Vitrimer composites: current status and future challenges

Materials Advances, Journal Year: 2022, Volume and Issue: 3(22), P. 8012 - 8029

Published: Jan. 1, 2022

Vitrimers: one step towards a greener future for the composite industry?

Language: Английский

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Fast Dynamic Siloxane Exchange Mechanism for Reshapable Vitrimer Composites

Journal of the American Chemical Society, Journal Year: 2022, Volume and Issue: 144(27), P. 12280 - 12289

Published: June 27, 2022

To develop siloxane-containing vitrimers with fast dynamic characteristics, different mechanistic pathways have been investigated using a range of catalysts. In particular, one siloxane exchange pathway has found to show behavior in useful temperature (180–220 °C) for its application vitrimers. The mechanism is involve 1,5,7-triazabicyclo [4.4.0] dec-5-ene (TBD) as an organic catalyst the presence hydroxyl groups. Using this new approach, ultrafast stress-relaxation characteristics (relaxation times below 10 s) prepared readily available epoxy resin and siloxane-amine hardener. Subsequently, low viscosity vitrimer enabled preparation glass fiber-reinforced composites industrially relevant vacuum-assisted infusion technique. resulting composite was successfully thermoformed into shape, which makes it possible envision second life such highly engineered materials.

Language: Английский

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Covalent Adaptable Networks Using β-Amino Esters as Thermally Reversible Building Blocks

Journal of the American Chemical Society, Journal Year: 2021, Volume and Issue: 143(24), P. 9140 - 9150

Published: June 14, 2021

In this study, β-amino esters, prepared by the aza-Michael addition of an amine to acrylate moiety, are investigated as building blocks for formation dynamic covalent networks. While such amino esters usually considered thermally nondynamic adducts, kinetic model studies presented here show that exchange occurs via both reaction and catalyst-free transesterification. This knowledge is transferred create ester-based adaptable networks (CANs) with coexisting dissociative associative reactions. The ease, robustness, versatility chemistry demonstrated using a variety readily available multifunctional acrylates amines. CANs reprocessed either or transesterification in presence hydroxyl moieties. results reprocessable, densely cross-linked materials glass transition temperature (Tg) ranging from -60 90 °C. Moreover, even low Tg materials, high creep resistance was at elevated temperatures up 80 When additional β-hydroxyl group-containing applied during network design, enhanced neighboring group participation effect allows reprocessing 10 times 150 °C within 30 min while maintaining their material properties.

Language: Английский

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Importance of Broad Temperature Windows and Multiple Rheological Approaches for Probing Viscoelasticity and Entropic Elasticity in Vitrimers

Macromolecules, Journal Year: 2021, Volume and Issue: 54(10), P. 4782 - 4791

Published: May 5, 2021

Model polydimethylsiloxane telechelic vitrimers with dynamic boronic ester bonds were synthesized to investigate the viscoelastic properties of networks extremely low Tg via multiple rheological approaches. Frequency sweeps and stress relaxation tests, conducted at more than 120 °C above Tg, show anticipated Arrhenius behavior time inverse temperature give same activation energy for a fixed molecular weight, obtained using variety analysis methods. Time–temperature superposition demonstrates that flow regime is thermorheologically simple, while modulus plateau increases increasing temperature, consistent conserved network topology associative bond exchange. As times decrease, rubbery increases, indicating decoupling terminal dynamics from mechanics. Below 40 °C, second lower emerges, which attributed transition dominated by reaction exchange kinetics dictated local polymer dynamics. Our work points importance assessing broad window approaches in probing networks.

Language: Английский

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Upcycling of Polyethylene Terephthalate to Continuously Reprocessable Vitrimers through Reactive Extrusion

Macromolecules, Journal Year: 2021, Volume and Issue: 54(2), P. 703 - 712

Published: Jan. 11, 2021

Vitrimers are expected to combine features of thermosets and thermoplastics but their continuous reprocessing is still a challenge; poly(ethylene terephthalate) (PET) has been widely used in our daily life, while its cross-linking upcycle contradicts with processability. Herein, we combined polyol tertiary amine structure diepoxy transform PET continuously reprocessable vitrimers through an industrial twin-screw extruder. The was determined by swelling rheology experiments, the vitrimer feature characterized stress relaxation oscillatory frequency sweep experiments. Creep resistance mechanical properties were improved greatly relative neat PET. Meanwhile, exhibited excellent reprocessability via compression, extrusion, injection molding suitable for production. According this work, any containing ester bonds should be able upgraded additional advantages such as creep resistance, dimensional stability, insolubility, etc., without sacrificing original

