Ultrahigh Mechanical Strength Research Articles

Cellulose nanofiber-created air barrier enabling closed-cell foams prepared via oven-drying

Cellulose foams are renewable and biodegradable materials that are promising substitutes for plastic foams. However, the scale-up fabrication of cellulose foams is severely hindered by technological complexity and cost- and time-consuming drying processes. Here, we developed a facile and robust method to fabricate cellulose foams via oven-drying following surfactant-assisted mechanical foaming of cellulose nanofibers (CNFs). CNFs in the air-water interface reduced the surface tension to stabilize bubbles in the wet foams, and generated densely arranged crystal barriers to seal air in the bubbles while oven-drying to prevent bubbles from collapsing. The optimal CNF foam has an ultra-low density of 12.10 mg/cm3, an ultra-high porosity of 99.14 %, and a low thermal conductivity of 34.87 mW/m/K, allowing it to act as an excellent thermal insulation material. Moreover, CNF foams can be easily integrated with diverse advanced properties such as flame retardancy, ultra-high mechanical strength, hydrophobicity, and magnetic responsiveness by incorporating functional components. The study paves the way for CNF foams to move toward practical applications.

A PET-enhanced PEO-ionic liquid-based gel polymer electrolyte for solid state lithium metal batteries

Gel polymer electrolytes (GPEs) are attractive for their promising prospect in lithium metal batteries (LMBs) owing to their outstanding thermal stability and remarkable electrochemical performance. Nevertheless, the practical application of traditional GPEs is significantly impeded by their limited mechanical strength. In order to address this issue, this study introduces an ultrathin and mechanically-strong poly(ethylene terephthalate) (PET) nonwoven fabric (PET-NW) as a rigid support layer for the GPEs composed of poly (ethylene oxide) (PEO) and ionic liquid (IL) EMIM-TFSI. The resulting PEO-IL/PET-NW-based GPE (NW GPE) demonstrates an excellent lithium ionic conductivity of 4.21 × 10−4 S cm−1, a lithium ion transference number of 0.20, and an ultrahigh mechanical strength of 53.2 MPa. These characteristics collectively contribute to the suppression of lithium dendrites growth and improved electrochemical performance of Li|NW GPE|LiFePO4 full cells which exhibit enhanced rate capability and cycling stability in comparison with Li|GPE-I30|LiFePO4 full cells. The employment of PET-NW in the fabrication of GPEs can pave a viable way for significant advancements in high-performance solid state LMBs for various practical applications.

Preparation of ultra-high permeability dual-layer Al2O3 hollow fiber supports for zeolite membrane fabrication

Four-channel dual-layer Al2O3 hollow fiber with ultra-high permeability and mechanical strength was prepared by co-extrusion and co-sintering technique for the first time and used as support for NaA zeolite membranes fabrication. The macroporous inner layer of the Al2O3 hollow fiber, composed by large Al2O3 particle, gives supports the high permeability and mechanical strength, while the thin out layer, composed by small particles, provides an even and smooth surface for zeolite membrane growth. By using SiO2 as the sintering aid, the sintering temperature of the inner layer was reduced and match with that of the outer layer. The effects of SiO2 adding amount, sintering temperature, Al2O3 particle size and their content on the structure and properties of the prepared hollow fiber were investigated systematically. At a sintering temperature of 1520 °C, a dual-layer hollow fiber with surface pore size of 0.38 μm and fracture load of 24.52 N, exhibits pure water flux as high as 22.23 m3 m 2 h−1 bar−1. The NaA membrane prepared on this support achieved a flux of 14.14 kg m−2 h−1 and a separation factor >10,000 in pervaporation separation of EtOH/H2O solution (90 wt%, 75 °C). This work provides an efficient and low-cost way to prepare ceramic hollow fiber support for high-performance zeolite membrane fabrication.

Falcon Probe: A High-Pressure and Robust Sampling Interface for Coupling Lossless Liquid Chromatography Injection with In Situ Nanoliter-Scale Sample Pretreatment.

