Kinetics of the iodine transfer polymerization of vinylidene fluoride

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 (C 6 F 13 I), 1‐iodo‐2 H, 2 H ‐perfluorooctane (C 6 F 13 CH 2 CF 2 I), and 1,1,2,2‐tetrafluoro‐3‐iodopropane (HCF 2 CF 2 CH 2 I). ITPs of VDF carried out in the presence of C 6 F 13 I and C 6 F 13 CH 2 CF 2 I showed the following: (1) a linear increase in DP n versus α VDF , which evidenced the controlled character of ITP, although the polydispersity indices were slightly high (ca 1.5), and (2) theoretical DP n values close to the targeted ones. In contrast, neither of these statements was observed for the ITP of VDF in the presence of HCF 2 CF 2 CH 2 I achieved under the same conditions, even if the synthesized oligomers could be reactivated. Although the C Tr values of C 6 F 13 I and C 6 F 13 CH 2 CF 2 I were close (i.e., 7.7 at 75 °C), that of HCF 2 CF 2 CH 2 I was lower (0.3 at 75 °C). The percentages of CF 2 I and CH 2 I functionalities were also assessed, and in the course of the reaction, a reduction of CF 2 I end groups was noted. Then, the mechanism of the ITP of VDF was proposed.