ArticleMarch 24, 2026

Molecular Steric Engineering Enables High-Strength and Self-Healing Polyurethane Elastomer for Flexible and Sensitive Nanosensors
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Shudiao Wei
Shudiao Wei
Engineering Research Center for Energy Conversion and Storage Technology of Guizhou, School of Chemistry and Chemical Engineering, Guizhou University, Guiyang 550025, China
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Weile Guo
Weile Guo
Engineering Research Center for Energy Conversion and Storage Technology of Guizhou, School of Chemistry and Chemical Engineering, Guizhou University, Guiyang 550025, China
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Aiqin Li
Aiqin Li
Engineering Research Center for Energy Conversion and Storage Technology of Guizhou, School of Chemistry and Chemical Engineering, Guizhou University, Guiyang 550025, China
More by Aiqin Li
Menglan Lv*
Menglan Lv
Engineering Research Center for Energy Conversion and Storage Technology of Guizhou, School of Chemistry and Chemical Engineering, Guizhou University, Guiyang 550025, China
*E-mail: [email protected]
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https://orcid.org/0009-0000-1512-774X
Lingli Kong
Lingli Kong
School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, China
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Chuanhui Xu
Chuanhui Xu
School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, China
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https://orcid.org/0000-0002-1212-3636
Ting Gu
Ting Gu
School of Chemistry and Chemical Engineering, Guizhou University, Guiyang 550025, China
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Bin Zhang*
Bin Zhang
Engineering Research Center for Energy Conversion and Storage Technology of Guizhou, School of Chemistry and Chemical Engineering, Guizhou University, Guiyang 550025, China
*E-mail: [email protected]
More by Bin Zhang
https://orcid.org/0000-0002-7176-699X

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ACS Applied Polymer Materials

Cite this: ACS Appl. Polym. Mater. 2026, 8, 7, 4944–4955

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https://doi.org/10.1021/acsapm.5c04892

Published March 24, 2026

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Abstract

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Acquiring a versatile polyurethane (PU) elastomer with both high mechanical properties and rapid low-temperature healing for flexible nanosensors represents a significant challenge. Inspired by the synergistic effects of dynamic bonds, we introduce the dynamic sextuple hydrogen bonds (H-bonds) from adipic dihydrazide (AD) and flexible dynamic disulfide bonds (S–S bonds) from the chain extender 3,3′-dithiobis(2-butanol) (DS) into PU main chains to fabricate a high-performance elastomer (PU-3) with remarkable mechanical robustness and rapid self-healing capability. Specifically, AD imparts PU-3 with an exceptional tensile strength of 40.5 MPa and a toughness of 287.8 MJ m^–3. A 1.1 g sample (50 mm × 10 mm × 1.3 mm) supports loads up to 11,000 times its own weight. In addition, the excellent DS unit, featuring four branched methyl groups with a substantially larger molecular volume, renders the PU-3 more flexible with an outstanding elongation at break of 1445.2%. Moreover, PU-3 exhibits excellent resilience, self-healing efficiency, and recyclability. As a result, a flexible polymer/carbon nanotube composite nanosensor is constructed from this elastomer matrix and multiwalled carboxylated carbon nanotubes (MWCNTs-COOH) as the conductive filler, exhibiting outstanding sensitivity and rapid response and recovery capabilities, thereby highlighting its potential for applications in health monitoring and intelligent wearable electronics.

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1. Introduction

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In recent years, the rapid convergence of flexible electronics with emerging fields such as smart wearables, healthcare monitoring, soft robotics, and foldable systems has positioned flexible nanosensors as essential components for environmental perception and signal transduction. (1−5) Consequently, the performance expectations for these nanosensors have evolved from simple flexibility and sensitivity toward integrated multifunctional performance. However, conventional nanosensors that rely solely on stable conductivity and stretchability are increasingly inadequate to meet the complex demands of current applications. (6−11) These applications impose more stringent requirements on the active materials for flexible nanosensors, demanding that they are nontoxic, highly deformable, and mechanically robust. Moreover, self-healing and recyclability have become critical features for prolonging device lifetime and mitigating the environmental impact of electronic systems. (12−19) At present, hydrogels, epoxy resins, (20) and polyurethane (PU) elastomers serve as the primary of soft matrices for constructing flexible nanosensors. (21,22) Nevertheless, achieving a balance between self-healing efficiency and mechanical performance remains a major challenge in this field. (23−25)

Among these materials, PU elastomers are particularly promising ones due to the high tunability of their molecular chain structure, (26) which can be adjusted by controlling the soft-to-hard segments ratio and the type of dynamic cross-linking agents. Recently, significant progress has been made through rational molecular design and the incorporation of dynamic reversible interactions, including disulfide bonds (S–S bonds), multiple hydrogen bonds (H-bonds), Diels–Alder covalent bonds, and metal–ligand coordination, to construct adaptive cross-linked networks. (27−34) For example, Guan et al. realized the enhanced toughness and self-repairability by constructing phase-separated microstructures and introducing H-bond interactions. (35) Similarly, Bao and co-workers reported a self-healing elastomer with superior tensile strength by employing quadruple H-bonds as reversible cross-linking motifs. (36) To further reinforce mechanical performance, recent studies have explored synergistic combinations of multiple H-bonds with other dynamic linkages, including S–S bonds and metal-coordination interactions. (37,38) Sheng et al. designed an elastomer incorporating S–S bonds within the main chain and quadruple H-bonds along the side chains, thereby achieving a well-balanced integration of mechanical robustness and healing efficiency. (39) Wang et al. fabricated a self-healing elastomer exhibiting high tensile strength, large elongation, and remarkable toughness through the synergistic incorporation of multiple H-bonds and metal–ligand coordination. (40) However, the large elongation of these elastomers, which are constructed through the coexistence of dynamic covalent linkages, has not yet been thoroughly investigated. (41−43) Furthermore, the traditional straight-chain aliphatic chain extenders containing dynamic S–S bonds are incorporated into PU segments, exhibiting the characteristics of low tensile strength, which would negatively affect the mechanical performance of PU elastomers. Hence, it is urgent to develop novel dynamic S–S bond-based chain extenders for constructing high-performance PU elastomers.

