High Healing Efficiency Research Articles

Dual Anticorrosive and Self-healing Coating Based on Multiresponsive Polyaniline Porous Microspheres.

In this work, a smart self-healing coating with long-term anticorrosion ability was developed based on multiresponsive polyaniline (PANI) porous microspheres. The polyaniline porous microspheres loaded with corrosion inhibitor (benzotriazole, BTA) was prepared by the emulsion template method and photopolymerization. The BTA loaded in the polyaniline microspheres acted as a corrosion inhibitor, while the polyaniline in the shell performed the multiple functions of corrosion inhibition, pH-responsive and photoresponsive release, and photothermal conversion. Owing to the inherent corrosion-inhibiting nature of BTA and PANI, the BTA-loaded polyaniline microsphere could endow coating with dual anticorrosive properties. The coating with polyaniline microspheres did not show any corrosion product after 700 h of salt spray testing, while obvious pitting corrosion could be observed for the blank coating after 100 h of the salt spray test. Thanks to the photothermal properties of PANI, the composite coating exhibited self-healing behavior under NIR light irradiation. The coating with 10 wt % polyaniline microspheres could achieve rapid closure and recover its barrier properties within 5 s of NIR irradiation. And the release of BTA could form a passivation film on scratches to further repair coating defects. The on-command responsive release, high healing efficiency, and excellent anticorrosion properties of this dual self-healing anticorrosion coating provide perspectives on extending the service life of metals.

Catalyst‐free epoxy resins with high‐performance and excellent healing efficiency via interpenetrating networks

AbstractThe difficult recycling and degradation in cured epoxy resins can be solved by introducing dynamic covalent bonds. However, the introduction of dynamic bonds degrades the properties of epoxy resins. In this paper, the dual‐cured epoxy resin with high mechanical properties and high healing efficiency were obtained by constructing interpenetrating networks (IPNs). The effect of IPNs on the recyclability of epoxy resins was investigated. The performance is as follows, the flexural and tensile strengths is 89 and 54.2 MPa, respectively, and the breakdown strength is 32.5 kV/mm. In addition, the recyclability and high healing efficiency of the dual‐cured epoxy resin were verified, and the effect of the hot‐pressing temperature and time on the properties of the recycled samples were investigated. Under certain hot‐pressing conditions, the flexural and tensile strengths of the recycled samples were recovered to 95.06% and 85.28%, respectively, and the breakdown strength was recovered to 83.6%.

High‐performance self‐healing epoxy by microencapsulated epoxy‐amine chemistry II: Performance of the system

AbstractThe self‐healing epoxy based on microencapsulated epoxy‐amine chemistry is a system with great potential for practical applications. Herein, microcapsules respectively containing epoxy and polyetheramine were fabricated using a microencapsulation technique via integrating electrospraying and interfacial polymerization (ES‐IP) and self‐healing epoxy based on the dual microcapsules were systematically investigated regarding the microcapsule dispersion, healing performance, failure mode, and mechanical properties. Microcapsules with different sizes were conveniently prepared by adjusting the injection rate. The microcapsules, regardless of the size, can be well dispersed in the epoxy matrix. The effects of the microcapsule size and concentration on the healing performance were studied. While full healing can be obtained for microcapsule >100 μm, high healing efficiency of about 90% and 70% can be achieved for microcapsules in 50 ~ 100 μm and ~ 50 μm, respectively. The healing performance decreases with the decreased microcapsule concentration. However, healing efficiency >70% can still be obtained when 5.0 wt% microcapsule of 50 ~ 100 μm were adopted. Mixed failure modes including adhesive failure, cohesive failure, and matrix failure, were observed, due to the good performance of the selected healant system. While the incorporated microcapsules, especially the small ones, evidently toughens the matrix, they deteriorate the tensile properties of the formulated self‐healing material.

Development and Investigation of a Nanoemulgel Formulated from Tunisian Opuntia ficus-indica L. Seed Oil for Enhanced Wound Healing Activity.

