Iodine Transfer Polymerization (ITP) of Vinylidene Fluoride (VDF). Influence of the Defect of VDF Chaining on the Control of ITP

Iodine transfer polymerization (ITP) of vinylidene fluoride (VDF) in the presence of two chain transfer agents (CTA, such as C 6 F 13 I and HC 2 F 4 CH 2 I) is presented. Various experimental conditions in terms of the nature of the radical initiators, time, temperature and initial [initiator] 0 /[VDF] 0 and [CTA] 0 /[VDF] 0 molar ratios influenced the yield of the reaction, the obtained average degree of polymerization in number, n, of PVDF−I, the defect of VDF-chaining, and the CX 2 I functionality (where X = H or F). The microstructures of these produced PVDF−I oligomers were characterized by 1 H and 19 F NMR spectroscopy which enabled one to assess the n values and to quantify the head-to-head or tail-to-tail defects of VDF-chainings. A low amount of defect of chaining in PVDF−I when C 6 F 13 I was used in contrast to a higher content from HC 2 F 4 CH 2 I. These PVDF−Is exhibited a favored −CH 2 CF 2 I functionality from the former CTA which was not observed in the latter one. A good agreement between the targeted and the obtained n values was noted for ITP of VDF in the presence of C 6 F 13 I (representative of normal addition) whereas that carried out from HC 2 F 4 CH 2 I (representative of inverse addition) led to experimental n values higher than the targeted ones in all cases. A low conversion of HC 2 F 4 CH 2 I was observed in contrast to that of C 6 F 13 I, which shows a better efficiency as the transfer agent.