Stabilization of Water-in-Water Emulsions by Nanorods

Abstract

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.

The relevance of structural features of cellulose and its interactions to dissolution, regeneration, gelation and plasticization phenomena

“…Nanocrystalline celluloses have also been used as stabilizers of emulsions. 176,[181][182][183][184] However, in comparison with cellulose derivatives, the mechanisms are very different. Cellulose derivatives behave similarly to any flexible or semi-flexible amphiphilic polymer, like graft and block copolymers, and provide steric stabilization.…”

Particle stabilized water in water emulsions

“…The latter was explained by the formation of a weak gel of droplets connected by aggregated clay platelets. Peddireddy, Nicolai, Benyahia and Capron (2016) observed that P/D emulsions were stable when as little as 0.05 wt% cellulose nanocrystals (CNC) were added that have a highly anisotropic rectangular parallelepiped structure with average dimensions 160 nm × 6 nm × 6 nm. For such particles G depends on the length (l) and the width (b) of the particles:…”

Dynamic Synthetic Cells Based on Liquid–Liquid Phase Separation

“…This has led severalg roups to describe such droplets as water-in-water (w/w) emulsions. Spherical colloidsw ith diameters typicallyg reater than 100 nm, including nanoparticles, [85,86] lipid vesicles [87,88] and protein clusters, [89] as well as high-aspect-ratio colloids, such as clays, [90] nanorods [91] or protein fibrils, [92] adsorb more effectively to interfaces with lows urface tension [92,93] and have therefore been used to stabiliseP EG/dextran aqueous two-phase systems (Figure 2D,E ), as well as complex coacervate droplets. Spherical colloidsw ith diameters typicallyg reater than 100 nm, including nanoparticles, [85,86] lipid vesicles [87,88] and protein clusters, [89] as well as high-aspect-ratio colloids, such as clays, [90] nanorods [91] or protein fibrils, [92] adsorb more effectively to interfaces with lows urface tension [92,93] and have therefore been used to stabiliseP EG/dextran aqueous two-phase systems (Figure 2D,E ), as well as complex coacervate droplets.…”