Fluoroalkyl Pentacarbonylmanganese(I) Complexes as Initiators for the Radical (co)Polymerization of Fluoromonomers

The use of [Mn(R(F))(CO)(5)] (R(F) = CF(3), CHF(2), CH(2)CF(3,) COCF(2)CH(3)) to initiate the radical polymerization of vinylidene fluoride (F(2)C=CH(2), VDF) and the radical alternating copolymerization of vinyl acetate (CH(2)=CHOOCCH(3), VAc) with tert-butyl 2-(trifluoromethyl)acrylate (MAF-TBE) by generating primary R(F)(•) radicals is presented. Three different initiating methods with [Mn(CF(3))(CO)(5)] (thermal at ca. 100 °C, visible light and UV irradiations) are described and compared. Fair (60%) to satisfactory (74%) polyvinylidene fluoride (PVDF) yields were obtained from the visible light and UV activations, respectively. Molar masses of PVDF reaching 53,000 g·mol(−1) were produced from the visible light initiation after 4 h. However, the use of [Mn(CHF(2))(CO)(5)] and [Mn(CH(2)CF(3))(CO)(5)] as radical initiators produced PVDF in a very low yield (0 to 7%) by both thermal and photochemical initiations, while [Mn(COCF(2)CH(3))(CO)(5)] led to the formation of PVDF in a moderate yield (7% to 23%). Nevertheless, complexes [Mn(CH(2)CF(3))(CO)(5)] and [Mn(COCHF(2))(CO)(5)] efficiently initiated the alternating VAc/MAF-TBE copolymerization. All synthesized polymers were characterized by (1)H and (19)F NMR spectroscopy, which proves the formation of the expected PVDF or poly(VAc-alt-MAF-TBE) and showing the chaining defects and the end-groups in the case of PVDF. The kinetics of VDF homopolymerization showed a linear ln[M](0)/[M] versus time relationship, but a decrease of molar masses vs. VDF conversion was noted in all cases, which shows the absence of control. These PVDFs were rather thermally stable in air (up to 410 °C), especially for those having the highest molar masses. The melting points ranged from 164 to 175 °C while the degree of crystallinity varied from 44% to 53%.