In this work, we developed a chain extender 3,3′-dithiobis(2-butanol) (DS), which contained four branched methyl groups, featuring a substantially larger molecular volume than the commonly used aliphatic disulfide-based extender bis(2-hydroxyethyl) disulfide (BS). At the same time, adipic dihydrazide (AD) containing multiple H-bonds was also incorporated into the PU system. Owing to the abundance of H-bond donors and acceptors in AD, it facilitates the formation of a dense and reversible supramolecular H-bonds network. These dynamic sextuple H-bonds function as strong, reversible physical cross-linking points, which are essential for achieving high tensile strength and toughness in PU elastomers. In contrast, the introduced S–S bonds act as dynamic covalent linkages with relatively low bond dissociation energy, allowing for bond exchange under medium thermal activation or applied stress. This cooperation between these two types of dynamic interactions effectively integrates the advantages of physical cross-linking and dynamic covalent bonding, leading to a pronounced enhancement in the overall mechanical performance of PU elastomers. Under low-temperature conditions, H-bonds primarily serve as temporary load-bearing junctions that efficiently transfer external stress and restrict excessive chain slippage, thereby preserving the mechanical strength. Simultaneously, the reversible cleavage and reformation of S–S bonds enhance segmental mobility, enabling the elastomer to maintain a high elongation at break. As a result, the synergistic action of H-bonds and S–S bonds allows the PU to retain both high mechanical strength and excellent elongation at break, even at low temperatures. (9) Therefore, DS and AD are synergistically incorporated into the PU backbone as chain extenders. Through this molecular engineering strategy, we successfully synthesized a PU elastomer (PU-3) containing multiple H-bonds and dynamic S–S bonds. Benefiting from these cooperative interactions, PU-3 exhibits excellent mechanical performance, achieving a tensile strength of 40.58 MPa, an impressive toughness of 287.8 MJ m^–3, and an ability to support loads up to 11,000 times its own weight. Moreover, PU-3 displays an ultrahigh elongation at break of 1445.2%, together with a remarkable self-healing efficiency of 97.5% after 12 h at 60 °C. Additionally, it can preserve 92.3% of its resilience after five stretching cycles at 500% strain. As controls, two other elastomers of PU-1 and PU-2 were synthesized. Specifically, PU-1 was synthesized using AD alone as the chain extender, resulting in an elastomer that contains only multiple H-bonds; meanwhile, PU-2 was produced by using BS and AD as the chain extenders, resulting in a network integrating both H-bonds and dynamic S–S bonds. Comparative evaluation reveals that PU-3 surpasses PU-1 in tensile performance and low-temperature healing behavior due to the introduction of flexible dynamic S–S bonds. Furthermore, relative to PU-2, DS exhibits a larger molecular volume than BS. This structural advantage enhances the segmental mobility of the PU-3 backbone, markedly enhancing the elongation at break while maintaining the tensile strength unchanged, thus rendering the mechanical performance of PU-3 superior to that of PU-2. Finally, to further explore the potential application of PU-3 in flexible nanosensors, a highly flexible polymer/carbon nanotube composite nanosensor was fabricated through blending multiwalled carboxylated carbon nanotubes (MWCNTs-COOH) with the PU-3 matrix. This sensor demonstrates excellent sensitivity as well as rapid response and recovery capabilities, enabling precise detection of physiological motions, such as respiration and joint bending, thereby highlighting its significant potential applications in smart wearable electronics and health monitoring systems.

2. Results and Discussion

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2.1. Preparation and Characterization of the Samples

To investigate the synergistic contributions of dynamic multiple H-bonds and reversible S–S bonds to the mechanical performance and autonomous healing behavior of PU elastomers, a series of PU samples were synthesized via a two-step polycondensation protocol. These materials included two systems of one containing exclusively multiple H-bonds and the other containing both H-bonds and S–S bonds in varied ratios. The detailed formulations were summarized in Table S1, while the overall synthetic procedures of PU-1, PU-2, and PU-3 were illustrated in Scheme S1. Their chemical structures were clearly confirmed by ¹H nuclear magnetic resonance (¹H NMR) spectroscopy, as shown in Figure S1a–c. In addition, as summarized in Table S2, the size exclusion chromatography (SEC) results show that all PU samples exhibit comparable number-average molar mass (M_n = 111.6–136.8 kg mol^–1), weight-average molar mass (M_w = 174.1–204.9 kg mol^–1), and dispersity (Đ = 1.50–1.56), respectively.

The molecular architecture of the representative PU-3 elastomer was displayed in Figure 1a, in which multiple H-bonds and dynamic S–S bonds were integrated along the polymer backbone. Specifically, the acylhydrazide moiety in AD reacts with the −NCO groups of IPDI to form acyl semicarbazide (AS) units enriched with H-bond donors and acceptors. The AS is connected through the flexible alicyclic hexatomic spacer, imparting outstanding mechanical performance to PU-3. In contrast, the dynamic S–S bonds derived from DS could introduce molecular mobility, thereby enhancing elongation at the break and facilitating autonomous repairability. Moreover, the bulky and sterically hindered structures of IPDI and DS disrupt regular chain packing, favoring the formation of an amorphous microstructure that further reinforces the mechanical performance. The dynamic bond interactions and network structure of PU-3 were schematically illustrated in Figure 1b,c.

Figure 1. (a) Molecular structure of the PU-3 elastomer. (b) Schematic of the network structure and dynamic bond interactions. (c) Proposed network structure of the PU-3 elastomer.

To confirm the chemical structure of the PU elastomers, as well as to elucidate their crystallization behavior, Fourier transform infrared (FTIR) spectroscopy, Raman spectroscopy, and X-ray diffraction (XRD) were systematically employed. As shown in Figure 2a, no absorption bands are observed in the range of 2250–2270 cm^–1, confirming the complete consumption of the −NCO groups and thus the complete reaction of IPDI during PU formation. (44) The characteristic absorptions at 3315 and 1543 cm^–1 correspond to the N–H stretching and bending vibrations of urethane groups (−NH–COO−), respectively, whereas the peak near 1714 cm^–1 is assigned to the C=O stretching vibration of the urethane linkages. In addition, the broad band centered at approximately 1105 cm^–1 arises from the C–O–C stretching vibration of the polyether backbone. In Figure 2b, Raman spectra further substantiate the presence of dynamic disulfide components, as evidenced by distinct peaks near 650 and 514 cm^–1, which can be attributed to the C–S and S–S stretching vibrations, respectively. To further clarify how the microstructure influenced the macroscopic properties of the PU samples, XRD analysis was performed, as shown in Figure 2c. All of the PU samples exhibit a broad diffraction halo around 2θ ≈ 20°, indicative of an amorphous morphology at room temperature. Complementary energy-dispersive X-ray spectroscopy (EDS) and scanning electron microscopy (SEM) analyses were carried out to probe the elemental composition and morphological characteristics, as shown in Figures 2d–f and S2. The EDS results reveal that PU-1 contains C, O, and N elements, while PU-2 and PU-3 additionally contain the S element, confirming the introduction of disulfide moieties into the polymer chains. The SEM micrographs, as presented in Figure S2, show the clear microphase-separated morphologies, where the darker domains correspond to the PTMEG rich soft segments and the brighter regions represent the hard-segment aggregates. (45) Owing to the thermodynamic incompatibility between these two phases, microphase separation naturally forms. Notably, the incorporation of dynamic S–S bonds improves the dispersion of the soft segments and suppresses excessive hard-domain aggregation, thereby optimizing the microphase morphology. Such morphological adjustments may contribute to the enhanced mechanical strength and elasticity of the PU elastomers.

