"Bottom-Up" Assembly of Nanocellulose Microgels as Stabilizer for Pickering Foam Forming

Microgels assembled from bio-based nanomaterials are a promising soft stabilizer for a Pickering system. In this study, nanocellulose microgels with foaming properties were constructed by electrostatic assembly between nisin and 2,2,6,6-tetramethyl piperidine-1-oxyl-oxidized cellulose nanocrystals (TOCNC). Pickering wet foam was prepared by using the microgels as a foaming stabilizer. Nanocellulose microgels exhibited better foaming ability and foam stability than TOCNCs. Quartz crystal microbalance with dissipation and transmission electron microscopy analyses confirmed that the nanocellulose microgels prepared under different nisin concentrations demonstrated significant differences in morphology, conformation, and structural strength. Microgel particles prepared at 0.03 and 0.06 wt % nisin concentrations had a unique dendritic microstructure. Microgels containing 0.06 wt % nisin displayed better foaming ability and foam stability. It was possible that the soft dendritic structure of the microgels could endow bubbles with sufficient thickness and strength to prevent coalescence. This novelty nanocellulose microgel is expected to be used for expanding the application of nanocellulose in the functional interfacial design of Pickering foams.