Superstrong Ionogel Enabled by Coacervation-Induced Nanofibril Assembly for Sustainable Moisture Energy Harvesting

Ionogels have grabbed significant interest in various applications, from sensors and actuators to wearable electronics and energy storage devices. However, current ionogels suffer from low strength and poor ionic conductivity, limiting their performance in practical applications. Here, inspired by the mechanical reinforcement of natural biomacromolecules through noncovalent aggregates, a strategy is proposed to construct nanofibril-based ionogels through complex coacervation-induced assembly. Cellulose nanofibrils (CNFs) can bundle together with poly(ionic liquid) (PIL) to form a superstrong nanofibrous network, in which the ionic liquid (IL) can be retained to form ionogels with high liquid inclusion and ionic conductivity. The strength of the CNF-PIL-IL ionogels can be tuned by the IL content over a wide range of up to 78 MPa. The optical transparency, high strength, and hygroscopicity enabled them to be promising candidates in moist-electricity generation and applications such as energy harvesting windows and wearable power generators. In addition, the ionogels are degradable and the ionogel-based generators can be recycled through dehydration. Our strategy suggests perspectives for the fabrication of high-strength and multifunctional ionogels for sustainable applications.

Creation of Wood-Based Hierarchical Superstructures via In Situ Growth of ZIF-8 for Enhancing Mechanical Strength and Electromagnetic Shielding Performance

Given the escalating prevalence of electromagnetic pollution, there is an urgent need for the development of high-performance electromagnetic interference (EMI) shielding materials. Herein, wood-based electromagnetic shielding materials have gained significant popularity due to their exceptional performance as building materials. In this study, a novel wood-based composite with electromagnetic shielding properties is developed. Through the in situ growth of zeolitic imidazolate framework-8 (ZIF-8) crystals on wood fibers, coupled with uniform integration of carbon nanotubes (CNTs), a multifunctional composite named ZIF-8/Poplar-CNT composite is synthesized via a one-step thermoforming process. The incorporation of CNTs endows the composites with excellent EMI shielding effectiveness (EMI SE). Among these elements, despite ZIF-8 crystals not possessing intrinsic electromagnetic shielding functionality, their distinctive dodecahedral structure proves adept at scattering and reflecting electromagnetic waves within the composites, further improving the electromagnetic shielding effect. Hence, the ZIF-8/Poplar-CNT composite (56.95 dB) has ≈10 dB higher EMI SE compared to that of the composites without ZIF-8 crystals. Meanwhile, ZIF-8 crystals endow the materials with excellent tensile strength (54.84 MPa, enhanced by 4 times). Moreover, the introduction of Zn2+ provides superior antibacterial properties. The potential applications of ZIF-8/Poplar-CNT composites extend to diverse areas such as building decoration, electronic products, and medical equipment.

Ultrarobust Actuator Comprising High-Strength Carbon Fibers and Commercially Available Polycarbonate with Multi-Stimulus Responses and Programmable Deformation

Polymer-based actuators have gained extensive attention owing to their potential applications in aerospace, soft robotics, etc. However, poor mechanical properties, the inability of multi-stimuli response and programmable deformation, and the costly fabrication procedure have significantly hindered their practical application. Herein, these issues are overcome via a simple and scalable one-step molding method. The actuator is fabricated by hot-pressing commercial unidirectional carbon fiber/epoxy prepregs with a commodity PC membrane. Notable CTE differences between the CF and PC layers endow the bilayer actuator with fast and reliable actuation deformation. Benefiting from the high strength of CF, the actuator exhibits excellent mechanical performance. Moreover, the anisotropy of CF endows the actuator with design flexibility. Furthermore, the multifunction of CF makes the actuator capable of responding to thermal, optical, and electrical stimulation simultaneously. Based on the bilayer actuator, we successfully fabricated intelligent devices such as light-driven biomimetic flowers, intelligent grippers, and gesture-simulating apparatuses, which further validate the programmability and multi-stimuli response characteristics of this actuator. Strikingly, the prepared gripper possesses a grasping capacity approximately 31.2 times its own weight. It is thus believed that the concept presented paves the way for building next-generation robust robotics.