With the increasing demand for trace sample analysis, injecting trace samples into liquid chromatography-mass spectrometry (LC-MS) systems with minimal loss has become a major challenge. Herein, we describe an in situ LC-MS analytical probe, the Falcon probe, which integrates multiple functions of high-pressure sample injection without sample loss, high-efficiency LC separation, and electrospray. The main body of the Falcon probe is made of stainless steel and fabricated by the computer numerical control (CNC) technique, which has ultrahigh mechanical strength. By coupling a nanoliter-scale droplet reactor made of polyether ether ketone (PEEK) material, the Falcon probe-based LC-MS system was capable of operating at mobile-phase pressures up to 800 bar, which is comparable to those of conventional ultraperformance liquid chromatography (UPLC) systems. Using the probe pressing microamount in situ (PPMI) injection approach, the Falcon probe-based LC-MS system showed high separation efficiency and good repeatability with relative standard deviations (RSDs) of retention time and peak area of 1.8% and 9.9%, respectively, in peptide mixture analysis (n = 6). We applied this system to the analysis of a trace amount of 200 pg of HeLa protein digest and successfully identified an average of 766 protein groups (n = 5). By combining in situ sample pretreatment at the nanoliter range, we further applied the present system in single-cell proteomic analysis, and 241 protein groups were identified in single 293 cells, which preliminarily demonstrated its potential in the analysis of trace amounts of samples with complex compositions.

Decoration of Ag Species into Reduced Graphene Oxide Foam as a Superelastic and Robust Host toward Stable Zn Metal Anodes under Dwell-Fatigue Condition.

Deep-sea equipment usually operates under dwell-fatigue condition, which means the equipped energy storage devices must survive under the changing pressure. Special mechanical designs should be considered to maintain the electrochemical performance of electrodes under this extreme condition. In this work, an effective assembly strategy is proposed to accommodate the dwell-fatigue loading using Ag decorated reduced graphene oxide (rGO) foam (denoted as AGF) as a superelastic and robust Zn host. The wet-press assembly process enables the formation of highly porous and robust framework. The strong synergetic effect between rGO and Ag further guarantees AGF's superelasticity and ultrahigh mechanical strength. Meanwhile, the homogeneously distributed Ag species on the rGO sheets act as zincophilic sites to effectively facilitate Zn plating. Furthermore, AGF offers enough space to address the expansion during the charge and discharge cycles. As expected, the symmetrical cell using this AGF@Zn host demonstrates a long lifespan over 400h at a depth-of-discharge of 50%. It is worth mentioning that the superelastic AGF host realizes stable Zn plating/stripping under varying pressures.

An Innovative Concept of Membrane-Free Redox Flow Batteries with Near-Zero Contact Distance Between Electrodes.

Given that the ion-exchange membrane takes up more than 30% of redox flow battery (RFB) cost, considerable cost reduction is anticipated with the membrane-free design. However, eliminating the membrane/separator would expose the membrane-free RFBs to a higher risk of short-circuits, and the dendrite growth may aggravate this issue. The current strategy based on expanding distances between electrodes is proposed to address short-circuit issues. Nevertheless, this approach would decrease the energy efficiency (EE) and could not restrain dendrite growth fundamentally. Herein, an inexpensive and electron-insulating boron nitride nanosheets (BNNSs)-Nylon hybrid interlayer (BN/Nylon) is developed for general membrane-free RFBs to achieve "near-zero distance" contact between electrodes. And the Lewis acid sites (B atoms) in BNNS can interact with the Lewis base anions in electrolytes, enabling a reduced Pb2+concentration gradient. Additionally, the ultrahigh thermal conductivity and mechanical strength of BNNSs promote the uniform plating/stripping process of Pb and PbO2. Compared with conventional soluble lead RFBs, introducing BN/Nylon interlayers boosts EE by ≈38.2% at 25mAcm-2, and extends the cycle life to 100 cycles. This innovative strategy premieres the application of the BN/Nylon interlayer concept, offering a novel perspective for the development of general membrane-free RFBs.

