Surfaktant

Surfaktant, also known as surfactant, is a substance that concentrates at interfaces between liquids, gases, or solids and lowers the interfacial tension. Most surfaktants are amphiphilic, possessing a hydrophobic tail and a hydrophilic head, which drives adsorption at interfaces and the self-assembly of aggregates such as micelles when the concentration exceeds the critical micelle concentration (CMC).

Surfactants are classified by the charge of their hydrophilic group: anionic (for example, sodium dodecyl sulfate), cationic (cetyltrimethylammonium bromide), nonionic (such as nonylphenol ethoxylates), and zwitterionic (betaines). They are widely used as detergents, emulsifiers, foaming and wetting agents, dispersants, and stabilizers in household, cosmetic, pharmaceutical, and food products, as well as in industrial formulations for polymerization, flotation, and pollutant remediation.

In medicine and biology, pulmonary surfactants reduce alveolar surface tension, preventing collapse of the air sacs. Exogenous surfactants from animal sources or synthetic formulations are used clinically to treat neonatal respiratory distress syndrome and to study lung function.

Environmental and safety considerations vary by chemical class. Surfactants differ in their biodegradability and aquatic toxicity; many anionic and nonionic surfactants biodegrade relatively quickly, while some quaternary ammonium and fluorinated surfactants may persist or pose ecological risks. Regulatory guidelines govern formulation, labeling and disposal.