Extraordinary Mechanical Strength Research Articles

Strong current in carbon nanoconductors: Mechanical and magnetic stability

Carbon nanoconductors are known to have extraordinary mechanical strength and interesting magnetic properties. Moreover, nanoconductors based on one- or two-dimensional carbon allotropes display a very high current-carrying capacity and ballistic transport. Here, we employ a recent, simple approach based on density functional theory to analyze the impact of strong current on the mechanical and magnetic properties of carbon nanoconductors. We find that the influence of the current itself on the bond-strength of carbon in general is remarkably low compared to e.g. typical metals. This is demonstrated for carbon chains, carbon nanotubes, graphene and polyacetylene. We can trace this to the strong binding and electronic bandstructure. On the other hand, we find that the current significanly change the magnetic properties. In particular, we find that currents in graphene zig-zag edge states quench the magnetism.

Adapting Conductivity and Mechanical Properties through Layer Thickness Variation in Copper Niobium Laminated Metallic Composites

Cu/Nb laminated metallic composites (LMCs) exhibit extraordinary mechanical strength while electrical conductivity is maintained at a high level. In this research, Cu‐based LMCs with varying volume fraction of niobium are produced via accumulative roll bonding (ARB) and additionally cold‐rolled and heat‐treated to identify the role of these heterogeneous phase boundaries on the overall sheet properties. Deformation structures in these layered materials are studied through scanning transmission electron microscopy investigations. The existence of an interface‐affected zone at the phase boundaries and mechanical intermixing is attributed to decreasing electrical and increasing mechanical properties, especially in very thin layered LMCs. Atom probe tomography measurements show that mechanical alloying occurs due to severe plastic deformation during ARB processing of the laminates. An additional subsequent heat treatment leads to chemical demixing at the interfaces of the phase boundaries.

Anti-Oxidized Self-Assembly of Multilayered F-Mene/MXene/TPU Composite with Improved Environmental Stability and Pressure Sensing Performances.

MXenes, as emerging 2D sensing materials for next-generation electronics, have attracted tremendous attention owing to their extraordinary electrical conductivity, mechanical strength, and flexibility. However, challenges remain due to the weak stability in the oxygen environment and nonnegligible aggregation of layered MXenes, which severely affect the durability and sensing performances of the corresponding MXene-based pressure sensors, respectively. Here, in this work, we propose an easy-to-fabricate self-assembly strategy to prepare multilayered MXene composite films, where the first layer MXene is hydrogen-bond self-assembled on the electrospun thermoplastic urethane (TPU) fibers surface and the anti-oxidized functionalized-MXene (f-MXene) is subsequently adhered on the MXene layer by spontaneous electrostatic attraction. Remarkably, the f-MXene surface is functionalized with silanization reagents to form a hydrophobic protective layer, thus preventing the oxidation of the MXene-based pressure sensor during service. Simultaneously, the electrostatic self-assembled MXene and f-MXene successfully avoid the invalid stacking of MXene, leading to an improved pressure sensitivity. Moreover, the adopted electrospinning method can facilitate cyclic self-assembly and the formation of a hierarchical micro-nano porous structure of the multilayered f-MXene/MXene/TPU (M-fM2T) composite. The gradient pores can generate changes in the conductive pathways within a wide loading range, broadening the pressure detection range of the as-proposed multilayered f-MXene/MXene/TPU piezoresistive sensor (M-fM2TPS). Experimentally, these novel features endow our M-fM2TPS with an outstanding maximum sensitivity of 40.31 kPa-1 and an extensive sensing range of up to 120 kPa. Additionally, our M-fM2TPS exhibits excellent anti-oxidized properties for environmental stability and mechanical reliability for long-term use, which shows only ~0.8% fractional resistance changes after being placed in a natural environment for over 30 days and provides a reproducible loading-unloading pressure measurement for more than 1000 cycles. As a proof of concept, the M-fM2TPS is deployed to monitor human movements and radial artery pulse. Our anti-oxidized self-assembly strategy of multilayered MXene is expected to guide the future investigation of MXene-based advanced sensors with commercial values.

