Stabilization of Water-in-Water Emulsions by Nanorods.

Water-in-water (W/W) emulsions formed by mixing incompatible water-soluble polymers cannot be stabilized with molecular surfactants. However, they can be stabilized by particles through the so-called Pickering effect. Recently, it was shown that its stabilization can be achieved also with nanoplates. Here, we show for the first time that even nanorods in the form of cellulose nanocrystals (CNCs) can efficiently stabilize W/W emulsions. Static light scattering and confocal microscopy techniques were used to determine the surface coverage by CNCs. In the presence of 50 mM NaCl very weak gels were formed by excess CNCs in the continuous phase. In this way creaming of the dispersed phase could be arrested. The nontoxicity, sustainability, and low cost of CNCs and the abundant availability of cellulose render these nanorods potentially highly suited for preparing W/W emulsions.