Phosphorylated-CNC/modified-chitosan nanocomplexes for the stabilization of Pickering emulsions

Cellulose nanocrystals (CNC) are sustainable nanomaterials that possess high tensile strength, stiffness and surface functional groups suitable for various types of modifications. In this study, phosphorylated cellulose nanocrystals (P-CNC) were prepared via acid hydrolysis with phosphoric acid to decorate phosphate groups on the surface of CNC. Also, chitosan was modified with glycidyltrimethylammonium chloride (GTMAC) to improve its solubility. GTMAC-Chitosan (GCh) and phosphorylated cellulose nanocrystals (P-CNC) were complexed via ionic gelation to produce GCh-P-CNC nanoparticles under mild sonication. Although sodium tripolyphosphate (TPP) is a common cross-linking agent used with chitosan, its application is compromised by its metastable structure that resulted in the rapid release of its encapsulated compound. Therefore, phosphorylated cellulose nanocrystal was developed as a "nanoparticle" cross-linker and a Pickering emulsifier. The nanocomplexes transformed from a rod-like to hard sphere and random coil morphology with increasing ratio of GCh/P-CNC. In comparison with TPP-Chitosan emulsion, Pickering emulsion prepared using GCh-P-CNC complex was more stable over 3 months without coalescence and phase separation.