Abstract
The synthesis and characterizations of fluorinated telomers based on vinylidene fluoride (VDF) by iodine transfer polymerization (ITP) are presented. These telomers were prepared in the presence of x-iodoperfluorinated functional chain transfer agents, C6F13I or C4F9I. ITPs were initiated by thermal decomposition of bis(4-tert-butylcyclohexyl) peroxydicarbonate (BBCHPDC), in solution (in the presence of acetonitrile). The obtained telomers were characterized by different analyses such as elemental analyses, nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy, size exclusion chromatography, X-ray diffraction (XRD), and finally by thermal analyses such as differential scanning calorimetry (DSC) and thermogravimetric analyses. These technical analyses enabled one to assess their chemical structures, various thermal properties, and their crystalline forms. The assignments of the characteristic signals obtained by 19F NMR spectroscopy enabled one to calculate the average degrees of polymerization (DPn) and percentages of ACH2CF2I end group functionalities that depend on the initiator and the fractionation process after reaction. A good control of polymerization was shown by the absence of reversed ACH2CF2ACF2CH2A (VDF–VDF dyads) and narrow polydispersity indices (<1.2). The XRD and DSC evidenced the influence of the chain length of the telomers on the crystallinity rate (>70%) and indicated two crystalline forms, a and b, that depended on DPn values