Vinylogous Urea—Urethane Vitrimers: Accelerating and Inhibiting Network Dynamics through Hydrogen Bonding

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(9)

Published: Jan. 10, 2024

Vinylogous urethane (VU

Language: Английский

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Catalyst‐Free α‐Acetyl Cinnamate/Acetoacetate Exchange to Enable High Creep‐Resistant Vitrimers

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(20)

Published: March 16, 2024

Vitrimers represent an emerging class of polymeric materials that combine the desirable characteristics both thermoplastics and thermosets achieved through design dynamic covalent bonds within polymer networks. However, these are prone to creep due inherent instability bonds. Consequently, there pressing demands for development robust stable chemistries. Here, we report a catalyst-free α-acetyl cinnamate/acetoacetate (α-AC/A) exchange reaction develop vitrimers with remarkable resistance. Small-molecule model studies revealed α-AC/A occurred at temperatures above 140 °C in bulk, whereas 120 °C, this was absent. For demonstration case polymers, copolymers derived from common vinyl monomers were crosslinked terephthalaldehyde produce tunable thermal mechanical performance. All resulting exhibited high stability, especially terms resistance while retaining commendable reprocessability when subjected temperatures. This work showcases as novel chemistry capable imparting stability cross-linked

Language: Английский

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Dynamic Covalent Bonds Enabled Carbon Fiber Reinforced Polymers Recyclability and Material Circularity

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: unknown

Published: July 20, 2024

Due to their remarkable features of lightweight, high strength, stiffness, high-temperature resistance, and corrosion carbon fiber reinforced polymers (CFRPs) are extensively used in sports equipment, vehicles, aircraft, windmill blades, other sectors. The urging need develop a resource-saving environmentally responsible society requires the recycling CFRPs. Traditional CFRPs, on hand, difficult recycle due permanent covalent crosslinking polymer matrices. combination adaptable networks (CANs) with fibers (CFs) marks new development path for closed-loop recyclable CFRPs resins. In this review, we summarize most recent developments from unique paradigm dynamic polymers, CANs. These sophisticated materials diverse functions, oriented towards CFs resin sustainability, further categorized into several active domains bonds, including ester imine disulfide boronic acetal linkages, etc. Finally, possible strategies future design CFPRs by combining chemistry innovation interface science proposed.

Language: Английский

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Oligosiloxane-Based Epoxy Vitrimers: Adaptable Thermosetting Networks with Dual Dynamic Bonds

ACS Applied Polymer Materials, Journal Year: 2024, Volume and Issue: unknown

Published: Feb. 7, 2024

Embedding dynamic covalent bonds into polymer compositions transforms static thermosets active materials with the reprocessability of thermoplastics and bulk properties cross-linked networks. This class next-generation materials, called adaptable networks, shows significant promise in composites, soft optoelectronics, robotics. Herein, we synthesized two oligosiloxane-based epoxy networks that provide fast bond exchange. Oligosiloxane diepoxides were cured stoichiometric amounts 1,2-phenylenediacetic acid to generate bonding mechanisms. The resulting provided access stress-relaxation times (1–10 min) at temperatures only 130 °C excellent reprocessability.

Language: Английский

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Thermoswitchable catalysis to inhibit and promote plastic flow in vitrimers

Chemical Science, Journal Year: 2024, Volume and Issue: 15(19), P. 7061 - 7071

Published: Jan. 1, 2024

Acid-base catalysis is a common strategy to induce covalent bond exchanges in dynamic polymer networks. Strong acids or strong bases can promote rapid network rearrangements, and are simultaneously preferred catalysts for chemical reactions where maximum efficiency at the lowest possible temperature aimed for. However, within context of networks, incorporation highly active negatively affect longer term application potential. Network dynamicity diminish through catalyst ageing quenching may prematurely activate exchanges, leading dimensional instability thus low creep resistance Herein, we present several examples explicitly explored weak (carboxylic acids) as using vinylogous urethanes (VU) well-understood protic acid catalysed vitrimer chemistry. Surprisingly, have found that sought-after long-term stability offered by does not necessarily bring lower activity high temperature. In fact, show remarkable thermoswitchable catalytic behaviour, going from an inactive hydrogen bonded state matrix protonated, with profound impact on reactivity rheology. Carboxylic different electronic steric environments clear trends their fine-tuning resulted most thermally responsive VU vitrimers studied date. Our findings point out choice design only poorly informed performance more traditional (in solvent), tailored holds great promise field vitrimers.

