Compositional ripening of particle-stabilized drops in a three-liquid system

Abstract

We present experimental studies of two aqueous drops, stabilized by colloidal silica, which are placed close to each other in a bath of toluene, ethanol and surplus colloidal silica. If one of the drops is enriched in ethanol while the other is pure water then we observe the spontaneous formation of small droplets at the surface of the water drop closest to its neighbour. These droplets are then observed to form all along the path to the ethanol enriched drop until they make a complete bridge. We relate this behaviour to the diffusion pathways on the underlying three-fluid phase diagram. We argue that the phenomena is a version of compositional ripening where the transfer of the dispersed phase leads to the spontaneous formation of droplets in the continuous phase. We show that, while the large drops are particle-stabilized, the spontaneously formed droplets are not. Instead the presence of surplus particles leads to the droplets gelling as an elastic bridge. The phenomenology at long times and at low particle concentrations becomes increasingly surprising.

Physicochemical hydrodynamics of droplets out of equilibrium

“…An even richer system with two big drops consisting of different aqueous liquids (one water drop, and one consisting of ethanol-water mixtures) in a bath of toluene as host liquid is studied in ref. [183]. The diffusion of the aqueous liquids through the toluene leads to the nucleation of aqueous microdroplets (inverse ouzo effect) in between the two bigger drops.…”

“…In case of ternary liquids with a solubility gap it can also lead to nucleation of microdroplets, as in ref. [183].…”

Further insights into release mechanisms from nano-emulsions, assessed by a simple fluorescence-based method

“…Recent works investigated the mass transfer between micrometric droplets focusing on complex emulsions like Pickering emulsions [25] and multiple emulsions [26], helped by developments of optical imaging with high-resolution cameras [27]. However, these experiments were conducted on macro or micro-scale emulsions, but not adaptable on nano-emulsions reaching the limit of such experimental approach.…”

Preparation and Characterization of Starch Nanoparticles from Potato Starch by Combined Solid‐State Acid‐Catalyzed Hydrolysis and Nanoprecipitation

“…A variety of methods based upon high‐power ultrasonication, microemulsion crosslinking, nanoprecipitation, enzymolysis and recrystallization and so on have been developed to synthesize SNPs. Nanoprecipitation is one of the most effective methods for preparing SNPs; this approach is also called the solvent exchange method, in which starch granules are dissolved in a solvent and precipitated in a nonsolvent to obtain SNPs.…”

“…Due to the biocompatibility, effectiveness, and nontoxicity of polysaccharides, starch nanoparticles (SNPs) have been widely utilized as carriers in drug-delivery systems [1,2] for drugs such as phenethylamine, [3] aspirin, [4] ciprofloxacin, [5] caffeine, [6] and curcumin. [7] A variety of methods based upon high-power ultrasonication, [8][9][10] microemulsion crosslinking, [11,12] nanoprecipitation, [13][14][15] enzymolysis and recrystallization [16,17] and so on have been developed to synthesize SNPs. Nanoprecipitation is one of the most effective methods [16][17][18][19] for preparing SNPs; this approach is also called the solvent exchange method, in which starch granules are dissolved in a solvent and precipitated in a nonsolvent to obtain SNPs.…”