ONE-STEP FORMATION OF W/O/W DOUBLE PICKERING EMULSIONS STABILIZED BY CELLULOSE NANOFIBRILS

Pickering emulsions are dispersions of immiscible liquids stabilized by solid particles, offering significant resistance to coalescence. Nanoparticles can be employed to produce simple or double emulsions. The former is particularly valuable for applications involving the encapsulation of hydrophobic and hydrophilic compounds, which facilitates controlled release and protection of active ingredients. Conventional multiple emulsion preparation methods require a two-step emulsification process involving two types of emulsifiers: lipophilic and hydrophilic stabilizers, typically surfactants or inorganic particles.¹ To develop more sustainable alternatives, cellulose nanofibrils (CNFs) stand out as promising biobased particles due to their renewability and biodegradability. However, they are mainly utilized to stabilize O/W simple emulsions.² This work explores a one-step method to produce multiple Pickering emulsions using a single type of functionalized CNF. Cationic or anionic CNFs were applied to stabilize almond oil emulsions, and their colloidal stability and morphology over time were analyzed using optical and confocal microscopy. Experimental results showed that both CNFs effectively stabilized oil-in-water droplets. In contrast, theoretical calculations using classical molecular dynamics simulations revealed that the water-in-oil droplet stabilization can be attributed to the oleic acid present in the oil phase. Furthermore, anionic CNFs exhibited greater efficiency in stabilizing W/O/W emulsions, preserving the multiple morphology for over two months under ambient conditions. These findings highlight the potential of functionalized CNFs as sustainable alternatives for designing double emulsions with applications in food, pharmaceutical, and cosmetic industries.

1. H.Zhao,Y.Yang,Y.Chen et al. Chemical Engineering Science 248 (2022) 117085. 

2. C. E. P Silva et al. Journal of Colloid and Interface Science 574 (2020) 207–216.