on the use of poorly degradable poly- and perfluorinated alkyl substances (PFAS). Some PFAS are toxic and bioaccumulating. Together with their high persistence, this leads to concern for both humans and the environment. At the beginning of 2023, five EU member states submitted a proposal to restrict the production, use and placing on the market of PFAS above certain concentration limits in accordance with the EU Chemicals Regulation REACH (Regulation (EC) No. 1907/2006). This emphasizes the importance of the search for PFAS alternatives.  

First results of a new coating process have been published by the working group of Irene Tagliaro at the Department of Materials Science at the University of Milano-Bicocca. The working group succeeded in developing a coating whose hydrophobic and transparent properties can be modeled. The process uses the non-toxic and degradable chitosan, which can be produced from the naturally occurring polysaccharide chitin. As the main component of crustacean claws, it is a common waste product in aquacultures.

The reaction involves modifying chitosan with fatty acid side chains and deposition by a solvent-free method. The amount of modified chitosan during deposition is crucial for hydrophobicity and transparency, which enables the production of coatings with different properties.

Based on the available data, the authors consider an improvement in surface morphology and an increase in material transparency possible.

Source: https://analyticalscience.wiley.com/content/article-do/pfas-free-chitosan-based-coatings