Covalent graphene-diamond heterostructure coating on tool surface with enhanced lubricity and anti-wear performance

Graphene possesses extraordinary mechanical strength while it is difficult to integrate graphene layers on macroscale mechanical components due to the weak adhesion strength. In this work, we integrated a top layer of graphene sheets on the diamond-coated tool through in-situ growth of graphene on the diamond grains. With the aid of liquid metal catalyst, ultrastrong C–C covalent bonds are formed in the graphene-diamond interface, which can radically eliminate the peeling off of graphene sheets due to the insufficient adhesion strength. Cutting tests revealed that this top-layer graphene can substantially reduce cutting force and tool flank wear when cutting high-silicon aluminum alloy, with the reduction respectively reaching 40 % and 20 %. During the machining process, the graphene sheets are flattened and they gradually form a compact layer covering on the diamond surface, which can not only lubricate the tool surface but also protect the diamond from wear with the ultrahigh intrinsic strength. Further cutting experiments demonstrated that the effectiveness of the graphene sheets can sustain over 3600 m of cutting distance. The achievement in this work provides a novel insight into the integration of covalent graphene-diamond heterostructures in mechanical systems/devices with outstanding macroscale lubricity and anti-wear performance.

Three-Dimensional Hollow Reduced Graphene Oxide Tube Assembly for Highly Thermally Conductive Phase Change Composites and Efficient Solar-Thermal Energy Conversion.

Due to their extraordinary mechanical strength and electrical and thermal conductivities, graphene fibers and their derivatives have been widely utilized in various functional applications. In this work, we report the synthesis of a three-dimensional (3D) hollow reduced graphene oxide tube assembly (HrGOTA) using the same wet spinning method as graphene fibers. The HrGOTA has high thermal conductivity and displays the unique capability of encapsulating phase change materials for effective solar-thermal energy conversion. The HrGOTA comprises layers of moisture-fused hollow reduced graphene oxide tubes (HrGOTs), whose individual thermal conductivity is up to 578 W m-1 K-1. By impregnating 1-octadecanol into HrGOTs, a 1-octadecanol-filled HrGOT phase change composite (PCC) with a latent heat of 262.5 J g-1 is obtained. This high latent heat results from the interfacial interaction between 1-octadecanol and the reduced graphene oxide tube, as evidenced by the shifts in XRD patterns of 1-octadecanol-filled and 1-octadecanol/multiwalled carbon nanotube-filled HrGOTA samples. In addition, 1 wt % multiwalled carbon nanotubes are added to the PCC to enhance visible light absorption. Because of their high thermal conductivity and visible light absorption rates, these new PCCs display high solar-thermal energy conversion and storage efficiencies of up to 81.7%, commensurate with state-of-the-art carbon-based PCCs but with significantly lower carbon weight percentages.

Exploring the Microstructural and Mechanical Properties of Next-Generation Super Alloys

The utilisation of next-generation superalloys is of utmost significance in the progression of contemporary engineering applications that necessitate extraordinary mechanical strength, stability at elevated temperatures, and resistance to corrosion. The present work aims to conduct a thorough investigation of the microstructural and mechanical properties of these advanced materials, providing insights into their distinct features and possible areas of application. The examination of microstructure involves the utilisation of several methodologies, including scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD). The present study comprehensively examines the complicated grain structures, phase compositions, and distribution of strengthening precipitates inside the superalloys using various methodologies. The correlation between processing factors and resultant microstructures is established, facilitating a more profound comprehension of the influence of microstructure on the mechanical properties of the alloy. The knowledge acquired from this investigation into the microstructural and mechanical characteristics of next-generation superalloys provides useful insights for engineers, researchers, and designers engaged in materials development and component design. Through the use of a comprehensive comprehension of the distinctive properties of these alloys, it becomes feasible to expand the limits of performance in exceedingly challenging conditions, so influencing the trajectory of high-temperature engineering applications in the future.

