ABSTRACT
Surfactants are molecules that lower surface tensions of liquids and interfacial tensions between liquid and solid or between two immiscible liquids. They have some affinity for interfaces because they are amphiphilic molecules. Soluble films are made of short amphiphilic molecules, and they are called Gibbs films. LB films are monolayers of surfactant molecules initially formed at the air–water interface and transferred to a solid support. In water, surfactants aggregate into micelles. Alcohols and hydrophilic fatty acids with long water-insoluble chains. The hydrophobic core of the micelles also serves to dissolve hydrophobic solutes in water. When shined with a monochromatic light, interference fringes are visible on the soap film. Between 1917 and 1940, Irving Langmuir studied the structure of surfactant films on the water surface. At the surface of a liquid, they spontaneously form a monolayer or monomolecular film. Due to line tension, the hole will close again while the internal liquid leaks to maintain the membrane tension close to zero.
