Surfactants are widely used fine chemical products. Surfactants are substances that can significantly reduce the surface tension of the target solution. Surfactants have fixed hydrophilic and lipophilic groups, which can be oriented on the surface of the solution. The molecular structure of surfactants is amphoteric: one end is a hydrophilic group, and the other end is a hydrophobic group.

　　The affinity of different parts of surfactant molecules for the two phases makes both phases regard them as the components of their own phase, and the molecules are arranged between the two phases, so that the surface of the two phases is equivalent to transferring into the interior of the molecule. Thus reducing the surface tension. Since both phases regard it as a component of the native phase, it is equivalent that neither phase forms an interface with the surfactant molecule, which is equivalent to partially eliminating the interface of the two phases in this way, reducing the surface tension and surface free energy.