page_title: Surfactant
section_title: Classification
hierarchical_section_title: Surfactant / Classification
caption_attribution_description: Deutsch: Tenside haben hyrophile und hydrophobe Enden
context_page_description: Surfactants are compounds that lower the surface tension between two liquids, between a gas and a liquid, or between a liquid and a solid. Surfactants may act as detergents, wetting agents, emulsifiers, foaming agents, and dispersants.
  The word surfactant is a blend of surface-active agent. Agents that increase surface tension are surface active in the literal sense but are not called surfactants since their effect is opposite to the common meaning. A common example is salting out, by adding an inorganic salt to an aqueous solution of a weakly polar substance, the substance will precipitate. The substance may itself be a surfactant, and it is one of the reasons why many surfactants are ineffective in sea water.
context_section_description: The "tails" of most surfactants are fairly similar, consisting of a hydrocarbon chain, which can be branched, linear, or aromatic. Fluorosurfactants have fluorocarbon chains. Siloxane surfactants have siloxane chains.
  Many important surfactants include a polyether chain terminating in a highly polar anionic group. The polyether groups often comprise ethoxylated (polyethylene oxide-like) sequences inserted to increase the hydrophilic character of a surfactant. Polypropylene oxides conversely, may be inserted to increase the lipophilic character of a surfactant.
  Surfactant molecules have either one tail or two; those with two tails are said to be double-chained.
  Most commonly, surfactants are classified according to polar head group. A non-ionic surfactant has no charged groups in its head. The head of an ionic surfactant carries a net positive, or negative charge. If the charge is negative, the surfactant is more specifically called anionic; if the charge is positive, it is called cationic. If a surfactant contains a head with two oppositely charged groups, it is termed zwitterionic.  Commonly encountered surfactants of each type include:
caption: Surfactant classification according to the composition of their head: non-ionic, anionic, cationic, amphoteric.
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