ADMET Polymerization

Lehman, Stephen E.; Wagener, Kenneth B.

doi:10.1002/9783527619481.ch38

Cited by 43 publications

(40 citation statements)

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“…Two examples are the acyclic diene metathesis method, which was extensively developed by Wagener's group [8][9][10] and follows a step-growth polymerization mechanism, or ROMP with an irreversible chain transfer in which a cyclic olefin monomer is polymerized in the presence of small quantities of an acyclic olefin. However, such polymerizations cannot be considered to be living, as molecular weight distributions are typically broad and block copolymers cannot be made 11 .…”

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confidence: 99%

Catalytic living ring-opening metathesis polymerization

Nagarkar

Kilbinger

2015

Nature Chem

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In living ring-opening metathesis polymerization (ROMP), a transition-metal-carbene complex polymerizes ring-strained olefins with very good control of the molecular weight of the resulting polymers. Because one molecule of the initiator is required for each polymer chain, however, this type of polymerization is expensive for widespread use. We have now designed a chain-transfer agent (CTA) capable of reducing the required amount of metal complex while still maintaining full control over the living polymerization process. This new method introduces a degenerative transfer process to ROMP. We demonstrate that substituted cyclohexene rings are good CTAs, and thereby preserve the 'living' character of the polymerization using catalytic quantities of the metal complex. The resulting polymers show characteristics of a living polymerization, namely narrow molecular-weight distribution, controlled molecular weights and block copolymer formation. This new technique provides access to well-defined polymers for industrial, biomedical and academic use at a fraction of the current costs and significantly reduced levels of residual ruthenium catalyst. In olefin metathesis reactions, olefinic bonds are rearranged with the help of a transition-metal catalyst 1,2 . In the early days following the discovery of this reaction, ill-defined catalysts 3 were used to carry out this transformation. After Herisson and Chauvin 4 had proposed a reaction mechanism, the olefin metathesis reaction was better understood and soon gained much popularity. Typical catalysts used for olefin metathesis reactions include those based on ruthenium (developed mainly by the Grubbs group 5 ), tungsten and molybdenum (developed mainly by the Schrock group 6 ). Owing to the low oxophilicity of ruthenium compared to those of molybdenum and tungsten, the ruthenium metathesis catalysts (commonly known as Grubbs' catalysts) are more tolerant towards many polar functional groups and residual impurities, as well as to water 7 . Therefore, these catalysts are the catalysts of choice in highly functional organic chemistry transformations as well as for the majority of metathesis polymerizations carried out today. Catalysts G1 (first generation) and G3 (third generation) are the most widely used ruthenium initiators for ring-opening metathesis polymerization (ROMP). In comparison to the G1 initiator, the third-generation catalyst G3 exhibits very fast initiation and propagation rates, and thereby gives polymers with very narrow dispersities and an excellent control over their molecular weights. Owing to its superior stability as well as the favourable polymerization kinetics, the third-generation Grubbs' catalyst G3 was used for this work. ROMP is a polymerization technique that uses the metathesis of cyclic olefins to synthesize linear polymers. Depending on the structure of the monomer, such polymerizations can be controlled perfectly to give polymers with a narrow molecular weight distribution and a controlled average molecular weight. Ring-strained monomers, li...

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confidence: 99%

Catalytic living ring-opening metathesis polymerization

Nagarkar

Kilbinger

2015

Nature Chem

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“…), especially removal of ethylene by-produced from the reaction medium should be prerequisite for obtainment of the high molecular weight polymers in this condensation polymerization [21][22][23]. The promising characteristics by adopting this approach can be summarized as follows: (1) the resultant polymers are defect-free (without termination of the conjugated units, without containing any negative impurities such as halogen, sulfur), (2) the resultant polymers (oligomers) possessed highly trans olefinic double bonds (because, as initially proposed by Thorn-Csányi et al [7,8,[11][12][13][14], the reaction proceeds via metallacycle intermediate, Scheme 3). Moreover, the resultant polymers prepared by Ru catalyst possessed well-defined polymer chain ends (as vinyl group) [22,[25][26][27][28][29][30]; therefore, modification of the conjugated materials can be demonstrated by utilization of the chain ends [25][26][27][28][29][30].…”

