Dried and Redispersible Cellulose Nanocrystal Pickering Emulsions

Area of Science:

• Materials Science
• Colloid and Surface Chemistry
• Green Chemistry

Background:

• Pickering emulsions offer a surfactant-free alternative for stabilizing oil-in-water mixtures.
• Cellulose nanocrystals (CNCs) are promising stabilizers due to their sustainability and unique properties.
• Developing stable, easily processable, and redispersible CNC-based emulsions remains a challenge.

Purpose of the Study:

• To investigate the impact of tannic acid (TA) and water-soluble cellulose derivatives on CNC-stabilized Pickering emulsions.
• To achieve dried CNC-stabilized emulsions that can be readily redispersed in water.
• To explore the potential for high oil content in these novel emulsion systems.

Main Methods:

• Emulsification of corn oil using CNCs and adsorbing polymers (methyl cellulose or hydroxyethyl cellulose).
• Freeze-drying of emulsions to form solid dry states.
• Addition of tannic acid post-emulsification to enhance redispersibility.
• Characterization of redispersed emulsions using Mastersizer and confocal microscopy.

Main Results:

• Freeze-dried CNC-stabilized emulsions without TA showed irreversible droplet coalescence.
• Addition of TA to the emulsions, followed by drying, resulted in redispersible solid emulsions.
• The TA-cellulose derivative complexation condensed the shell around oil droplets, preventing coalescence.
• Redispersed emulsions retained high oil content (up to 94 wt %) with minimal change in droplet size.

Conclusions:

• Tannic acid and cellulose derivatives enable the production of the first dried and redispersible CNC-based Pickering emulsions.
• These findings open new avenues for utilizing green, surfactant-free emulsions in food, cosmetic, and pharmaceutical industries.
• The developed processing method offers a sustainable approach to creating stable, high-oil-content emulsions.