by the use of fumed silica, Fe 3O 4 nano particles. o/w Pickering emulsions can be stabilized e.g. This type of Pickering emulsions is generally stabilized by nano particles whose contact angle is less than 90º. Oil-in-water Pickering emulsion refers to an emulsion where droplets of oil are dispersed in water as the continuous phase. have been successfully used to create stable Pickering emulsions.įacts Worth Knowing Oil-in-water (o/w) Pickering emulsions Whilst bare as well as functionalized silica (SiO 2) is one of the most commonly used particle, other particles such as Fe 3O 4, hydroxyapatite, monodisperse polystyrene latex particles, cyclodextrine and maltodextrine, halloysite nanotubes, hematite (α-Fe 2O 3) microparticles, poly(methyl methacrylate) (PMMA), insoluble chitosan/gelatin-B complex particles etc.

For diisobutyl adipate at least 8% silica are required to obtain a stable emulsion.Īll prepared emulsions have shown to be stable for at least 6 months. To obtain stable, transparent emulsions of butanol, ethyl acetate, butyl lactate, and diethyl adipate in the aqueous phase 6% of silica was required. to disperse the adsorbed particles into the water phaseĪt first, hydrophilic fumed silica powders (such as Aerosil® 200 or Aerosil® 380) was dispersed as 100nm agglomerates into water using an ultrasonic device.Īt the second step, a stable o/w emulsions with 20 wt% of oil and 2–10nm diameter droplet size were prepared by sonication.Sonication is used for both steps of the preparation of a pickering emulsion: Furthermore, sonication breaks the aggregates and agglomerates of nanoparticles and creates a highly polydisperse emulsion. The high mechanical shear forces of ultrasonic homogenization overcome the energy barrier between the phase interfaces. Particle shape and particle size effect the stability of the emulsion, too. The solid nanoparticles, which are adsorbed between the oil–water interface, are partly immersed in water and oil medium, so that the stabilizing nanoparticles can have hydrophilic, hydrophobic or amphiphilic properties. This means that even highly concentrated emulsions can be efficiently stabilized as Pickering emulsions. The droplet coating of solid particles functions as a rigid barrier against coalescence. Furthermore, Pickering emulsions show an enhanced stability in comparison to emulsions that are stabilized by conventional emulsifiers. for pharmaceutical and cosmetic products. The formation without emulsifier is especially interesting for the formulation of products for which the use of surfactants have negative effects, e.g. However, if solid particles are added to the mixture, they will bind to the surface of the interface and prevent the droplets from coalescing, thus causing the emulsion to be more stable. If oil and water are mixed and small oil droplets are formed and dispersed throughout the water, eventually the droplets will coalesce to decrease the amount of energy in the system. Thereby, Pickering emulsions can be considered as “emulsifier-free” or “surfactant-free” since they are stabilized by solid particles. Pickering emulsions are stabilized by adsorbed solid particles instead of an emulsifier or surfactant. Ultrasonic is the perfect tool to create Pickering emulsions by firstly dispersing the stabilizing particles into the water phase and secondly to emulsify the oil/water phase.Pickering emulsions convince by their “emulsifier-free” character and their enhanced stability.Pickering emulsions are stabilized by solid particles.