How do emulsifiers work?

How do emulsifiers work?

To understand this, we first need to understand the merger process. Coalescence is a process in which similar particles in an emulsion come together to form larger and larger particles, resulting in separation of the dispersed phase and the dispersion medium.

Emulsifiers help prevent coalescence by forming a physical barrier between the dispersed phase and the dispersion medium. As we have seen before, emulsifiers (such as soap) have both hydrophilic and hydrophobic ends. Therefore, they can be attached to both polar and non-polar substances.

When it is added to an o/w emulsion, its molecules surround the oil drop, its non-polar tail/hydrophobic end (hydrocarbon chain) extends into the oil, and its polar head/hydrophilic end (carboxylate ion) faces water.

This arrangement makes the adhesion between oil (dispersed phase) and water (dispersion medium) stronger. This newly formed adhesion force will exceed the cohesion between oil-oil and water-water. Therefore, oil particles will not tend to clump together to form larger particles. This helps prevent coalescence and thus stabilizes the emulsion.