Enhancing Durability and Capacity Retention of Ultrafine-Grained Aluminum Foil Anodes in Lithium-Ion Batteries

In this study, we present our successful fabrication of commercial-grade pure aluminum anode foil (99.5%, 2NAl) with an ultrafine-grained (UFG) microstructure and high hardness, achieved through cold rolling. Under identical rolling conditions, a coarse-grained microstructure with a low hardness was attained from the high-purity Al foil (99.99%, 4NAl). The UFG 2NAl foil exhibited enhanced lithium-ion diffusivity and reduced nucleation and activation overpotentials for forming the β-LiAl phase compared to the 4NAl foil. The high-density grain boundaries in the UFG 2NAl foil facilitated the rapid formation of a uniform β-LiAl phase layer on its surface, thereby mitigating mechanical damage within the β-LiAl phase layer caused by volume changes during the lithiation and delithiation processes. The high hardness of the UFG 2NAl sample effectively prevented macroscopic plastic deformation during cycling, thus preserving the integrity of the β-LiAl phase layer and inhibiting the formation of cracks within the unreacted Al matrix. The collective advantages of reduced overpotential, enhanced Li-ion diffusivity, and high resistance to mechanical damage and plastic deformation in UFG 2NAl contribute to its superior durability and capacity retention compared to the high-purity Al in electrochemical cycling.

Preparation and Mechanical Properties of Flexible Prepreg Resin with High Strength and Low Creep

In this study, aiming at the problem of low strength and high creep caused by medium-low modulus flexible resin based on the formulation design idea of high-molecular-weight epoxy resin (E12)-reinforced flexible epoxy-terminated urethane resin (EUR), a flexible epoxy prepreg resin with high strength and low bending creep was prepared to be suitable for hot melt processing technology. Flexible EUR was synthesized by grafting flexible polyurethane segments onto the epoxy side chain by urethane bonding. By adjusting the ratio of E12 and EUR, the effects of different ratios of the two components on the mechanical properties and viscoelasticity of the resin were systematically studied with dicyandiamide as the latent curing system. Research has found that when the E12 content is between 20%wt and 40%wt, the resin system has the best coating viscosity at 65 °C to 85 °C. The molecular weight and the content of aromatic heterocyclic groups of the resin determine the strength and creep behavior of the resin. When the content of E12 in the system is less than 50%wt, modulus and strength increase linearly, but after more than 50%wt E12 content, the modulus is almost unchanged and the strength begins to decrease. By increasing the content of E12 in the resin, the creep behavior of the resin is greatly reduced. When the content of E12 increases to 50%wt, the bending creep is the lowest.

A High-Strength Solid Oxide Fuel Cell Supported by an Ordered Porous Cathode Membrane

The phase inversion tape casting has been widely used to fabricate open straight porous supports for solid oxide fuel cells (SOFCs), which can offer better gas transmission and minimize the concentration polarization. However, the overall weak strength of the macro-porous structure still limits the applications of these SOFCs. In this work, a novel SOFC supported by an ordered porous cathode membrane with a four-layer configuration containing a finger-like porous 3 mol% yttria- stabilized zirconia (3YSZ)-La0.8Sr0.2Co0.6Fe0.4O3-δ (LSCF) catalyst, porous 8 mol% yttria-stabilized zirconia (8YSZ)-LSCF catalyst, and dense 8YSZ porous 8YSZ-NiO catalyst is successfully prepared by the phase inversion tape casting, dip-coating, co-sintering, and impregnation process. The flexural strength of the open straight porous 3YSZ membrane is as high as 131.95 MPa, which meets the requirement for SOFCs. The cathode-supported single cell shows a peak power density of 540 mW cm-2 at 850 °C using H2 as the fuel. The degradation mechanism of the SOFC is investigated by the combination of microstructure characterization and distribution of relaxation times (DRT) analysis.

High-Toughness and High-Strength Solvent-Free Linear Poly(ionic liquid) Elastomers

Solvent-free elastomers, unlike gels, do not suffer from solvent evaporation and leakage in practical applications. However, it is challenging to realize the preparation of high-toughness (with both high stress and strain) ionic elastomers. Herein, high-toughness linear poly(ionic liquid) (PIL) elastomers are constructed via supramolecular ionic networks formed by the polymerization of halometallate ionic liquid (IL) monomers, without any chemical crosslinking. The obtained linear PIL elastomers exhibit high strength (16.5 MPa), Young's modulus (157.49 MPa), toughness (130.31 MJ m-3 ), and high crack propagation insensitivity (fracture energy 243.37 kJ m-2 ), owing to the enhanced intermolecular noncovalent interactions of PIL chains. Furthermore, PIL elastomer-based strain, pressure, and touch sensors have shown high sensitivity. The linear noncovalent crosslinked network endows the PIL elastomers with self-healing and recyclable properties, and broad application prospects in the fields of flexible sensor devices, health monitoring, and human-machine interaction.