The aim of this study is to develop a nanoemulgel encapsulating a Tunisian Prickly Pear (Opuntia ficus-indica L.) seed oil (PPSO) to assess, for the first time, the in vivo efficacy of this nanoformulation on wound healing. Phytocompounds of this oil have been reported in the literature as having powerful pharmacological activities. However, it remains poorly exploited due to low bioavailability. A nanoemulsion (NE) was designed by determining the required hydrophilic-lipophilic balance (HLB) and subsequently characterized. The mean droplet size was measured at 56.46 ± 1.12 nm, with a polydispersity index (PDI) of 0.23 ± 0.01 using dynamic light scattering. The zeta potential was -31.4 ± 1.4 mV, and the morphology was confirmed and assessed using transmission electron microscopy (TEM). These characteristics align with the typical properties of nanoemulsions. The gelification process resulted in the formation of a nanoemulgel from the optimum nanoemulsion. The high wound healing efficiency of the nanoemulgel was confirmed compared to that of a medicinally marketed cream. The outcomes of this research contribute valuable insights, for the first time, into the potential therapeutic applications of PPSO and its innovative pharmaceutical formulation for wound healing.

Novel recyclable epoxy resin with releasable residual stress and synergistically enhanced dielectric properties and healing ability

It has been a challenge to improve the performance of epoxy insulation in the whole life cycle by achieving the reduction of residual stress during manufacturing, the healing of damages during application, and the recycling after decommissioning. In this paper, a novel recyclable epoxy resin (SEP) with releasable residual stress and synergistically enhanced dielectric properties and healing ability was successfully developed by introducing dynamic thiocarbamate bonds (DTBs). A reduction in residual stresses by 45 % was detected after SEP was annealed at 30 °C below the glassy transition temperature (Tg) for 8 h, during which the mechanical properties remained unchanged. Synergistically improved dielectric properties and damage-healing ability were also observed in SEP. A high healing efficiency of 94.4 % for electrical breakdown damage was found in SEP, meanwhile its dielectric properties were superior to commercial epoxy resin. Additionally, SEP featured good recyclability, including reprocessability and degradability. All those excellent properties were ascribed to the dissociation and recombination of DTBs triggered by thermal stimulation. This work provides an effective solution to a series of issues throughout the full lifecycle of epoxy materials.

Self‐Healing and Toughness Triboelectric Materials Enabled by Dynamic Nanoconfinement Quenching

AbstractSelf‐healing materials that integrate excellent mechanical properties and high healing efficiency meet the requirements of flexible electronic sensors for mechanical flexibility and reliability. In the field of wearable devices, they are of great significance for improving the stability of the equipment and reducing the frequency of replacement. However, the high strength of materials often limits their self‐healing ability. When damage occurs, it will hinder the microstructural adjustment and fluidity of the material at the damaged site, thus negatively affecting the activation and execution of the self‐healing mechanism. In this study, a strength‐toughness and room‐temperature self‐healing triboelectric material is prepared by the dynamic nanoconfinement effect and the quenching effect of ethanol (referred to as the DNCQ strategy). The quenching effect of ethanol improves the aggregation of nanocluster phase, and the constructed nanoconfined network skillfully balances the contradiction between mechanical properties and self‐healing ability. The obtained triboelectric material has high tensile strength (27.1 MPa), toughness (97.9 MJ m−3), and excellent healing efficiency (88.6%). The self‐powered pressure distribution sensing array based on triboelectric materials can accurately reflect the pressure distribution of the object, which has potential application prospects in the field of wearable devices.

Self-healing and reprocessable biobased non-isocyanate polyurethane elastomer with dual dynamic covalent adaptive network for flexible strain sensor

Owing to the nontoxicity of monomers, non-isocyanate polyurethane elastomers have attracted considerable attention, yet the synthesis and functionalization are still challenging. Herein, self-healing and reprocessable biobased non-isocyanate polyurethane (NIPU) elastomers with dual dynamic covalent adaptive network (DDCAN) by disulfide bonds and dynamic imine bonds were synthesized as substrate for the construction of flexible strain sensor with MXene as conductive substance. The tensile strength and elongation at break of the NIPU elastomer were 3.22 MPa and 234 %, respectively. Thanks to the formation of DDCAN, the NIPU elastomer showed high healing efficiency of 97.5 % after healing at room temperature for 24 h. Interestingly, the NIPU elastomer possessed superior reprocessing capability and the tensile strength after three reprocessing cycles reached 136.1 % of the original one, which was attributed to the increase of crosslinking points caused by topological rearrangement. In addition, the NIPU elastomer-based flexible strain sensor exhibited fast response (response time = 60 ms) and excellent repeatability (1000 bending-releasing cycles) and was successfully applied for human motion detection and speech recognition. The findings in this work conceivably stand out as a new methodology for the preparation of biobased and functional elastomers, which will greatly promote the sustainable development and application of flexible electronics.

