Supramolecular interactions in softwood kraft lignin nanoparticles

Area of Science:

• Materials Science
• Polymer Chemistry
• Colloid Science

Background:

• Lignin, a renewable resource, shows promise for functional nanomaterials.
• Understanding lignin's structure-property relationships is crucial but underdeveloped.
• Lignin nanoparticles (LNPs) are of interest for various applications.

Purpose of the Study:

• To investigate the size and colloidal stability of lignin nanoparticles (LNPs).
• To explore the influence of preparation methods on LNP characteristics.
• To elucidate the structure-property relationships governing LNP formation.

Main Methods:

• Preparation of LNPs from softwood kraft lignin (SKL) using the solvent-antisolvent method.
• Controlled variation of solvent (ethylene glycol, THF) addition rates.
• Characterization of LNP size and colloidal stability.
• Molecular dynamics simulations to understand interaction mechanisms.

Main Results:

• Lignin chain conformational rearrangements significantly impact nuclei formation.
• Slow solvent addition yields smaller LNPs with minimized hydrodynamic volume.
• Rapid solvent addition results in larger LNPs due to higher aggregation numbers.
• Hydrogen bonds and π-π stacking interactions are critical in LNP formation.
• Surface concentration of phenolic and guaiacyl units affects LNP zeta-potential.

Conclusions:

• Solvent addition rate is a critical parameter controlling LNP size and aggregation.
• The study provides insights into the self-assembly mechanisms of lignin.
• Findings advance the understanding of colloidal lignin for technological applications.