Coalescence and demulsification

Let us turn to the final step which is coalescence. We can identify three crucial steps in the process of droplet coalescence (Fig. 12.13)  

Any of the three steps can be rate-determining depending on the specific nature of the system. For a detailed discussion see Ref. [551], 

---

How does the nature of a surfactant molecule aflFect the emulsion stability Which molecular parameters directly affect the emulsion stability and which are less important Why do some surfactants tend to stabilize OAV emulsions and others W/0 What surfactant concentration is sufficient to prevent coalescence Why does the addition of some surfactants to a stable emulsion cause rapid coalescence and demulsification These questions have been addressed since the beginning of this century. Already in these very early studies, correct experimental trends were established. However, only relatively recently, with the advances in the physics of surfactant monolayers, has a mechanistic picture of emulsion coalescence started to emerge. 

---