Article Cite This: Macromolecules XXXX, XXX, XXX−XXX
Metal Acetylacetonate−Bidentate Ligand Interaction (MABLI) (Photo)activated Polymerization: Toward High Performance AmineFree, Peroxide-Free Redox Radical (Photo)initiating Systems Patxi Garra,†,§ Frédéric Dumur,‡ Didier Gigmes,‡ Malek Nechab,‡ Fabrice Morlet-Savary,†,§ Céline Dietlin,†,§ Simon Gree,†,§ Jean Pierre Fouassier, and Jacques Lalevée*,†,§ †
Université de Haute-Alsace, CNRS, IS2M UMR 7361, Cedex F-68100 Mulhouse, France Université de Strasbourg, France ‡ Aix Marseille Univ, CNRS, Institut de Chimie Radicalaire ICR, UMR 7273, F-13397 Marseille, France §
S Supporting Information *
ABSTRACT: Free radical polymerization (FRP) initiation from metal acetylacetonate−bidentate ligand interaction (MABLI) under mild conditions (room temperature, under air) is discussed here for different metal centers (Mn, V, and Cu). First, without light, in MABLI systems such as V(acac)3/ 2-diphenylphosphinobenzoic acid (2dppba), Mn(acac)3/ 2dppba, or Cu(acac)2/2dppba, electron-rich aryl (Ar•) radicals were conveniently and efficiently produced by the reaction of electron-poor acac• radicals with the iodonium salt (Iod), leading to an enhancement of pure redox (no light) polymerizations. Second, it was found that V(III)*/Iod reaction is generating aryl (Ar•) radicals at a high enough rate to initiate a photopolymerization process upon mild irradiation (LED@405 nm). This reaction can be implemented in redox photoactivated systems (e.g., using three-component V(acac)3/2dppba/Iod systems) in order to spectacularly enhance a slow redox process from 40 °C exothermicity in 800 s to 93 °C in less than 200 s. Third, an impressive chemical bleaching (without light) was reported for the Mn(acac)3/2dppba reaction. Photoactivation of the Mn(acac)3/2dppba/Iod system led to outstanding FRP initiation efficiencies (
