Pickering emulsions are emulsions stabilised with solid particles, which are distributed at the oil-water interface. They were discovered a century ago but have become extremely interesting for research in recent decades. Compared to conventional emulsions, Pickering emulsions are more stable, low-toxic and biologically more favorable, as such surfactants are absent or present in smaller proportions. Knowledge of the placement of particles at the interface is increasing, and researchers are mainly looking for a connection between the surface characteristics of particles and the type and stability of the resulting emulsion - stabilisation of oil-in-water emulsion is more successful with more hydrophilic particles, stabilisation of water-in-oil emulsions with more hydrophobic particles. Solid particles are irreversibly adsorbed on the intermediate phase, which is possible due to the partial wetting of the particles, which is defined by the contact angle. Stability is also affected by other factors: concentration, size, shape and surface properties of the particles, type of oil phase and the ratio between oil and water phase, interfacial tension, etc. All of these parameters are interrelated and changing one parameter often results in changes of others. Pickering emulsions are mostly prepared by high shear techniques (rotor-stator homogenizer, high pressure homogenization and ultrasonic disintegration) and low shear techniques (membrane emulsification and microfluidic technology). In the cosmetics industry, emulsions are one of the most commonly used media. The advantages of particle-stabilised formulations are: greater stability, better permeation through the skin, better sensory effects, controlled and slow release of active ingredients, better rheological profile and durability. Stability can be achieved by using various substances such as silica, chitosan, cellulose and starch. Their surface properties can be altered and improved for stability, solubility, absorption, rheological properties, and sensory sensation.
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