![]() White coloured particles dislike both phases equally and away from 90° the graphic changes the particle colour to reflect where it likes to be. But as the particle gets closer to the water or the oil in terms of contact angle, it is happier to be sitting in the relevant phase and not around the drop. In this region, whether it is o/w or w/o the particles are nicely clustered around the drop. The graphic gives some idea of why a 90° contact angle is likely to be optimal. The disadvantage is related to the advantage: the tough particle shell is slow to equilibrate during production so it is hard to get the emulsion into the final desired equilibrium drop size. At this point whether the emulsion is o/w or w/o depends on the o:w ratio, with the larger component tending to form the continuous phase.Ī great advantage of a Pickering emulsion is that they are relatively stable once made. The reason for the 90° "rule" is that in practice this gives optimal emulsification efficiencies as indicated in the app. Worry that your nanosized particles will get classed as nanoparticles and involve you in all sorts of Health & Safety and consumer issues.Use particles with a 90°contact angle or else use Janus particles with are 50% hydrophilic, 50% hydrophobic.The particles must be considerably smaller in size than the desired emulsion drop size.it is hydrophobic) the emulsion will be w/o If the contact angle of the particle with oil is it is hydrophilic) the emulsion will be o/w If the contact angle of the particle with water is The reality is somewhat less attractive, though there are plenty of such emulsions out there. The idea of such Pickering Emulsions is very attractive to those who meet it for the first time. HLD - Hydrophilic Lipophilic DifferenceĪn alternative to surfactants for forming an emulsion is the use of fine particles that form the shell around the oil drop or water drop.
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