Rational construction of micron-sized zero-valent iron/graphene composite for enhanced Cr(VI) removal from aqueous solution

Micron-sized zero-valent iron (mZVI) has been widely used in wastewater treatment. However, the readily formation of FeCr hydroxide passivation layer limited its application in Cr(VI)-containing wastewater treatment. This study reports the rational construction of mZVI/graphene composite (mZVI/G) through a simple and environmental-friendly mechanochemical method. Owing to the extraordinary mechanical strength, graphene nanosheets intertwine with the mZVI particles to form a strong coupled system, leading to the decoupling of water corrosion of Fe0 to two half reactions:1) Fe0 as anode lose electron to produce Fe(II); 2) Graphene nanosheets serve as cathode for hydrogen gas formation involving atomic hydrogen (H*) as intermediate. Compared to carbon nanotubes and activated carbon, graphene nanosheets could stabilize H* due to the electron sponge effect related to large π conjugation system. When mZVI/G was used for Cr(VI) removal, the Cr(VI) species were preferentially adsorbed onto the graphene nanosheets, on which to be reduced to Cr(III) by Fe(II) as well as H*. The mZVI/G achieved a stable Cr(VI) removal capacity for eight consecutive cycles, reaching 102.35 mg·g-1 with the optimal composition, which was 11, 3.12 and 2.17 times higher than that of physical mixed mZVI and GO, mZVI/AC and mZVI/CNT, respectively. Moreover, mZVI/G can achieve efficient removal of Cr(VI) over a wide pH range (3.0 – 9.0). Given the low cost and green chemistry nature, the mechanochemical synthesized mZVI/G was considered to be a promising material for the treatment of Cr(VI) contaminated water.

Biological composite fibers with extraordinary mechanical strength and toughness mediated by multiple intermolecular interacting networks

Biological composite fibers with extraordinary mechanical strength and toughness mediated by multiple intermolecular interacting networks

Stretchable Self-Healing Plastic Polyurethane with Super-High Modulus by Local Phase-Lock Strategy.

In this work, a multiblock polyurethane (PU-Im) consisting of polyether and polyurethane segments with imidazole dangling groups is demonstrated, which can further coordinate with Ni2+ . By controlling the ligand content and metal-ligand stoichiometry ratio, PU-Im-Ni complex with vastly different mechanical behavior can be obtained. The elastomer PU-2Im-Ni has extraordinary mechanical strength (61MPa)andexcellenttoughness(420 MJ m-3 ), but the plastic PU-4Im-Ni exhibits super-high modulus (515 MPa),strength(63 MPa),andgoodstretchability(≈800%). The metal-ligand interaction between polyurethane segments and Ni2+ is proved by Raman spectra, dynamic mechanical analysis (DMA), and transmission electron microscopy (TEM). The polyurethane segments domain formed by microphase separation is dynamically "locked" by Ni2+ coordinated with imidazole, revealing a local phase-lock effect. The phase-locking hard domains reinforce the PU-Im-Ni complex and maintain stimuli-responsive self-healing ability, while the free polyether segments provide stretchability. Primarily, the water environment with plasticization effect serves as an effective and eco-friendly self-healing approach for PU-Im-Ni plastic. With the excellent mechanical performance, thermal/aquatic self-healing ability, and unique damping properties, the PU-Im-Ni complexes show potential applications in self-healing engineering plastic and cushion protection fields.

Transdermal delivery of sinapine thiocyanate by gelatin microspheres and hyaluronic acid microneedles for allergic asthma in guinea pigs

Dissolving microneedles (MNs) are an efficient, safe, and generally painless method for transdermal distribution of poorly permeable medicines. Here, dissolving composite MNs were prepared from sinapine thiocyanate (ST)-loaded gelatin microspheres (GMS) and hyaluronic acid (HA). To immobilize ST in MNs, we used a two-step centrifuging and molding method. When ST-GMS/ST-HA MNs were placed on the skin, they showed extraordinary mechanical strength and dissolved slowly. In vitro, skin implantation ability was assessed with fluorescein isothiocyanate staining, which revealed progressive penetration from the puncture site into deeper tissues. The feasibility of transdermal delivery of ST-GMS/ST-HA MNs in allergic asthma guinea pigs was then determined through in vivo pharmacodynamic and pharmacokinetic tests. The results indicated that ST-GMS/ST-HA MNs, in comparison with the traditional subcutaneous application approach, achieved both high efficiency and continuous release of ST. Therefore, this device is promising for the delivery ST for allergic asthma therapy.

