<i>Cis</i>-Selective Metathesis to Enhance the Living Character of Ring-Opening Polymerization: An Approach to Sequenced Copolymers

Short, Amy L.; Fang, Cheng; Nowalk, Jamie A.; Weiss, Ryan M.; Liu, Peng; Meyer, Tara Y.

doi:10.1021/acsmacrolett.8b00460

Cited by 24 publications

(24 citation statements)

References 38 publications

(51 reference statements)

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“…For example, the simple switch from a trans to a cis double bond in the macrocycle adds significant living character to what would otherwise be a solely entropy‐driven equilibrium process. Meyer and coworkers demonstrated that lower dispersities, improved molecular weight control, and the ability to create block copolymers were possible for cis ‐olefin‐containing monomers. High monomer conversion (ca.…”

Section: Selective Ed‐rompmentioning

confidence: 99%

Recent developments in entropy‐driven ring‐opening metathesis polymerization: Mechanistic considerations, unique functionality, and sequence control

Pearce

Foster

O’Reilly

2019

J. Polym. Sci. Part A: Polym. Chem.

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Entropy‐driven ROMP (ED‐ROMP) involves polymerization of olefin‐containing macrocyclic monomers under entropically favorable conditions. Macrocycles can be prepared from a variety of interesting molecules which, when polymerized, impart unique functionality to the resulting polymer backbone such as degradable linkages, biological moieties, crystallizable groups, or supramolecular hosts. In addition, the sequence of atoms in the cyclic monomer is preserved within the polymer repeating units, allowing for facile preparation of sequence‐defined polymers. In this review article, we consider how the mechanism of ROMP applies to ED polymerizations, how olefinic macrocycles are synthesized, and how polymerization conditions can be tuned to maximize conversion. Recent works in the past 10 years are highlighted, with emphasis on methods which can be employed to achieve fast polymerization kinetics and/or selective head‐to‐tail regiochemistry, thus improving polymerization control. ED‐ROMP, with its unique capability to produce polymers with well‐defined polymer backbone microstructure, represents an essential complement to other, well‐established, metathesis methodologies such as ROMP. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1621–1634

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Section: Selective Ed‐rompmentioning

confidence: 99%

Recent developments in entropy‐driven ring‐opening metathesis polymerization: Mechanistic considerations, unique functionality, and sequence control

Pearce

Foster

O’Reilly

2019

J. Polym. Sci. Part A: Polym. Chem.

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“…Ring‐opening metathesis polymerization (ROMP) has the potential to introduce these features, but it has proven difficult to maintain livingness of the polymerizations along with the introduction of labile backbone functionality. Entropy‐driven ROMP has granted access to degradable polyesters with generally high dispersities, though recent developments by Meyer have shown that polymerization control can be obtained with the use of cycic Z ‐olefins . The installation of a disulfide, phosphate, or acetal unit into 7 and 8‐membered cycloolefin derivatives results in degradable materials, but the monomers cannot homopolymerize to high molecular weights due to reduced ring strain .…”

Section: Figurementioning

confidence: 99%

Modular Approach to Degradable Acetal Polymers Using Cascade Enyne Metathesis Polymerization

Sui

Crolais

et al. 2019

Angew Chem Int Ed

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A modular synthetic approach to degradable metathesis polymers is presented using acetal‐containing enyne monomers. The monomers are prepared in a short and divergent synthetic sequence that features two points of modification to tune polymerization behavior and introduce molecular cargo. Steric and stereochemical elements are critical in the monomer design in order to provide rapid and living polymerizations capable of generating block polymers. The developed polyacetal materials readily undergo pH‐dependent degradation in aqueous mixtures, and the rate of hydrolysis can be tuned through post‐polymerization modification with triazolinedione click chemistry. This presents a new scaffold for responsive metathesis polymers that may find use in applications that requires controllable breakdown and release of small molecules.

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“…The MCO, cis-Eg(LGLM) 2 , was prepared by Z-selective metathesis. 45 The enhanced selectivity of the catalyst for cis-MCO leads to more living polymerization character, as highlighted in Figure 3. Dispersities of < 1.1 were maintained throughout the reaction and consistently higher molecular weights were obtained.…”

Section: Cis-vs Trans-olefin Studiesmentioning

confidence: 99%

Sequence-Controlled Polymers Through Entropy-Driven Ring-Opening Metathesis Polymerization: Theory, Molecular Weight Control, and Monomer Design

et al. 2019

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The bulk properties of a copolymer are directly affected by monomer sequence, yet efficient, scalable, and controllable syntheses of sequenced copolymers remain a defining challenge in polymer science. We have previously demonstrated, using polymers prepared by a step-growth synthesis, that hydrolytic degradation of poly(lactic-co-glycolic acid)s is dramatically affected by sequence. While much was learned, the step-growth mechanism gave no molecular weight control, unpredictable yields, and meager scalability. Herein, we describe the synthesis of closely-related sequenced polyesters prepared by entropy-driven ring-opening metathesis polymerization (ED-ROMP) of strainless macromonomers with imbedded monomer sequences of lactic, glycolic, 6hydroxy hexanoic, and syringic acids. The incorporation of ethylene glycol and metathesis linkers facilitated synthesis and provided the olefin functionality needed for ED-ROMP. Ring-closing to prepare the cyclic macromonomers was demonstrated using both ring-closing metathesis and macrolactonization reactions. Polymerization produced macromolecules with controlled molecular weights on a multigram scale. To further enhance molecular weight control, the macromonomers were prepared with cis-olefins in the metathesis-active segment. Under these selectivity-enhanced (SEED-ROMP) conditions, first-order kinetics and narrow dispersities were observed and the effect of catalyst initiation rate on the polymerization was investigated. Enhanced living character was further demonstrated through the preparation of block copolymers. Computational analysis suggested that the enhanced polymerization kinetics were due to the cis-macrocyclic olefin being *

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Cis-Selective Metathesis to Enhance the Living Character of Ring-Opening Polymerization: An Approach to Sequenced Copolymers

Cited by 24 publications

References 38 publications

Recent developments in entropy‐driven ring‐opening metathesis polymerization: Mechanistic considerations, unique functionality, and sequence control

Recent developments in entropy‐driven ring‐opening metathesis polymerization: Mechanistic considerations, unique functionality, and sequence control

Modular Approach to Degradable Acetal Polymers Using Cascade Enyne Metathesis Polymerization

Sequence-Controlled Polymers Through Entropy-Driven Ring-Opening Metathesis Polymerization: Theory, Molecular Weight Control, and Monomer Design

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