Section: Methodsmentioning

confidence: 98%

“…Recently, it has been demonstrated that acyclic diene metathesis (ADMET) polymerization [7][8][9][10][11] offers a new possibility as the efficient route of π-conjugated materials [12][13][14][15][16][17][18][19][20][21][22][23][24]. We first demonstrated a synthesis of high molecular weight, all trans poly(9,9-di-n-octyl-fluorene-2,7-vinylene) (PFV) by ADMET polymerization of 2,7-divinyl-9,9-di-n-octyl-fluorene using Schrock type molybdenum-alkylidene [21].…”

Section: Methodsmentioning

confidence: 99%

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Acyclic Diene Metathesis (ADMET) Polymerization for Precise Synthesis of Defect-Free Conjugated Polymers with Well-Defined Chain Ends

Haque

Nomura

2015

Catalysts

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This accounts introduces unique characteristics by adopting the acyclic diene metathesis (ADMET) polymerization for synthesis of conjugated polymers, poly(arylene vinylene)s, known as promising molecular electronics. The method is more suitable than the other methods in terms of atom efficiency affording defect-free, stereo-regular (exclusive trans) polymers with well-defined chain ends; the resultant polymers possess better property than those prepared by the conventional methods. The chain ends (vinyl group) in the resultant polymer prepared by ruthenium-carbene catalyst(s) can be modified by treating with molybdenum-alkylidene complex (olefin metathesis) followed by addition of various aldehyde (Wittig type cleavage), affording the end-functionalized polymers exclusively. An introduction of initiating fragment, the other conjugated segment, and one-pot synthesis of end-functionalized block copolymers, star shape polymers can be achieved by adopting this methodology.

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“…Acyclic diene metathesis (ADMET) polymerization [15] or other desired properties of the target polymer. This methodology therefore afforded synthesis of defect free, high molecular weight, all trans poly(9,9-di-n-octyl-fluorene-2,7-vinylene) (PFV) [30], poly(2,5-dialkyl-pheny-lene-1,4-vinylene)s (PPVs) [31], and poly(N-alkylcarbazole-2,7-vinylene)s (PCVs) [32], poly(thienylene vinylene)s [34]- [40] by using Schrock type molybdenum-alkylidene, and ruthenium-carbene catalysts (Scheme 6).…”

Section: Introduction: Backgroundmentioning

confidence: 99%

ADMET Polymerization: Greener Method for Synthesis of End-Functionalized Poly(Arylene Vinylene)s

Haque¹,

Nomura²

2017

GSC

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Recent results for synthesis of conjugated polymers, poly(arylene vinylene)s exemplified as poly(fluorene vinylene)s and poly(phenylene vinylene)s, by acyclic diene metathesis (ADMET) polymerization have been introduced. The methods using molybdenum and ruthenium catalysts afforded defect-free, high molecular weight polymers with all trans olefinic double bonds, and significant reduction of by-products (halogen, sulfur etc.) in addition of decrease of structurally defects have been attained. The methods also demonstrated precise synthesis of end-functionalized polymers that showed unique optical properties combined with the end groups. Catalytic one-pot syntheses of end-functionalized poly(9,9-dialkylfluorene-2,7-vinylene)s have been attained by both ruthenium (by chain-transfer) and molybdenum catalysts and the method should provide more green route for synthesis of conjugated materials with better device performance.

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ADMET Polymerization

Cited by 43 publications

References 171 publications

Catalytic living ring-opening metathesis polymerization

Catalytic living ring-opening metathesis polymerization

Acyclic Diene Metathesis (ADMET) Polymerization for Precise Synthesis of Defect-Free Conjugated Polymers with Well-Defined Chain Ends

ADMET Polymerization: Greener Method for Synthesis of End-Functionalized Poly(Arylene Vinylene)s

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