Tailoring kraft lignin for high-performance nanoparticles: from structure to function

Area of Science:

• Biorefinery science
• Polymer chemistry
• Nanotechnology

Background:

• Kraft lignin (KL) is an abundant, underutilized byproduct of biorefineries.
• Its phenolic structure offers potential for advanced materials and nanotechnology.
• Developing efficient methods to valorize KL is crucial for sustainable biorefining.

Purpose of the Study:

• To investigate sequential fractionation of KL using acetic acid (HOAc) as a green solvent.
• To produce and characterize lignin nanoparticles (LNPs) from selected KL fractions.
• To understand the structure-property relationships of LNPs for tailored applications.

Main Methods:

• Sequential fractionation of KL using acetic acid at concentrations from 10% to 60%.
• Selection of promising fractions (KL_30%, KL_40%, KL_50%, FR) based on yield and molar mass (Mw).
• LNP preparation via antisolvent precipitation and characterization of their properties.

Main Results:

• Fractionation yielded KL fractions with distinct Mw and chemical compositions.
• An inverse correlation between Mw and LNP hydrodynamic diameter was observed.
• KL_50% produced the smallest LNPs, indicating Mw is not the sole determinant of particle size.
• Lignin's chemical functionality significantly impacts LNP aggregation, surface charge, and stability.

Conclusions:

• Acetic acid is effective for sequential KL fractionation, yielding diverse lignin fractions.
• LNP size and properties are influenced by both Mw and chemical functionality.
• Optimized fractionation and understanding of structure-function relationships can enable tailored LNPs for nanotechnology and advanced materials.