Doctoral researcher Alexander Henn presents the potential use of lignin for anti-fogging in eyewear, for example. Credit: Alexander Henn / Aalto-yliopisto.
Researchers from FinnCERES have developed a glass coating derived from wood waste materials that can be used as an anti-fogging or anti-reflective coating. The coating could be used to replace traditional synthetic materials and is created entirely from a waste product.
Lignin is a common waste product from paper production and is often burned to product heat because processing it in other ways is difficult. Researchers have theorized that lignin could be used to create nanoparticles for anti-fogging coatings, however, their use in transparent films has not been successful until recently.
"Optical coatings need to be transparent, but so far, even rather thin lignin particle films have been visible. We knew that small particles appear less turbid, so I wanted to see if I could make invisible particle films by pushing the particle size to a minimum," said Alexander Henn - lead author of the study.
In the study, published in Chemical Engineering Journal, the researchers used acetylated lignin along with improved methodologies to esterify it in only minutes and at 60°C. The team also demonstrated that the films could be used to create colored films from the same lignin nanoparticles by controlling the thickness of the coating along with layering the films to create different structural colors.
The researchers believe the films could be profitably scaled up thanks to the ease of the reaction along with the excellent yields. "Lignin-based products could be commercially valuable and simultaneously act as carbon sinks, helping relieve the current fossil fuel-dependence and reduce carbon dioxide emissions," said Professor Monika Österberg. "High value-added applications like this are important to drive lignin valorization and move us away from using lignin only as a fuel."