Rapidly reprocessable, degradable epoxy vitrimer and recyclable carbon fiber reinforced thermoset composites relied on high contents of exchangeable aromatic disulfide crosslinks

Composites Part B Engineering, Journal Year: 2020, Volume and Issue: 199, P. 108278 - 108278

Published: July 31, 2020

Language: Английский

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

Journal of the American Chemical Society, Journal Year: 2019, Volume and Issue: 141(35), P. 13753 - 13757

Published: Aug. 21, 2019

Vitrimers are network polymers that undergo associative bond exchange reactions in the condensed phase above a threshold temperature, dictated by exchangeable bonds comprising vitrimer. For vitrimers, chemistries reliant on poorly nucleophilic partners (e.g., hydroxy-functionalized alkanes) or electrophilic bonds, catalysts required to lower which is undesirable catalyst leaching deactivation diminishes its influence over time and may compromise reuse. Here we show how access catalyst-free catalyst-dependent polyester vitrimers obviating conventional ester favor of oxime–esters. Poly(oxime–ester) (POE) synthesized using thiol–ene click chemistry, affording high stretchability malleability. POE readily recycled with little degradation their initial mechanical properties, suggesting exciting opportunities for sustainable plastics.

Language: Английский

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Rheological Properties of Covalent Adaptable Networks with 1,2,3-Triazolium Cross-Links: The Missing Link between Vitrimers and Dissociative Networks

Macromolecules, Journal Year: 2020, Volume and Issue: 53(6), P. 1884 - 1900

Published: March 9, 2020

Vitrimers, in stringent contrast to dissociative networks, involve associative covalent exchanges and remain fully cross-linked at all temperatures. However, we have previously reported on poly(1,2,3-triazolium) dynamic networks that exhibit linear rheological characterization indistinguishable from vitrimers although being based a exchange process, i.e., de-N-alkylation re-N-alkylation reactions. Herein, highlight the main features of adaptable (CANs) discuss their respective behaviors. After giving detailed overview extent potential polymer having 1,2,3-triazolium cross-links particular CANs involving trans-N-alkylation general, perform comparative described aliphatic 1,2,3-triazolium-based new bicomponent thermosetting system issued mixing polystyrene chains complementary benzyl iodide 1,2,3-triazole pendent groups. We propose simple but comprehensive methodology enables proper comparison between types CANs, networks. Owing combination high glass transition temperature network fast this network, it is possible characterize both relaxation with single experiments. provide clear experimental evidence located within narrow range, dependences these two transitions are distinct follow WLF Arrhenius models, respectively.

Language: Английский

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Biobased vitrimers: Towards sustainable and adaptable performing polymer materials

Progress in Polymer Science, Journal Year: 2022, Volume and Issue: 127, P. 101515 - 101515

Published: Jan. 12, 2022

Language: Английский

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Polybutadiene Vitrimers Based on Dioxaborolane Chemistry and Dual Networks with Static and Dynamic Cross-links

Macromolecules, Journal Year: 2019, Volume and Issue: 52(18), P. 7102 - 7113

Published: Sept. 12, 2019

Vitrimers are polymer networks able to change their topology through degenerate exchange reactions. As a result, they behave like elastic solids when the of network is frozen and viscoelastic liquids at high temperatures. Controlling dynamics molecular essential regulate solid-to-liquid transition temperature in elastomeric vitrimers. In this study, such materials were prepared by radical grafting bis-thiol dioxaborolane onto low molar mass unentangled polybutadiene. All resulting vitrimers fully relax stress reprocessable recyclable. Because thermoplastic precursor, number cross-links per chain, reaction, these dissolve tetrahydrofuran after prolonged immersion time room temperature. Creep-recovery experiments various temperatures show that both viscosity activation energy can be controlled manipulating cross-linking density. This feature offers new perspective on developing with improved creep resistance service desirable flow properties processing order prepare elastomers resistance, we dual dynamic static cross-links. Even fractions sufficient form percolated network, recyclable exhibit strong adhesion welding times as short 2 min 150 °C.

