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

• Mn2(CO)10 mediates the iodine degenerative transfer photopolymerization of VDF.
• Mn2(CO)10 quantitatively activates both PVDFCH2CF2I & PVDFCF2CH2I chain ends.
• Block copolymerization of with neopentyl styrene sulfonate affords PVDF-b-PNeoSS.
• Thermal, TMS-I or LiBr deprotection methods fail.
• Deprotection with NaN3 cleanly affords PVDF-b-Poly (Styrene Sodium Sulfonate).

Mn2(CO)10-photomediated activation of perfluoro alkyl iodides under visible light was applied in the initiation of the polymerization of neopentyl styrene sulfonate (NeoSS) and of vinylidene fluoride (VDF). In the latter case, an iodine degenerative controlled radical polymerization also enabled the synthesis of PVDF-I with high chain end functionality, suitable for block copolymer synthesis. As such, quantitative Mn2(CO)10 activation of both PVDFCH2CF2I and PVDFCF2CH2I chain ends enabled the clean synthesis of PVDF-b-PNeoSS block copolymers. While subsequent deprotection of the neopentyl group was attempted by several methods, pure thermal decomposition was revealed to be more of a surface process, and while both (CH3)3SiI and LiBr deprotections failed, NaN3 in dimethyl sulfoxide was proven to allow for a complete removal of the protecting group to cleanly afford PVDF-b-PSSNa. These procedures provide simpler, cleaner and powerful avenues towards the synthesis of well-defined sulfonated and fluorinated block copolymers for fuel cell membranes.

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