![]() Specifically, the behavior at the interface and the ability to stabilize the emulsions can be governed by the shape of particles ( 19). The shapes of the particles can be different due to the diverse nature, composition, and structure of these biopolymers. Particles made of natural edible resources such as polysaccharides ( 16, 17), protein ( 18) have been broadly used to stabilize Pickering emulsions to satisfy diverse needs, from food and cosmetic industries to catalysis, tissue engineering, and drug delivery. Recently, with the development of biomacromolecules materials science, varieties of novel particles with adjustable surface wettability and better biocompatibility were used to stabilize Pickering emulsions ( 15). However, their applications in cosmetic products, food technology, as well as pharmaceutical industries were extremely limited due to their biodegradability and biocompatibility concerns. Furthermore, it has been applied to some novel areas, such as oil recovery. Subsequently, Pickering emulsion stabilized by inorganic solid nanoparticles such as silica particles ( 11), polymer lattices ( 12), and clay ( 13) received a wide scope of research attention because of the development of chemical engineering and material science ( 14). Initially, Pickering emulsions did not draw enough attention because of the limitation of materials which showed partial wetting in both phases. ![]() These all could provide significantly higher stability. ( 9, 10) presented a fact that the form of a network of particles in the continuous phase can generate a barrier to improving the stability of many gel-like emulsions of moderately high oil volume fraction. ( 9) considered that the capillary pressure due to the anisotropic shapes of solid particles can prevent the interface film drainage. Some researchers have provided different stability functions of particles in Pickering emulsion. Particles can provide a space barrier between the two immiscible phases to prevent droplets' coalescence ( 7) and Ostwald ripening in Pickering emulsions ( 8). There are prime differences in the behavior of the low-molecular-weight surfactants and natural polymers, particles with sizes ranging from just several nanometers to micrometers during the preparation and stabilization of the Pickering emulsions. Hence, the emulsion stabilized by particles was identified and described as “Pickering emulsion”, which can be oil-in-water (O/W), water-in-oil (W/O), water-in-water (W/W) ( 3), or even multiple ( 4– 6). Subsequently, Pickering ( 2) put forward to stabilize emulsions by using nanoparticles and microparticles, which promoted the progress of emulsion research. They are first discovered by Ramsden ( 1) in 1903 that the mixture of wax and water could be stabilized by solids, thus forming emulsions. Pickering emulsions are stabilized by solid or soft nano (micro) particles.
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