Electrolyte-Controlled Permeability in Nanocellulose-Stabilized Emulsions

Particle-stabilized emulsions, so-called Pickering emulsions (PEs), are a promising low-tech avenue to precisely engineered materials for applications in drug delivery, catalysis, or water remediation. The particle assembly at the liquid-liquid interface provides superior stability and an adjustable permeability, which is a key parameter for controllable compound capture and release. However, understanding the complex factors that control the particle assembly in detail is a still-remaining challenge limiting practical applications of PEs in an industrial framework. In this study, the properties of oil-in-water emulsions, stabilized by cellulose nanocrystals (CNCs), are investigated. It is shown how high ionic strength leads to low polydispersity droplets, with restricted permeability across the oil-water interface due to the dense packing of the CNC layer. In contrast, lower electrolyte concentration enables enhanced uptake through the interface, while providing the required stability for the reusability of the material. The authors continue to study the impact of the electrolyte content on the dynamic responses of the emulsions, leading to a liquid-liquid system with tunable cyclic uptake and release levels. Overall, the results highlight the potential of nanocellulose-stabilized emulsions as tunable and robust material platform with well-defined permeability characteristics-made in a simple way.