Figure 2. (a) FTIR spectra of PU-1, PU-2, and PU-3 elastomers. (b) Raman spectra. (c) XRD patterns. (d–f) Elemental mapping images of PU-1, PU-2, and PU-3 obtained from EDS. (g) Storage modulus (E′). (h) Loss modulus (E″). (i) Loss factor (tan δ).

Furthermore, differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were conducted to evaluate the thermal characteristics of the PU elastomers, as presented in Figure S3a,b. From DSC curves, no discernible endothermic or exothermic transitions are observed within the temperature range from −80 to 100 °C, indicating that all PU samples possess an intrinsically amorphous phase. This observation is consistent with the XRD results discussed above. In addition, the thermal decompositions at T_5% weight loss occur near 300 °C for all of the PU samples, demonstrating their excellent thermal stability. To further elucidate the dynamic viscoelastic behavior of all PU elastomers, dynamic mechanical analysis (DMA) was performed, and the relative temperature-dependent evolutions of the storage modulus (E′), loss modulus (E″), and loss factor (tan δ) were displayed in Figure 2g–i. As shown in Figure 2g, the temperature increased from −80 to 100 °C, and the mechanical responses of the polymers underwent gradual and systematic changes. At low temperatures, the network is predominantly stabilized by H-bond interactions, which effectively restrict chain mobility and maintain high E′. Due to the higher H-bond content of PU-1 compared to PU-2 and PU-3, it exhibits the highest E′ at low temperature. With increasing temperature, however, the segments containing dynamic S–S bonds exhibit pronounced thermal responsiveness. The enhanced mobility of these flexible domains, together with the relaxation of H-bond segments, (46) facilitates chain rearrangement and network expansion, thereby contributing to the progressive decrease in E′. Among the three samples, the flexible domains in the PU-3 backbone exhibit the highest mobility, resulting in the fastest E′ decline rate. In contrast, PU-2 displays a higher E′ decline rate than PU-1 owing to the incorporation of dynamic flexible S–S bonds, as these dynamic covalent linkages enhance chain mobility relative to the H-bond-dominated cross-linking network of PU-1. Meanwhile, since PU-1 relies exclusively on H-bond interactions imparting relatively rigid cross-linking, it exhibits the slowest E′ decline rate. During this relaxation process, energy dissipation mainly originates from localized segmental motions and intermolecular friction. As the temperature continued to rise, the cooperative motion of polymer chains is weakened, resulting in a gradual reduction in E″. Nevertheless, the multiple H-bond interactions derived from AD segments continue to provide effective structural reinforcement, maintaining overall chain connectivity. Upon further heating, the progressive weakening of H-bonds increases the configurational freedom, while the dynamic cleavage and recombination of S–S bonds impart an additional relaxation pathway. These two mechanisms act synergistically to induce a steady decrease in the E″ of all PU samples. Notably, the E″ of PU-1 exhibited a faster continuous attenuation rate than that of PU-2 and PU-3, as shown in Figure 2h. This difference stems from the dynamic cleavage and recombination of S–S bonds in the backbones of the latter two samples, reflecting the characteristic of continuous energy dissipation mediated by reversible dynamic bonds. Across the entire testing range, E′ consistently exceeds E″, indicating that the PU elastomers retain solid-like characteristics and sufficient stiffness, which are advantageous for suppressing structural deformation and ensuring long-term stability. The glass transition temperatures (T_g) of the elastomers were also tested, as presented in Figure 2i. PU-1 exhibits a T_g of approximately −60 °C. After incorporating dynamic disulfide cross-linkers, the relatively lower bond energy and flexible molecular architecture of S–S bonds disrupt the packing of the rigid segments and reduce the overall chain stiffness. As a result, the T_g values of PU-2 and PU-3 shift further downward to around −65 °C, both well below ambient temperature. Therefore, all of these PU samples remain in a highly elastic and deformable state under typical conditions.

2.2. Mechanical Properties and Fatigue Resistance of the Samples

The mechanical performance of the PU elastomers is primarily governed by the synergistic effects of multiple hydrogen bonds and dynamic S–S bonds. To elucidate the influence of AD and DS contents on the mechanical behavior, tensile tests were conducted on a series of PU samples; the test results are presented in Table S3. The corresponding stress–strain curves are presented in Figure 3a,b. All samples exhibit a characteristic elastomeric profile without a distinct yield point, confirming that the synthesized polymers behave as genuine elastomers. Specifically, PU-1 demonstrates a tensile strength of 48.8 MPa, an elongation at break of 886.5%, and a toughness of 200.2 MJ m^–3. In contrast, PU-2 and PU-3 show tensile strengths of 31.1 and 40.5 MPa, elongations at break of 970.7% and 1443.9%, and toughness values of 120.1 and 287.8 MJ m^–3, respectively. Compared with PU-1, both PU-2 and PU-3 exhibit markedly increased elongation at break but reduced tensile strength. This behavior can be attributed to the introduction of dynamic S–S bonds, which enhance the flexibility of the polymer network and facilitate chain mobility, thereby improving elongation at break. Simultaneously, the reduction in AD content weakens the density of H-bond interactions among urea and carbamate groups, leading to a decrease in tensile strength. Moreover, in comparison with PU-2, PU-3 exhibits remarkably enhanced mechanical performance, which can be primarily attributed to the molecular characteristics of the employed chain extender. The DS units incorporated into PU-3 possess a substantially larger molecular volume than BS, providing increased free volume for polymer chains and facilitating interchain slippage, thereby leading to a higher elongation at break. In addition, the four aliphatic branched methyl groups on the DS effectively promote microphase separation within the PU system, allowing PU-3 to accommodate larger deformation without fracture during tensile loading. As a result, both the elongation at break and toughness of PU-3 are significantly superior to those of PU-2.

