ONE-STEP PRODUCTION OF MULTIPLE PICKERING EMULSIONS STABILIZED BY CELLULOSE NANOFIBRILS

Pickering emulsions are a mixture of two or more liquids that are usually immiscible and stabilized by particles, offering high resistance to coalescence. Nanoparticles can be used to create simple or more complex systems, such as multiple emulsions. In recent years, interest in multiple emulsions has grown significantly due to their potential applications in encapsulating hydrophobic and hydrophilic compounds. These systems are valuable for isolating, protecting, and facilitating the targeted release of various substances and are usually produced using two emulsifiers, lipophilic and hydrophilic, or inorganic nanoparticles.¹ To design more sustainable products, cellulose nanofibrils (CNFs) are attractive candidates for creating Pickering emulsions, as they are renewable and biodegradable.² This work demonstrated a simple methodology for producing multiple Pickering emulsions in one step using a single type of functionalized CNF. Dispersions containing cationic or anionic CNFs were applied to stabilize almond oil emulsions. Colloidal stability and droplet morphology were assessed over time by optical and confocal microscopies. Experimental and theoretical results indicate that both CNFs stabilized oil-in-water droplets, while the oleic acid present in the oil was responsible for stabilizing water-in-oil droplets. Moreover, anionic CNFs demonstrated greater efficiency in stabilizing W/O/W emulsions, preserving the multiple morphology of the droplets for over two months under environmental conditions. Therefore, functionalized CNFs offer ecological alternatives for creating multiple emulsions with relevant applications in food, pharmaceutical, and cosmetic formulations.