Structural Features of Fluorinated Surfactants. The Hydrophobe

To understand how surfactants function and to select a surfactant for a specific purpose, it is necessary to classify surfactants according to their structural features. 

Like all surfactants, fluorinated surfactants are either ionic or nonionic. Ionic surfactants can, unlike nonionic surfactants, dissociate into ions in an aqueous medium. The hydrophobic part can belong to a negative or positive ion. Some surfactants have negatively and positively charged functional groups on the same backbone. The surfactants can therefore be classified into four types  

Anionic surfactants—the hydrophobic part is an anion, for example, RfCOO Na, where Rf is a fluorine-containing hydrophobe. 

Cationic surfactants—the hydrophobic part is a cation, for example, C7Fi5CONH(CH2)3N+ (CHshr. 

Amphoteric surfactants— have at least one anionic and one cationic group at their isoelectric point. 

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