Synthesis and polymerization of fluorinated monomers bearing a reactive lateral group - Part 7. Copolymerization of tetrafluoroethylene with omega-hydroxy trifluorovinyl monomers

The radical copolymerization of tetrafluoroethylene (TFE) and trifluoroviny l omega-hydroxy comonomers [F2C=CF(CH2)(m)OH with m = 1 (FA1) and m = 3 (FA 3)] for the synthesis of fluorinated polymers bearing hydroxy side groups i s presented. FA1 was prepared by dehydrofluorination of 2,2,3,3-tetrafluoro propanol, whereas FA3 was obtained in a three-step scheme starting from the radical addition of 1,2-dichloroiodotrifluoroethane to allyl alcohol. The copolymerization conditions (in bulk or in solution in di n-butyl ether) an d the polymer compositions considerably influenced the molecular weights, t he molecular weight distributions, and the thermal properties of these copo lymers. The kinetics of copolymerization of both couples enabled to determi ne the reaction order to the initiator (being 0.9) and the close values of apparent activation energies for [TFE/FA1 (E-a = 52.4 kJ.mol(-1)) and for T FE/FAS (E-a = 46.8 kJ.mol(-1))] couples. From the Tidwell and Mortimer meth od, the relative reactivity ratios were calculated by elemental analysis or by F-19-NMR spectroscopy, showing a higher reactivity of the TFE to incorp orate the copolymer (r(TFE) = 2.47 and r(FA1) = 0.41; r(TFE) = 1.57 and r(F A3) = 0.45). The high values of the reaction order to the initiator and low molecular weights of copolymers were associated to the allylic chain trans fer of the hydroxy comonomers and a mechanism of copolymerization was propo sed. The comonomer diad and triad distribution was determined by the statis tic theory and allowed one to calculate the average length of the comonomer sequences. Finally, the thermal decomposition of these cooligomers showed that those containing FA3 units are more thermostable than those synthesize d from FA1, and that the higher the fluorinated alcohol content, the faster the thermal decomposition. (C) 1999 John Wiley & Sons, Inc.