Kinetics of the iodine transfer polymerization of vinylidene fluoride
Résumé
The kinetics of the iodine transfer polymerization (ITP) of vinylidene fluoride (VDF) was achieved in the presence of three different chain-transfer agents (CTAs): 1-iodoperfluorohexane (C6F13I), 1-iodo-2H,2H-perfluorooctane (C6F13CH2CF2I), and 1,1,2,2-tetrafluoro-3-iodopropane (HCF2CF2CH2I). ITPs of VDF carried out in the presence of C6F13I and C6F13CH2CF2I showed the following: (1) a linear increase in DPn versus VDF, which evidenced the controlled character of ITP, although the polydispersity indices were slightly high (ca 1.5), and (2) theoretical DPn values close to the targeted ones. In contrast, neither of these statements was observed for the ITP of VDF in the presence of HCF2CF2CH2I achieved under the same conditions, even if the synthesized oligomers could be reactivated. Although the CTr values of C6F13I and C6F13CH2CF2I were close (i.e., 7.7 at 75 °C), that of HCF2CF2CH2I was lower (0.3 at 75 °C). The percentages of CF2I and CH2I functionalities were also assessed, and in the course of the reaction, a reduction of CF2I end groups was noted. Then, the mechanism of the ITP of VDF was proposed.