In Situ Generated Crude Trithiocarbonate for Visible Light-Mediated RAFT Polymerization of Acrylates**

Reversible addition-fragmentation chain transfer (RAFT) radical polymerization holds great promise in the design and massive production of functional polymeric materials. However, its practical application was restricted by the scale-up production of chain transfer agents, the insufficient oxygen tolerance, and its environmental impact. In this work, a trithiocarbonate (TTC)-based RAFT agent ethyl 2-(((butylthio)carbonothioyl)thio)propanoate was synthesized in situ using shelf-stable RAFT precursors, i. e., sodium n-butyl trithiocarbonate (TTCS) and ethyl 2-bromopropionate (EBrP). The crude product was then directly used in RAFT polymerization of acrylates under the irradiation of LED at 405 nm. First-order polymerization kinetics was evidenced by proton nuclear magnetic resonance and size exclusion chromatography analysis. The measured molecular weights were close to the theoretical values and the dispersities of poly(tert-butyl acrylate)s (PtBAs) are as low as 1.08, thanks to the light-induced activation of the RAFT agent. Well-defined PtBA is also obtained in the presence of air, due to the intrinsic catalytic behavior of TTC. The proposed method greatly simplifies the set-up of RAFT polymerization without compromising its control for the polymerization. And it also contributes to reducing the cost and environmental impact of the RAFT polymerization, being promising for the industrialization of RAFT polymerization.