Cationic surfactants

Cationic surfactants are defined as surfactants that have a positively charged functional group, but not additionally a negatively charged group. Like any surfactant, cationic surfactants are also composed of a polar and a non-polar part. Various alkyl groups serve as the non-polar part.

The polar group is usually a quaternary ammonium unit, so they are often tetraalkylammonium salts. Cationic surfactants are also known as invert soaps.

In pharmaceutical preparations, however, cationic surfactants/emulsifiers are used less in their emulsifier function. They are rather used due to their antimicrobial effect. Examples are ammonium compounds such as benzalkonium chloride, cetylpyridinium chloride.