Strong double networked hybrid cellulosic foam for passive cooling

Up to now, energy conservation, emission reduction, and environmental protection are still the goals that humanity continuously pursues. Passive radiative cooling is a zero-consumption cooling technology, which gains more and more attention. However, the contraction between mechanical strength and cooling performance of traditional radiative cooling materials still limits their scalable production. In this work, we developed a strong double-networked hybrid cellulosic foam via crosslinking recyclable CNF and PVA with a silane coupling agent in the freeze-drying process. Meanwhile, nano zinc oxide and MOF were added to improve the mechanical and solar scattering of foam. Benefiting from the synergistic solar scattering of ZnO and MOF and the stable double crosslinking network, the as-prepared hybrid cellulosic foam exhibits high solar reflectivity of 0.965, high IR emissivity of 0.94, ultrahigh mechanical strength of and low thermal conductivity. Based on above results, the hybrid cellulosic foam shows high-performance daytime cooling efficiency of 7.5 °C under direct sunlight in the hot region (Nanjing, China), which can serve as outdoor thermal-regulation materials. This work demonstrates that biomass materials possess the enormous potential of in thermal regulating materials, and also provides great possibilities for their applications in energy conservation, environmental protection and green building materials.

Graphene Failure under MPa: Nanowear of Step Edges Initiated by Interfacial Mechanochemical Reactions.

The low wear resistance of macroscale graphene coatings does not match the ultrahigh mechanical strength and chemical inertness of the graphene layer itself; however, the wear mechanism responsible for this issue at low mechanical stress is still unclear. Here, we demonstrate that the susceptibility of the graphene monolayer to wear at its atomic step edges is governed by the mechanochemistry of frictional interfaces. The mechanochemical reactions activated by chemically active SiO2 microspheres result in atomic attrition rather than mechanical damage such as surface fracture and folding by chemically inert diamond tools. Correspondingly, the threshold contact stress for graphene edge wear decreases more than 30 times to the MPa level, and mechanochemical wear can be described well with the mechanically assisted Arrhenius-type kinetic model, i.e., exponential dependence of the removal rate on the contact stress. These findings provide a strategy for improving the antiwear of graphene-based materials by reducing the mechanochemical interactions at tribological interfaces.

Aligned Bamboo Fiber‐Induced Crystallinity Mitigation of Lightweight Polymer Composite Enables Ultrahigh Strength and Unprecedented Toughness

AbstractLightweight polymer composites promise incredible applications in aerospace, seaprobes, and medical apparatus. However, their performance is generally limited by a trade‐off between mechanical strength and toughness. Herein, a crystallinity mitigating strategy driven by highly aligned bamboo macrofibers embedded in a polycaprolactone polyol (PCL) matrix for producing ultrastrong and tough lightweight polymer composites is proposed. The embedded bamboo macrofibers have oxygen‐containing functional groups on the fiber surface, that can interact with functional groups (ester and hydroxyl groups) in the molecular chains of the PCL in the form of hydrogen bonds, thus preventing the aggregation of molecular chains and the crystallization of PCL, which ultimately leads to unprecedented toughness. Meanwhile, the bamboo macrofibres with intrinsically aligned microstructure, can enable effective stress transfer and dissipation, providing remarkable ultrahigh strength. As a result, the obtained lightweight polymer composite achieves ultrahigh mechanical strength (31.5 MPa) and superior toughness (21.7 MJ m−3) at an unprecedented low density (1.07 g cm−3), representing the state‐of‐the‐art in reported lightweight polymers. Such lightweight polymer composite has the potential to greatly expedite the practical realization of artificial medical materials, including orthopedic instruments and joint prostheses.

Self-healing polyurethane elastomer with ultra-high mechanical strength and enhanced thermal mechanical properties

Polyurethane (PU) materials are widely used due to their excellent comprehensive properties including high strength, good wear resistance and weather resistance. To further improve the service life and safety of polyurethane materials, self-healing polyurethane materials have been developed. However, self-healing polyurethane generally suffers from low mechanical strength and poor thermal mechanical properties. Here, we have constructed a strong dual network by introducing benzene-1,4-diboronic acid (PDBA) into poly(urethane-urea) (PUU). On one hand, PDBA can form coordination bonds with nitrogen atoms in PUU, leading to the formation of a dual network consisting of boron-nitrogen coordination and hydrogen bonding. This dual network imparts PUU with a maximum tensile strength of 84.2 MPa. On the other hand, boron-nitrogen coordination is more stable than hydrogen bonding at high temperature, thereby significantly enhancing the thermal mechanical properties of PUU (the mechanical strength of PUU-PDBA-50 % and PUU-PDBA-100 % increased by 1.8 times and 2.4 times, respectively, compared to PUU at 100 °C). Meanwhile, the dynamic nature of the dual network endows the material with self-healing ability.

