10.1021/acs.macromol.9b00940.s001 Yuna Song Yuna Song Youngmu Kim Youngmu Kim Yeonjin Noh Yeonjin Noh Varun Kumar Singh Varun Kumar Singh Santosh Kumar Behera Santosh Kumar Behera Abasi Abudulimu Abasi Abudulimu Kyeongwoon Chung Kyeongwoon Chung Reinhold Wannemacher Reinhold Wannemacher Johannes Gierschner Johannes Gierschner Larry Lüer Larry Lüer Min Sang Kwon Min Sang Kwon Organic Photocatalyst for ppm-Level Visible-Light-Driven Reversible Addition–Fragmentation Chain-Transfer (RAFT) Polymerization with Excellent Oxygen Tolerance American Chemical Society 2019 ppm-level catalyst loadings Excellent Oxygen Tolerance PET-RAFT low-energy light irradiation conditions OPC CTA polymerization trithiocarbonate-based chain-transfer agent oxygen tolerance 2019-07-17 18:35:45 Journal contribution https://acs.figshare.com/articles/journal_contribution/Organic_Photocatalyst_for_ppm-Level_Visible-Light-Driven_Reversible_Addition_Fragmentation_Chain-Transfer_RAFT_Polymerization_with_Excellent_Oxygen_Tolerance/8947070 A highly efficient organic photocatalyst (OPC) for photoinduced electron/energy-transfer reversible addition–fragmentation chain-transfer (PET-RAFT) polymerization was identified through a systematic catalyst design and discovery. The devised OPC offers excellent control over PET-RAFT polymerizations of methyl methacrylate at very low catalyst loadings (5 ppm), that is, ca. 5–50 times lower loadings than other OPCs reported so far. Moreover, excellent oxygen tolerance was achieved using the discovered OPC combined with trithiocarbonate-based chain-transfer agent (CTA) under low-energy light irradiation conditions. In depth experimental and computational investigations revealed that (1) strong visible-light absorption and efficient generation of long-lived triplet states of the OPC due to its unique molecular structure and (2) the oxidation stability and no rate retardation of trithiocarbonate-based CTA are the key to the outstanding oxygen tolerance and ppm-level catalyst loadings. Our approach is thus believed to address a variety of challenging tasks related to polymer synthesis and living additive manufacturing.