Redox‐Active Verdazyl Radical Polymers via Postpolymerization Modification of Active Ester Polymers

Organic radical polymers (ORPs) are constructed with 1,5‐dimethyl‐6‐oxoverdazyl radicals for assessment as redox‐active materials. The ORPs were synthesized through the postpolymerization modification (PPM) of poly(pentafluorophenyl methacrylate) ( P1 ) and poly(pentafluorophenyl acrylate) ( P2 ) with either 1,5‐dimethyl‐3‐( p‐ aniline)‐6‐oxoverdazyl ( 1 ), 1,5‐dimethyl‐3‐(4‐methylamine‐(1,1ʹ‐biphenyl))‐6‐oxoverdazyl ( 2 ) or 1,5‐dimethyl‐3‐(4‐methylamine‐(1,1ʹ‐biphenyl))‐6‐oxoverdazyl (3). To overcome the limited stability of 1 , radicals containing bulky C ₃ substituents and alkyl spacers to the heteroatom of the 4‐methylamine or 4‐hydroxymethyl moiety were synthesized from high yielding (78%–98%) Suzuki–Miyaura cross‐couplings. The large cell potential (E° _cell ( 3 ) = 1.67 V) and radical stability ensure these are well suited to fundamental electrochemical proof of concept studies when incorporated into a polymer. Variable radical attachment (0%–75%) was observed in PPM reactions. The ester aminolysis of P2 yielded the highest radical containing polymer ( P2‐2 ; 75%). As a proof‐of‐concept electrochemical demonstration, P2‐2 and P2‐3 exhibited a reversible redox couple at 3.43 V (vs. Li/Li ⁺ ), successfully validating the redox activity of the verdazyl‐functionalized polymers in a coin cell.