Language: Английский

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Supramolecular Organic Nanofiller: A New Reinforcement Strategy for Dynamic Covalent Polymer Networks Toward Upcycling of Carbon Fiber Composites

Advanced Materials, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 22, 2025

Abstract Dynamic covalent polymer networks (DCPN) provide an important solution to the challenging recyclability of thermoset elastomers. However, dynamic bonds exhibit relatively weak bond energies, considerably decreasing mechanical properties DCPN. Herein, a novel reinforcement strategy for DCPN involving in situ formation supramolecular organic nanofillers through asynchronous polymerization is proposed. Owing difference reactivity isocyanate groups and gradual deblocking aldimine, cross‐linking hexamethylene diisocyanate isocyanate‐terminated prepolymer containing oxime–urethane with deblocked tris(2‐aminoethyl)amine facilitates transition from molecular interpenetration chains into immiscible polymerization. This results thermodynamic incompatibility between hyperbranched clusters long chains, inducing spontaneous nanofillers. Compared traditional strategies, improve Furthermore, interactions enable network excellent recyclability. The unique prepared allow their combination carbon fibers (CF) form CF composites outstanding personal‐protection applications, achieving composite upcycling. study offers on upcycling high‐performance composites.

Language: Английский

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Structure–Property Relationships of Elastomeric Vinylogous Urethane Thermosets and Their Application as Closed-Loop Recyclable Strain Sensors

Macromolecules, Journal Year: 2025, Volume and Issue: 58(4), P. 1923 - 1934

Published: Feb. 5, 2025

Developing closed-loop recyclable thermosets and understanding their structure–property relationships are essential steps in advancing a circular materials economy. Here, we present vinylogous urethane (VU) thermoset with recyclability, synthesized through the reaction of polytetrahydrofuran bisacetoacetate (aPTHF) tris(2-aminoethyl)amine (TREN). These VU polymers exhibit high elasticity, only 3–9% residual strain observed after cyclic tensile testing at maximum 100%, depending on molecular weight aPTHF network cross-link density. The two structural parameters also allow modulation mechanical stress-relaxation properties elastomers. To investigate hydrolysis linkages within hydrophobic matrix, employed heterogeneous system using biphasic mixture HCl CDCl3. Our findings show that VUs remain stable pure water but can be dissociated under acidic conditions, dissociation rate accelerated higher temperatures and/or presence concentrations. detailed investigations indicate potential elastomers as sustainable substrates for wearable sensors. We therefore conduct case study synthesizing sensor incorporation multiwalled carbon nanotubes (MCNs) into elastomer matrix. robustly detect various movements. Moreover, treatment both neat polymer composite diethyl ether solvent allows excellent recovery (>90%) TREN (86%), without discernible damage to MCNs reclaimed from latter.

Language: Английский

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Characterising different molecular landscapes in dynamic covalent networks

Chemical Science, Journal Year: 2022, Volume and Issue: 13(43), P. 12865 - 12875

Published: Jan. 1, 2022

A novel characterisation method is presented to link molecular reactivity changes material properties of reprocessable thermosets with unique performance.

Language: Английский

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Overcoming the Tradeoff Between Processability and Mechanical Performance of Elastomeric Vitrimers

Advanced Functional Materials, Journal Year: 2023, Volume and Issue: 33(52)

Published: Sept. 15, 2023

Vitrimers are polymer networks with dynamic covalent bonds that allow the network to reconfigure its connectivity while maintaining a constant number of chemical at all temperatures. The melt viscosity vitrimers thus gradually decreases temperature. This behavior makes more difficult process than typical thermoplastics using conventional processing techniques, such as extrusion. Although many strategies have been reported address this issue, it remains challenging overcome key tradeoff between improving processability or mechanical performance. Herein, work presents new strategy for overcoming in context elastomeric vitrimers. approach entails cross‐linking functionalized low‐glass transition ( T g ) matrix an incompatible high‐ featuring pendant groups complementary reactivity. When compared homogeneous vitrimer, microphase‐separated materials prepared by reactive extrusion present improved tensile properties and creep resistance room temperature also exhibiting enhanced high These consequence combination phase separation soft hard phases, restriction reactions within interfacial zones, judicious selection be use

Language: Английский

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Phase separation in supramolecular and covalent adaptable networks

Soft Matter, Journal Year: 2023, Volume and Issue: 19(16), P. 2857 - 2877

Published: Jan. 1, 2023

In this review we highlight the underlying mechanisms of phase separation in dynamic polymer networks, distinguishing between supramolecular networks and covalent adaptable discuss effect on material properties.

Language: Английский

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