Group-transfer polymerization. 1. A new concept for addition polymerization with organosilicon initiators

Webster, Owen W.; Hertler, W. R.; Sogah, Dotsevi Y.; Farnham, William B.; RajanBabu, T. V.

doi:10.1021/ja00355a039

Cited by 862 publications

(516 citation statements)

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“…Finally, it makes sense to characterize the ion pairs associated with low molecular weight living chains of poly(alkyl)methacrylates (3, Scheme 3) [67]. This review will mainly focus on the structure of the lithium ester enolate for the three types of models (1,2,3), that has been investigated by IR and NMR spectroscopy, conductimetry and measurements of colligative properties. Kinetic data and stereochemistry of the chain growth will also be emphasized.…”

Section: Preamblementioning

confidence: 99%

“…In this respect, group transfer polymerization [1,2], metal free anionic polymerization [3], covalent living polymerization [4], controlled radical polymerization [5] and ligated anionic polymerization (LAP) [6] are worth being mentioned. Nowadays, these techniques actively contribute to the engineering of versatile products such as plastics, adhesives and elastomers containing a number of different reactive functions.…”

Section: Introductionmentioning

confidence: 99%

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Anionic polymerization of methacrylic monomers: characterization of the propagating species

Zune

Jérôme

1999

Progress in Polymer Science

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Ligation of the anionic species responsible for the polymerization (LAP) of alkyl(meth)acrylates has much contributed to improve polymerization control. This ligated anionic polymerization has been firstly studied by using model compounds, such as low molecular weight lithium ester enolates. Recently, effort has been devoted to the direct analysis of the species that propagate the anionic polymerization of (meth)acrylates. In addition to IR, multinuclear NMR spectroscopy has been very instrumental in the elucidation of the structure and aggregation of the active species and how these characteristic features are modified by the addition of various types of ligands. This substantial progress in the characterization of the polyalkyl(meth)acrylate anions, ligated or not, is reported in this review.

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Section: Preamblementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Anionic polymerization of methacrylic monomers: characterization of the propagating species

Zune

Jérôme

1999

Progress in Polymer Science

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“…Originally, group transfer polymerization (GTP) of methyl methacrylate (MMA) was assumed to proceed via an associated mechanism [1,2]. Starting with silyl ketene acetals as initiators, an active centre is supposed to be created by the coordination of a nucleophilic catalyst to the silicon atom, providing a pentacoordinated *To whom correspondence should be addressed.…”

Section: Introductionmentioning

confidence: 99%

Metal-free anionic polymerization of methyl methacrylate

Fieberg

Broska

Heibel

et al. 1998

Designed Monomers and Polymers

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Abstract�Results on the metal-free anionic polymerization of methyl methacrylate (MMA) are presented. MMA was polymerized in tetrahydrofuran, using tetrabutylammonium diethyl 2-ethylmalonate and tetrabutylammonium 2-nitropropanate as initiators. Immediate polymerization was observed only in cases where the initators did not contain traces of their precursor molecules, the presence of which causes an appreciable inhibition period. This is attributed to the transfer reaction between active species and the precursor molecules. Only after their consumption can the major polymerization start. Using very pure initiators, no inhibition period was observed. Curves from dilatometric measurements showed the existence of an induction period. As usual, this is attributed to an initiation reaction which is slower than the propagation reaction. It is more clearly marked for tetrabutylammonium diethyl 2-ethylmalonate than for tetrabutylammonium 2-nitropropanate as initiator. All polymerizations of MMA usually go to complete consumption of the monomer. However, termination reactions have to be taken into account as well. The well-known intramolecular cyclization reaction was not observed in the MMA system. Here, a Hofmann elimination reaction terminates the growing of chains, which is due to the butyl ligands of the ammonium cation, where a β-hydrogen atom can be transferred to the growing chain under the formation of tri-n-butylamine and 1-butene. To eliminate this termination step, tetramethylammonium diethyl 2-ethylmalonate was synthesized and used as the initiator for the polymerization of MMA. Now transalkylation under the formation of a methyl group terminated the saturated chain end and trimethyl amine could be detected as a second termination reaction. Neither of the termination reactions seems to be very fast. The molecular weight distributions of the synthesized polymers are relatively broad.

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“…The first strategy for achieving "living" (meth)acrylate polymerization through modification of the ionic nature of the endgroup was group transfer polymerization (GTP), developed by Webster and Sogah et al at DuPont in 1983 (75)(76)(77)(78)(79)(80). This process involves initiation with a silyl ketene acetal or related compound, producing a silyl enolate propagating species.…”

Section: Group Transfer Polymerizationmentioning

confidence: 99%

“…Nucleophilic catalysts fonction by promoting displacement at the silyl group through a hexavalent intermediate (for an associative process) and are needed only in low concentrations (< 0.1 mol % of initiator). A wide range of nucleophiles may be used, including fluoride, bifluoride (BF2"), azide, cyanide, cyanate, nitrite, carboxylates, phenolates, sulfinates, and sulfonamidates (75)(76)(77)(86)(87)(88)(89). Lewis acid catalysts function by coordinating to the monomer carbonyl group and are thus needed in higher concentrations (> 10 mol % of initiator).…”

Section: Group Transfer Polymerizationmentioning

confidence: 99%

The Organometallic Polymerization of (Meth)acrylates: An Overview

Boffa

2000

ACS Symposium Series

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Metal-mediated (meth)acrylate polymerizations provide a good example of the versatility and importance of transition metal catalysis in polymer design. This chapter surveys several of these processes with respect to "living" behavior, experimental condition and monomer restrictions, and types of polymer architectures available.In addition to anionic methods, Group Transfer Polymerization (GTP) with silyl enolates or zirconocenes, organolanthanide-and aluminum porphyrin-initiated polymer ization, and Atom Transfer Radical Polymerization (ATRP) are discussed.Polymethacrylate and polyacrylate materials play an important role in our society. Almost two billion pounds of polymer products based on acrylic esters are produced each year for applications such as window plastics, dental materials, paints, contact lenses, fibers, and viscosity modifiers.Polymethacrylates-particularly poly(methyl methacrylate) (PMMA)-possess high strength, high impact resistance, excellent heat and chemical stability, and a highly amorphous nature which results in excellent optical clarity. For these reasons, they are used widely as building plastics (Plexiglas, Lucite). Polyacrylates are less rigid due to their lower glass transition temperatures, and as latex emulsions form the basis for durable automobile and house paints and coatings. Random copolymers of (meth)acrylates with vinylidene chloride (Sarari), acrylonitrile, and ethylene find applications as clothing fibers, tubing, gaskets, disposable gloves, and heat-and oil-resistant automotive elastomers.Despite the commercial utility of polymethacrylates and polyacrylates, refinements in synthetic methodology these macromolecules have lagged behind that of other polymers. The great majority of acrylic ester products in use today are still produced by radical polymerization, which allows little if any control over the fine points of the polymerization process. This is the result of the traditionally illcontrolled nature of acrylate polymerization. While chain termination and transfer side reactions may be largely eliminated for other monomers, such as styrene and dienes, through the use of controlled anionic polymerization, the (meth)acrylate ester

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Group-transfer polymerization. 1. A new concept for addition polymerization with organosilicon initiators

Cited by 862 publications

References 1 publication

Anionic polymerization of methacrylic monomers: characterization of the propagating species

Anionic polymerization of methacrylic monomers: characterization of the propagating species

Metal-free anionic polymerization of methyl methacrylate

The Organometallic Polymerization of (Meth)acrylates: An Overview

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