Stepwisely Assembled Multicomponent Fiber with High Water Content and Superior Mechanical Properties for Artificial Ligament

The ligament, which connects bones at the joints, has both high water content and excellent mechanical properties in living organisms. However, it is still challenging to fabricate fibrous materials that possess high water content and ligament-like mechanical characteristics simultaneously. Herein, the design and preparation of a ligament-mimicking multicomponent fiber is reported through stepwise assembly of polysaccharide, calcium, and dopamine. In simulated body fluid, the resulting fiber has a water content of 40 wt%, while demonstrating strength of ≈120 MPa, a Young's modulus of ≈3 GPa, and a toughness of ≈25 MJ m-3 . Additionally, the multicomponent fiber exhibits excellent creep and fatigue resistance, as well as biocompatibility to support cell growth in vitro. These findings suggest that the fiber has potential for engineering high-performance artificial ligament.

A Polymer-Based Metallurgical Route to Produce Aluminum Metal-Matrix Composite with High Strength and Ductility

In this investigation, an attempt was made to develop a new high-strength and high-ductility aluminum metal-matrix composite. It was achieved by incorporating ceramic reinforcement into the metal which was formed in situ from a polymer by pyrolysis. A crosslinked PMHS polymer was introduced into commercially pure aluminum via friction stir processing (FSP). The distributed micro- and nano-sized polymer was then converted into ceramic particles by heating at 500 °C for 10 h and processed again via FSP. The produced composite showed a 2.5-fold increase in yield strength (to 119 MPa from 48 MPa) and 3.5-fold increase in tensile strength (to 286 MPa from 82 MPa) with respect to the base metal. The ductility was marginally reduced from 40% to 30%. The increase in strength is attributed to the grain refinement and the larger ceramic particles. High-temperature grain stability was obtained, with minimal loss to mechanical properties, up to 500 °C due to the Zenner pinning effect of the nano-sized ceramic particles at the grain boundaries. Fractures took place throughout the matrix up to 300 °C. Above 300 °C, the interfacial bonding between the particle and matrix became weak, and fractures took place at the particle-matrix interface.

High-strength and high-toughness ECM films with the potential for peripheral nerve repair

Extracellular matrix (ECM) scaffolds are widely applied in the field of regeneration as the result of their irreplaceable biological advantages, and the preparation of ECM scaffolds into ECM hydrogels expands the applications to some extent. However, weak mechanical properties of current ECM materials limit the complete exploitation of ECM's biological advantages. To enable ECM materials to be utilized in applications requiring high strength, herein, we created a kind of new ECM material, ECM film, and evaluated its mechanical properties. ECM films exhibited outstanding toughness with no cracks after arbitrarily folding and crumpling, and dramatically high strength levels of 86 ± 17.25 MPa, the maximum of which was 115 MPa. Such spectacular high-strength and high-toughness films, containing only pure ECM without any crosslinking agents and other materials, far exceed current pure natural polymer gel films and even many composite gel films and synthetic polymer gel films. In addition, both PC12 cells and Schwann cells cultured on the surface of ECM films, especially Schwann cells, showed good proliferation, and the neurite outgrowth of the PC12 cells was promoted, indicating the application potential of ECM film in peripheral nerve repair.

Recycling Coal Fly Ash for Super-Thermal-Insulating Aerogel Fiber Preparation with Simultaneous Al2O3 Extraction

A large quantity of coal fly ash is generated worldwide from thermal power plants, causing a serious environmental threat owing to disposal and storage problems. In this work, for the first time, coal fly ash is converted into advanced and novel aerogel fibers and high-purity α-Al2O3. Silica-bacterial cellulose composite aerogel fibers (CAFs) were synthesized using an in situ sol-gel process under ambient pressure drying. Due to the unique "nanoscale interpenetrating network" (IPN) structure, the CAFs showed wonderful mechanical properties with an optimum tensile strength of 5.0 MPa at an ultimate elongation of 5.8%. Furthermore, CAFs with a high porosity (91.8%) and high specific surface area (588.75 m2/g) can inherit advanced features, including excellent thermal insulation, stability over a wide temperature range, and hydrophobicity (contact angle of approximately 144°). Additionally, Al2O3 was simultaneously extracted from the coal fly ash to ensure that the coal fly ash was fully exploited. Overall, low-cost woven CAFs fabrics are suitable for wearable applications and offer a great approach to comprehensively use coal fly ash to address environmental threats.

