Stabilisation of water-in-water emulsions by montmorillonite platelets

Abstract

The formation of water-in-water emulsions from the aqueous two phase system containing polyethylene oxide and pullulan, stabilised by montmorillonite platelets, was investigated. A novel approach of preparing the emulsions at non-equilibrium polymer concentrations was successfully utilised to control viscosity during mixing and allow the use of low energy emulsification methods. Polyethylene oxide adsorbed to the platelets much more strongly than pullulan favouring the formation of pullulan-in-polyethylene oxide emulsions which remained stable for a period of weeks. Polarising microscopy and small angle light scattering were used to show that droplets were most likely stabilised against coalescence by the adsorption of randomly oriented aggregates of platelets and against creaming by the formation of chains of droplets bridged by the adsorbed aggregates. Montmorillonite platelets were therefore shown to stabilise water-in-water emulsions and their preference for emulsion type was driven by the adsorption of the polymers to the particle surface.

Controlling the Size of Two-Dimensional Polymer Platelets for Water-in-Water Emulsifiers

“… 29 The larger platelets also provide a greater barrier toward rotation, thus providing a more stable emulsion. 19 Using a droplet relaxation method, 81 , 83 the emulsion using large platelets also showed a drop in interfacial tension in comparison to the small platelet emulsion, indicating that surface area, and not simply a 2D shape, plays a key role in determining interfacial properties ( Table S4, Figures S17 and S18 ). It should be noted that, previously, small Gibbsite (clay) platelets at similar loading levels were shown to produce more stable emulsions than larger platelets.…”

Fabrication of Human Keratinocyte Cell Clusters for Skin Graft Applications by Templating Water-in-Water Pickering Emulsions

“…Most of these methods are very limited by the amount of cell spheroids that can be produced. Nguyen et al [23] and Ganley et al [24] showed that water-in-water Pickering emulsions could be stabilized by solid particles. A more comprehensive review on stabilization of w/w Pickering emulsion with colloid particles was published by Dickinson [25].…”

Supramolecular Compartmentalized Hydrogels via Polydopamine Particle-Stabilized Water-in-Water Emulsions

“…18−20 Several other examples of stabilization of water-in-water emulsions using various nanoparticles have also been reported. 21−23 However, these methods have some limitations and cannot be specifically applied to form every stable arbitrary ATPS emulsion. An alternative surfactant-free route to stabilize emulsions has been recently demonstrated by the group of Ulijn, who have generated stable oil-in-water emulsions by creating an interfacial compartmentalized gel network around the dispersed droplets.…”