ma9b00940_si_001.pdf (12.05 MB)
Organic Photocatalyst for ppm-Level Visible-Light-Driven Reversible Addition–Fragmentation Chain-Transfer (RAFT) Polymerization with Excellent Oxygen Tolerance
journal contribution
posted on 2019-07-17, 18:35 authored by Yuna Song, Youngmu Kim, Yeonjin Noh, Varun Kumar Singh, Santosh Kumar Behera, Abasi Abudulimu, Kyeongwoon Chung, Reinhold Wannemacher, Johannes Gierschner, Larry Lüer, Min Sang KwonA 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.