Lignin Nanoparticles for Coatings and Adhesives
Increasing the utilization of biomaterials is an effective way to enhance the cyclicity of the global material flow. Lignin is the second most abundant natural polymer but is not used significantly for any application due to its heterogeneous structure and poor water-solubility. However, lignin in nanoparticle morphology solves many of these issues. Lignin nanoparticles can be dispersed in water, have a homogeneous surface structure, and can be functionalized in various ways.Utilizing the amphiphilicity of lignin nanoparticles, and their reactivity with epoxies, we have shown that highly effective water-based surface coatings can be prepared. These coatings are not only breathable, but also resistant to abrasion, stains, solvents, and sunlight. Despite their high lignin content of almost 70%, the coatings are also hydrophobic, in contrast to most other lignin-based coatings. Particulate coatings have many benefits, which usually stem from their hydrophobicity. They are usually made from metal-oxide particles, most of which have harmful side effects, especially when inhaled. Usual particulate coatings require a binder (often a polymer film) that keeps the particles attached to their substrate. The lignin nanoparticle coatings, on the other hand require no binder, are easy to prepare, and are highly user- and environmentally friendly. We have also been able to utilize lignin for strong and water-based plywood adhesives using the same principles. This technology can not only increase the availability and use of particulate coatings, but also increase the use of lignin as a biomaterial.