Pickering emulsions stabilized by hydrophobically modified nanocellulose containing various structural characteristics

Cellulose nanocrystals (CNCs) and cellulose nanofibrils (CNFs) extracted from renewable resources possess many attractive characteristics, making them ideal Pickering emulsion stabilizers. However, unmodified pristine CNCs with high surface charge density are not effective in stabilizing oil–water emulsions, thereby limiting their application as interfacial stabilizers. Grafting hydrophobic polymers onto CNCs enhanced their wettability by the oil phase, which reduced the interfacial tension. Thus, hydrophobic modification was performed by grafting cinnamoyl chloride or butyryl chloride to the surface of CNFs. The modified CNFs were further hydrolyzed for 1 or 2 h to produce nanocellulose of varying sizes and hydrophobicity, and they were effective Pickering emulsifiers. The effect of nanocellulose concentration, polarity of solvents, hydrophobicity, size and electrolyte on the characteristics of the Pickering emulsions were examined and elucidated.