Figure 3. (a) Stress–strain curves of the PU samples. (b) Toughness bar chart for different samples. (c, e) Cyclic tensile tests conducted at 500% strain for five consecutive loading–unloading cycles. (f) Performance comparison. (g) Fracture energy of PU-3. (h) Photograph of a notched PU-3 sample stretched to 800% strain.

To further assess the fatigue resistance and energy dissipation behavior of the PU elastomers, dumbbell-shaped specimens (20 × 4 × 0.5 mm) were subjected to consecutive loading–unloading cycles under both constant and incremental deformation modes. As shown in Figures 3c–e and S4a–c, five successive cyclic tensile tests are performed at a fixed strain of 500% and progressively increasing strains from 100% to 500%. Both PU-1 and PU-2 display pronounced hysteresis loops during the first loading–unloading cycle, primarily resulting from the rupture of noncovalent H-bonds within the polymer network, which leads to substantial energy dissipation. With increasing cycle number, the area of the hysteresis loop gradually decreases, indicating that the disrupted noncovalent interactions cannot fully and rapidly reform. (45) In contrast, PU-3 exhibits a distinctive cyclic response, with the hysteresis loops of each cycle almost completely overlapping. This reflects the stable and repeatable elastic recovery performance. After five cycles, PU-3 achieves a rebound rate of approximately 92.3%, which is much better than that of PU-1 and PU-2, demonstrating its outstanding resilience and efficient energy dissipation capability. Furthermore, as illustrated in Figure 3f, PU-3 outperforms most reported PU elastomers in terms of both rebound behavior and elongation at break, highlighting its superior mechanical adaptability and durability.

Given the outstanding energy dissipation capability of PU-3, it is reasonable to further infer that it should also display superior resistance to crack propagation. To validate this hypothesis, fracture energy tests were systematically performed, as illustrated in Figure 3g,h. A PU-3 elastomer with 1 mm unnotched can be elongated to 8.32 times its initial length, exhibiting a tensile strength of 17.2 MPa and an elongation at break of 830.1%. Moreover, calculations based on the stress–strain curves collected before and after fracture reveal that the maximum fracture energy of PU-3 reaches 209.2 kJ m^–2, confirming its exceptional toughness. The excellent crack resistance of PU-3 primarily arises from the synergistic effects of dynamic H-bonds and S–S bonds. During crack propagation, H-bonds near the crack tip continuously break and reform, dissipating substantial mechanical energy through reversible bond rupture, which effectively blunts the crack tip and slows crack growth. Simultaneously, stress-induced covalent exchange of the dynamic S–S bonds enables localized rearrangement of the polymer network, redistributing stress away from the crack tip. The cooperative action of these dynamic interactions significantly enhances energy dissipation, contributing to superior fracture toughness and crack resistance. Collectively, these findings demonstrate that the unique hierarchical structure of PU-3 endows the elastomer with robust crack resistance and mechanical reliability.

2.3. Self-Healability of the PU Elastomers

The dynamic rupture and reformation of multiple H-bonds, together with the reversible cleavage and recombination of S–S bonds, continuously dissipate energy during deformation. This mechanism not only enhances the toughness of the PU elastomers but also imparts a self-healing capability following mechanical damage. To systematically evaluate the contribution of dynamic hydrogen bonds and S–S bonds to the self-healing behavior, tensile tests were performed on the three PU elastomers at 60 °C after various healing durations, as illustrated in Figure 4a,b. PU-1, which contains only hydrogen bonds, exhibits limited self-repair capability, achieving a stress self-healing efficiency of merely 45% after 12 h at 60 °C. In contrast, PU-2 and PU-3, incorporating both H-bonds and dynamic S–S bonds, show progressive recovery of mechanical properties with an increasing healing time. The corresponding stress–strain curves and self-healing efficiencies for PU-2 and PU-3 were presented in Figure 4c–f, respectively. After 12 h of healing at 60 °C, PU-2 reaches a self-healing efficiency of 90.1%, with a tensile strength of 28.0 MPa and elongation at break of 914.5%, whereas PU-3 achieves an outstanding healing efficiency of 97.5%, maintaining a tensile strength of 38.9 MPa and an elongation at break of 1472.7%. Even after repeated damage, the healed PU-3 elastomer retains remarkable mechanical robustness, confirming its superior self-repair performance. The optical observations of the self-healing process, as shown in Figure 4g, further verify these findings. When completely severed and subsequently rejoined, the PU-3 sample regains structural integrity within 9 h at 60 °C and is capable of supporting a 5 kg weight, as depicted in Figure 4h, demonstrating excellent mechanical recovery. The outstanding self-healing capability of PU-3 originates from the cooperative effect of multiple H-bonds interactions and dynamic S–S bonds within the polymer network. Upon mechanical damage, reversible H-bonds rapidly reform at the fractured interfaces during the early stage of healing, providing initial physical adhesion and partially restoring mechanical integrity. Under medium thermal stimulation, dynamic S–S bonds undergo exchange reactions, enabling polymer chains to diffuse across the damaged interface and reconstruct the polymer networks. Concurrently, the rearrangement of H-bonds further stabilizes the supramolecular structure within the healed region. This self-healing phenomenon is characterized by fast interfacial adhesion governed by H-bonds, followed by disulfide bond-driven network reorganization, which accounts for the high self-healing efficiency under relatively medium temperature conditions.

Figure 4. (a, b) Stress–strain curves and bar chart of self-healing at various times at 60 °C for PU-1, (c, d) PU-2, and (e, f) PU-3, respectively. (g) Optical images of the self-healing process of PU-3. (h) Photograph of PU-3 after healing lifting a 5 kg weight.

2.4. Recyclability of the PU Elastomers

As illustrated in Figure 5a, the PU-3 elastomer was initially cut into small fragments and dissolved in tetrahydrofuran (THF) under continuous stirring at room temperature to obtain a homogeneous solution. This solution was then carefully poured into a polytetrafluoroethylene (PTFE) mold (100 mm × 100 mm × 10 mm), degassed under a vacuum to eliminate trapped air bubbles, and subsequently dried in an oven at 70 °C for 24 h to remove residual solvent. Thereafter, the dried film was further cured in a vacuum oven at 80 °C for an additional 24 h to achieve a fully regenerated elastomer.

Figure 5. (a) Schematic illustration of the recycling process of the PU-3 elastomer. (b) FTIR spectra of the original and recycled PU-3 sample. (c) XRD patterns of the original and recycled PU-3 sample. (d) Stress–strain curves of PU-3 after two recycling cycles. (e) Demonstration of the recycled PU-3 elastomer lifting a 12 kg weight.

