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

Abstract

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%.

Vinylidene fluoride polymerization by metal-free selective activation of hydrogen peroxide: microstructure determination and mechanistic study

“…17 In addition, a signal at 5.65 ppm ( 19 F NMR: -93.46 ppm) was identified as CH 2 =CFgenerated by the β-F elimination reaction. [60][61][62] In addition, three triplets assigned to the dimethyl carbonate radicals initiated polymerization of VDF 60,63 were identified in the 4.46 to 4.27 ppm range ( 19 F NMR: -93.19 ppm). After the qualitative identification of the chain-end functions of the prepared PVDFs (Table 5, entry 13), the relative quantity of each of them could be estimated based on NMR analysis.…”

Cobalt complexes of an OSNSO-tetrapodal pentadentate ligand: Synthesis, structures and reactivity

“…While the low valent metal complex ([L/Mt x ]) acts as activator of the halogen-capped dormant chain (P-Y) in ATRP, leading to the active radical species (P • ) and the deactivator ([L/Mt x+1 -Y]), it serves as deactivator in OMRP, via direct carbon/polymer-metal bond formation, resulting in an organometallic dormant species ([L/Mt x+1 -P], Scheme 1). Recently, we focused our attention on the development of iron-based moderating systems for the ATRP of reactive monomers such as methyl methacrylate (MMA) [21][22][23], and on manganese- [24,25] and cobalt-based systems [26][27][28][29][30][31][32][33] for the OMRP of less activated monomers (LAMs = monomers leading to poorly stabilized radicals) such as vinyl acetate (VAc) or vinylidene fluoride (VDF).…”