Poly(oxime–ester) Vitrimers with Catalyst-Free Bond Exchange

He, Changfei; Shi, Shaowei; Wang, Dong; Helms, Brett A.; Russell, Thomas P.

doi:10.1021/jacs.9b06668

Cited by 170 publications

(145 citation statements)

References 35 publications

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“…Vitrimers, a novel class of polymers with dynamic reversible covalent crosslinks, have been receiving considerable attention. [12][13][14][15][16][17] By reshuffling their topology structures via rapid reversible exchange reactions, vitrimers have been noticed to be reprocessable and recyclable. 18 The introduction of vitrimer conception into elastomeric networks has been implemented to endow covalently crosslinking elastomers with recyclability.…”

Section: Introductionmentioning

confidence: 99%

A catalyst-free and recycle-reinforcing elastomer vitrimer with exchangeable links

et al. 2020

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Section: Introductionmentioning

confidence: 99%

A catalyst-free and recycle-reinforcing elastomer vitrimer with exchangeable links

et al. 2020

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“…Scheme S10. Incorporation of cellulose monomer into polyurethane film (9) Pentaerythritol ethoxylate (15/4 EO/OH, 0.1 equiv. ), polyethylene glycol (M n ~ 400 g/mol, 0.8 equiv.…”

Section: Scheme S4 Synthesis Of Carboxylic Acid-containing 6-memberementioning

confidence: 99%

Incorporating Functionalized Cellulose to Increase the Toughness of Covalent Adaptable Networks

Swartz

Dichtel

2020

ACS Appl. Mater. Interfaces

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Covalent adaptable networks (CANs) are cross-linked polymers that have mechanical properties similar to thermosets at operating conditions, yet can be reprocessed by cross-link exchange reactions that are activated by a stimulus. Although CAN exchange dynamics have been studied for many polymer compositions, the tensile properties of these demonstration systems are often inferior compared to commercial thermosets. In this study, we explore toughening CANs capable of forming covalent bonds with a reactive filler to characterize the trade-off between improved toughness and longer reprocessing times. Polycarbonate (PC) and polyurethane (PU) CANs were toughened by incorporating cellulose modified with cyclic carbonate groups as a reactive filler with loadings from 1.3-6.6 wt%. The addition of 6.6 wt% of the cellulose derivative resulted in a 3.2-fold increase in average toughness for the PC CANs, yet only increased the characteristic relaxation time of stress relaxation (*) via disulfide exchange at 180 °C from 63 s to 365 s. The cellulose-containing samples also showed >80% recovery in crosslinking density and mechanical properties after reprocessing. The addition of 3.2 wt% of the functionalized cellulose into a PEG-based PU CAN led to a 2.3-fold increase in toughness, while increasing * at 140 °C from 106 s to 157 s. These findings demonstrate the promise of functionalized cellulose as an inexpensive, renewable, and sustainable filler that toughens CANs containing hydroxyl groups. File list (3) download file view on ChemRxiv 2020_03_ChemRxiv_Swartz_Manuscript.pdf (1.31 MiB) download file view on ChemRxiv 2020_03_ChemRxiv_Swartz_TOC.jpg (68.46 KiB) download file view on ChemRxiv 2020_03_ChemRxiv_Swartz_Supporting_Information.pdf (5.12 MiB)

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“…1 Since then, the literature has focused on altering the exchange reaction (either catalytically controlled or catalyst-free) and adapting chemistries to different polymer backbones. 2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27 Other studies explored the properties of vitrimer composites and the addition of nondynamic cross-links to the network. 14,28,29,30,31,32,33,34,35 These research efforts established that modifying vitrimer chemistry provides a pathway for tuning mechanical properties, 36,37,38 stress relaxation, 39,40,41,42 shape memory, 43,44,45 and the ability to self-heal and adhere to other materials.…”

Section: Introductionmentioning

confidence: 99%

Linear Viscoelasticity and Flow of Self-Assembled Vitrimers: The Case of a Polyethylene/dioxaborolane System

Ricarte

Tournilhac²,

Cloître³

et al. 2019

Preprint

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For vitrimer systems obtained by dynamic cross-linking of polymer chains, incompatibility effects between the cross-links and polymer backbone can lead to microphase separation, resulting in a network made of cross-linked aggregates. Additionally, when there is a wide distribution of the number of cross-links per chain, macrophase separation can occur. Here, we investigate the linear viscoelasticity and flow of a polyethylene (PE) vitrimer that has cross-linkable dioxaborolane maleimide grafts, which aggregate into a hierarchical nanostructure. To elucidate the role of selfassembly, noncross-linked graft functionalized PE was first studied. It had a terminal relaxation time that was orders of magnitude larger than both neat PE and partially peroxide cross-linked PE.When dioxaborolane cross-linker was added to form the vitrimer, the resulting material could not achieve terminal relaxation within 8 hr. The graft-poor soluble and graft-rich insoluble portions of the PE vitrimer were then isolated and characterized. The soluble portion expressed similar flow behavior as neat PE, while the insoluble portion -which is a network of cross-linked aggregatesrelaxed very little over 8 hr. When the insoluble and soluble portions were blended, the rheological behavior of the original vitrimer was basically recovered, showing that the soluble portion acts as a lubricant. When the insoluble portion was blended with neat PE, the material relaxed much more stress, but still did not reach steady-state flow within 8 hr. When high stresses were applied, however, PE vitrimer flowed. Nonlinear rheology experiments revealed melt fracture at high strains and suggested that flow is enabled by rapid healing, which follows fracture events. The presence of macroscopic phase separation facilitated flow.

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Poly(oxime–ester) Vitrimers with Catalyst-Free Bond Exchange

Cited by 170 publications

References 35 publications

A catalyst-free and recycle-reinforcing elastomer vitrimer with exchangeable links

A catalyst-free and recycle-reinforcing elastomer vitrimer with exchangeable links

Incorporating Functionalized Cellulose to Increase the Toughness of Covalent Adaptable Networks

Linear Viscoelasticity and Flow of Self-Assembled Vitrimers: The Case of a Polyethylene/dioxaborolane System

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