The Function of Surfactants

The function of surfactants

1. Wetting effect

When a solid is in contact with a liquid, the original solid/gas and liquid/gas interfaces disappear and a new solid/liquid interface is formed, a process called wetting. For example, textile fiber is a porous substance with a huge surface, when the solution is spread along the fiber, it will enter the space between the fibers and drive the air out, turning the original air/fiber interface into a liquid/fiber interface, which is a typical wetting process; At the same time, the solution enters the fiber, a process called osmosis. Surfactants that help wetting and osmosis occur are called wetting agents and penetrants.

2. Emulsification

Emulsification refers to the role of two non-phase liquid solutions (such as oil and water), in which one liquid is evenly dispersed to the other liquid in a very small particle (size 10-8~10-5m) to form an emulsion. The dispersion of oil droplets into water is called oil-in-water emulsion (O/W), and the dispersion of water droplets into oil is called water-in-oil emulsion (W/O). The surfactant that can help emulsify is called emulsifier. Surfactants used as emulsifiers have both stabilizing and protecting effects.

3. Decontamination effect

Due to the emulsification of surfactant, the oil and dirt particles separated from the solid surface can be stably emulsified and dispersed in aqueous solution, and no longer deposited to the cleaned surface to form re-contamination.

4. Foaming effect

The state in which a gas is dispersed in a liquid is called a bubble. If a liquid is easy to film and not easy to break, this liquid will produce a lot of foam when stirred. The gas/liquid surface area of the system is greatly increased after the foam is produced, which makes the system become unstable, so the foam is easy to burst. When the surfactant is added to the solution, the surfactant molecules are adsorbed at the gas/liquid interface, which not only reduces the surface tension between the gas and liquid phases, but also forms a single molecular film with a certain mechanical strength so that the foam is not easy to break.