Macromolecules, Vol.48, No.19, 7060-7070, 2015
Radical Copolymerization of Vinylidene Fluoride (VDF) with Oligo(hexafluoropropylene oxide) Perfluorovinyl Ether Macromonomer To Obtain PVDF-g-oligo(HFPO) Graft Copolymers
The synthesis of PVDF-g-oligo(HFPO) graft copolymers, where VDF and HFPO stand for vinylidene fluoride and hexafluoropropylene oxide, respectively, is presented. First, an oligo(HFPO)-OCF=CF2 macromonomer was prepared from two methods starting from oligo(HFPO) acyl fluoride in 34 to 54% yield. Then, the radical copolymerization of VDF with that comonomer, initiated by tert-butyl peroxypivalate (TBPPi) or perfluoro-3-ethyl-2,4-dimethyl-3-pentyl persistent radical (PPFR) was studied under various conditions. The resulting PVDF-g-oligo(HFPO) graft copolymers were produced in good isolated yields (74 to 89%). The molar percentages and molecular weights of the graft copolymers were assessed by F-19 and H-1 NMR spectroscopy. Molar percentages of VDF and oligo(HFPO)-OCF=CF2 comonomers reached up to 99% and 11%, respectively, while the molecular weights ranged from 25 000 to 77 000 g/mol. Their thermal properties were also studied and showed: (1) satisfactory thermostability (T-d) in the 410 to 494 degrees C range under air and (2) melting temperature (T-m) between 138 to 159 degrees C, while (3) the glass transition (T-g) ranged from -79 to -54 degrees C.