Compatibilization of Polyamide 6/Cyclic Olefinic Copolymer Blends for the Development of Multifunctional Thermoplastic Composites with Self-Healing Capability.

This study investigated the self-healing properties of PA6/COC blends, in particular, the impact of three compatibilizers on the rheological, microstructural, and thermomechanical properties. Dynamic rheological analysis revealed that ethylene glycidyl methacrylate (E-GMA) played a crucial role in reducing interfacial tension and promoting PA6 chain entanglement with COC domains. Mechanical tests showed that poly(ethylene)-graft-maleic anhydride (PE-g-MAH) and polyolefin elastomer-graft-maleic anhydride (POE-g-MAH) compatibilizers enhanced elongation at break, while E-GMA had a milder effect. A thermal healing process at 140 °C for 1 h was carried out on specimens broken in fracture toughness tests, performed under quasi-static and impact conditions, and healing efficiency (HE) was evaluated as the ratio of critical stress intensity factors of healed and virgin samples. All the compatibilizers increased HE, especially E-GMA, achieving 28.5% and 68% in quasi-static and impact conditions, respectively. SEM images of specimens tested in quasi-static conditions showed that all the compatibilizers induced PA6 plasticization and crack corrugation, thus hindering COC flow in the crack zone. Conversely, under impact conditions, E-GMA led to the formation of brittle fractures with planar surfaces, promoting COC flow and thus higher HE values. This study demonstrated that compatibilizers, loading mode, and fracture surface morphologies strongly influenced self-healing performance.

Biomechanical analysis of combi-hole locking compression plate during fracture healing: A numerical study of screw configuration.

Locking compression plates (LCPs) have become a widely used option for treating femur bone fractures. However, the optimal screw configuration with combi-holes remains a subject of debate. The study aims to create a time-dependent finite element (FE) model to assess the impacts of different screw configurations on LCP fixation stiffness and healing efficiency across four healing stages during a complete fracture healing process. To simulate the healing process, we integrated a time-dependent callus formation mechanism into a FE model of the LCP with combi-holes. Three screw configuration parameters, namely working length, screw number, and screw position, were investigated. Increasing the working length negatively affected axial stiffness and healing efficiency (p < 0.001), while screw number or position had no significant impact (p > 0.01). The time-dependent model displayed a moderate correlation with the conventional time-independent model for axial stiffness and healing efficiency (ρ ≥ 0.733, p ≤ 0.025). The highest healing efficiency (95.2%) was observed in screw configuration C125 during the 4-8-week period. The results provide insights into managing fractures using LCPs with combi-holes over an extended duration. Under axial compressive loading conditions, the use of the C125 screw configuration can enhance callus formation during the 4-12-week period for transverse fractures. When employing the C12345 configuration, it becomes crucial to avoid overconstraint during the 4-8-week period.

High‐performance epoxy vitrimer composites based on double dynamic covalent bonds

AbstractThermoset epoxy resin materials can be endowed with unique dynamic properties by introducing dynamic covalent bonds (DCB) into the cross‐link network of the epoxy resin. However, it remains a challenge to obtain epoxy materials with high mechanical, thermodynamic, and dynamic properties. In this work, a series of epoxy vitrimers with double DCBs were prepared by using a curing agent with imine bonds (PAMD) and an epoxy resin with disulfide bonds (BGPDS). PAMD and BGPDS are cross‐linked and form a uniform aromatic framework that ensures the mechanical and thermal properties of the material. High‐density DCBs ensure the dynamic performance of epoxy vitrimer. In addition, tetra‐needle‐like ZnO whiskers (T‐ZnOw) were added to the epoxy vitrimer for further reinforcement. The results demonstrated that epoxy vitrimer composites with T‐ZnOw content of 10 wt.% exhibit high tensile strength, high Tg, high healing efficiency, shape reconfiguration, reprocessing and rapid degradation. The degradation products can recycle and produce new epoxy vitrimer, leading to a closed‐loop recycling which reduced the environmental pollution and resource waste.

