Rapid Stress Relaxation and Moderate Temperature of Malleability Enabled by the Synergy of Disulfide Metathesis and Carboxylate Transesterification in Epoxy Vitrimers

Chen, Mao; Zhou, Lin; Wu, Yeping; Zhao, Xiuli; Zhang, Yongjun

doi:10.1021/acsmacrolett.9b00015

Cited by 294 publications

(258 citation statements)

References 42 publications

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“…5a). 49 Also, Dichtel and co-workers observed that applying the disulde exchange in polyhydroxyurethane networks resulted in more rapid reprocessing of PHU networks, i.e. within 30 min at about 150 C (Fig.…”

Section: Vitrimer Hybrids: Combination Of Dynamic Bond Exchanges and mentioning

confidence: 93%

Vitrimers: directing chemical reactivity to control material properties

et al. 2020

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Section: Vitrimer Hybrids: Combination Of Dynamic Bond Exchanges and mentioning

confidence: 93%

Vitrimers: directing chemical reactivity to control material properties

et al. 2020

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“…By using a disulfide‐containing carboxylic acid as a crosslinker in epoxy vitrimers, simultaneous disulfide metathesis and carboxylate transesterification were enabled. Among other desirable outcomes, full recovery of mechanical strength for at least four cycles at 100 °C in 1 h was achieved 69. Aside from synergistic approaches, the relevant literature continually relays examples of new chemistries, or new variations of old chemistries.…”

Section: Stimuli Responsiveness Of Cansmentioning

confidence: 99%

Toward Stimuli‐Responsive Dynamic Thermosets through Continuous Development and Improvements in Covalent Adaptable Networks (CANs)

et al. 2020

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Covalent adaptable networks (CANs), unlike typical thermosets or other covalently crosslinked networks, possess a unique, often dormant ability to activate one or more forms of stimuli‐responsive, dynamic covalent chemistries as a means to transition their behavior from that of a viscoelastic solid to a material with fluid‐like plastic flow. Upon application of a stimulus, such as light or other irradiation, temperature, or even a distinct chemical signal, the CAN responds by transforming to a state of temporal plasticity through activation of either reversible addition or reversible bond exchange, either of which allows the material to essentially re‐equilibrate to an altered set of conditions that are distinct from those in which the original covalently crosslinked network is formed, often simultaneously enabling a new and distinct shape, function, and characteristics. As such, CANs span the divide between thermosets and thermoplastics, thus offering unprecedented possibilities for innovation in polymer and materials science. Without attempting to comprehensively review the literature, recent developments in CANs are discussed here with an emphasis on the most effective dynamic chemistries that render these materials to be stimuli responsive, enabling features that make CANs more broadly applicable.

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“…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. 21,46 Due to this versatility, vitrimers are now being tested for a variety of high-end applications.…”

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confidence: 99%

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

et al. 2020

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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, mostly due to entropic effects.Here, we investigate the linear viscoelasticity and flow of a polyethylene (PE) vitrimer that has cross-linkable dioxaborolane maleimide grafts, which self-assemble into a hierarchical nanostructure. To elucidate the role of self-assembly, we first studied dioxaborolane graft functionalized PE that was non-cross-linked. 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 h. The soluble and insoluble portions of the PE vitrimer were then isolated and characterized. The soluble portion, which was graft-poor, expressed similar flow behavior as neat PE, while the insoluble portion -which was a graft-rich network of cross-linked aggregatesrelaxed very little over 8 h. 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 h. 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. IntroductionVitrimers are covalent networks that engage in thermoactivated associative exchange reactions. 1,2,3 Under cooling, they undergo a reversible topology freezing transition, analogous to the glass transition of amorphous silica. In contrast to dissociative cross-links, the associative cross-links of vitrimers preserve network connectivity at all times and temperatures below degradation conditions, yet still enable the network topology to fluctuate. 1,2,3 The consequences of the topology freezing transition on materials properties were investigated for epoxy/acid systems that underwent catalyst-driven transesterification. 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. 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 adher...

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Rapid Stress Relaxation and Moderate Temperature of Malleability Enabled by the Synergy of Disulfide Metathesis and Carboxylate Transesterification in Epoxy Vitrimers

Cited by 294 publications

References 42 publications

Vitrimers: directing chemical reactivity to control material properties

Vitrimers: directing chemical reactivity to control material properties

Toward Stimuli‐Responsive Dynamic Thermosets through Continuous Development and Improvements in Covalent Adaptable Networks (CANs)

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

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