Cross-linked lignin coatings produced by UV light and SF6 plasma treatments
Lignin is one of the most abundant macromolecules in vascular plants and has been studied for many years due to its high availability and low cost, regarding that lignin is the main by-product of the paper pulping process, and also typically burned as fuel. Despite that, lignin has only a few industrial applications. In a recently published study, lignin was extracted from sugar cane bagasse by Soda pulping and its coatings were prepared using solutions with different solvents on various substrates (silicon wafers, paper, steel and glass) by spin-coating.
Reduction of hydroxyl groups on the surface of lignin coatings
Two methods were tested in order to promote cross-linking on the surface of lignin coatings: SF6 plasma treatment and ultra-violet radiation. Both treatments reduced the amount of hydroxyl groups on the surface leading to more stable, cross-linked coatings as observed by FTIR and thermal analysis. Ultra-violet light radiation turned lignin coatings hydrophilic while stable superhydrophobic lignin coatings were obtained using SF6 plasma.
The study is published in: Progress in Organic Coatings Volume 128, March 2019, Pages 82-89.
Image source: Pixabay