Double dynamic bonds tough hydrogel with high self‐healing properties based on acylhydrazone bonds and borate bonds

AbstractHydrogels with excellent self‐healing properties have specific applications in smart polymer materials, but they often do not have excellent mechanical properties, or the preparation process of hydrogels is too complicated. Here, we prepared a multi‐functional intelligent hydrogel using a simple water bath one‐pot method through the synergistic effect of dual dynamic cross‐linked agents, including acylhydrazone bonds (the first cross‐linked agent) and borate ester bonds (the second cross‐linked agent), at the same time hydrogen bonds provided physical interaction. The hydrogel exhibited excellent self‐healing ability (up to 91%) and extraordinary mechanical strength (tensile stress 173.1405 kPa and hysteresis energy of 1.8659 MJ m−3). The research used chemical cross‐linked (acylhydrazone bonds and borate ester bonds) and physical cross‐linked (hydrogen bonds). The prepared hydrogel had the dual advantages of excellent self‐healing performance and high mechanical strength. The hydrogel can be used in smart materials, such as working pressure tissues and sensing materials that require a certain degree of mechanical strength and self‐healing properties, and also provides a design strategy for preparing hydrogels with high mechanical strength and excellent self‐healing properties.

Mechanistic insights into the selective mass-transport and fabrication of holey graphene-based membranes for water purification applications

• Critical review on holey graphene (HG)-based membrane for water purification. • HG membranes have high efficiency, selectivity, and superior water permeability. • Mechanistic insights into the mass-transport of HG-based membranes are discussed. • An overview on the fabrication methodologies of HG-based membranes is highlighted. • The performance development of HG-based membranes and challenges are detailed. Graphene (Gr) and its derivative nanomaterials enable a novel approach to manipulate selective mass transport mechanisms at the sub-nanoscale level. These nanomaterials can maintain d-spacing at the sub-nanoscale level amidst their rigid nanosheet frame structure. Unlike other nanomaterials, they have outstanding features such as atomic thickness, extraordinary mechanical strength, and superior chemical stability. Although they could be utilized to overcome crucial challenges in various water purification applications, they usually suffer from swelling and limited penetration. Holey graphene (HG; also known as nanoporous graphene or graphene nano-mesh) is an exceptional derivative of Gr created by eliminating some atoms from the graphite structure to create distributed pores in the atomic structure of Gr nanosheets. These pores, occasionally with ample reactive functional groups near their boundaries, resulted in favorable defects features, which influence the intact Gr nanosheets structure, however they are beneficial in different water purification and desalination applications. In this review, the different approaches for fabricating HG-based membranes along with mass-transport mechanisms including experimental and simulation outcomes are presented and discussed. Related applications that exploit the extraordinary structure of the HG nanomaterial are also reviewed.

Optimal protein sequence design mitigates mechanical failure in silk beta-sheet nanocrystals

Spider silk fiber possesses exceptional mechanical properties such as high tensile strength, toughness, and elasticity in tensile loading. Previous experimental and computational studies have shown that extraordinary mechanical strength of silk fiber is mostly attributed to the hierarchical arrangement of antiparallel β-sheet nanocrystals and role of β-strand length, arrangements, and H-bond interactions. Despite these studies, the dependence of mechanical properties of silk nanocrystal on their sequence motifs remains largely unexplored.

Conformal surface-nanocoating strategy to boost high-performance film cathodes for flexible zinc-ion batteries as an amphibious soft robot

To satisfy the increasing power demand for the rapid development of wearable and portable electronics, the design of quasi-solid-state aqueous zinc-ion batteries (QAZIBs) requires the advancement of flexible electrodes possessing excellent electrochemical performance and extraordinary mechanical strength. This purpose could be realized by utilizing electrospinning to obtain flexible film cathodes composed of layer-structured transition metal dichalcogenides@nitrogen-doped carbon nanofibers (TMD@N-CNFs), attributed to the synergetic effect between the nanostructured TMDs (for capacity) and interwoven 1D N-CNFs (for flexibility). However, their potentials are seriously impeded by the dissolution and structural instability of active materials during zinc-ion (de)intercalation process, leading to insufficient rate capability and much-shortened cycle life. Herein, to address this big challenge, we have demonstrated the approach of developing an ultrathin Al2O3 coating layer by atomic-layer-deposition (ALD) to greatly boost the electrochemical performance of vanadium diselenide nanosheets@N-CNFs (Al2O3@VSe2 NSs@N-CNFs) film cathode in flexible QAZIBs. Moreover, the ALD-Al2O3 nanocoating provides desperately necessary mechanical robustness in the cross-2D nanosheet direction of VSe2 standing on the N-CNFs surface, as confirmed by finite element simulation results. Consequently, the QAZIB delivers an outstanding stack energy density of ∼125 Wh kg−1, an ultrahigh rate capability of 65.2% capacity retention after 200-fold increase in current density and an excellent cycling performance of 86.2% retention after 2500 cycles. Finally, we integrate the flexible QAZIB into a soft inchworm robot, which achieves reversible actuation both on land and in water and keeps good electrochemical stability, showing the prospective potentials of introducing energy storage devices for soft robotics with broad multifunctional applications.

