Visualizing Dynamic Interfacial Assembly in Pickering Emulsions with Fluorescent Cellulose Nanofibers

Area of Science:

• Materials Science
• Colloid and Surface Chemistry
• Nanotechnology

Background:

• Understanding cellulose nanofiber (CNF) adsorption at oil-water interfaces is crucial for Pickering emulsion (PE) stabilization.
• Current models often simplify the dynamic and molecular-scale adsorption processes.

Purpose of the Study:

• To visualize and analyze the dynamic interfacial adsorption behavior of CNF in PE at the molecular scale.
• To develop a novel fluorescence-based strategy for studying CNF-PE interactions.

Main Methods:

• Preparation of oil-in-water PE using fluorescence-grafted TEMPO-oxidized CNF (Acd-CNF) and Nile Red-stained dodecane.
• Utilizing time-lapse confocal laser scanning microscopy to observe Acd-CNF adsorption onto preformed PE.
• Detecting interfacial fluorescence response through molecular proximity of fluorophores.

Main Results:

• Slowly introduced Acd-CNF dispersions spontaneously adsorb onto existing CNF-stabilized PE.
• Formation of heterogeneous and multilayered interfacial architectures, not a uniform monolayer.
• Demonstration of dynamic and hierarchical CNF adsorption processes at oil-water interfaces.

Conclusions:

• CNF adsorption in PE is a dynamic, hierarchical process, contradicting simplified static models.
• The fluorescence-grafting strategy offers a new experimental framework for designing PE.
• This approach facilitates the rational design of interface-engineered soft materials.