May Trifluoromethylation and Polymerization of Styrene Occur from a Perfluorinated Persistent Radical (PPFR)? |
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Authors: | Dr Benoit Briou Olinda Gimello Cedric Totee Dr Taizo Ono Dr Bruno Ameduri |
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Institution: | 1. ICGM, ENSCM, CNRS, Université Montpellier, 34296 Montpellier, France;2. PAC CNRS-UM-ENSCM, ICGM Montpellier, 34296 Montpellier, France;3. Fluorine Division, Research & Development Center, Mitsubishi Materials Electronic Chemicals Co, Ltd, 3-1-6, Barajima, Akita, 010-8585 Japan |
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Abstract: | The radical polymerization of styrene (St) initiated by a trifluoromethyl radical generated from a perfluorinated highly branched persistent radical (PPFR) is presented with an isolated yield above 70 %. The release of .CF3 radical occurred from a temperature above 85 °C. Deeper 1H and 19F NMR spectroscopies of the resulting fluorinated polystyrenes (CF3-PSts) evidenced the presence of both CF3 end-group of the PSt chain and the trifluoromethylation of the phenyl ring (in meta-position mainly). PPFR]0/St]0 initial molar ratios of 3:1, 3:10 and 3:100 led to various molar masses ranging from 1750 to 5400 g mol?1 in 70–86 % yields. MALDI-TOF spectrometry of such CF3-PSts highlighted polymeric distributions which evidenced differences between m/z fragments of 104 and 172 corresponding to styrene and trifluoromethyl styrene units, respectively. Such CF3-PSt polymers were also compared to conventional PSts produced from the radical polymerization of St initiated by a peroxydicarbonate initiator. A mechanism of the polymerization is presented showing the formation of a trifluoromethyl styrene first, followed by its radical (co)polymerization with styrene. The thermal properties (thermal stability and glass transition temperature, Tg) of these polymers were also compared and revealed a much better thermal stability of the CF3-PSt (10 % weight loss at 356–376 °C) and a Tg of around 70 °C. |
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Keywords: | fluorinated radicals MALDI spectrometry NMR spectroscopy radical polymerization styrene |
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