Preparation and fireproofing performance of the wollastonite-metakaolin-based geopolymer foams

This paper aims to investigate the physical properties and fire resistance of wollastonite-metakaolin-based geopolymer foams (WMGFs). Both compressive and flexure strengths of WMGFs are significantly improved since wollastonite fibers possess inherent stiffness and provide effective crack control. Meanwhile, wollastonite addition promotes viscosity of geopolymer slurry to some extent and then determines pores formation in foaming process, which is also crucial for mechanical strength development. The thermal conductivity of the specimens rises triflingly with elevated wollastonite addition corresponding to slightly decrease in porosity. Owing to the steady skeleton structure of WMGFs, the highest reverse-side temperature of sliced blocks is merely 202.7 °C after exposed to fire for 3 h, showing that the reduction in thermal conductivity has no negative impact on fire resistance of specimens. Physicochemical stability of wollastonite under high temperature and alkaline environment is confirmed to be vital for sustaining integrated porous skeleton structure of geopolymer foams. Therefore, geopolymer foams reinforced by wollastonite possess extraordinary mechanical strength and fire resistance, revealing strong possibility for fire protection.

ZnO/graphene heterostructure nanohybrids for optoelectronics and sensors

The discovery of graphene has prompted an intensive exploration and research of heterostructure nanohybrids that integrate functionalities of semiconductor nanostructures with graphene's high charge carrier mobility, extraordinary mechanical strength, and flexibility for various applications. Among others, zinc oxide (ZnO) presents a promising candidate due to its unique physical properties including direct bandgap in ultraviolet spectrum, ferroelectricity, and hence piezoelectricity, moderate Debye length for electron depletion effect in ZnO nanostructures (quantum dots, nanowire, nanoparticles), etc. For ZnO/graphene heterostructure nanohybrids, the low thermal budget for growth of crystalline ZnO makes it possible for direct deposition of ZnO on graphene with controlled morphology and interface, enabling a large spectrum of devices including photodetectors, gas sensors, strain sensors, and self-power devices. In this Perspective, we discuss the recent progress made in ZnO/graphene heterostructure nanohybrids through understanding and engineering the ZnO/graphene interface to realize high performance. An overview of the remaining issues and future perspectives toward commercialization of the ZnO/graphene heterostructure nanohybrids will also be provided.

Polyacrylamide Hydrogel Composite E-skin Fully Mimicking Human Skin.

Transparent e-skin that can fully mimic human skin with J-shaped mechanical-behavior and tactile sensing attributes have not yet been reported. In this work, the skin-like hydrogel composite with J-shaped mechanical behavior and highly transparent, tactile, soft but strong, flexible, and stretchable attributes is developed as structural strain sensing element for e-skin. Piezo-resistive polyacrylamide (PAAm) hydrogel is used as supporting matrix to endow high transparency, softness, flexibility, stretch-ability and strain sensing capability desired for e-skin. Ultrahigh molecular weight polyethylene (UHMWPE) fiber with a wavy configuration is designed as reinforcement filler to provide the tunable strain-limiting effect. As a result, the as-prepared UHMWPE fiber/PAAm composite e-skin presents unique "J-shape" stress-strain behavior akin to human skin. And the PAAm composite can switch from supersoft to highly stiff in the designed strain range up to 100% with a prominent tensile strength of 48.3 MPa, which enables it to have the high stretch-ability and excellent load-bearing ability, simultaneously. Moreover, finite element model is developed to clarify the stress distribution and damage evolution for the UHMWPE fiber/PAAm composite during the tensile process. The PAAm composite exhibits not only an excellent strain sensing performance with a long-term reliability up to 5000 loading-unloading cycles but also an extraordinary softness and mechanical strength with a low initial modulus of 6.7 kPa, which is matchable with soft human epidermis. Finally, the e-skin is used for demonstrations in monitoring various human activities and protecting structural integrity in designed strain ranges. The strategy for reinforcing piezo-resistive hydrogel with wavy-shaped UHMWPE fibers proposed here is promising for the development of transparent, flexible, soft but strong e-skin with a tunable strain-limiting effect akin to human skin.

