Impact of Particles on Breakage and Coalescence Processes during the Preparation of Solid-Stabilized Emulsions

The dynamics of droplet breakage and coalescence is crucial for Pickering emulsion-based processes. We tracked the evolution of droplet size in real time using a probe-based microscope (PVM; Mettler-Toledo, U.S.). Our results showed that placing the PVM probe at any given location in the tank can provide information on the transient droplet size for a given process. We also studied the impact of particles during different stages of silicone oil-in-water emulsions stabilized with soda lime glass microspheres under controlled operating conditions. The particles lowered breakage efficiency by modifying the properties of the continuous phase in the early stage of emulsification (within 10 min) where droplet breakage predominates. We also studied the effect of the interface-coverage potential ratio on the coalescence process. The dynamic balance of breakage and coalescence was disrupted when emulsification was controlled by the coverage potential. We obtained a bimodal size distribution of droplets using a formulation containing insufficient particles and a narrow unimodal size distribution with a formulation that provided sufficient particles to cover the system-generated interface. These two outcomes likely resulted from different breakage mechanisms.