Mild-Temperature Mn₂(CO)₁₀-Photomediated Controlled Radical Polymerization of Vinylidene Fluoride and Synthesis of Well-Defined Poly(vinylidene fluoride) Block Copolymers

Abstract

By contrast to typical high-temperature (100-250 °C) telo-/polymerizations of gaseous fluorinated monomers, carried out in high-pressure metal reactors, the visible light, Mn(2)(CO)(10)-photomediated initiation of vinylidene fluoride (bp = -83 °C) polymerization occurs readily from a variety of alkyl, semifluorinated, and perfluorinated halides at 40 °C, in low-pressure glass tubes and in a variety of solvents, including water and alkyl carbonates. Perfluorinated alkyl iodide initiators also induce a controlled radical polymerization via iodine degenerative transfer (IDT). While IDT proceeds with accumulation of the less reactive P(m)-CF(2)-CH(2)-I vs the P(n)-CH(2)-CF(2)-I chain ends, Mn(2)(CO)(10) enables their subsequent quantitative activation toward the synthesis of well-defined poly(vinylidene fluoride) block copolymers with a variety of other monomers.

Mn2(CO)10-photomediated synthesis of poly(vinylidene fluoride)-b-poly(styrene sulfonate)

“…Thus, such chain ends will accumulate with increasing conversion to broaden the PDI, and eventually will lead to loss of control. Indeed, to date there is no evidence of the reversible activation of the ''bad'' PVDFACF 2 ACH 2 AY chain ends, and the only current approach to FM-CRP, remains the iodine degenerative transfer [15,[36][37][38][39][40][41] (IDT: P Å n þ P m AI P n AI þ P Å m ) [7][8][9][10][11][12][13]42]. Nonetheless, addition fragmentation CRP methods may afford some level of control especially in VDF copolymerizations [43][44][45][46].…”

“…Thus, development of chemistry that allows small-scale, (1 g) polymerizations to be carried out at room temperature (rt) in inexpensive, low-pressure glass tubes is needed towards fast screening of multiple catalysts and conditions, as well as for photocatalysis. However, to the best of our knowledge, although the iodine degenerative transfer controlled radical polymerization of VDF has been available for a long time [52], and has been studied in great detail [53][54][55][56], prior to our recent work [7][8][9][10], there were no reports on metal-mediated FM or VDF polymerizations, let alone VDF-CRP or VDF photopolymerizations [11].…”

“…We have very recently reported the first examples of mild temperature, low pressure, visible light mediated VDF free radical and respectively iodine degenerative transfer, controlled radical photopolymerizations, using the photochemically labile Mn 2 (CO) 10 [8] or hypervalent iodides [9], in conjunction with a variety of alkyl and perfluroalkyl halides, as well as…”

“…Moreover, we have also shown that while the concentration of PVDFACH 2 ACF 2 AI chain end decreases and that of PVDFACF 2 ACH 2 AI chain end increases with conversion, their sum, the total iodine chain end functionality, remains relatively constant, and >90%, a value suitable for block copolymer synthesis. Most importantly, Mn 2 (CO) 10 enables the complete activation of both PVDFACH 2 ACF 2 AI and PVDFACF 2 ACH 2 AI, thus enabling the first examples well-defined PVDF block copolymers with a variety of alkenes [8][9][10].…”

Macromolecular design and application using Mn2(CO)10‐based visible light photoinitiating systems

“…56,57 The visible-light-induced ITP of vinylidene fluoride affords well-defined telechelics with very high (>95%) iodide chain-end fidelity using bifunctional alkyl and perfluoroalkyl iodides. These macroinitiators are further used for the polymerization of various monomers such as VA, tert-butyl acrylate (tBA), MMA, IP, St and ACN to obtain corresponding ABA triblock copolymers.…”