After two consecutive recycling cycles, the regenerated PU-3 elastomer was characterized by using FTIR and XRD analyses, respectively, to evaluate its chemical structure and morphology. As shown in Figure 5b, the characteristic absorption peaks corresponding to the major functional groups in the recycled elastomer match those of the pristine sample in both position and relative intensity, indicating preservation of the chemical structure. Moreover, the XRD patterns, as shown in Figure 5c, reveal that both the recycled and original elastomers exhibit a broad amorphous diffraction peak around 2θ ≈ 20°, demonstrating that the regenerated elastomer retains the amorphous morphology of the pristine material. The mechanical performance of the recycled samples was systematically assessed, as illustrated in Figure 5d. After the first recycling cycle, both the tensile strength and elongation at the break were fully retained. Following the second recycling cycle, the tensile strength remained essentially unchanged, while the elongation at break decreased by only 10% relative to that of the pristine sample, demonstrating excellent mechanical stability and durability. From an environmental standpoint, the recyclability of PU-3 can effectively minimize material waste and extend its service lifetime, underscoring its potential for sustainable applications in flexible electronics and related technologies. Furthermore, as shown in Figure 5e, a sample with 1.1 g (50 mm × 10 mm × 1.3 mm) was capable of supporting a 12 kg dumbbell without any observable damage, highlighting its outstanding structural integrity. Collectively, these results confirm that the PU-3 elastomer possesses outstanding recyclability while maintaining its original mechanical and morphological properties, thereby satisfying the requirements for high-performance, sustainable materials in practical applications.

2.5. Preparation and Potential Applications for Flexible and Sensitive Nanosensors

The PU-3 elastomer, characterized by superior mechanical performance and excellent biocompatibility, may serve as an ideal substrate for flexible nanosensors. To impart electrical conductivity, MWCNTs-COOH were incorporated as conductive fillers, owing to their outstanding electrical properties. The fabrication process of the flexible and sensitive polymer/carbon nanotube composite nanosensor was schematically illustrated in Figure 6a. To evaluate the strain-sensing capability, the relative resistance variation (ΔR/R₀) was measured under different strain levels ranging from 3% to 300%, as presented in Figure 6b. The results indicate that during repeated stretching cycles ΔR/R₀ remains stable and increases monotonically with applied strain, thereby demonstrating the reliable performance and wide strain-detection range. The sensitivity factor, expressed as the gauge factor (GF = ΔR/(R₀·ε), where ε is the strain), was calculated and is displayed in Figure 6c. The high coefficient of determination (R² = 0.9705) confirms a strong linear relationship between ΔR/R₀ and strain, highlighting the excellent sensitivity and reproducibility of the flexible and sensitive polymer/carbon nanotube composite sensor. Additionally, nine consecutive loading–unloading tensile cycling test was performed on the sensor under a strain of 300%, and the result is presented in Figure S5. After nine continuous cycles, only a slight decrease in the resistance signal amplitude was observed, indicating a marginal attenuation in the GF under high strain amplitudes. Notably, during the unloading process, the electrical resistance rapidly returned to its initial value, demonstrating that the sensor can still maintain stable and reliable electrical response behavior under repeated high-strain deformation. This favorable performance is attributed to the excellent elastic recovery of the elastomeric substrate along with an efficient stress dissipation arising from the synergistic interaction of dynamic H-bonds and reversible S–S bonds. Benefiting from the intrinsic flexibility and elasticity of the PU-3 matrix, the nanosensor exhibits ultrafast dynamic response characteristics, with response and recovery times of 78 and 89 ms at 100% strain, respectively, as shown in Figure 6d, enabling precise and real-time strain monitoring. Furthermore, as shown in Figure 6f, the remarkable sensitivity and rapid response of the flexible and sensitive polymer/carbon nanotube composite nanosensor make it particularly suitable for detecting subtle human motions such as breathing, joint bending, and muscle contraction. For instance, when attached to a mask, the ΔR/R₀ signal exhibits clearly distinguishable peaks corresponding to breathing cycles, as presented in Figure 6e. Similarly, when placed on the throat, the sensor can effectively differentiate between spoken words, as illustrated in Figures 6g and S6. Moreover, distinct signal profiles are generated for words such as “drink” and “apple”, accurately reflecting their phonetic characteristics, thereby demonstrating the potential in speech recognition and voice monitoring applications.

Figure 6. (a) Schematic illustration of the fabrication process of the flexible and sensitive polymer/carbon nanotube composite nanosensor. (b) Relative resistance variation (ΔR/R₀) of the sensor under tensile strains ranging from 3% to 300%. (c) GF of the nanosensor, where GF = ΔR/(R₀·ε) and ε denotes strain. (d) Response and recovery times of the sensor at 100% strain. (e) Real-time signal output of the sensor during mouth breathing. (f) Schematic representation of the potential applications in human motion monitoring. (g) Signal response of the sensor during throat articulation of the word “drink”. (h) Electrical response of the sensor during finger bending and stretching at angles of 30°, 45°, 60°, and 90°. (i) Signal output during wrist bending and (j) signal response during walking and stair climbing.

Finally, the additional bioapplications were also performed, as presented in Figure 6h–j. In Figure 6h, the joint-bending tests reveal that the sensor produces distinct and stable electrical responses as the finger is bent to 30°, 45°, 60°, and 90°, respectively. As shown in Figures 6i and S7, the generated signals from the wrist and elbow bending display highly periodic variations, indicating consistent sensing performance. Moreover, when mounted on the knee, the sensor accurately captures electrical responses associated with knee flexion during activities such as walking and stair climbing, as depicted in Figure 6j, further confirming its stability, reliability, and multisite applicability for human motion detection. Collectively, these results underscore the potential of the flexible and sensitive polymer/carbon nanotube composite sensors for applications in wearable electronics, biomedical monitoring, and next-generation flexible display technologies.