Microstructural and mechanical characterization of additively manufactured parts of maraging 18Ni300M steel with water and gas atomized powders feedstock

The demand for manufacturing components with complex geometries, good mechanical properties, and material efficiency has surged across various industries, encompassing aerospace, military, nuclear, and naval sectors. Laser powder bed fusion (LPBF), as an additive manufacturing (AM) process, has emerged as a promising method for producing ultra-high mechanical strength alloys, like maraging 300 steel (18Ni300M). However, in numerous studies in the literature concerning the effects of processing parameters on the properties of 18Ni300M steel parts fabricated through LPBF, limited attention has been given to the influence that powder atomization methods may exert on the final properties of these parts. This article investigated the effect of gas atomization (GA) and water atomization (WA) processes on the microstructure of 18Ni300M steel powders and the mechanical properties, microstructure, and chemical composition of LPBF-produced parts. The results revealed significant distinctions in the morphology, aggregation degree, and particle size distribution between the GA and WA powders, which directly influenced the microstructure and affected the amount of defects in LPBF-produced parts. Despite the similar mechanical response found in the WA and GA specimens in the elastic region, the samples produced with the WA batch presented a brittle behavior with a ductility of only 4.06%, whereas the GA parts had an elastoplastic behavior with an elongation of 11.52%. The bulks from the WA batch produced in the LPBF process were compromised due to powder contamination with oxygen, which increased gas porosity and effected fragile oxide particles visible on the fracture surface.

Self-Healing Luminescent Elastomers with Ultrahigh Mechanical Strength, Superior Toughness, and Stimuli-Responsive Luminescence

Self-Healing Luminescent Elastomers with Ultrahigh Mechanical Strength, Superior Toughness, and Stimuli-Responsive Luminescence

Formation and ultrahigh mechanical strength of multicomponent Co-based bulk glassy alloys

A glassy phase with glass transition (GT) was formed in a wide B content range of 12–31 at% for (Co0.75Cr0.125Mo0.125)100-xBx alloys. The appearance of GT at the low metalloid content of 12%B among Co-, Fe- and Ni-based alloys is the first, in contrast to the absence of GT for (Fe0.75Cr0.125Mo0.125)88B12 and (Ni0.75Cr0.125Mo0.125)88B12 alloys. The Co-based 12%B glassy alloy crystallized through unique three stages, i.e., glass (G) → [G + hcp + fcc] → [G + fcc] → [fcc + M23B6]. The appearance of GT is due to the necessity of long-range rearrangement of constituent elements for the simultaneous precipitation of hcp and fcc phases from glassy phase. The glass transition temperature, crystallization temperature, Vickers hardness (Hv) and Young's modulus for the Co-based glassy alloys increase linearly with increasing B content and reach 904 K, 946 K, 1566 and 188 GPa, respectively, at 31%B. The good bending plasticity is retained up to 29%B. The crystallization of the 27–29%B alloy occurs through G → [G + M23B6] → [M23B6 + M2B] and the ultrahigh Hv above 2000 is attained for the metastable [G + M23B6] phase state. The glassy alloy rod with a diameter of 1 mm was prepared for the 27%B alloy and exhibited ultrahigh yield strength of 4700 MPa, plastic strain of 1% and high oxidation resistance up to about 1200 K. The Co-based bulk glassy alloy with simultaneously high strength, ultrahigh hardness and high oxidation resistance, is promising for the future high hardness and heat-resistance materials.

