Structure and synthesis of fluorinated surfactants

Straight-chain perfluoroalkanoic or perfluoroalkanesulphonic acids fluorides derived by electrofluorination can be subjected to hydrolysis, esterification, amidation and other modifying, as illustrated with the following reactions [124, 126]  

Ethoxylated fluorosurfactants can be further modified with proper reaetants, sueh as P2O5, benzyl chloride, allyl chloride, glycidyl (meth)acrylate, epiehlorohydrin, etc., to obtain either required dispersing effects, or inert behaviour in aprotie and aggressive media, or cross-linking with finishing substrates. 

The addition of solubilising groups has often much specificity for fluorinated surfactants. Thus, perfluoroalkylethyl iodides obtained by a telomerisation process (see above) can be converted into intermediates and surfactants described in a great number of patents and scientific literature. Some examples are shown schematically in Fig. 1.5. 

CioFi90(CH2CH20)mCioFi9, m 23 reaches a surface tension of 22 mN/m at 20 °C [129]. At the same time the branched-chain fluorochemicals work at very low concentrations ( 0.1 %) and are more attractive from the economical point of view [123, 126, 130]. 

The acid fluorides resulting from the hexafluoropropylene oxide oligomerisation are capable to condense with benzene or toluene by means of a Friedel-Crafts catalyst such as AICI3 [128c]  

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