High Strength MXene/PBONF Heterogeneous Membrane with Excellent Ion Selectivity for Efficient Osmotic Energy Conversion

Layered MXene nanofluidic membranes still face the problems of low mechanical property, poor ion selectivity, and low output power density. In this work, we successfully constructed heterostructured membranes with the combination of the layered channels of the MXene layer on the top and the nanoscale poly(p-phenylene-benzodioxazole) nanofiber (PBONF) layer on the bottom through a stepwise filtration method. The as-prepared MXene/PBONF-50 heterogeneous membrane exhibits high mechanical properties (strength of 221.6 MPa, strain of 3.2%), high ion selectivity of 0.87, and an excellent output power density of 15.7 W/m2 at 50-fold concentration gradient. Excitingly, the heterogeneous membrane presents a high power density of 6.8 W/m2 at a larger testing area of 0.79 mm2 and long-term stability. This heterogeneous membrane construction provides a viable strategy for the enhancement of mechanical properties and osmotic energy conversion of 2D materials.

High-Strength Carbon Nanotube Fibers from Purity Control by Atomized Catalytic Pyrolysis and Alignment Improvement by Continuous Large Prestraining

Transferring the high strength of individual carbon nanotubes (CNTs) to macroscopic fibers is still a major technical challenge. In this study, CNT fibers are wound from a hollow cylindrical assembly. In particular, atomized catalytic pyrolysis is utilized to produce the fiber and control its purity. The pristine fiber is then continuously prestrained to have a highly aligned structure for subsequent full densification. Experimental measurements show that the final fiber possesses a high tensile strength (8.0 GPa), specific strength (5.54 N tex-1 (tex: the weight (g) of a fiber of 1 km long)), Young's modulus (350 GPa), and elongation at break (4%). Such an excellent combination is superior to that of any other existing fiber and attributed to the efficient stress transfer among the highly aligned and packed CNTs. Our study provides a new strategy involving atomized catalysis for developing superstrong CNT assemblies such as fibers and films for practical applications.

Chemically Recyclable Biobased Non-Isocyanate Polyurethane Networks from CO2 -Derived Six-membered Cyclic Carbonates

Non-isocyanate polyurethanes (NIPUs) are widely studied as sustainability potential, because they can be prepared without using toxic isocyanates in the synthesis process. The aminolysis of cyclic carbonate to form NIPUs is a promising route. In this work, a series of NIPUs is prepared from renewable bis(6-membered cyclic carbonates) (iEbcc) and amines. The resulting NIPUs possess excellent mechanical properties and thermal stability. The NIPUs can be remolded via transcarbamoylation reactions, and iEbcc-TAEA-10 (the molar ratio of tris(2-aminoethyl)amine in amines is 10%) still get a recovery ratio of 90% in tensile stress after three cycles of remolding. In addition, the obtained materials can be chemically degraded into bi(1,3-diol) precursors with high purity (>99%) and yield (>90%) through alcoholysis. Meanwhile, the degraded products can be used to regenerate NIPUs with similar structures and properties as the original samples. The synthetic strategy, isocyanate-free and employing isoeugenol and carbon dioxide (CO2 ) as building blocks, makes this approach an attractive pathway to NIPU networks taking a step toward a circular economy.

Robust Osteoconductive β-Tricalcium Phosphate/L-poly(lactic acid) Membrane via Orientation-Strengthening Technology

L-poly(lactic acid) (PLLA) is a biodegradable material with multiple biomedical application potentials, especially as a membrane for guided bone regeneration. In terms of its low strength and poor osteogenic activity, improving these two properties is the key to resolve the limitations of PLLA for bone-associated applications. Herein, an orientation-strengthening technology (OST) was developed to reinforce PLLA's mechanical strength by introducing biocompatible β-tricalcium phosphate (β-TCP) to improve the crystallinity of PLLA, allowing for the formation of a highly oriented architecture to acquire an advanced membrane with high mechanical property. Furthermore, the addition of β-TCP nanoparticles significantly promotes the osteogenic activity of the composites. The tensile strength of the membrane containing 5 wt % β-TCP was 220 MPa, which was 4-folds that of the native polylactic acid fabricated via the conventional method. The oriented microstructure enhanced both the mechanical strength and the osteogenic activity of the material. The parallel grooves on the material surface are similar to the mineralized collagen fibers on the bone surface, which promoted the growth and differentiation of osteoblasts, with β-TCP further contributing to the osteoconductive effect. The combination of β-TCP and orientation-strengthening effect endows the material with higher mechanical properties and bioactivities, which provides an advanced manufacturing strategy for the preparation of PLLA-based materials for bone repair.

