Breathable Lignin Nanoparticles as Reversible Gas Swellable Nanoreactors

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology

Background:

• Stimuli-responsive lignin nanoparticles (LNPs) are crucial for advanced applications.
• Previous LNPs had low lignin content (<25 wt.%) with unclear roles.
• Developing high-lignin content, responsive LNPs is a significant challenge.

Purpose of the Study:

• To prepare oxygen (O₂)-responsive lignin nanoparticles (LNPs) with high lignin content (>75 wt.%).
• To investigate the stimuli-responsive behavior and stability of these novel hybrid LNPs (hy-LNPs).
• To explore the potential of these hy-LNPs as tunable nanoreactors.

Main Methods:

• Coprecipitation of Softwood Kraft lignin (SKL) with a modified fluorinated oleic acid ester (SKL-OlF).
• Formation of colloidal stable hybrid LNPs (hy-LNPs) with varying SKL-OlF content (10-50 wt.%).
• Testing reversible swelling behavior upon O₂/N₂ bubbling and stability at low pH.

Main Results:

• Successfully prepared O₂-responsive hy-LNPs with >75 wt.% lignin content.
• Demonstrated reversible swelling (~35% volume increase) and morphology change (spherical to core-shell) upon O₂/N₂ exposure.
• Observed enhanced stability under harsh conditions (pH < 2.5) due to a hydration barrier effect.

Conclusions:

• The developed hy-LNPs offer a straightforward method for creating stimuli-responsive nanomaterials.
• These particles exhibit tunable responsiveness to O₂ gas and enhanced stability.
• The O₂-responsive LNPs represent a new generation of smart lignin-based nanomaterials with potential in nanoreactors and beyond.