Agradecimentos: We thank IQ-UNICAMP for providing infrastructure and access to analysis equipment, and Prof. Fernando Galembeck and Dr. Douglas Soares for providing access to the AFM facility. We acknowledge Prof. Eliana Duek and Priscila Breda (Biomaterial Laboratory, PUC-SP) for providing GPC analysis and access to the OM facility. Financial support was granted by São Paulo Research Foundation (FAPESP, grant 2018/23769-1), National Council for Scientific and Technological Development (CNPq, grants 140558/2017-9 and 420031/2018-9), and Coordenação de Aperfeiçoamento de Pessoal de Nível Superior – Brazil (CAPES, financial code 001) Ver menos

Abstract: In spite of the increasing amount of literature on the production and application of lignin nanoparticles (LNPs), little or no attention has been paid so far to the influence of different production methods on the properties of these nanostructures. Herein, we propose a comprehensive study to assess the impact of several factors on the color, morphology, colloidal stability, antioxidant capacity, and UV-shielding performance of LNPs. LNPs were obtained by two different routes: a bottom-up approach based on the self-assembly in a solvent-antisolvent system with acetone/lignin/water; or a top-down approach based on the ultrasonication of never-dried lignin aqueous suspensions. The starting lignin was extracted from elephant grass leaves or stems, so that the influence of anatomical origin and molecular weight could also be investigated. Moreover, lignin was oxidized prior to being converted into LNPs, allowing for comparisons between different oxidation degrees. This study showed that interesting properties of LNPs can be easily tailored and combined focusing on the various applications of these versatile nanostructures. In a model application, different types of LNPs were incorporated into poly(vinyl alcohol)-based nanocomposites, modulating the UV-protection capability of the polymer matrix Ver menos