Tunable Nitrogen Defects on Graphitic Carbon Nitride toward the Visible-Light-Induced Reversible-Deactivation Radical Polymerization

Introducing nitrogen defects has been confirmed to improve the photoactivity of graphitic carbon nitride, but this strategy is far from being employed in the field of photo-polymerization. Here, the nitrogen-deficient graphitic carbon nitride (g-C 3 N x ) is proposed as an effective photocatalyst for photoinduced electron/energy transfer reversible addition–fragmentation chain transfer (PET-RAFT) polymerization under visible light. The g-C 3 N x was prepared through the thermal polymerization of melamine with the pre-treatment by using the different kinds of preparation tailoring agents (PTAs). It has been revealed that both the amount and the type of the PTA have a profound impact on the reaction rate and the induction period of this visible-light-driven PET-RAFT polymerization, attributed to modulating the optical absorption boundary and the carrier transport efficiency of g-C 3 N x by the introduced defects of nitrogen vacancies and cyano groups. Under the optimal condition with 0.5 g of NaOH being employed as the PTA, a monomer conversion higher than 90% was obtained in the PET-RAFT polymerization, almost doubled in comparison to the conversion catalyzed by pristine g-C 3 N 4 under the parallel 10 h of blue light (λ max = 465 nm) irradiation, and the induction period was also dramatically shortened. The as-synthesized polymers exhibit a kinetically controlled molecular weight with low dispersity (PDI < 1.2). Moreover, high end-group fidelity, universal monomer/chain transfer agent adaptation, and reliable reused capability are shown on the 2D sheets of g-C 3 N x being applied as the potential semiconductor catalyst for PET-RAFT polymerization under visible light.