Malleable and Recyclable Poly(urea‐urethane) Thermosets bearing Hindered Urea Bonds

Zhang, Yanfeng; Ying, Hanze; Hart, Kevin R.; Wu, You; Hsu, Aaron J.; Coppola, Anthony M.; Kim, Tae Ann; Yang, Ke; Sottos, Nancy R.; White, Scott R.; Cheng, Jianjun

doi:10.1002/adma.201601242

Cited by 353 publications

(282 citation statements)

References 31 publications

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“…Thus, this material still featured sufficient hardness at high temperatures compared to other self-healing systems. 10,36 These results indicate that neither depolymerization of the whole polymer nor complete decrosslinking occurred, which was further proven by testing the P4 reference, which featured comparable mechanical performance at both temperatures. Consequently, the mechanical integrity of the specimen was ensured.…”

Section: Resultsmentioning

confidence: 70%

“…The follow-up study by the same authors described an improvement in the mechanical properties by using a denser polymer network, which could be completely depolymerized under thermal treatment, resulting in the formation of the educts. 36 Consequently, remendability as well as recyclability of the polymer network was possible. However, this behavior was associated with the nearly complete depolymerization of the network and, thus, a (partial) decrease in the mechanical integrity of the material.…”

Section: Introductionmentioning

confidence: 99%

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Intrinsic self-healing polymers with a high E-modulus based on dynamic reversible urea bonds

et al. 2017

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The straightforward synthesis of a urea polymer network is presented. Commercially available monomers are polymerized using light-induced polymerization, resulting in networks crosslinked by hindered urea molecules. These moieties are reversible and, thus, can be converted into the starting compounds (that is, isocyanate and amine) by a simple thermal treatment. This process is monitored using differential scanning calorimetry as well as Raman and infrared spectroscopy. Furthermore, the self-healing ability of these polymer networks is investigated using scratch-healing tests as well as bulk-healing investigations using tensile testing. The resultant materials have a high E-modulus, are able to heal scratches at temperatures above 70°C multiple times and their mechanical properties can be partially regenerated. The underlying healing mechanism is based on the reversible opening of the urea bonds and exchange reactions between two functional groups, which were confirmed from a spectroscopic analysis. In summary, these new materials are a new type of intrinsically healable polymers and provide a first step toward hard and healable polymers.

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Section: Resultsmentioning

confidence: 70%

Section: Introductionmentioning

confidence: 99%

Intrinsic self-healing polymers with a high E-modulus based on dynamic reversible urea bonds

et al. 2017

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“…Besides these works, some other studies also concentrated on the design and synthesis of novel degradable thermosetting resins by using either dynamic or ordinary covalent bonds23242526272829303132333435. Although whether these new resins can produce high-performance CFRCs applicable in high-tech fields and meanwhile realize unimpaired withdrawal of CFs remains unclear, these contributions are important and guide the subsequent studies.…”

mentioning

confidence: 99%

Multiply fully recyclable carbon fibre reinforced heat-resistant covalent thermosetting advanced composites

et al. 2017

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Nondestructive retrieval of expensive carbon fibres (CFs) from CF-reinforced thermosetting advanced composites widely applied in high-tech fields has remained inaccessible as the harsh conditions required to recycle high-performance resin matrices unavoidably damage the structure and properties of CFs. Degradable thermosetting resins with stable covalent structures offer a potential solution to this conflict. Here we design a new synthesis scheme and prepare a recyclable CF-reinforced poly(hexahydrotriazine) resin matrix advanced composite. The multiple recycling experiments and characterization data establish that this composite demonstrates performance comparable to those of its commercial counterparts, and more importantly, it realizes multiple intact recoveries of CFs and near-total recycling of the principal raw materials through gentle depolymerization in certain dilute acid solution. To our best knowledge, this study demonstrates for the first time a feasible and environment-friendly preparation-recycle-regeneration strategy for multiple CF-recycling from CF-reinforced advanced composites.

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“…Polyurethane (PU) thermosets, generally synthesized from diisocyanates and polyols, are a very versatile group of materials with outstanding properties 1. But as a result of permanent crosslinks, they cannot be reshaped, reprocessed, or rehealed after curing, leading to serious environment pollution and a huge waste of resources 2,3. To solve the problem, an effective strategy has been developed by introducing dynamic covalent bonds into the networks 2–6.…”

Section: Introductionmentioning

confidence: 99%

“…But as a result of permanent crosslinks, they cannot be reshaped, reprocessed, or rehealed after curing, leading to serious environment pollution and a huge waste of resources 2,3. To solve the problem, an effective strategy has been developed by introducing dynamic covalent bonds into the networks 2–6. Until now, different kinds of dynamic PU thermosets have been reported, which contain reversible bonds like aromatic disulfide exchange,7 Diels–Alder reaction,8 reversible alkoxyamine,9 etc.…”

Section: Introductionmentioning

confidence: 99%

A Transparent, High Refractive, Shape‐Memory, Healable, and Recyclable Phenolic Polyurethane Thermoset: Unexpected Roles of Bromine Substituents and Tertiary Amine Catalysts

Bai

Jiao

2020

Macro Chemistry & Physics

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The applications of polyurethane (PU) thermosets are limited by the lack of plasticity after curing due to permanent crosslinks. Besides, the low refractive index is insufficient for optical devices. Here, a transparent, high refractive, recyclable, and healable PU thermoset is developed based on dynamic bromined phenyl‐carbamate bonds (BPCB). It exhibits tensile strength of ≈52 MPa, good shape‐memory ability, and can be reprocessed or healed nearly completely at 110 °C in 30 min. Tertiary amine catalysts and bromine substituents jointly play unexpected roles to promote the forward and reverse reactions significantly, leading to high bond‐exchange efficiency of BPCB. Furthermore, the introducing of BPCB can endow the material with higher refractive index (nD = 1.5850) simultaneously. In summary, this material is of potential as dynamic PU thermoset in various fields, especially in advanced optical devices.

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Malleable and Recyclable Poly(urea‐urethane) Thermosets bearing Hindered Urea Bonds

Cited by 353 publications

References 31 publications

Intrinsic self-healing polymers with a high E-modulus based on dynamic reversible urea bonds

Intrinsic self-healing polymers with a high E-modulus based on dynamic reversible urea bonds

Multiply fully recyclable carbon fibre reinforced heat-resistant covalent thermosetting advanced composites

A Transparent, High Refractive, Shape‐Memory, Healable, and Recyclable Phenolic Polyurethane Thermoset: Unexpected Roles of Bromine Substituents and Tertiary Amine Catalysts

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