Shifting the mechanical strength-healing efficiency trade-off of polyurethanes by incorporating boronic ester bonds and hydrogen bonding

It is challenging to design and synthesize elastomers with both good mechanical performance and high healing efficiency because their mechanisms are mutually exclusive. This work aims to shift the trade-off between them by incorporating dynamic non-covalent bonds via 2-ureido-4[1H]-pyrimidione (UPy) and dynamic covalent bonds via boronic ester bonds into polyurethane. The quadruple hydrogen bonds between UPy dimers serve as physical crosslinks, improving the overall mechanical properties of the polyurethane, while the boronic esters facilitate its healing. The resulting polyurethane can achieve an ultimate stress of 27.4 MPa and a healing efficiency of 90 %. The effect of healing time on the healing efficiency is modeled and discussed.

Mechanically robust, self-reporting and healable polyurethane elastomers by incorporating symmetric/asymmetric chain extenders.

Self-healing elastomers usually show poor mechanical properties and environmental stability, and they cannot self-report mechanical/chemical damage. Herein, an innovative design strategy is reported that combines symmetric/asymmetric chain extenders to create large yet disordered hard domains within polyurethane (PU) elastomers, enabling the integration of mechanical robustness and self-reporting and self-healing capabilities to overcome both mechanical and chemical damage. Specifically, large yet disordered hard domains were created by governing the molar contents of asymmetric fluorescent 2-(4-aminophenyl)-5-aminobenzimidazole (PABZ) and symmetric 4-aminophenyl disulfide (APDS). Such a structural feature led to a small free-volume fraction, prominent strain-induced crystallization (SIC), and high energy of dissipation, enabling the PU elastomer to display outstanding mechanical strength (60.7 MPa) and toughness (177.9 MJ m-3). Meanwhile, the loose stacking of disordered hard domains imposed small restriction on network chains and imparted the network with high relaxation dynamics, leading to high healing efficiency (97.8%). More importantly, the fluorescence intensity was stimulus-responsive and thus the PU elastomer could self-report mechanical/chemical damage and healing processes. The PU elastomer also showed potential application prospects in information encoding and encryption. Furthermore, selecting polydimethylsiloxane as one of the soft segments could effectively endow the PU elastomer with intrinsic hydrophobicity. Therefore, this work provides valuable guidance for designing multi-functional materials with anti-counterfeiting, self-reporting, and healing properties as well as high mechanical properties and hydrophobicity.

Mechanically Robust and Self‐Healing Polyurethane Elastomer Based on Hierarchical Hydrogen Bonds

AbstractIt is a formidable challenge to fabricate mechanically robust and self‐healing polymeric materials. In this work, a facile but effective approach based on constructing hierarchical hydrogen bonds (H‐bonds) is used to combine high mechanical robustness and healing efficiency into one artificial polyurethane (PU) elastomer. The infrared spectrum and molecular simulations demonstrate the formation of hierarchical H‐bonds, which are assembled by the strong and weak H‐bonds. The hierarchical H‐bonds appear to have two advantages. On the one hand, the hierarchical breaking of the strong and weak H‐bonds can effectively strengthen and toughen the PU elastomer. The strong H‐bonds maintain the integrity of the PU network, while the weak H‐bonds dissipate considerable energy during stretching; on the other hand, the rapid dissociation and organization of hierarchical H‐bonds provides the driving force for the healing process. Thus, the hierarchical H‐bonds efficiently solve the inherent contradiction between mechanical strength and healing dynamics. As a result, the PU elastomer exhibits excellent mechanical properties (32.5 MPa of tensile strength and 84.1 MJ m−3 of toughness). Meanwhile, this PU elastomer shows high healing efficiency (91.4%) and also exhibits 100% scratch recovery. This design strategy may provide a simple yet effective way to produce robust self‐healing polymeric materials.

