Bimolecular termination in living ring opening metathesis polymerization

Feast, W. James; Gibson, Vernon C.; Khosravi, Ezat; Marshall, Edward L.; Mitchell, Jonathan Paul

doi:10.1016/0032-3861(92)90352-w

Cited by 47 publications

(34 citation statements)

References 13 publications

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“…All stock solutions were prepared in a nitrogen-filled glovebox and capped with screw-cap, septum-topped vials with vent needles. Reactions were run in open vials in a nitrogen-filled glovebox to eliminate potential coupling from oxygen 18 . tert -Butyl ester norbornene imide (tBENI) ( 3 ) was chosen for all homopolymer experiments due to the ease of synthesizing the material in high purity.…”

Section: Resultsmentioning

confidence: 99%

Pulsed-Addition Ring-Opening Metathesis Polymerization: Catalyst-Economical Syntheses of Homopolymers and Block Copolymers

2009

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Poly(tert-butyl ester norbornene imide) homopolymers and poly(tert-butyl ester norbornene imideb-N-methyl oxanorbornene imide) copolymers were prepared by pulsed-addition ring-opening metathesis polymerization (PA-ROMP). PA-ROMP is a unique polymerization method that employs a symmetrical cis-olefin chain transfer agent (CTA) to simultaneously cap a living polymer chain and regenerate the ROMP initiator with high fidelity. Unlike traditional ROMP with chain transfer, the CTA reacts only with the living chain end, resulting in narrowly dispersed products. The regenerated initiator can then initiate polymerization of a subsequent batch of monomer, allowing for multiple polymer chains with controlled molecular weight and low polydispersity to be generated from one metal initiator. Using the fast-initiating ruthenium metathesis catalyst (H 2 IMes) (Cl) 2 (pyr) 2 RuCHPh and cis-4-octene as a CTA, the capabilities of PA-ROMP were investigated with a Symyx robotic system, which allowed for increased control and precision of injection volumes. The results from a detailed study of the time required to carry out the end-capping/initiatorregeneration step were used to design several experiments in which PA-ROMP was performed from one to ten cycles. After determining the rate of catalyst death, a single, low polydispersity polymer was prepared by adjusting the amount of monomer injected in each cycle, maintaining a constant monomer/catalyst ratio. Additionally, PA-ROMP was used to prepare nearly perfect block copolymers by quickly injecting a second monomer at a specific time interval after the first monomer injection, such that chain transfer had not yet occurred. Polymers were characterized by gel permeation chromatography with multi-angle laser light scattering.

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Section: Resultsmentioning

confidence: 99%

Pulsed-Addition Ring-Opening Metathesis Polymerization: Catalyst-Economical Syntheses of Homopolymers and Block Copolymers

2009

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“…The small peak at shorter elution times in Figure 1a for ROMP PENb (and its hydrogenated derivatives) corresponds to twice the peak molecular weight and has been attributed to termination by coupling of the living ROMP chains with trace O 2 . [15] Norbornene yields an atactic product with this Schrock catalyst, [8] and given the presence of both endo and exo isomers in the monomer, and likely regio-irregularity in the polymer, no crystallinity was expected or observed in any of the polymers studied here, either before or after hydrogenation. Unsaturated ROMP PENb showed T g ¼ 34 8C by DSC (Figure 2).…”

Section: Resultsmentioning

confidence: 99%

Poly(phenylethylnorbornene)s and their Hydrogenated Derivatives

Bishop

2008

Macromol. Rapid Commun.

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Ring‐opening metathesis polymerization (ROMP) was used to synthesize novel ring‐opened poly[5‐(2‐phenylethylnorbornene)]. Hydrogenation can produce two different saturated derivatives, with the phenyl groups either preserved or saturated to cyclohexyl groups. These two different hydrogenated products allowed us to compare the effect of replacing the pendant phenyl groups with cyclohexyl groups on properties such as the glass transition temperature (Tg). We found that Tg decreased by only 2 °C (from 28 to 26 °C) upon replacement of the phenyl groups. This contrasts with the effect of saturating the phenyl groups in the addition polymer of 5‐(2‐phenylethylnorbornene), where the Tg increased by 34 °C, from 215 to 249 °C, a remarkable difference in magnitude and direction compared with the ROMP polymers.

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“…The treatment of a living ROM polymer 11b initiator with molecular oxygen led to monoaldehyde‐end‐capped polymers in high yields 243. With W‐ or Mo‐based initiators, the analogous synthetic protocol would lead to a coupling reaction, thereby yielding polymers with doubled molecular weight 17, 243, 244. The synthesis of a homologous series of unsaturated oligomeric esters by cross metathesis of cyclopentene and MMA is reported for initiator 36 215, 216.…”

Section: Applications In Polymer Synthesismentioning

confidence: 99%

Ruthenium‐based metathesis initiators: Development and use in ring‐opening metathesis polymerization

Frenzel

Nuyken

2002

J. Polym. Sci. A Polym. Chem.

161

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For many years, olefin metathesis has been a central topic of industrial and academic research because of its great synthetic utility. The employed initiators cover a wide range of compounds, from simple transition-metal salts to highly sophisticated and well-defined alkylidene complexes. Currently, ruthenium-based catalysts are at the center of attention because of their remarkable tolerance toward oxygen, moisture, and numerous functionalities. This article focuses on recent developments in the field of ring-opening metathesis polymerization using ruthenium-based catalysts. ruthenium-based initiators and their applications to the preparation of advanced polymeric materials are briefly reviewed.

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Bimolecular termination in living ring opening metathesis polymerization

Cited by 47 publications

References 13 publications

Pulsed-Addition Ring-Opening Metathesis Polymerization: Catalyst-Economical Syntheses of Homopolymers and Block Copolymers

Pulsed-Addition Ring-Opening Metathesis Polymerization: Catalyst-Economical Syntheses of Homopolymers and Block Copolymers

Poly(phenylethylnorbornene)s and their Hydrogenated Derivatives

Ruthenium‐based metathesis initiators: Development and use in ring‐opening metathesis polymerization

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