May Trifluoromethylation and Polymerization of Styrene Occur from a Perfluorinated Persistent Radical (PPFR)?

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 . CF 3 radical occurred from a temperature above 85 °C. Deeper 1 H and 19 F NMR spectroscopies of the resulting fluorinated polystyrenes (CF 3 ‐PSts) evidenced the presence of both CF 3 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 CF 3 ‐PSts highlighted polymeric distributions which evidenced differences between m / z fragments of 104 and 172 corresponding to styrene and trifluoromethyl styrene units, respectively. Such CF 3 ‐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, T g ) of these polymers were also compared and revealed a much better thermal stability of the CF 3 ‐PSt (10 % weight loss at 356–376 °C) and a T g of around 70 °C.