Synthesis and polymerization of fluorinated monomers bearing a reactive lateral group - Part 7. Copolymerization of tetrafluoroethylene with omega-hydroxy trifluorovinyl monomers
B. Ameduri et al., Synthesis and polymerization of fluorinated monomers bearing a reactive lateral group - Part 7. Copolymerization of tetrafluoroethylene with omega-hydroxy trifluorovinyl monomers, J APPL POLY, 73(2), 1999, pp. 189-202
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.