Design of Double Emulsions by Osmotic Pressure Tailoring

Abstract

A method was developed allowing in situ adjustment of water-in-oil-in-water double emulsion (W/O/W) morphologies by tailoring the osmotic pressure of the water phases. The control of internal droplet size is achieved by altering the chemical potential of the external and internal water phases by dissolving neutral linear polysaccharides of suitable molecular weights. As a consequence of the different chemical potentials in the two aqueous phases, transport of water takes place modifying the initial morphology of the double emulsion. Self-diffusion 1H nuclear magnetic resonance (1H NMR) was used to assess transport mechanisms of water in oil, while a numerical model was developed to predict the swelling/shrinking behavior of W/O/W double emulsions. The model was based on a two-step procedure in which the equilibrium size of a single internal water droplet was first predicted and then the results of the single droplet were extended to the entire double emulsion. The prediction of the equilibrium size of an internal droplet was derived by the equalization of the Laplace pressure with the osmotic pressure difference of the two aqueous phases, as modeled by mean-field theory. The double emulsion equilibrium morphologies were then predicted by upscaling the results of a single drop to the droplet size distribution of the internal W/O emulsion. Good agreement was found between the theoretical predictions and the measurement of double emulsion droplet size distribution. Therefore, the present model constitutes a valuable tool for in situ control of double emulsion morphology and enables new possible applications of these colloidal systems.

Water-in-Oil-in-Water (W/O/W) Double Emulsion Morphology and Its Degradation on Instant Noodle Seasoning

“…Low temperature and room temperature storage seasoning show droplet structure change without a core, whereas high-temperature storage seasoning shows droplets which experience external phase swelling. This is consistent with droplet instability scheme according to Mezzenga et al (2004), which stated that the disappearance of droplet core phenomenon occurs because of water diffusion from internal phase to external phase, whereas the swelling phenomenon occurs because of oil droplet coalescence. This is supported by Dickinson's (2011) opinion which stated that the coalescence mechanism that happens in both phases causes the displacement of some or all dispersed components from the internal phase to the external phase.…”

Synthesis of Oil-Laden Poly(ethylene glycol) Diacrylate Hydrogel Nanocapsules from Double Nanoemulsions

“…[33][34][35][36][37] While microcapillary-based methods offer precise control over droplet sizes and distribution, they have low throughput (typically less than 1 mL/hr for a single device 38 ), and device limitations make nanoscale droplet production infeasible without significant technological advances. On the other hand, bulk emulsification has been used to successfully form nanoscale multiple emulsions, but is significantly more difficult to control, typically resulting in a large dispersity of both size and morphology.…”

Ibuprofen-in-cyclodextrin-in-W/O/W emulsion – Improving the initial and long-term encapsulation efficiency of a model active ingredient

“…It would be of interest to investigate the W/O/W emulsion stability at varying osmotic pressure gradients, as this property is known to influence the encapsulation efficiency (Benichou, et al, 2004). The osmotic regulation of W/O/W emulsions is complicated by both the Laplace pressure of the inner droplets and non-ideal solute behavior (Hattrem, et al, 2014;Mezzenga, Folmer, & Hughes, 2004). In addition, the association of inclusion complexes would affect the osmolarity of the inner water phase.…”