Anionic fluorinated surfactants phosphates

Table 1.4 shows examples of fluorinated surfactants featuring a phosphate hydrophile. In general, the phosphates are less prone to cause foaming than other anionic fluorinated surfactants and some phosphate ester salts function as antifoaming agents. 

Fluorinated siufactants have been evaluated for paper uses since die early 1960s [13, 95, 96]. Perfiuorooctyl sulfonamido ethanol-based phosphates were the first substances used to provide grease repellence to food contact papers [97-99]. Fluorotelomer thiol-based phosphates and polymers followed [100-102]. Since paper fibers and phosphate-based fluorinated surfactants are both anionic, cationic bridge molecules need to be used in order to ensure the electrostatic adsorption of the surfactant onto the paper fiber. These surfactants are added to paper through the wet end press where cellulosic fibers are mixed with paper additives before entering the paper forming table of a paper machine. This treatment provides excellent... 

Amphoteric fluorinated surfactants have at least one anionic and at least one cationic group at about their isoelectric point [181]. The cationic group is usually a quaternary amine or a protonated tertiary or secondary amine. The anionic functionality is a carboxylate, sulfonate, sulfate, or phosphate group. Most widely used fluorinated surfactants are carboxybetaine-type amphoteric surfactants which have, like betaines, a cationic amine functionality and an anionic carboxylate group. Instead of a carboxylate group, the anionic component of sulfatobetaines is a sulfate group and that of sulfobetaines is a sulfonate group. 

Anionic, cationic, and nonionic fluorinated surfactants are used in various metal treatment processes. Metal surfaces are treated to prevent corrosion, reduce mechanical wear, or enhance the aesthetic appearance. Fluorinated surfactants are used in the phosphating process for aluminum and in bright dips for copper and brass. Some fluorinated surfactants (e.g., the anionic surfactants Zonyl FSA and Zonyl FSP) are strongly adsorbed on metals and provide water and solvent repel-lency [1]. 

At the end of the 1990s statistics show that the non-ionic surfactants achieved the highest growth in production rates world-wide, though anionic surfactants (anionics) maintained the dominant position in the surfactant market. Today they are produced in a larger variety by the petrochemical industry than all other types of surfactants. Their production spectrum covers alkyl sulfates (ASs), secondary alkane sulfonates (SASs) and aryl sulfonates and carboxylates via derivatives of partly fluorinated or perfluorinated alkyl surfactants to compounds with an alkylpolyglycolether substructure combined with an anionic moiety such as alkylether sulfates (AESs), phosphates, phosphonates or carboxylates. 

CH2li2 6rl5i ,w3.M+, or alkyl caboxylates H(Cih n W2-M+ withn typically 7-15 and M+ an alkali metal cation, generally sodium, or they may be anionic, such as H(CH2- 12 3+C1- or H(CH2 12 3 3+C1-. The alkyl chains need not be normal i.e., they may be branched, and may be fluorine-substituted. Some natural surfactants are also of importance e.g., lecithins such as 1,2-diacyl glycero-3-phosphate, with the acyl groups being H(CH2 an< n typica-Hy 12 18, the latter possibly oleyl, i.e., unsaturated. 

Polyfluorinated compounds comprise hundreds of chemicals characterized by hydrophobic linear alkyl chains partially or fully fluorinated (as the perfluorinated compounds [PFCs]) and containing different functional groups. Polyfluorinated compounds include perfluoroalkyl sulfonamides (PFASAs), fluorotelomer alcohols (FTOHs), polyfluorinated alkyl phosphates (PFAPs), fluorotelomer unsaturated carboxylic acids (FTUCAs), perfluoroalkyl acids (PFAAs), and their salts. The most common PFAAs are perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkyl sulfonic acids (PFASs). In particular, PFASs contain one or more fluorinated alkyl chains bonded to a polar head, which at neutral pH can be charged (anionic, cationic, and amphiphilic surfactants) or noncharged (nonionic surfactants). 

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