3. Conclusions

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In summary, a PU elastomer (PU-3) integrating multiple H-bonds and flexible dynamic S–S bonds was successfully synthesized, which exhibited an excellent combination of mechanical properties and outstanding elongation at break. This performance advantage is attributed to the DS unit containing four branched methyl groups, which not only possesses a substantially large molecular volume but also incorporates highly flexible dynamic S–S bonds. Through the synergistic effect of these structural features, the elastomer is endowed with superior mechanical performance. Furthermore, the elastomer demonstrates excellent resilience and self-healing efficiency and recyclability. Specifically, PU-3 exhibits a high tensile strength of 40.5 MPa, superior toughness of 287.8 MJ m^–3, and remarkable elongation at break of 1443.2%. It achieves a self-healing efficiency of 97.5% after repair at 60 °C for 12 h, and even after five cycles of cyclic stretching at a strain of 500%, it retains an impressive resilience rate of 92.1%. Furthermore, after two rounds of solvent recycling treatment, its mechanical properties show almost no degradation, and a 1.1 g sample (50 × 10 × 1.3 mm) can still effortlessly bear a 12 kg load, which fully demonstrates the excellent robustness and durability. Interestingly, PU-3 can serve as an ideal substrate for flexible sensing applications. A flexible polymer/carbon nanotube composite nanosensor was fabricated using PU-3 as the substrate by incorporating MWCNTs-COOH as conductive fillers. The resulting flexible nanosensor maintains stable electrical performance under strains up to 300% and exhibits high sensitivity for detecting various physiological signals, including respiration, throat vibration during phonation, and joint motion, across a strain range of 3–300%. This ultrafast dynamic response, combined with the mechanical flexibility and durability, enables accurate and real-time monitoring of human activities. Collectively, these results underscore the considerable potential of the flexible nanosensors for next-generation smart wearable electronics, biomedical monitoring systems, and flexible robotic applications.

4. Experimental Section

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4.1. Materials

3-Mercapto-2-butanol, sodium thiosulfate, ethyl acetate (EtOAc), bis(2-hydroxyethyl) disulfide (BS), activated carbon, poly(oxytetramethylene) glycol (PTMEG, M_n = 2000 g mol^–1), isophorone diisocyanate (IPDI), dibutyltin dilaurate (DBTDL), adipic dihydrazide (AD), and N,N-dimethylacetamide (DMAc) were supplied by Anhui Zesheng Technology Co., Ltd. Potassium iodide (KI) was purchased from Shanghai Macklin Biochemical Co., Ltd. Hydrogen peroxide solution (H₂O₂, 30 wt %) was obtained from Chongqing Chuandong Chemical (Group) Co., Ltd. Multiwalled carboxylated carbon nanotubes (MWCNTs-COOH) were provided by Shenzhen Suiheng Technology Co., Ltd. Prior to use, PTMEG was first vacuum-dried at 110 °C for 2 h to remove residual moisture.

4.2. Synthesis of DS

Initially, 3-mercapto-2-butanol (3.0 g, 28.0 mmol) and KI (1.0 g, 6.0 mmol) were sequentially charged into a 100 mL two-necked round-bottom flask, followed by the addition of EtOAc (40.0 mL) as the reaction solvent. The resulting mixture was stirred at 35 °C, after which H₂O₂ (5.0 mL) was added dropwise to initiate the oxidation reaction. During this process, the reaction solution gradually changed from colorless to brownish yellow. Upon continuous stirring for 3 h, Na₂S₂O₃ (1.2 g, 7.6 mmol) was added to quench any residual oxidant, resulting in a solution returning to a colorless state. Subsequently, the reaction mixture was extracted with EtOAc, filtered, and treated with activated carbon to remove impurities. Finally, the solvent was removed under reduced pressure, affording the target compound of DS as a colorless oily liquid. The synthetic route of DS and its corresponding ¹H NMR spectrum are shown in Scheme S2 and Figure S8. The ¹³C NMR and high-resolution mass spectra (HRMS) are presented in Figures S9 and S10, respectively. ¹H NMR (400 MHz, DMSO-d₆): δ 4.81 (d, J = 30.8 Hz, 2H), 3.76 (s, 2H), 2.80 (d, J = 42.4 Hz, 2H), 1.22–1.17 (m, 6H), 1.09 (dd, J = 16.3, 6.2 Hz, 6H). ¹³C NMR (101 MHz, DMSO-D₆): δ 70.76, 41.66, 20.53, 19.66. HRMS (ESI) m/z [M + Na]⁺ calcd for C₈H₁₈O₂S₂: 233.0604, found: 233.0648.

4.3. Synthesis of PU Elastomers

A series of PU elastomers with distinct dynamic interactions were synthesized via a two-step polycondensation strategy, including those containing only H-bonds and those with varying ratios of H-bonds to S–S bonds. In the first step, the prepolymer was prepared by reacting PTMEG with IPDI under controlled conditions. Subsequently, DS and AD were sequentially added to the prepolymer at different molar ratios as chain extenders to perform the chain-extension reaction, ultimately yielding a series of PU elastomers. Among these, the formulation exhibiting the best overall mechanical performance was designated as PU-3. For comparison, PU-1, containing only H-bonds, was synthesized by using AD alone as the chain extender, whereas PU-2, containing both H-bonds and S–S bonds, was prepared by sequentially incorporating DS and BS as chain extenders under identical reaction conditions.

Here, the synthesis of PU-3 was promoted as a representative example. Initially, PTMEG (8.0 g, 4.0 mmol) was charged into a 100 mL three-neck round-bottom flask and dried under a vacuum at 120 °C for 2 h to remove residual moisture. Under a nitrogen atmosphere, IPDI (1.78 g, 8.0 mmol) and DBTDL (0.04 g) were added, followed by the addition of DMAc (10.0 mL), and the mixture was stirred at 80 °C for 3 h to obtain the IPDI–PTMEG prepolymer. After the prepolymer was cooled to 40 °C, AD (0.56 g, 3.2 mmol) dissolved in DMAc (40.0 mL) was gradually introduced and allowed to react under nitrogen protection for 12 h. Subsequently, the reaction temperature was raised to 60 °C, and DS (0.17 g, 0.8 mmol) dissolved in DMAc (5.0 mL) was added, after which the mixture was stirred for an additional 4 h to ensure complete chain extension. Upon completion of the reaction, the resulting mixture was poured into a PTFE mold (100 × 100 × 10 mm), degassed under a vacuum to remove any trapped air bubbles, and dried at 70 °C for 24 h to eliminate the solvent. Finally, the obtained film was postcured under vacuum at 80 °C for 24 h, yielding a transparent, uniform, and flexible PU elastomer film.

