Researchers at Stockholm University have discovered an easy route to produce functional nanoparticles based on renewable lignin and fatty acids. The new methodology opens new opportunities for development of sustainable materials.

Two key authors of the study, Adrian Moreno (left) and Jinrong Liu (right) observe an aluminium specimen with the new anticorrosion coating.

Two key authors of the study, Adrian Moreno (left) and Jinrong Liu (right) observe an aluminium specimen with the new anticorrosion coating.

Recent years have seen a rapid progress in materials that build on the natural antioxidant activity and water barrier properties of lignin. Especially lignin nanoparticles that are very small compact spheres (diameter of 0.00001 cm) have attracted attention as possible candidates to substitute fossil materials in many kinds of applications such as composites, emulsions, and coatings. However, instability of these particles in solvents and water under acidic and basic conditions have restricted their advanced uses.

The discovery from Stockholm University overcomes this fundamental barrier without compromising biodegradability of lignin. The team used oleic acid, one of the most common natural fatty acids, to synthesize lignin oleate nanoparticles that are stable in aqueous dispersions. These particles displayed previously unknown stability that allowed using robust acid and base catalysis to functionalize their surfaces.

Scanning electron microscopy image of lignin-based anticorrosion particulate coatings on aluminum.

According to Dr. Adrian Moreno who was responsible for a majority of the experimental work, the materials developed in this research hold potential for industrial applications. “In addition to the easy and scalable chemical modifications, we demonstrated the particles as anticorrosion coatings on aluminum with competitive performance compared to the state of the art”, Dr. Moreno explains. The functionalized particles also showed excellent behavior as water purification agents in a broad pH range.

Assistant Professor Mika Sipponen who coordinated the work foresees that lignin holds many unprecedented opportunities for future’s sustainable materials. “Lignin is an essential structural component of wood. The chemistry that we used is not new. Instead, the novelty of our work lies in the ease at which the nanoparticles can be tailored to meet different application needs. This new methodology significantly extending lignin’s functionality and paves the way for new high-performance materials”, Sipponen says. 

 

The work was published in Angewandte Chemie on 1 July (Open Access).

 

Moreno, A., Liu, J., Gueret, R., Hadi, S.E., Bergström, L., Slabon, A., Sipponen, M.H. Unravelling the Hydration Barrier of Lignin Oleate Nanoparticles for Acid- and Base-Catalyzed Functionalization in Dispersion State. https://doi.org/10.1002/anie.202106743

 

Further information:

Mika Sipponen, Assistant Professor

mika.sipponen@mmk.su.se