Experimental study of the effect of crystalline aluminum oxide nanofibers on the properties of oil-based drilling fluids

This work presents first-of-its kind research on the effect of alumina nanofibers (ANF) on drilling emulsions. ANF is a new generation crystalline nanofiber material with ultra-high mechanical strength and stability. From a physicochemical point of view, the material constitutes alumina nanofibers with a unidirectional dispersed structure and a faceted surface. Such characteristics provide ANF with a wide range of possibilities for interacting with various polymer matrices, as well as with ceramic and metallic materials. A number of characteristics and properties, such as viscosity, rheology, structure formation, filtration and antifriction properties, clay swelling kinetics, and stability of oil-based drilling fluids (OBDF) modified with aluminum oxide nanofibers, have been studied. These studies have demonstrated the positive effect of nanofibers on all functional characteristics of drilling fluids. It was found that nanofibers significantly change the rheological characteristics, reduce filtration losses, and reduce the coefficient of friction of drilling fluids without significantly degrading their colloidal stability in the concentration range not exceeding 1 wt%. The addition of ANF doubles the effective viscosity and yield strength, reduces filtration losses by a factor of 2.5, reduces the coefficient of friction by almost two times, and does not impair the colloidal and thermal stability of oil-based drilling fluids. This paves the way for the use of this material as the most promising one in drilling fluid development.

Barnacle inspired high-strength hydrogel for adhesive.

Barnacle exhibits high adhesion strength underwater for its glue with coupled adhesion mechanisms, including hydrogen bonding, electrostatic force, and hydrophobic interaction. Inspired by such adhesion mechanism, we designed and constructed a hydrophobic phase separation hydrogel induced by the electrostatic and hydrogen bond interaction assembly of PEI and PMAA. By coupling the effect of hydrogen bond, electrostatic force and hydrophobic interaction, our gel materials show an ultrahigh mechanical strength, which is up to 2.66 ± 0.18MPa. Also, benefit from the coupled adhesion forces, as well as the ability to destroy the interface water layer, the adhesion strength on the polar materials can be up to 1.99 ± 0.11MPa underwater, while that of the adhesion strength is about 2.70 ± 0.21MPa under silicon oil. This work provides a deeper understanding of the underwater adhesion principle of barnacle glue. Furthermore, our bioinspired strategy would provide an inspiration for the fabrication of high mechanical gel materials, and the rapid strong adhesive used in both water and organic solvents.

Engineering of Chain Rigidity and Hydrogen Bond Cross-Linking toward Ultra-Strong, Healable, Recyclable, and Water-Resistant Elastomers.

High-performance elastomers have gained significant interest because of their wide applications in industry andourdaily life. However, it remains a great challenge to fabricate elastomers simultaneously integrating ultra-high mechanical strength, toughness, and excellent healing and recycling capacities. In this study, ultra-strong, healable, and recyclable elastomers are fabricated by dynamically cross-linking copolymers composed of rigid polyimide (PI) segments and soft poly(urea-urethane) (PUU) segments with hydrogen bonds. The elastomers, which are denoted as PIPUU, have a record-high tensile strength of ≈142MPa and an extremely high toughness of ≈527MJm-3 . The structure of the PIPUU elastomer contains hydrogen-bond-cross-linked elastic matrix and homogenously dispersed rigid nanostructures. The rigid PI segments self-assemble to generate phase-separated nanostructures that serve as nanofillers to significantly strengthen the elastomers. Meanwhile, the elastic matrix is composed of soft PUU segments cross-linked with reversible hydrogen bonds, which largely enhance the strength and toughness of the elastomer. The dynamically cross-linked PIPUU elastomers can be healed and recycled to restore their original mechanical strength. Moreover, because of the excellent mechanical performance and the hydrophobic PI segments, the PIPUU elastomers are scratch-, puncture-, and water-resistant.

Super strong and tough anisotropic hydrogels through synergy of directional freeze-casting, metal complexation and salting out

