The radical telomerization of vinylidene fluoride (or 1,1-difluoroethylene, VDF) with iodotrifluoromethane initiated by tert -butyl peroxypivalate is presented. The VDF telomers obtained were characterized by 1 H and 19 F NMR spectroscopy and by matrix-assisted laser desorption−ionization time-of-flight mass spectrometry (MALDI TOF MS) that revealed low polydispersity indexes showing a pseudo-living character of this reaction regarded as an iodine transfer polymerization process. CF 3 and CF 2 I end groups appear as suitable labels in the 19 F NMR spectra to assess the number-average molar masses of these VDF telomers ( M̄ n ). Both these techniques showed a good agreement in terms of degree of telomerization, and the first examples of MALDI−TOF mass spectra of fluorotelomers are presented. Interestingly, all telomers obtained exhibit the structure CF 3 CH 2 CF 2 (VDF) n I, showing that (i) the trifluoromethyl radical preferentially attacked the methylene site of VDF with a high regioselectivity; (ii) the only transfer reaction arose from that to the CF 3 I and not from the monomer, the initiator, the solvent, or the polymer; and (iii) a very low defect of VDF chaining (0.73% regarded as the lowest one noted in the literature) was observed.
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Améduri et al. (2004) studied this question.