Controlled Radical Polymerization of Methacrylic Monomers in the Presence of a Bis(ortho-chelated) Arylnickel(II) Complex and Different Activated Alkyl Halides
TL;DR: In this article, a novel class of homogeneous nickel(II) catalysts, denoted as Ni(NCN)Br, is reported to mediate in the presence of activated alkyl halides, e.g., CCl4 or α-halocarbonyl compounds, and remarkably enough, poly(methyl methacrylate) (PMMA) with molecular weight up to at least 105 g/mol was synthesized in a controlled fashion.
Abstract: A novel class of homogeneous nickel(II) catalysts, i.e [Ni{o,o‘(CH2NMe2)2C6H3}Br], denoted as Ni(NCN‘)Br, is reported to mediate in the presence of activated alkyl halides, e.g., CCl4 or α-halocarbonyl compounds, a well-controlled radical polymerization of methacrylic monomers [methyl and n-butyl methacrylate), (MMA, n-BuMA)] at rather low temperatures (<100 °C). The number-average molecular weight of the polymer gradually increased with the monomer conversion and was inversely proportional to the initiator concentration of alkyl halides. The molecular weight distribution (MWD) remained very narrow during the whole course of the polymerization (MWD < 1.3). All the experimental data including a successful block copolymerization (n-BuMA-b-MMA) experiment were in agreement with a living polymerization process, and remarkably enough, poly(methyl methacrylate) (PMMA) with molecular weight up to at least 105 g/mol was synthesized in a controlled fashion. Increased thermal stability of the PMMA is a further indi...
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TL;DR: In this article, a review of recent mechanistic developments in the field of controlled/living radical polymerization (CRP) is presented, with particular emphasis on structure-reactivity correlations and "rules" for catalyst selection in ATRP, for chain transfer agent selection in reversible addition-fragmentation chain transfer (RAFT) polymerization, and for the selection of an appropriate mediating agent in stable free radical polymerisation (SFRP), including organic and transition metal persistent radicals.
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Additional excerpts
...ATRP has been successfully mediated by a variety of metals, including those from Groups 4 (Ti [112]), 6 (Mo [77,113,114]), 7 (Re [115]), 8 (Fe, [116–119] Ru, [120,121] Os [78]), 9 (Rh, [122] Co [123]), 10 (Ni, [124,125] Pd [126]), and 11 (Cu [89,127])....
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TL;DR: This review discusses the synthetic methodologies that are currently available for the preparation of platinum group metal complexes containing pincer ligands and especially emphasizes different applications that have been realized in materials science such as the development and engineering of sensors, switches, and catalysts.
Abstract: Since the first reports in the late 1970s on transition metal complexes contain- ing pincer-type ligands—named after the particular coordination mode of these ligands—these systems have at- tracted increasing interest owing to the unusual properties of the metal centers imparted by the pincer ligand. Typical- ly, such a ligand comprises an anionic aryl ring which is ortho,ortho-disubsti- tuted with heteroatom substituents, for example, CH2NR2 ,C H 2PR2 or CH2SR, which generally coordinate to the met- al center, and therefore support the MC s bond. This commonly results in a terdentate and meridional coordina- tion mode consisting of two metalla- cycles which share the MC bond. Detailed studies of the formation and the properties of a large variety of pincers containing platinum group metal complexes have provided direct access to both a fundamental under- standing of a variety of reactions in organometallic chemistry and to a range of new applications of these complexes. The discovery of alkane dehydrogenation catalysts, the mecha- nistic elucidation of fundamental transformations (for example, CC bond activation), the construction of the first metallodendrimers for sustain- able homogeneous catalysis, and the engineering of crystalline switches for materials processing represent only a few of the many highlights which have emanated from these numerous inves- tigations. This review discusses the synthetic methodologies that are cur- rently available for the preparation of platinum group metal complexes con- taining pincer ligands and especially emphasizes different applications that have been realized in materials science such as the development and engineer- ing of sensors, switches, and catalysts.
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TL;DR: Atom transfer radical polymerization (ATRP) is one of the most successful methods to polymerize styrenes, (meth)acrylates and a variety of other monomers in a controlled fashion, yielding polymers with molecular weights predetermined by the ratio of the concentrations of consumed monomer to introduced initiator and with low polydispersities as discussed by the authors.
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References
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TL;DR: In this paper, free radical polymerization was used to obtain polystyrene and poly(styrene-co-butadiene) with narrow polydispersity (1.19-1.36) in the presence of 2,2,6, 6,6-tetramethyl-1-piperidinyloxy using benzoyl peroxide as initiator
Abstract: Polystyrene and poly(styrene-co-butadiene) with narrow polydispersity (1.19-1.36) could be obtained by free radical polymerization in solution, bulk or suspension in the presence of 2,2,6,6-tetramethyl-1-piperidinyloxy using benzoyl peroxide as initiator
1,863 citations
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TL;DR: An extension of ATRA to atom transfer radical addition, ATRP, provided a new and efficient way to conduct controlled/living radical polymerization as mentioned in this paper, using a simple alkyl halide, R-X (X = Cl and Br), as an initiator and a transition metal species complexed by suitable ligand(s), M t n /L x, e.g., CuX/2,2'-bipyridine, as a catalyst.
Abstract: An extension of atom transfer radical addition, ATRA, to atom transfer radical polymerization, ATRP, provided a new and efficient way to conduct controlled/living radical polymerization. By using a simple alkyl halide, R-X (X = Cl and Br), as an initiator and a transition metal species complexed by suitable ligand(s), M t n /L x , e.g., CuX/2,2'-bipyridine, as a catalyst, ATRP of vinyl monomers such as styrenes and (meth)acrylates proceeded in a living fashion, yielding polymers with degrees of polymerization predetermined by Δ[M]/[I] 0 up to M n ≃ 10 5 and low polydispersities, 1.1 < M w /M n < 1.5. The participation of free radical intermediates was supported by analysis of the end groups and the stereochemistry of the polymerization. The general principle and the mechanism of ATRP are elucidated. Various factors affecting the ATRP process are discussed.
1,628 citations