Molecularly Engineered Unparalleled Strength and Supertoughness of Poly(urea‐urethane) with Shape Memory and Clusterization‐Triggered Emission

Wang, Xiaoyue; Xu, Jing; Zhang, Xinrui; Yang, Zenghui; Zhang, Yaoming; Wang, Tingmei; Wang, Qihua

doi:10.1002/adma.202205763

Cited by 64 publications

(32 citation statements)

References 65 publications

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“…[40] Therefore, optimization of the strength and distribution of the hydrogen-bonding interactions inside PU elastomers is envisaged as a feasible approach to further improve the mechanical properties. [41] In addition to the high mechanical strength, other properties (e.g., degradability, biosafety) may also be important for some special applications in the biomedical field. Construction of the biodegradable PU elastomers with extremely high mechanical strength and toughness is still urgently desired.…”

Section: Introductionmentioning

confidence: 99%

Extremely Strong and Tough Biodegradable Poly(urethane) Elastomers with Unprecedented Crack Tolerance via Hierarchical Hydrogen‐Bonding Interactions

et al. 2023

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generation and propagation of cracks, and will directly affect the service life, applicability, reliability and safety of materials. However, high strength and high toughness are mutually exclusive. [1,2] Elastomers as one of the most widely used materials typically have a compromise between strength and toughness, which limits their applications in impact-resistant environments, biomedical devices, soft robotics, wearable electronics, etc. [3][4][5][6][7][8][9] As an effective strategy, increasing the energy dissipation in the structure has been demonstrated to improve the strength and toughness of elastomers. [10][11][12][13][14][15] First, the incorporation of nano-fillers enables the formation of nano-holes in regions off-domain under high strain, while increasing energy dissipation through bridging and entanglement effects. However, this method is limited by the uneven dispersion of nanoparticles due to the commonly poor compatibility with the matrix. [10,11,16,17] Second, a stable and robust covalently crosslinked network can significantly improve the mechanical properties, but the high cross-linking density may limit the slip of the segments which may reduce the material ductility. [18] Most notably, inspired by the structure of a large number of natural materials such as spider silk, [19,20] mussels, [21][22][23] bones [24] and muscle fibers, [25,26] The elastomers with the combination of high strength and high toughness have always been intensively pursued due to their diverse applications. Biomedical applications frequently require elastomers with biodegradability and biocompatibility properties. It remains a great challenge to prepare the biodegradable elastomers with extremely robust mechanical properties for in vivo use. In this report, we present a polyurethane elastomer with unprecedented mechanical properties for the in vivo application as hernia patches, which was obtained by the solvent-free reaction of polycaprolactone (PCL) and isophorone diisocyanate (IPDI) with N,N-bis(2-hydroxyethyl)oxamide (BHO) as the chain extender. Abundant and hierarchical hydrogen-bonding interactions inside the elastomers hinder the crystallization of PCL segments and facilitate the formation of uniformly distributed hard phase microdomains, which miraculously realize the extremely high strength and toughness with the fracture strength of 92.2 MPa and true stress of 1.9 GPa, while maintaining the elongation-at-break of ≈1900% and ultrahigh toughness of 480.2 MJ m −3 with the unprecedented fracture energy of 322.2 kJ m −2 . Hernia patches made from the elastomer via 3D printing technology exhibit outstanding mechanical properties, biocompatibility, and biodegradability. The robust and biodegradable elastomers demonstrate considerable potentials for in vivo applications.

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Section: Introductionmentioning

confidence: 99%

Extremely Strong and Tough Biodegradable Poly(urethane) Elastomers with Unprecedented Crack Tolerance via Hierarchical Hydrogen‐Bonding Interactions

et al. 2023

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“…The D value for PU ‑HMDI‑200% is bigger than that for PU ‑HMDI‑0% due to the dissociation of H-bonding and expansion of entangled molecular chains along with the increase in strain. However, the intensity of the scattering peak is weaker because the dissociation of H-bonding during stretching altered the microstructure, leading to attenuating microphase separation …”

Section: Resultsmentioning

confidence: 99%

“…The systolic and diastolic function of mimosa is attributed to a periodic nanostructure . Inspired by natural structural materials, many groundbreaking research studies have been reported, such as record-high mechanical robustness of poly(urethane-urea) elastomers, artificial muscle fibers, and reversible morphing hydrogels . These high-performance and multifunctional shape-changing polymers are promising in soft actuators, artificial muscles, biological medical devices, and large self-unfolding structures in extreme environments.…”

Section: Introductionmentioning

confidence: 99%

Humidity-Responsive Shape Memory Polyurea with a High Energy Output Based on Reversible Cross-Linked Networks

