An antistatic agent is a compound used for treatment of materials or their surfaces in order to reduce or eliminate buildup of static electricity generally caused by the triboelectric effect. Its role is to make the surface or the material itself slightly conductive, either by being conductive itself, or by absorbing moisture from the air, so some humectants can be used. The molecules of an antistatic agent often have both hydrophilic and hydrophobic areas, similar to those of a surfactant; the hydrophobic side interacts with the surface of the material, while the hydrophilic side interacts with the air moisture and binds the water molecules.
Internal antistatic agents are designed to be mixed directly into the material, external antistatic agents are applied to the surface.
Common antistatic agents are based on long-chain aliphatic amines (optionally ethoxylated) and amides, quaternary ammonium salts (e.g., behentrimonium chloride or cocamidopropyl betaine), esters of phosphoric acid, polyethylene glycol esters, or polyols. Indium tin oxide can be used as transparent antistatic coating of windows. It is also possible to use conductive polymers, like PEDOT:PSS and conducting polymer nanofibers, particularly polyaniline nanofibers.
Antistatic agents are also added to some military jet fuels, to impart electrical conductivity to them and avoid buildup of static charge that could lead to sparks igniting fuel vapors. Stadis 450, with dinonylnaphthylsulfonic acid (DINNSA) as the active ingredient, is the agent added to some distillate fuels, solvents, commercial jet fuels, and to the military JP-8. Stadis 425 is a similar compound, for use in distillate fuels and solvents.