Mn2(CO)10-Induced RAFT Polymerization of Vinyl Acetate, Methyl Acrylate, and Styrene

Abstract

A dinuclear manganese complex [Mn 2 (CO) 10 ] induced the controlled/living radical polymerization of various conjugated and unconjugated vinyl monomers including vinyl acetate, methyl acrylate, and styrene in conjunction with dithiocarbonyl compounds [R-SC(S)Z] under weak visible light at 40 C. The obtained polymers had controlled molecular weights, narrow molecular weight distributions, and well-defined chain-end groups originating from R-SC(S)Z, as indicated by SEC, 1 H NMR, and MALDI-TOF-MS analyses. The polymerization most probably proceeds via the reversible activation of the C-SC(S)Z bond by Á Mn(CO) 5 via the metal-catalyzed process and/or by the carbon-centered radical species via the additionfragmentation chain transfer (RAFT) process.KEY WORDS: Vinyl Acetate / Acrylate / Styrene / Living Radical Polymerization / RAFT Polymerization / Manganese Complex / Various aspects of the controlled/living radical polymerization have been significantly developed in this decade, including a variety of initiating systems, controllable monomers, polymer structures, fusion with other substances, and applications to functional materials. Among the numerous initiating systems, there are now three representatives in terms of wide applicability and good controllability; i.e., the nitroxide-mediated radical polymerization (NMP), 1,2 metal-catalyzed living radical polymerization or atom transfer radical polymerization (ATRP), [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] and reversible addition-fragmentation chain transfer (RAFT) 18 polymerization or macromolecular design via interchange of xanthate (MADIX). 19 Although the components and the mechanisms are different, they are all based on the reversible transient activation of the dormant covalent species into the growing radical species. However, each system has its own characteristics or features due to the differences, which suggests that the choice of initiating systems is important depending on the monomers, conditions, purposes, etc.The metal-catalyzed living radical polymerization or ATRP is one of the best methods in terms of the well-defined architecture of the polymers from a variety of conjugated monomers, such as methacrylates, acrylates, acrylamides, acrylonitrile, and styrenes. This polymerization is generally initiated by the carbon radical generated from the alkyl halide upon the activation of the carbon-halogen bond by the transition metal catalyst, and then proceeds via the metalcatalyzed reversible activation of the carbon-halogen terminal into the growing radical species. One growing polymer chain end is thus generated from one carbon-halogen bond, which can permit the well-defined polymer synthesis. Although various transition metals, such as ruthenium, 3 20 The choice of the metal complexes including metals and ligands as well as the halides is important for the precise control of the polymerizations depending on the monomers.In contrast, the RAFT/MADIX system with the dithiocarbonyl compounds [R-SC(S)Z] is one of the most widely applica...

Grafting of Polymer Brushes from Xanthate‐Functionalized Silica Particles

“…The increase in dispersity when high molar masses are targeted is caused by reverse VAc additions generating less reactive xanthate‐terminated species (PVAc‐CHOAc‐CH 2 ‐XA, where XA represents the xanthate moiety). Indeed, these CH 2 ‐XA‐terminated chains only exchange at a meaningful rate with the minority CH 2 ‐terminated radicals; they accumulate in the reaction medium and lead to a slowdown of the MADIX equilibrium . The VAc RAFT polymerization conducted here thus proceeded with the expected degree of control.…”

Photochemically Enabled Iodine Degenerative Transfer Controlled Radical Homo- and Block Copolymerization of Vinylidene Fluoride at Ambient Temperatures with Mn2(CO)10and Visible Light

“…Very recently, Mn 2 (CO) 10 was nevertheless employed as a photo-activator of alkyl iodides (IDT) (116)(117)(118), or RAFT reagents (119) in controlled radical photo(co)polymerizations of VAc, acrylates, styrene and alkenes. Here, Mn(CO) 5 • was shown to irreversibly activate the iodine terminated chains or the initiator (102), but the in-situ generated Mn(CO) 5 -I (85) was not involved in the IDT.…”

Macromolecular design and application using Mn2(CO)10‐based visible light photoinitiating systems

“…69,70 These radicals can initiate the polymerization of both conjugated (acrylate or methacrylate) and unconjugated (VA) monomers, whereas the RAFT agents allow the process to be mediated in a controlled manner. The RAFT process can be conducted at ambient temperature using visible (green light-emitting diode with max of 565 nm) or sunlight irradiation and produces well-defined polymers with predetermined molecular weights and a high degree of chain-end functionality originating from the RAFT agents.…”