Photocontrolled Synthesis of N-Type Conjugated Polymers

Current approaches to synthesize π-conjugated polymers are dominated by thermally driven, transition metal-mediated methods. Herein we show that electron-deficient Grignard monomers readily polymerize under visible light irradiation at room temperature in the absence of a catalyst. The product distribution can be tuned by the wavelength of irradiation based on the absorption of the polymer. Conversion studies are consistent with an uncontrolled chain-growth process; correspondingly, chain extension produces blocky all-conjugated copolymers. Preliminary results demonstrate that the polymerization can be expanded to donor-acceptor alternating copolymers. We anticipate that this method can serve as a platform to access new architectures of n-type conjugated polymers without the need for transition metal catalysis.