Control of Particle Adsorption for Stability of Pickering Emulsions in Microfluidics

Abstract

Studying the stability of Pickering emulsion is of great interest for applications including catalysis, oil recovery, and cosmetics. Conventional methods emphasize the overall behavior of bulk emulsions and neglect the influence of particle adsorbing dynamics, leading to discrepancies in predicting the shelf-life of Pickering emulsion-based products. By employing a microfluidic method, the particle adsorption is controlled and the stability of the Pickering emulsions is consequently examined. This approach enables us to elucidate the relationship between the particle adsorption dynamics and the stability of Pickering emulsions on droplet-level quantitatively. Using oil/water emulsions stabilized by polystyrene nanoparticles as an example, the diffusion-limited particle adsorption is demonstrated and investigated the stability criteria with respect to particle size, particle concentration, surface chemistry, and ionic strength. This approach offers important insights for application involving Pickering emulsions and provides guidelines to formulate and quantify the Pickering emulsion-based products.

Biocompatible and pH‐Responsive Colloidal Surfactants with Tunable Shape for Controlled Interfacial Curvature

“…The properties of colloidal surfactants, such as particle size, shape, and surface wettability, can greatly influence the type and stability of Pickering emulsions . If the particles are too hydrophilic or too hydrophobic, they remain dispersed in the water or oil phase instead of accumulating at the interface, and no stable emulsions can be achieved .…”

Rapid Stabilization of Droplets by Particles in Microfluidics: Role of Droplet Formation

“…ChemSystemsChem 2019, 1, e1900007 (16)(17)(18)(19)(20)(21)(22)(23)(24) www.chemsystemschem.org 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 coalescence, obtaining highly stable emulsions (α > 0.999) even for τ values as low as 8.6 ms and presenting a small decrease on stability (α = 0.997) for τ > 30 ms.…”

“…ChemSystemsChem 2019, 1, e1900007 (16)(17)(18)(19)(20)(21)(22)(23)(24) www.chemsystemschem.org Where δ is the particle diameter, and 1 p is the particle density, estimated as 0.165 g cm À 3 through titration with sodium hydroxide as introduced by Sears, (see supporting information). [34]…”

“…[12][13][14] From an engineering perspective, Pickering emulsions also have a limited throughput of production: the typical timescale required to stabilize them (~600 ms) is significantly higher than the needed for surfactant stabilized emulsions (~35 ms or less). [15][16][17][18] The bottle-neck in the throughput lies in the stabilization time of the emulsion, which relates to the inability of the nanoparticles to quickly and efficiently reach the interface. A method typically used to reduce the droplet stabilization time scale consists of increasing the concentration of particles in the continuous phase to a large excess.…”

Solar‐Inspired Water Purification Based on Emerging 2D Materials: Status and Challenges

“…The growth of 2D materials, beginning with graphene, [13,14] brings some new potentials to this field due to their distinct morphology. [15][16][17][18][19][20][21] First, solar light covers a wide spectrum from visible to infrared light. The absorption of 2D materials can cover a broad range of the electromagnetic spectrum due to their multitudinous electronic properties.…”