Surface modification improves fabrication of pickering high internal phase emulsions stabilized by cellulose nanocrystals

The high hydrophilicity of cellulose nanocrystals (CNCs) greatly limits their application in the Pickering emulsion formulations. The work for the first time reports that a simple surface modification with octenyl succinic anhydride (OSA; food-grade) can remarkably improve the emulsification performance of CNCs, and facilitate the fabrication of the Pickering high-internal-phase-emulsions (HIPEs). The OSA modification occurred between the corresponding anhydride and the surface hydroxyl groups of CNCs, which remarkably increased their surface hydrophobicity. Stable and gel-like Pickering HIPEs with fine droplets could be easily fabricated using OSA-modified CNCs, even at very low particle concentrations in aqueous phase. The findings would be of crucial importance for greatly extending the applications of CNCs in emulsion formulations in the food and pharmaceutical fields.