A resilience assessment framework for microencapsulated self-healing cementitious composites based on a micromechanical damage-healing model

In this paper, a resilience assessment framework for microencapsulated self-healing cementitious composites is proposed based on a micromechanical damage-healing model. A 3D micromechanical analytical model is constructed to analyze the performance evolution during the damage-healing process of self-healing concrete. The resilience assessment of microencapsulated self-healing concrete is defined by virtue of the residual stiffness, self-healing effect on stiffness and damage cumulative on stiffness, which corresponds to three main features of resilience; namely, the robustness, recoverability and adaptability. The assessment results indicate that the release of healing agents within microcapsules and healing process of extended microcracks allows the microencapsulated self-healing concrete to have higher resilience than conventional concrete. Moreover, a parameter sensitivity analysis is conducted to investigate the influence of the healing efficiency, the applied initial damage and the fracture toughness of the repaired microcrack on resilience of microencapsulated self-healing concrete. The results indicate that higher healing efficiency and applied initial damage leads to high resilience, and fracture toughness of the repaired microcrack makes less difference to the results. The findings of this paper lay a theoretical foundation for the resilience design of self-healing material layer of underground structures.

Dual responsive microwave heating-healing system in asphalt concrete incorporating coal gangue and functional aggregate

The development of multifunctional asphalt concrete with a high heating-healing capability has emerged as a crucial focus in achieving pavement maintenance and sustainable infrastructure. However, striking a balance between achieving a high healing efficiency without compromising mechanical strengths and preventing aggregation of functional additives has presented a challenge. To address this, a novel concept of a dual responsive microwave heating-healing system in asphalt concrete is proposed, which incorporates coal gangue (CG) and functional aggregates. By incorporating functional aggregates, a robust and functional skeleton structure can be established within the asphalt concrete, facilitating the healing of microcracks at the interfaces between aggregates and asphalt. Simultaneously, the inclusion of CG in the asphalt mixture facilitates the healing of microcracks within the mastic. Remarkably, the incorporation of dual functional additives in the optimized asphalt concrete results in only a marginal decrease of 2% in maximum tensile strength and 1.5% in crack resistance compared to plain porous asphalt samples. Furthermore, the optimized asphalt samples exhibit healing index values exceeding 60% after undergoing five damage-healing cycles. To develop heating-healing asphalt concrete, it is recommended to utilize 100% CG in combination with functional aggregates. This comprehensive approach takes into account the valuable reuse of CG powder, as well as the associated environmental and economic benefits. This study introduces a promising strategy for achieving a highly efficient heating-healing capability in asphalt concrete, presenting significant potential for its practical applications in the field of sustainable pavement engineering.

A Janus supramolecular hydrogel prepared by one-pot method for wound dressing

Despite the adhesive hydrogels have gained progress and popularity, it is still an enormous challenge to develop a smart adhesion hydrogel for clinical medicine, which is an asymmetric adhesion hydrogel with on-demand detachment. Motivated by the thermal phase transition mechanism of gelatin, we have synthesized a Janus supramolecular hydrogel dressing with skin temperature-triggered adhesion by a simple one-pot process. This hydrogel has asymmetric and controllable adhesion, which not only can become the external objects barrier but also can achieve repeated adhesion and on-demand detachment triggered by temperature in tens of seconds. This hydrogel presents great mechanical performance (compressive strain of 65 %, 1.38 MPa) owing to the presence of supramolecular interactions in the hydrogel. Additionally, this hydrogel exhibits excellent antibacterial activity and biocompatibility. The synergistic effect of modified gelatin and ionic liquid greatly facilitates wound healing of full-thickness skin with high wound healing efficiency (98.45 %). Therefore, thanks to all these advantages, the Janus supramolecular hydrogel can be applied for wound management and treatment, which has huge potential in healing skin wounds.

Smart Materials with Dual Functionality: Repeatable Damage-Detection and Self-Healing.

Polymer materials are extensively used because of their excellent performance; however, when used for a long time, they break and eventually lose their original properties. Thus, smart polymer materials that can repeatedly detect and repair damage must be urgently developed to increase their durability and lifespan. In this study, a smart material with dual functionality (damage-detection and self-healing) is developed via a facile method of incorporating spiropyran (SP) beads, which exhibit changes in color and fluorescence when damaged, into a Diels-Alder (DA)-based self-healing matrix. When polyurethane (PU) is added to the DA-based matrix, the dual functionality exhibits a strong dependence on the proportion of PU. Because the PU ratio affects two opposing factors (damaged area and load-bearing capacity), the damage-detecting ability exhibits the best performance at 40 wt % PU, where both factors are optimized. A high healing efficiency of 96% is achieved via a dynamic DA reaction. In particular, the repeatability of the dual-functionality is successfully attained through the reversibility of the SP beads and DA networks, where the detection and healing efficiencies are reduced by 15 and 23%, respectively, after 10 cycles. Furthermore, the reprocessed fractured specimens exhibit excellent recyclability.

