Photons and photocatalysts as limiting reagents for PET-RAFT photopolymerization

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Vol. 456; p. 141007
• Main Authors: Parnitzke, Bryan, Nwoko, Tochukwu, Bradford, Kate G.E., De Alwis Watuthanthrige, Nethmi, Yehl, Kevin, Boyer, Cyrille, Konkolewicz, Dominik
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.01.2023
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2022.141007

[Display omitted] •Typical batch PET-RAFT was found to be limited by photocatalyst and light intensity.•A universal scaling law was developed describing various geometries and reaction conditions.•Polymerization through oxygen approaches required a critical catalyst loading loadings.•PET-RAFT is subject to less retardation than conventional RAFT. The kinetics of photoinduced electron/energy transfer - reversible addition fragmentation chain transfer (PET-RAFT) polymerization were investigated using a model system of methyl acrylate (MA) in the presence of trithiocarbonate chain transfer agents and tris(2-phenylpyridine)iridium(III) (Ir(ppy)3) as the photocatalyst. A powerful polymerization through oxygen approach was developed. Efficient PET-RAFT occurred under blue, violet, and green light with catalyst loadings of 10 ppm. Minimal polymerization was observed under orange or red light. Kinetic scaling analysis was developed to evaluate the impact of light intensity, catalyst loading and geometry of both the light source and the reaction vessel. A universal scaling law was developed for Ir(ppy)3 and other energy transfer catalyzed PET-RAFT, allowing both polymerization through oxygen and deoxygenated systems from the literature to be described across a range of light intensities, reaction conditions and geometries. Finally, the scaling analysis indicates that PET-RAFT systems should be subject to less retardation than conventional RAFT systems, due to the chain transfer agent being involved in radical generation steps.