Controlling the Ring‐Opening Polymerization Process Using External Stimuli

Chen, Min; Chen, Changle

doi:10.1002/cjoc.201900358

Cited by 26 publications

(18 citation statements)

References 31 publications

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“…[14][15][16][17] Redox control strategies (Scheme 1, IV) can be used to generate two or more different catalyst systems using only a single catalyst precursor for olefin polymerization and copolymerization. [18][19][20] In addition to the aforementioned strategies, metalmetal cooperativity effects have been extensively explored for polymerization and have proven effective at modulating polymer microstructures, as well as comonomer incorporation for copolymerization (Scheme 1, V). [21][22][23][24][25] However, this technique requires the synthesis of binuclear or multinuclear transition-metal catalysts, which can be complicated and time-consuming.…”

Section: Introductionmentioning

confidence: 99%

Interplay of Supramolecular Chemistry and Photochemistry with Palladium-Catalyzed Ethylene Polymerization

2021

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Metal-metal cooperativity effects have been extensively explored in olefin polymerization, along with the design and preparation of many binuclear transition metal catalysts. However, their synthesis and the tuning of metal-metal distance are complicated and time-consuming. In this contribution, a supramolecular chemistry strategy was used to construct multinuclear olefin polymerization catalysts. Urea functional groups were installed into several α-diimine palladium catalysts to enable hydrogenbonding-induced self-assembly. Compared with methylated counterparts (devoid of supramolecular interactions), the assembled structures and their catalytic properties were affected by the concentration, ligand sterics, temperature, and solvents, which ultimately changed the polymerization properties. Furthermore, the introduction of azobenzene units into the catalyst framework gave rise to photoresponsive behaviors in the assembled catalysts. During ethylene polymerization and copolymerization with methyl acrylate, important parameters were easily modulated, including the activity, comonomer incorporation, polymer branching density, molecular weight, and molecular weight distribution. The introduction of supramolecular chemistry and photochemistry strategies to transition-metal-catalyzed olefin polymerization opens up new possibilities for the design of new polyolefin materials.

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Section: Introductionmentioning

confidence: 99%

Interplay of Supramolecular Chemistry and Photochemistry with Palladium-Catalyzed Ethylene Polymerization

2021

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“…Controlling polymerization using external stimuli is a rapidly evolving research area [1–3] . Ideally, multiple catalytically‐active species can be generated from a single catalyst precursor via the installation of stimuli‐responsive elements.…”

Section: Methodsmentioning

confidence: 99%

Photoresponsive Palladium and Nickel Catalysts for Ethylene Polymerization and Copolymerization

Peng

Chen

2021

Angewandte Chemie

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In this contribution, we install an azobenzene functionality in olefin polymerization catalysts and use light to modulate their properties via photoinduced trans–cis isomerization of the azobenzene moiety. The initially targeted azobenzene‐functionalized α‐diimine palladium and nickel catalysts are not photoresponsive. To address this issue, an imine–amine system bearing interrupted conjugation with the metal center, and a sandwich‐type α‐diimine system bearing an azobenzene unit at a position covalently far from the metal center were prepared and studied. We demonstrate that light can be used to tune their properties in ethylene polymerization and copolymerization with polar comonomers, enabling light‐induced control of the polymerization processes, polymer microstructures and polymer properties. More interestingly, the light‐mediated property changes were attributed to ligand electronic effects in one system and ligand steric effects in the other.

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“…[ 20‐22 ] The properties of polyesters and their block or grafted copolymers or derivatives can vary with molecular weight (MW), comonomer composition, sequence, etc ., [ 23‐24 ] and might sometimes be controlled by external stimuli. [ 25‐26 ]…”

Section: Background and Originality Contentmentioning

confidence: 99%

Coordination Insertion Mechanism of Ring‐Opening Polymerization of Lactide Catalyzed by Stannous Octoate^†

et al. 2021

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Main observation and conclusion Ring‐opening polymerization (ROP) of cyclic esters in the presence of stannous octoate (Sn(Oct)2) is the main way to obtain biodegradable aliphatic polyesters, an important family of biodegradable polymers which have been widely used and still rapidly developed in the fields of biomedical polymers and environment‐friendly materials. The underlying mechanism is thought via a coordination‐insertion way, but the pathway is still open owing to the absence of direct experimental evidence. Herein, we inquire this issue through density functional theory (DFT) calculations. According to our DFT calculations and the following Curtin‐Hammett evaluation, the carbonyl oxygen has a significant advantage over the ester oxygen, and thus the ring is opened mainly through pathway A instead of pathway B. The stannous octoate is identified as a catalyst rather than an initiator. We eventually summarize the main stages during the whole polymerization of lactide.

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Controlling the Ring‐Opening Polymerization Process Using External Stimuli

Cited by 26 publications

References 31 publications

Interplay of Supramolecular Chemistry and Photochemistry with Palladium-Catalyzed Ethylene Polymerization

Interplay of Supramolecular Chemistry and Photochemistry with Palladium-Catalyzed Ethylene Polymerization

Photoresponsive Palladium and Nickel Catalysts for Ethylene Polymerization and Copolymerization

Coordination Insertion Mechanism of Ring‐Opening Polymerization of Lactide Catalyzed by Stannous Octoate^†

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Controlling the Ring‐Opening Polymerization Process Using External Stimuli

Cited by 26 publications

References 31 publications

Interplay of Supramolecular Chemistry and Photochemistry with Palladium-Catalyzed Ethylene Polymerization

Interplay of Supramolecular Chemistry and Photochemistry with Palladium-Catalyzed Ethylene Polymerization

Photoresponsive Palladium and Nickel Catalysts for Ethylene Polymerization and Copolymerization

Coordination Insertion Mechanism of Ring‐Opening Polymerization of Lactide Catalyzed by Stannous Octoate†

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Coordination Insertion Mechanism of Ring‐Opening Polymerization of Lactide Catalyzed by Stannous Octoate^†