Journal of Polymer Science Part A: Polymer Chemistry, Vol.49, No.1, 82-92, 2011
Synthesis and Characterization of Functional Fluorinated Telomers
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 omega-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 F-19 NMR spectroscopy enabled one to calculate the average degrees of polymerization (DPn) and percentages of -CH2CF2I 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 -CH2CF2-CF2CH2- (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 beta, that depended on DPn values. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: 82-92, 2011
Keywords:chain transfer agent;differential scanning calorimetry;elemental analysis;fluoropolymers;FTIR and F-19 NMR spectroscopies;vinylidene fluoride telomerization;X-ray diffraction