Language: Английский

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Suppressing Creep and Promoting Fast Reprocessing of Vitrimers with Reversibly Trapped Amines

Angewandte Chemie International Edition, Journal Year: 2022, Volume and Issue: 61(9)

Published: Jan. 4, 2022

We report a straightforward chemical strategy to tackle current challenges of irreversible deformation in low Tg vitrimers at operating temperature. In particular, vinylogous urethane (VU) were prepared where reactive free amines, necessary for material flow, temporarily shielded inside the network backbone, by adding small amount dibasic ester curing mixture. The amines could be released as chain ends from resulting dicarboxamide bonds via thermally reversible cyclisation an imide moiety. Indeed, (re)generation required nucleophilic defects ensured reprocessing and rapid flow higher temperature, exchange dynamics are (re)activated. As result, VU obtained with limited creep service yet good reprocessability elevated temperatures. Thus, exerting strong control on molecular level over availability exchangeable functional groups, remarkable improvement properties was obtained.

Language: Английский

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Multiple H‐Bonding Cross‐Linked Supramolecular Solid–Solid Phase Change Materials for Thermal Energy Storage and Management

Advanced Materials, Journal Year: 2023, Volume and Issue: 36(11)

Published: Dec. 13, 2023

Solid-solid phase change materials (SSPCMs) are considered among the most promising candidates for thermal energy storage and management. However, application of SSPCMs is consistently hindered by canonical trade-off between high TES capacity mechanical robustness. In addition, they suffer from poor recyclability due to chemical cross-linking. Herein, a straightforward but effective strategy fabricating supramolecular with latent heat strength proposed. The polymer employs multiple H-bonding interactions as robust physical cross-links. This enables SSPCM enthalpy transition (142.5 J g

Language: Английский

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New Advances in Covalent Network Polymers via Dynamic Covalent Chemistry

Chemical Reviews, Journal Year: 2024, Volume and Issue: 124(12), P. 7829 - 7906

Published: June 3, 2024

Covalent network polymers, as materials composed of atoms interconnected by covalent bonds in a continuous network, are known for their thermal and chemical stability. Over the past two decades, these have undergone significant transformations, gaining properties such malleability, environmental responsiveness, recyclability, crystallinity, customizable porosity, enabled development integration dynamic chemistry (DCvC). In this review, we explore innovative realm polymers focusing on recent advances achieved through application DCvC. We start examining history fundamental principles DCvC, detailing its inception core concepts noting key role reversible bond formation. Then reprocessability DCvC is thoroughly discussed, starting from milestones that marked evolution progressing to current trends applications. The influence crystallinity then reviewed, covering diversity, synthesis techniques, functionalities. concluding section, address challenges faced field speculates potential future directions.

Language: Английский

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3D printing of dynamic covalent polymer network with on-demand geometric and mechanical reprogrammability

Nature Communications, Journal Year: 2023, Volume and Issue: 14(1)

Published: March 10, 2023

Delicate geometries and suitable mechanical properties are essential for device applications of polymer materials. 3D printing offers unprecedented versatility, but the typically fixed after printing. Here, we report a photo-printable dynamic covalent network that can undergo two independently controllable bond exchange reactions, allowing reprogramming geometry Specifically, is designed to contain hindered urea bonds pendant hydroxyl groups. The homolytic between allows reconfiguring printed shape without affecting topology properties. Under different conditions, transformed into urethane via reactions with groups, which permits tailoring freedom reprogram in an on-demand fashion opportunity produce multiple products from one single step.

Language: Английский

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Circularity in polymers: addressing performance and sustainability challenges using dynamic covalent chemistries

Chemical Science, Journal Year: 2023, Volume and Issue: 14(20), P. 5243 - 5265

Published: Jan. 1, 2023

This review provides a multidisciplinary overview of the challenges and opportunities for dynamic covalent chemistry-based macromolecules towards design new, sustainable, recyclable materials circular economy.

Language: Английский

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