Language: Английский

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Facile Preparation of Polyimine Vitrimers with Enhanced Creep Resistance and Thermal and Mechanical Properties via Metal Coordination

Macromolecules, Journal Year: 2020, Volume and Issue: 53(8), P. 2919 - 2931

Published: April 9, 2020

Vitrimers undergoing dynamic bond exchange enable reprocessing and recycle of thermosets. However, vitrimers are susceptible to creep, leading their poor dimensional stability, which limits applications. Here, a facile method via integration metal complexes was utilized address this issue, cross-linked polyimine selected as an example vitrimer. Three different were introduced into vitrimer one-pot preparation involving the formation cross-linking polyimine. The addition 0.5 mol % Cu2+ relative imine reduced creep degree from 30% 20% at 60 °C, resistance enhanced with increasing content. Loading 5 increased initial temperature about 100 °C raised Arrhenius activation energy (Ea) for stress relaxation 52.3 67.7 kJ mol–1. ability suppress followed order Fe3+ > Mg2+, reached around 120 Fe3+. Meanwhile, polyimine–metal complex still exhibited excellent recyclability. Moreover, introduction coordination structures thermal mechanical properties, solvent, acid resistance. Thus, is efficient approach achieve high-temperature resistance, chemical stability based on Schiff base.

Language: Английский

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Phase Separation and Self-Assembly in Vitrimers: Hierarchical Morphology of Molten and Semicrystalline Polyethylene/Dioxaborolane Maleimide Systems

Macromolecules, Journal Year: 2018, Volume and Issue: 52(2), P. 432 - 443

Published: Dec. 28, 2018

Vitrimers - a class of polymer networks which are covalently crosslinked and insoluble like thermosets, but flow when heated thermoplastics contain dynamic links and/or crosslinks that undergo an associative exchange reaction. These enable vitrimers to have interesting mechanical/rheological behavior, self-healing, adhesive, shape memory properties. We demonstrate can self-assemble into complex meso- nanostructures backbone monomers strongly interact. featuring polyethylene (PE) as the dioxaborolane maleimide crosslinkable moiety were studied in both molten semi-crystalline states. observed PE macroscopically phase separated rich poor regions, characterized extent separation by optical transmission measurements. This explain relatively low fractions overall crystallinities vitrimers. Using synchrotron-sourced small-angle X-ray scattering (SAXS), we discovered their linear precursors micro-phase hierarchical nanostructures. Fitting SAXS patterns model suggests persist melt amorphous fraction state may be described aggregates packed mass fractal arrangement. findings point out incompatibility effects between network components resulting self-assembly must considered for understanding behavior rational design vitrimer materials.

Language: Английский

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Covalent Adaptable Networks with Tunable Exchange Rates Based on Reversible Thiol–yne Cross‐Linking

Angewandte Chemie International Edition, Journal Year: 2019, Volume and Issue: 59(9), P. 3609 - 3617

Published: Dec. 17, 2019

Abstract The design of covalent adaptable networks (CANs) relies on the ability to trigger rearrangement bonds within a polymer network. Simple activated alkynes are now used as versatile reversible cross‐linkers for thiols. click‐like thiol–yne cross‐linking reaction readily enables network synthesis from polythiols through double Michael addition with and tunable second step. resulting thioacetal moieties robust but dynamic linkages. A series different have been synthesized systematically probed their produce linkages, both in kinetic studies small molecule models, well stress relaxation creep measurements thiol–yne‐based CANs. results further rationalized by DFT calculations, showing that bond exchange rates can be significantly influenced choice alkyne cross‐linker.

Language: Английский

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

Macromolecules, Journal Year: 2020, Volume and Issue: 53(5), P. 1852 - 1866

Published: Feb. 18, 2020

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

Language: Английский

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Network Design to Control Polyimine Vitrimer Properties: Physical Versus Chemical Approach

Macromolecules, Journal Year: 2020, Volume and Issue: 53(10), P. 3796 - 3805

Published: May 13, 2020

A family of biobased polyimine elastomeric vitrimers was synthesized by reactions between di- and trifunctional polyetheramines a furan-based dialdehyde. By varying the triamine to diamine ratio molar mass diamine, set cross-linked networks with similar chemical structures but different cross-link densities obtained. All these materials exhibit vitrimeric behavior because dynamic nature imine bonds. This fundamental study clearly reveals that density has drastic effect on relaxation properties vitrimers. For instance, times activation energies reduced when vitrimer decreased. shows can be controlled sole modification network physical without introduction catalyst, change in structure, or additional groups. In addition, fast dual process been evidenced during stress experiments, which could potentially lead double modes based supramolecular interactions. The selective solubility also demonstrated, opening interesting possibilities for recycling while still offering robustness against aggressive conditions such as highly basic solutions. Finally, high thermal stability designed provide an reprocessability tunable mechanical properties, showing versatility this sustainable materials.

Language: Английский

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