Leng

2022

ACS Appl. Mater. Interfaces

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High-performance shape memory polymers with multifunctions are essential in sensors, wearable flexible electronics, artificial muscle actuators, and reversible morphing structures. In this work, a transparent and humidity-responsive shape memory polyurea featuring a high tensile strength (51 MPa), a high recovery stress (12 MPa) with an high energy output (0.98 J/g), and tolerance to extreme environments (retains great malleability at −196 °C) is prepared through constructing a bioinspired hard−soft nanophase structure and through hierarchical hydrogen bonding in the molecular network. The hard segment of a strong hydrogen bonding region is in charge of humidity-responsive behavior, and the soft segment of a weak bonding region provides the flexibility of the molecular chain. Furthermore, the periodicity of the phase-separated domains is 12 nm as characterized by small-angle X-ray scattering. The hydrogen bonding cross-linked network can be opened under the action of stress and re-bonded by heating, just like a zipper structure of reversible linking property. This unique molecular structure contributes to the humidity-responsive behavior of polyurea rolling up 160°in 20 s on the palm, as well as a high energy output lifting a 100 g weight exceeding 1631 times its own mass to 60 mm. The molecular structure of the hard−soft nanophase and the hierarchical hydrogen bonding offer an effective approach toward achieving a high-performance shape memory polymer with humidity-sensitive functions.

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“…Luminescent materials have received increasing interest due to their versatile applications in biomedical and engineering fields. − Particularly, room-temperature phosphorescence (RTP), featuring a long persistent afterglow and a large Stokes shift under mild conditions, is important for the design of advanced optical materials with great potential in information security, bioimaging, chemical sensing, etc. − A conventional strategy is to incorporate molecular chromophores into polymers and elastomers for RTP; however, these chromophores often have aromatic groups and require sophisticated design and organic synthesis. In recent years, polymeric phosphors with clusterization-triggered emission (CTE) properties are recognized as an emerging class of RTP materials and have attracted tremendous attention. − These materials are usually metal-free and contain no aromatic groups as the luminescent centers. Their nonconjugated electron-rich groups (e.g., carbonyl) are nonluminescent in the isolated state; however, while they are clustered, through-space conjugation induces extended electron delocalization that results in lowered energy gaps and finally the clusteroluminescence. − This unique mechanism affords CTE-based polymeric phosphors with many attributes such as easy preparation and tunable RTP properties. , However, CTE-based polymeric phosphors are sensitive to environmental conditions and easily quenched. , When exposed to a good solvent such as in a gel state, the hydration of polymers and swelling of networks cause cluster disaggregation and increased flexibility of polymer chains, leading to enhanced nonradiative decay and reduced fluorescence and phosphorescence.…”

Section: Introductionmentioning

confidence: 99%

Polymerization-Induced Crystallization of Dopant Molecules: An Efficient Strategy for Room-Temperature Phosphorescence of Hydrogels

Zhang

Hou

et al. 2023

J. Am. Chem. Soc.

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Conventional hydrogels such as polyacrylamide and polyacrylic acid ones seldom exhibit phosphorescences at ambient conditions, which limit their applications as optical materials. We propose and demonstrate here a facile strategy to afford these hydrogels with room-temperature phosphorescence by polymerization-induced crystallization of dopant molecules that results in segregation and confinement of the gel matrix with carbonyl groups and thus clusterization-induced phosphorescence. As a model system, crown ethers (CEs) are dissolved in an aqueous solution of concentrated acrylamide that greatly increases the solubility of CEs. During the polymerization process, CEs crystallize to form large spherulites in the polyacrylamide hydrogel. The crystallization arises from the drastically reduced solubility of CEs after the conversion of monomers to polymers during the gel synthesis. The resultant composite hydrogel with a water content of 67 wt % exhibits extraordinary phosphorescence behavior yet maintains good stretchability and resilience. We found that the partial gel matrix is squeezed and confined by in situ-formed crystals, leading to carbonyl clusters and thus phosphorescence emission. The composite gel shows green phosphorescence with an emission peak at 512 nm and a lifetime of 342 ms. The afterglow emission is detectable by the naked eye for several seconds. This strategy has good universality, as validated in other hydrogels with different polymeric matrices and dopant molecules. The development of hydrogels with good mechanical and phosphorescent properties should merit the design of multifunctional soft machines with applications in biomedical and engineering fields.

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Molecularly Engineered Unparalleled Strength and Supertoughness of Poly(urea‐urethane) with Shape Memory and Clusterization‐Triggered Emission

Abstract: Research data are not shared.

Cited by 64 publications

References 65 publications

Extremely Strong and Tough Biodegradable Poly(urethane) Elastomers with Unprecedented Crack Tolerance via Hierarchical Hydrogen‐Bonding Interactions

Extremely Strong and Tough Biodegradable Poly(urethane) Elastomers with Unprecedented Crack Tolerance via Hierarchical Hydrogen‐Bonding Interactions

Humidity-Responsive Shape Memory Polyurea with a High Energy Output Based on Reversible Cross-Linked Networks

Polymerization-Induced Crystallization of Dopant Molecules: An Efficient Strategy for Room-Temperature Phosphorescence of Hydrogels

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