Fast Dynamic Siloxane Exchange Mechanism for Reshapable Vitrimer Composites

Journal of the American Chemical Society, Год журнала: 2022, Номер 144(27), С. 12280 - 12289

Опубликована: Июнь 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.

Язык: Английский

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A Highly Dynamic Covalent Polymer Network without Creep: Mission Impossible?

Angewandte Chemie International Edition, Год журнала: 2022, Номер 61(48)

Опубликована: Сен. 26, 2022

Dynamic covalent polymer networks provide an interesting solution to the challenging recyclability of thermosets and elastomers. One remaining design constraints, however, is balancing thermal reprocessability in form material flow with dimensional stability during use. As a result, many chemistries are being investigated order improve bond reactivity control robustness. This Minireview highlights number promising concepts, particular emphasis on disconnecting chemical low high temperature regimes obtain creep resistant, yet highly dynamic networks. In addition, we will highlight impact sharp changes when applying extrapolation-based approaches rheological analysis. confident that abandoning myth "permanent" aid development sustainable polymeric materials can truly combine benefits thermoplastic thermoset behaviour.

Язык: Английский

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Adhesion mechanism and application progress of hydrogels

European Polymer Journal, Год журнала: 2022, Номер 173, С. 111277 - 111277

Опубликована: Май 20, 2022

Язык: Английский

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

Nature Communications, Год журнала: 2023, Номер 14(1)

Опубликована: Март 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.

Язык: Английский

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Spiroborate-Linked Ionic Covalent Adaptable Networks with Rapid Reprocessability and Closed-Loop Recyclability

Journal of the American Chemical Society, Год журнала: 2023, Номер 145(16), С. 9112 - 9117

Опубликована: Апрель 14, 2023

Covalent adaptable networks (CANs) represent a novel class of polymeric materials crosslinked by dynamic covalent bonds. Since their first discovery, CANs have attracted great attention due to high mechanical strength and stability like conventional thermosets under service conditions easy reprocessability thermoplastics certain external stimuli. Here, we report the example ionic (ICANs), type ionomers, consisting negatively charged backbone structures. More specifically, two ICANs with different compositions were prepared through spiroborate chemistry. Given nature linkages, resulting ionomer display rapid closed-loop recyclability mild conditions. The mechanically broken into smaller pieces can be reprocessed coherent solids at 120 °C within only 1 min nearly 100% recovery properties. Upon treating dilute hydrochloric acid room temperature, valuable monomers easily chemically recycled in almost quantitative yield. This work demonstrates potential bonds as linkage for development new reprocessable recyclable thermosets.

Язык: Английский

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Taking dynamic covalent chemistry out of the lab and into reprocessable industrial thermosets

Nature Reviews Chemistry, Год журнала: 2025, Номер unknown

Опубликована: Янв. 31, 2025

Язык: Английский

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High-T_g and Degradable Isosorbide-Based Polybenzoxazine Vitrimer

ACS Sustainable Chemistry & Engineering, Год журнала: 2021, Номер 10(1), С. 594 - 602

Опубликована: Дек. 27, 2021

This work describes new fully bio-based vitrimers prepared from isosorbide, a renewable sugar-based chemical. Isosorbide was reacted with 4-hydroxypropionic acid, paraformaldehyde, mono-ethanolamine, and/or furfurylamine via consecutive solvent-free Fischer esterification and Mannich-like ring-closure reactions. The two-step synthesis led to the formation of di-telechelic benzoxazine-terminated isosorbide monomer, containing ester bonds aliphatic hydroxyl furan groups. atom economy factor yields 85%. structural features resulting products were substantiated by spectroscopic techniques. ring-opening polymerization monitored rheological differential scanning calorimetry (DSC) measurements. Very high Tg values afforded substructure measured (from 143 193 °C), which increase ring content. Internally catalyzed transesterification reactions conferred fast dynamic exchanges (τ* = 300 s at 180 °C). Self-healing chemical mechanical recycling also demonstrated. Finally, degradability polybenzoxazine demonstrated as well. materials highly stable in pH-neutral water, even 80 °C for 60 days, but owing structure, pronounced degradation observed under acidic or alkaline conditions. In summary, is suitable building block design degradable 100% recyclable high-Tg vitrimers.

Язык: Английский

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Reprocessing of Covalent Adaptable Polyamide Networks through Internal Catalysis and Ring-Size Effects

Journal of the American Chemical Society, Год журнала: 2021, Номер 143(38), С. 15834 - 15844

Опубликована: Сен. 15, 2021

Here, we report the introduction of internally catalyzed amide bonds to obtain covalent adaptable polyamide networks that rely on dissociation equilibrium between dicarboxamides and imides. While are usually considered be robust thermally stable, present study shows their dynamic character can activated by a smart choice available building blocks without addition any external catalyst or other additives. Hence, range polyamide-based with variable mechanical viscoelastic properties have been obtained in systematic study, using straightforward curing process dibasic ester amine compounds. Since involves cyclic imide formation, correlation ring size thermomechanical viscosity profile was studied for five- seven-membered intermediates, depending chosen monomer. This resulted marked temperature response activation energies 116–197 kJ mol–1, yielding sharp transition elastic viscous behavior. Moreover, ease versatility this chemistry platform were demonstrated selecting variety amines, resulting densely cross-linked Tg values ranging from −20 110 °C. With approach, it is possible design amorphous an acute response, allowing good reprocessability and, simultaneously, high resistance irreversible deformation at elevated temperatures.

Язык: Английский

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Controlling Dynamics of Associative Networks through Primary Chain Length

Macromolecules, Год журнала: 2022, Номер 55(22), С. 10052 - 10061

Опубликована: Ноя. 2, 2022

Dynamic networks couple the robust nature of thermosets with shapeability and recyclability thermoplastics. Though a wealth exchange chemistries can be leveraged to fabricate dynamic networks, reversibly cross-linked systems that are comprised primarily chains nonexchangeable backbones increase network complexity render flow behavior difficult predict. Here, we report polymethacrylate-based vitrimers prepared by cross-linking β-ketoester-containing polymers multifunctional amines demonstrate molecular weight dispersity primary tuned actively tailor dynamics resulting networks. Vitrimers similar composition cross-link density made from below well above entanglement exhibited distinct viscoelastic properties energies activation ranging 93 264 kJ/mol. Resistance creep increased dramatically increasing chain length. Finally, blending prepolymers skew Mn above/below Me was demonstrated, showing distinguishable effect prepolymer breadth skewness on vitrimer flow. Our results suggest tailoring chain-length distribution is viable strategy design materials predictable customizable behavior.

Язык: Английский

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Viscoelasticity of Polymers with Dynamic Covalent Bonds: Concepts and Misconceptions

Macromolecules, Год журнала: 2023, Номер 56(21), С. 8688 - 8696

Опубликована: Ноя. 3, 2023

Polymers with dynamic covalent bonds are an exciting class of materials properties and potential applications that rapidly gain significant attention from diverse scientific communities. While the number publications on this emerging topic increases exponentially, navigating through literature reveals a series physical inconsistencies in previously established concepts some misconceptions data analysis interpretation. The current paper presents practices often applied to characterization systems emphasizes particular may lead critical divergences misinterpretations results. We particularly focus should be avoided interpretation stress–relaxation viscoelastic estimates bond dissociation energy. Instead, we suggest using traditional approaches have been polymer for decades. Lastly, emphasize challenges full understanding microscopic behavior vitrimers.

Язык: Английский

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