Imine-based covalent organic framework as photocatalyst for visible-light-induced atom transfer radical polymerization

Photoinduced atom transfer radical polymerization (ATRP) is an economical and environment-friendly method for synthesizing polymers with pre-designable structures and precise molecular weight. Although significant progress for copper-mediated photoinduced ATRP has been achieved, several drawbacks still remain, such as poor electron transfer capability and absorption bands of photocatalysts near UV region. Herein, imine-based covalent organic framework, TAPPy-TPA-COF , has been synthesized as potential heterogeneous photocatalyst for photoinduced ATRP. The “living” feature of polymerizations of methyl methacrylate (MMA) can be well controlled by efficiency maintain the balance between activation and inactivation of Cu^I and Cu^II. The chain extension experiments have further demonstrated the chain-end fidelity of polymers. Meanwhile, the catalyst recycle experiments have revealed stability of TAPPy-TPA-COF toward ATRP processes. These results support the feasibility of using COFs as heterogeneous photocatalysts for copper-mediated ATRP under visible light irradiation.