This brief introduction into interfacial phenomena is designed to help users of interfacial measuring techniques better understand which instrument is most suitable for a specific problem and which possibilities exist to interpret the measured data.

There are many motivations for interfacial studies. Many applications are based on foams or emulsions. An emulsion consists of a huge number of drops of different sizes interacting with each other. When two drops contact each other, a liquid film is formed which is stabilized by adsorbed molecules, such as surfactants.

The film is composed of two adsorption layers. Therefore, the properties of these layers—even when subjected to deformations like compression, expansion, or shear—are of essential importance for understanding the formation and stabilization of emulsions. The situation with foams is very similar, and comparable scientific challenges arise.

Schematic representation of an emulsion system and adsorption layers.