Effects of hydrogel-encapsulated bacteria on the healing efficiency and compressive strength of concrete

Microbial-induced calcium carbonate precipitation is a promising technology for self-healing concrete due to its capability to seal microcracks. The main goal of this study was to evaluate the effects of adding hydrogel-encapsulated bacteria on the compressive strength and the self-healing efficiency of concrete. To achieve this objective, 12 sets of mortar samples were prepared, including three different mineral precursors (magnesium acetate, calcium lactate, and sodium lactate), at two concentrations (67.76 and 75.00 ​mM/L), and under two different biological conditions (with and without bacteria). In addition, a set of plain mortar samples was prepared to serve as a control. For each sample set, three mortar cubes and three beams were prepared and subjected to compression and flexural strength tests. From the compression tests, it was found that the sample containing calcium lactate along with yeast extract and bacteria displayed the best results. As for the flexural tests, once cracked, the beams were subjected to 28 ​d of wet/dry cycles (16 ​h of water immersion and 8 ​h of drying), where the bottom crack width was monitored (at 0, 3, 7, 14, 28 ​d of wet/dry cycles). Once the sample with the highest healing efficiency was identified (the one containing calcium lactate and hydrogel-encapsulated bacteria), the study was scaled up to concrete specimens. Two sets of concrete cylinders (consisting of three control samples and three samples with bacteria along with calcium lactate) were tested under compression in order to evaluate the effect of the bacteria-precursor combination on the concrete mechanical properties. The samples that yielded the greatest compressive strength were the ones containing calcium lactate and bacteria, displaying an improvement of 17% as compared to the control specimen. Furthermore, a flexural strength recovery analysis was performed on the concrete specimens revealing that the control showed better flexural strength recovery than the bacteria-containing variant (41.5% vs. 26.1%) after 28 ​d of wet/dry cycles. A healing efficiency analysis was also performed on the cracked samples, revealing that the control displayed the best results. These results are due to the fact that the control specimen showed a narrower crack width in comparison to the bacteria-containing samples.

Quadruple H-Bonding and Polyrotaxanes Dual Cross-linking Supramolecular Elastomer for High Toughness and Self-healing Conductors.

Tough and self-healable substrates can enable stretchable electronics long service life. However, for substrates, it still remains a challenge to achieve both high toughness and autonomous self-healing ability at room temperature. Herein, a strategy by using the combined effects between quadruple H-bonding and slidable cross-links is proposed to solve the above issues in the elastomer. The elastomer exhibits high toughness (77.3 MJ m-3 ), fracture energy (≈127.2 kJ m-2 ), and good healing efficiency (91 %) at room temperature. The superior performance is ascribed to the inter and intra crosslinking structures of quadruple H-bonding and polyrotaxanes in the dual crosslinking system. Strain-induced crystallization of PEG in polyrotaxanes also contributes to the high fracture energy of the elastomers. Furthermore, based on the dual cross-linked supramolecular elastomer, a highly stretchable and self-healable electrode containing liquid metal is also fabricated, retaining resistance stability (0.16-0.26 Ω) even at the strain of 1600 %.

Quadruple H‐Bonding and Polyrotaxanes Dual Cross‐linking Supramolecular Elastomer for High Toughness and Self‐healing Conductors

AbstractTough and self‐healable substrates can enable stretchable electronics long service life. However, for substrates, it still remains a challenge to achieve both high toughness and autonomous self‐healing ability at room temperature. Herein, a strategy by using the combined effects between quadruple H‐bonding and slidable cross‐links is proposed to solve the above issues in the elastomer. The elastomer exhibits high toughness (77.3 MJ m−3), fracture energy (≈127.2 kJ m−2), and good healing efficiency (91 %) at room temperature. The superior performance is ascribed to the inter and intra crosslinking structures of quadruple H‐bonding and polyrotaxanes in the dual crosslinking system. Strain‐induced crystallization of PEG in polyrotaxanes also contributes to the high fracture energy of the elastomers. Furthermore, based on the dual cross‐linked supramolecular elastomer, a highly stretchable and self‐healable electrode containing liquid metal is also fabricated, retaining resistance stability (0.16–0.26 Ω) even at the strain of 1600 %.