4.4. Fabrication of Flexible and Sensitive Polymer/Carbon Nanotube Composite Nanosensors

After obtaining the PU-3 polymer solution, MWCNTs-COOH (5 wt %) were first dispersed in DMAc (30.0 mL) via ultrasonication for 1 h to ensure a homogeneous distribution of the nanotubes. Subsequently, this dispersion was slowly introduced into the PU-3 solution, and the mixture was stirred vigorously for 5 h to achieve thorough mixing. The resulting composite solution was then carefully poured into a PTFE mold (100 mm × 100 mm × 10 mm) and subjected to vacuum treatment to remove any entrapped air bubbles. Thereafter, the film was dried at 70 °C for 24 h to eliminate residual solvent, followed by postcuring under vacuum at 80 °C for additional 24 h. Ultimately, a flexible and sensitive polymer/carbon nanotube composite nanosensor with a uniform morphology and excellent flexibility was obtained.

4.5. Instrumentation and Characterization

The ¹H NMR and ¹C NMR spectra were measured on a 400 MHz spectrometer (Bruker AVANCE III, Bruker BioSpin, Germany), using chloroform-d (CDCl₃) and dimethyl sulfoxide (DMSO-d₆) as solvents. The mass spectrum was recorded on a Thermo Scientific Q Exactive Plus mass spectrometer (Thermo Fisher Scientific, USA). SEC measurements were performed on a Waters e2695 SEC system (Waters, USA). During the SEC tests, the mobile phase was chromatographically pure tetrahydrofuran, with a flow rate maintained at 0.3 mL min^–1 and a column temperature controlled at 30 °C. FTIR spectra were employed on a Thermo Nicolet iS50 spectrometer (Thermo Fisher Scientific, USA) in the range 4000 to 500 cm^–1. Raman spectra were recorded using a LabRAM HR Evolution confocal Raman microscope (Horiba Jobin Yvon, France), with the measurement conducted over a wavenumber range of 1200 to 200 cm^–1. XRD patterns were recorded on a Bruker D8 ADVANCE diffractometer (Bruker, Germany) at a scanning speed of 10° min^–1. SEM images were captured using a Hitachi SU5000 scanning electron microscope (Tokyo, Japan). EDS mapping was conducted to analyze the elemental distribution on the sample surface. DSC was performed on a PerkinElmer DSC 8500 instrument (Waltham, MA, USA). The measurements were performed using approximately 5 mg of the sample, with a temperature range of −80 to 100 °C, a heating rate of 10 °C min^–1, and a nitrogen atmosphere. TGA was carried out using a BXT-TTBDY-1250 analyzer (BAXIY, Germany), heating the sample from 30 to 800 °C at a rate of 10 °C min^–1 under nitrogen atmosphere. DMA 850 analyzer (New Castle, DE, USA) across a temperature range of −80 to 100 °C at a heating rate of 10 °C min^–1 and a frequency of 1 Hz. Mechanical properties were characterized using a UTM6104 universal testing machine (SUNS Technology Co., Ltd., Shenzhen, China) at room temperature (25 °C) at a crosshead speed of 50 mm min^–1. A multimeter Keithley 2450 SourceMeter (USA) was used to record the strain sensitivity of the flexible polymer/carbon nanotube composite sensor as well as the real-time resistance characteristics as a multifunction sensor. The sensitivity factor GF was calculated as follows:

GF = \frac{(R - R_{0}) / R_{0}}{ε} = \frac{Δ R / R_{0}}{ε}

(1)

where GF denotes the gauge (sensitivity) factor, R₀ is the initial resistance of the specimen (Ω), R is the instantaneous resistance during deformation (Ω), and ε corresponds to the applied strain.

4.6. Mechanical Properties Testing

(1)	The specimens were prepared in a standard dumbbell geometry with an effective testing region of 20.0 mm × 4.0 mm × 0.5 mm. All tensile measurements were conducted at a constant crosshead speed of 50 mm min^–1, and each formulation was tested at least three times to ensure reproducibility of the results. The tensile stress (σ) and elongation at break (ε) were obtained from the corresponding stress–strain profiles and calculated using the following equations: $σ = \frac{F}{b \times d}; ε = \frac{L - L_{0}}{L_{0}} \times 100 %$ (2) where σ represents the tensile stress, F denotes the maximum tensile force at the moment of specimen fracture, b refers to the width of the effective area of the specimen, d represents the thickness of the specimen, ε symbolizes the elongation at break of the specimen, L signifies the maximum length upon specimen fracture, and L₀ represents the standard length of the sample, which is set as 20 mm.
(2)	The toughness (τ) of the specimen can be acquired by computing the area enclosed by the stress (σ)–strain (ε) curve, in accordance with the following formula: $τ = \int_{0}^{ε_{\max}} σ d ε$ (3) where ε denotes the strain of the specimen, σ represents the stress of the specimen, and ε_max symbolizes the elongation at break of the sample.
(3)	In the cyclic testing procedure, the loading/unloading rate was determined at a constant pace with a strain rate of 50 mm min^–1 under room temperature. The specimen was elongated to 500% elongation and subsequently underwent continuous loading and unloading cycles five times without interruption.
(4)	For the fracture energy evaluation, the Greensmith approach was adopted to test both notched specimens (crack length: 1 mm) and their unnotched counterparts at a loading rate of 3 mm min^–1. The samples used in the measurements had a gauge length of 10.0 mm, a width of 5.0 mm, and a thickness of 0.5 mm. The fracture energy G_c was determined according to the following expression: $G_{c} = \frac{6 w c}{\sqrt{λ_{c}}}$ (4) where λ_c refers to the elongation at break of the notched sample and c indicates the notch length of 1.0 mm. The term w corresponds to the strain energy, which is obtained by integrating the stress–strain curve of the unnotched specimen up to ε_c(ε_c = λ_c – 1).
(5)	For the self-healing experiments, the samples were first bisected, and the freshly cut surfaces were immediately brought into contact. The specimens were then subjected to healing at various temperatures. The self-healing efficiency was subsequently calculated using the following definition: $η = \frac{σ_{healed}}{σ_{o riginal}} \times 100 %$ (5) where η denotes the self-healing efficiency, σ_healed corresponds to the tensile stress of the healed specimen, and σ_original represents the tensile stress of the original specimen.

Supporting Information

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The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsapm.5c04892.

