Telomerisation of tetrafluoroethylene

The telomerisation of tetrafluoroethylene was photochemically initiated in the presence of oxygen, leading to telechelic fluorinated polyethers 5 [65] ... 

In contrast to the telomerisation of tetrafluoroethylene with perfluoroalkyl iodides (RFI), the addition of these telogens to this olefin has not been quite investigated. This may be explained by the fact that the RF(CF2CFCl)nI telomers produced are more efficient telogens than the starting RFI transfer agents as it can be seen in the previous section. Table 13 sums up the results of the literature. 

The process of telomerisation of tetrafluoroethylene with trifluoromethyl iodide or pentafluoroethyl iodide is initiated by UV irradiation or by a catalyst. In the latter case the reaction is carried out under pressure and at / = 80-220 °C ... 

In the examples described below, it can be considered that the anionic telomerisation of hexafluoropropylene oxide (HFPO) and of tetrafluoroethylene, or the cationic telomerisation of fluorinated oxiranes or oxetanes were successful. 

Tetrafluoroethylene is obviously the most used monomer in telomerisation because of its good ability to polymerise (by comparison to other monomers), its low price and the properties of the obtained perfluorinated chains. Furthermore, such an olefin is symmetrical and does not lead to problems of regio-selectivity and defects in chaining. However, it is the most difficult to handle owing to its hazardous behaviour towards oxygen and pressure. 

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