Aggregation Phenomena in Lignin

The present chapter describes a survey of the aggregation phenomena occurring during lignin nanostructures formation, the main variables affecting them, the most common strategies for their preparation and their applications. The interactions affecting the conformation of single lignin chains in a specific solvating environment pertain to cohesive, dispersive, and dipolar forces, as well as to the formation of H-bonds. With respect to extrinsic factors, the solvating ability of the chosen medium, lignin concentration, pH of the medium, ionic strength, the nature of specific ions in the solvating environment, and temperature demonstrated all significant impact on lignin aggregation. By modulating intrinsic and extrinsic factors, the possibility to tailor the nature of lignin aggregates is emerging as witnessed by the development of several methodologies for the preparation of lignin-nanoaggregates. In this scenario, lignin-based nanoparticles and nano-capsules are finding applications across multiple fields. Among these, the most promising applications are those directly related to enhancing the quality of our lives, such as in agriculture, UV-shielding materials, and drug delivery systems.