Stable Hollow‐Structured Silicon Suboxide‐Based Anodes toward High‐Performance Lithium‐Ion Batteries

AbstractSilicon has been regarded as an attractive high‐capacity anode material for next‐generation lithium‐ion batteries (LIBs). However, Si anodes suffer from huge volume variation during cycling, which poses a critical challenge for stable battery operation. Compared with Si, Si suboxide (SiOx) is one of the most promising candidates for high‐energy‐density LIBs because of its alleviated swelling and highly stable cycling performance. Whereas, the poor electronic conductivity and low (initial) Coulombic efficiency of SiOx anodes severely hinder practical applications for LIBs. Herein, for the first time, these issues are successfully solved through rationally designing hollow‐structured SiOx@carbon nanotubes (CNTs)/C architectures with graphitic carbon coatings and in situ growth of CNTs. When applied as anodes in LIBs, the SiOx@CNTs/C anodes exhibit high reversible capacity, high initial Coulombic efficiency (88%), outstanding cycling performance, and extraordinary mechanical strength during the calendaring process (200 MPa). This work paves the way for developing SiOx‐based anode materials for high‐energy‐density LIBs.

Turning Rubber into a Glass: Mechanical Reinforcement by Microphase Separation.

Supramolecular associations provide a promising route to functional materials with properties such as self-healing, easy recyclability or extraordinary mechanical strength and toughness. The latter benefit especially from the transient character of the formed network, which enables dissipation of energy as well as regeneration of the internal structures. However, recent investigations revealed intrinsic limitations in the achievable mechanical enhancement. This manuscript presents studies of a set of telechelic polymers with hydrogen-bonding chain ends exhibiting an extraordinarily high, almost glass-like, rubbery plateau. This is ascribed to the segregation of the associative ends into clusters and formation of an interfacial layer surrounding these clusters. An approach adopted from the field of polymer nanocomposites provides a quantitative description of the data and reveals the strongly altered mechanical properties of the polymer in the interfacial layer. These results demonstrate how employing phase separating dynamic bonds can lead to the creation of high-performance materials.

Fabrication of Double-Network Hydrogels with Universal Adhesion and Superior Extensibility and Cytocompatibility by One-Pot Method.

Hydrogels, which demand simultaneously tailorable mechanical properties and excellent biocompatibility, act as a promoting material for biomedical applications, e.g., tissue engineering scaffolds, wound dressing materials, and cartilage substitutes. Double-network hydrogels (DN hydrogels) have attracted widespread concerns due to their extraordinary mechanical strength and toughness, while traditional DN hydrogels are limited in terms of their biofunctionality. Based on the DN hydrogels composed of agar and acrylamide (AM), we incorporate vinylphosphoric acid (VPA) into the network to obtain agar/PAM/PVPA hydrogels with universal adhesion and superior cytocompatibility. Meanwhile, the agar/PAM/PVPA hydrogel maintains its high strength and toughness. It is noted that the elongation of the agar/PAM/PVPA hydrogel (molar ratio of VPA is 2%) is up to 3418.9 ± 54.9%. The cell experiment also demonstrates that the addition of VPA in a proper concentration can promote cell adhesion and proliferation. Furthermore, the hydrogel has the potential to be used as 3D printing and injectable materials because of the thermoreversible sol-gel agar. The reported agar/PAM/PVPA hydrogel in this work with universal adhesion, excellent mechanical properties, and excellent cytocompatibility is able to be used for biomedical applications as scaffolds, wound dressing materials, or cartilage repair materials.