Strong and tough ionic conductive hydrogel is one of the key raw materials for the development of high-performance flexible electronic products. However, it is still challenging to prepare ionic conductive hydrogel materials with the integration of ultra-high mechanical strength, extremely high toughness and ionic conductivity. In this work, a simple strategy is proposed to prepare super strong and tough hydrogels through multi-length scale synergistic strengthening. The directional freeze-casting would endow hydrogels with good anisotropic structure at the micro-scale and the post-treatment of soaking in the saturated Na3Cit and Al2(SO4)3 composite solution would introduce metal complexation and chain entanglement to realize network structure densification at the sub-micro and nano-scale. These effects have been proven to be positive and synergistic, which can significantly increase the tensile strength, toughness and Young's modulus of the poly(vinyl alcohol)/carboxymethyl chitosan (PVA/CMCS) hydrogel. The optimum tensile strength, toughness, Young's modulus and tear energy of PVA/CMCS/Na3Cit/Al2(SO4)3 hydrogel reach 25.9 MPa, 90.9 MJ/m3, 422.6 MPa and 118.2 MJ/m2. This super strong and tough conductive hydrogel was assembled into a sensor and combined with Morse code to realize information transmission, encryption and decryption. This work provides a new scheme for the preparation of ultra-strong ionic conductive hydrogel for flexible electronics.

Preparation and characterizations of an injectable and biodegradable high-strength iron-bearing brushite cement for bone repair and vertebral augmentation applications.

Brushite cements have good osteoconductive and resorbable properties, but the low mechanical strength and poor injectability limit their clinical applications in load-bearing conditions and minimally invasive surgery. In this study, an injectable brushite cement that contains monocalcium phosphate monohydrate (MCPM) and β-tricalcium phosphate (β-TCP) as its solid phase and ammonium ferric citrate (AFC) solution as the aqueous medium was designed to have high mechanical strength. The optimized formulation achieved a compressive strength of 62.8 ± 7.2 MPa, which is above the previously reported values of hand-mixing brushite cements. The incorporation of AFC prolonged the setting times and greatly enhanced the injectability and degradation properties of the cements. In vitro and in vivo experiments demonstrated that the brushite cements exhibited good biocompatibility and bone regeneration capacity. The novel brushite cement is promising for bone healing in load-bearing applications.

Enzymatically-mineralized double-network hydrogels with ultrahigh mechanical strength, toughness, and stiffness.

Background: Synthetic hydrogels are commonly mechanically weak which limits the scope of their applications. Methods: In this study, we synthesized an organic-inorganic hybrid hydrogel with ultrahigh strength, stiffness, and toughness via enzyme-induced mineralization of calcium phosphate in a double network of bacterial cellulose nanofibers and alginate-Ca2+. Results: Cellulose nanofibers formed the first rigid network via hydrogen binding and templated the deposition of calcium phosphate, while alginate-Ca2+ formed the second energy-dissipating network via ionic interaction. The two networks created a brick-mortar-like structure, in which the "tortuous fracture path" mechanism by breaking the interlaced calcium phosphate-coated bacterial cellulose nanofibers and the hysteresis by unzipping the ionic alginate-Ca2+ network made a great contribution to the mechanical properties of the hydrogels. Conclusion: The optimized hydrogel exhibited ultrahigh fracture stress of 48 MPa, Young's modulus of 1329 MPa, and fracture energy of 3013 J/m2, which are barely possessed by the reported synthetic hydrogels. Finally, the hydrogel represented potential use in subchondral bone defect repair in an ex vivo model.

Refined microstructure and ultrahigh mechanical strength of (TiN + TiB)/Ti composites in situ synthesized via laser powder bed fusion

• (TiN + TiB)/Ti composites were in-situ synthesized via laser powder bed fusion with a near-full density. • Refined microstructure and ultrahigh mechanical strength were achieved in the printed composite as compared with the pure Ti. • The in-situ synthesis process of TiN/TiB precipitates and underlying strengthening mechanisms were investigated. Titanium matrix composites reinforced by titanium nitride (TiN) and titanium boride (TiB) were in-situ synthesized via laser powder bed fusion (L-PBF) using premixed boron nitride (BN) and titanium powders. The optimal BN content was determined as 0.5 wt%, and a near-full density was achieved with optimized process parameters. The microstructure of the printed composite consisted of α-Ti matrix doped with N, as well as nano-sized TiN and TiB precipitates. The ultimate tensile strength of the printed composite sample was enhanced by ∼85% from ∼590 MPa to ∼1100 MPa as compared with the pure Ti counterpart, whereas the elongation was reduced to ∼3%. This research provides insights into the additive manufacturing of metal composites with near-full density and enhanced mechanical strength.