Deeper Spectroscopic Characterizations of Vinylidene Fluoride (VDF) Oligomers Prepared via Iodine Transfer Polymerization (ITP)

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The iodine transfer polymerization of vinylidene fluoride (or 1,1-difluoroethylene, VDF) controlled by 1-iodoperfluoroalkanes or 1,8-diiodoperfluoroctane led to oligo(VDF)s containing one or two iodine end-atom(s). Their deep characterizations utilizing size exclusion chromatography (SEC or GPC), 1 H and 19 F NMR and FT-IR spectroscopies, and matrix-assisted laser desorption-ionization time-of-flight mass spectrometry (MALDI-TOF) revealed low dispersities, indicating a pseudoliving nature of the reaction. In addition, Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) deeply facilitated the identification of various oligo(VDF) structures, especially R F (VDF) n I and side R F (VDF) n H oligomers. From the 19 F NMR spectra, the signals assigned to the CF 3 and CF 2 I end groups are valuable labels to determine the number-average molar masses ( M n ) of such VDF oligomers. The 19 F NMR, FT-ICR MS, and MALDI-TOF MS data evidenced good agreement in terms of the VDF unit numbers and end groups, while their head to head and tail to tail VDF–VDF defect of chainings, calculated from NMR data, were quite low (4.0% and 1.2%, respectively). Although the controlled behavior of these iodine transfer polymerizations (ITPs) was not studied, the dispersities of the resulting oligo(VDF) species were rather narrow (1.16–1.52) for molar masses reaching up to 4300 g·mol –1 . Their thermal characteristics, achieved by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA), evidenced crystalline oligo(VDF)-I with increasing melting points (up to 169 °C) and increasing thermal stabilities (up to 365 °C under air) for M n values ranging from 1300 to 4300 g·mol –1 .

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