Synthetic routes and characterization data; ¹H NMR spectra, ¹³C NMR spectra, and mass spectrum of monomer; ¹H NMR spectra of PUs; SEC test results of PUs; SEM characterization results of PUs; TGA and DSC data of PUs; cyclic tensile test results of PUs; signal output diagrams of throat vibration during the utterance of the Chinese word “apple” collected by the sensor; signal output diagrams of elbow flexion states collected by the sensor (PDF)

ap5c04892_si_001.pdf (880.21 kb)

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Author Information

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Corresponding Authors
- Menglan Lv - Engineering Research Center for Energy Conversion and Storage Technology of Guizhou, School of Chemistry and Chemical Engineering, Guizhou University, Guiyang 550025, China; https://orcid.org/0009-0000-1512-774X; Email: [email protected]
- Bin Zhang - Engineering Research Center for Energy Conversion and Storage Technology of Guizhou, School of Chemistry and Chemical Engineering, Guizhou University, Guiyang 550025, China; https://orcid.org/0000-0002-7176-699X; Email: [email protected]
Authors
- Shudiao Wei - Engineering Research Center for Energy Conversion and Storage Technology of Guizhou, School of Chemistry and Chemical Engineering, Guizhou University, Guiyang 550025, China
- Weile Guo - Engineering Research Center for Energy Conversion and Storage Technology of Guizhou, School of Chemistry and Chemical Engineering, Guizhou University, Guiyang 550025, China
- Aiqin Li - Engineering Research Center for Energy Conversion and Storage Technology of Guizhou, School of Chemistry and Chemical Engineering, Guizhou University, Guiyang 550025, China
- Lingli Kong - School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, China
- Chuanhui Xu - School of Chemistry and Chemical Engineering, Guangxi University, Nanning 530004, China; https://orcid.org/0000-0002-1212-3636
- Ting Gu - School of Chemistry and Chemical Engineering, Guizhou University, Guiyang 550025, China
Author Contributions
S.W.: writing–original draft, material synthesis, data curation. W.G.: data analysis, chart beautification. A.L.: data mapping. M.L.: equipment provision, data analysis, manuscript revision. L.K.: material testing. C.X.: equipment provision. T.G.: equipment provision. B.Z.: supervision, formal analysis, manuscript revision, conceptualization.
Notes
The authors declare no competing financial interest.

Acknowledgments

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This work was supported by the National Natural Science Foundation of China (52373175), the Guizhou Provincial Basic Research Program (General Program) (MS[2025]603), the High-Level Innovative Talents Foundation of Guizhou Province (QKHPTRC-GCC[2023]-024), the Natural Science Foundation of Guizhou Province (QKHPTRC-CXTD[2023]005), and the Science and Technology Innovation Team of the Higher Education Department of Guizhou Province (QJJ[2023]053).

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Abstract
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Figure 1
Figure 1. (a) Molecular structure of the PU-3 elastomer. (b) Schematic of the network structure and dynamic bond interactions. (c) Proposed network structure of the PU-3 elastomer.
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Figure 2
Figure 2. (a) FTIR spectra of PU-1, PU-2, and PU-3 elastomers. (b) Raman spectra. (c) XRD patterns. (d–f) Elemental mapping images of PU-1, PU-2, and PU-3 obtained from EDS. (g) Storage modulus (E′). (h) Loss modulus (E″). (i) Loss factor (tan δ).
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Figure 3
Figure 3. (a) Stress–strain curves of the PU samples. (b) Toughness bar chart for different samples. (c, e) Cyclic tensile tests conducted at 500% strain for five consecutive loading–unloading cycles. (f) Performance comparison. (g) Fracture energy of PU-3. (h) Photograph of a notched PU-3 sample stretched to 800% strain.
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Figure 4
Figure 4. (a, b) Stress–strain curves and bar chart of self-healing at various times at 60 °C for PU-1, (c, d) PU-2, and (e, f) PU-3, respectively. (g) Optical images of the self-healing process of PU-3. (h) Photograph of PU-3 after healing lifting a 5 kg weight.
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Figure 5
Figure 5. (a) Schematic illustration of the recycling process of the PU-3 elastomer. (b) FTIR spectra of the original and recycled PU-3 sample. (c) XRD patterns of the original and recycled PU-3 sample. (d) Stress–strain curves of PU-3 after two recycling cycles. (e) Demonstration of the recycled PU-3 elastomer lifting a 12 kg weight.
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Figure 6
Figure 6. (a) Schematic illustration of the fabrication process of the flexible and sensitive polymer/carbon nanotube composite nanosensor. (b) Relative resistance variation (ΔR/R₀) of the sensor under tensile strains ranging from 3% to 300%. (c) GF of the nanosensor, where GF = ΔR/(R₀·ε) and ε denotes strain. (d) Response and recovery times of the sensor at 100% strain. (e) Real-time signal output of the sensor during mouth breathing. (f) Schematic representation of the potential applications in human motion monitoring. (g) Signal response of the sensor during throat articulation of the word “drink”. (h) Electrical response of the sensor during finger bending and stretching at angles of 30°, 45°, 60°, and 90°. (i) Signal output during wrist bending and (j) signal response during walking and stair climbing.
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Supporting Information
Supporting Information
The Supporting Information is available free of charge at https://pubs.acs.org/doi/10.1021/acsapm.5c04892.
- Synthetic routes and characterization data; ¹H NMR spectra, ¹³C NMR spectra, and mass spectrum of monomer; ¹H NMR spectra of PUs; SEC test results of PUs; SEM characterization results of PUs; TGA and DSC data of PUs; cyclic tensile test results of PUs; signal output diagrams of throat vibration during the utterance of the Chinese word “apple” collected by the sensor; signal output diagrams of elbow flexion states collected by the sensor (PDF)
- ap5c04892_si_001.pdf (880.21 kb)
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Molecular Steric Engineering Enables High-Strength and Self-Healing Polyurethane Elastomer for Flexible and Sensitive NanosensorsClick to copy article linkArticle link copied!

ACS Applied Polymer Materials

Abstract

1. Introduction

2. Results and Discussion

2.1. Preparation and Characterization of the Samples

Figure 1

Figure 2

2.2. Mechanical Properties and Fatigue Resistance of the Samples

Figure 3

2.3. Self-Healability of the PU Elastomers

Figure 4

2.4. Recyclability of the PU Elastomers

Figure 5

2.5. Preparation and Potential Applications for Flexible and Sensitive Nanosensors

Figure 6

3. Conclusions

4. Experimental Section

4.1. Materials

4.2. Synthesis of DS

4.3. Synthesis of PU Elastomers

4.4. Fabrication of Flexible and Sensitive Polymer/Carbon Nanotube Composite Nanosensors

4.5. Instrumentation and Characterization

4.6. Mechanical Properties Testing

Supporting Information

Terms & Conditions

Author Information

Acknowledgments

References

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Abstract

Figure 1

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Figure 3

Figure 4

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Figure 6

References

Supporting Information

Supporting Information

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Molecular Steric Engineering Enables High-Strength and Self-Healing Polyurethane Elastomer for Flexible and Sensitive Nanosensors
Click to copy article linkArticle link copied!