A Versatile Disorder-to-Order Technology to Upgrade Polymers into High-Performance Bioinspired Materials

Biodegradable polymer as traditional material has been widely used in the medical and tissue engineering fields, but there is a great limitation as to its inferior mechanical performance for repairing load-bearing tissues. Thus, it is highly desirable to develop a novel technology to fabricate high-performance biodegradable polymers. Herein, inspired by the bone's superstructure, a versatile disorder-to-order technology (VDOT) is proposed to manufacture a high-strength and high-elastic modulus stereo-composite self-reinforced polymer fiber. The mean tensile strength (336.1 MPa) and elastic modulus (4.1 GPa) of the self-reinforced polylactic acid (PLA) fiber are 5.2 and 2.1 times their counterparts of the traditional PLA fiber prepared by the existing spinning method. Moreover, the polymer fibers have the best ability of strength retention during degradation. Interestingly, the fiber tensile strength is even higher than those of bone (200 MPa) and some medical metals (e.g., Al and Mg). Based on all-polymeric raw materials, the VDOT endows bioinspired polymers with improved strength, elastic modulus, and degradation-controlled mechanical maintenance, making it a versatile update technology for the massive industrial production of high-performance biomedical polymers.

Nano-CeO2-Loaded Polyzwitterionic Double-Network High-Strength Hydrogel for Highly Enhanced Synergistic Marine Antifouling

Although many antibiofouling materials have been developed based on either bacterial-killing or antiadhesion effects, the integration of both the effects in one material remains challenging for achieving highly enhanced synergistic antibiofouling. In this study, we have explored a nano-CeO2-loaded double-network hydrogel by introducing CeO2 nanorods into a polyzwitterionic hydrogel via a simple one-pot method for achieving highly efficient antifouling. First, the CeO2 nanorods dispersed in the hydrogel, as an outstanding nanozyme, have highly efficient bacterial-killing performance. Second, the superhydrophilic polyzwitterionic hydrogel provides a dense hydrated layer on the surface and subsequently excellent broad-spectrum antiadhesion behavior. Most importantly, the bacterial killing and antiadhesion of this hydrogel can work synergistically to largely improve the marine-antifouling performance. Moreover, the double-network structure of this hydrogel, including the covalently cross-linked polyzwitterion hard network and the physically cross-linked poly(vinyl alcohol) soft network, can provide greatly improved mechanical properties (2.44 MPa of tensile strength reaches and 21.87 MPa of compressive strength). As a result, among the existing marine-antifouling hydrogels, the CeO2-loaded polyzwitterionic double-network hydrogel can achieve outstanding antifouling performance, which can sustain for over 6 months in a real marine environment. This work provides a promising marine-antifouling hydrogel, which will also inspire antifouling research of a new strategy and materials.

High Strength Titanium with Fibrous Grain for Advanced Bone Regeneration

Pure titanium is widely used in clinical implants, but its bioinert properties (poor strength and mediocre effect on bone healing) limit its use under load-bearing conditions. Modeling on the structure of collagen fibrils and specific nanocrystal plane arrangement of hydroxyapatite in the natural bone, a new type of titanium (Ti) with a highly aligned fibrous-grained (FG) microstructure is constructed. The improved attributes of FG Ti include high strength (≈950 MPa), outstanding affinity to new bone growth, and tight bone-implant contact. The bone-mimicking fibrous grains induce an aligned surface topological structure conducive to forming close contact with osteoblasts and promotes the expression of osteogenic genes. Concurrently, the predominant Ti(0002) crystal plane of FG Ti induces the formation of hydrophilic anatase titanium oxide layers, which accelerate biomineralization. In conclusion, this bioinspired FG Ti not only proves to show mechanical and bone-regenerative improvements but it also provides a new strategy for the future design of metallic biomaterials.

Heat Treatment Optimization for a High Strength Al-Mn-Sc Alloy Fabricated by Selective Laser Melting

A selective laser-melted Al-Mn-Sc alloy with 99.9% relative density has been obtained in this work through systematic process optimization. The as-fabricated specimen had the lowest hardness and strength, but the highest ductility. The aging response has shown that 300 °C/5 h is the peak aged condition, and it had the highest hardness, yield strength, ultimate tensile strength, and elongation at fracture. Such a high strength was attributed to the uniformly distributed nano-sized secondary Al₃Sc precipitates. A further increase in aging temperature to 400 °C resulted in an over-aged condition, which contained a reduced volume fraction of secondary Al₃Sc precipitates and resulted in a reduced strength.

Preparation and Properties of a Lightweight, High-Strength, and Heat-Resistant Rigid Cross-Linked PVC Foam

A rigid poly(vinyl chloride) foam with a cross-linked network structure was prepared by adding 3-glycidoxypropyltriethoxysilane (KH-561) into the universal formulation. The resulting foam had excellent heat resistance because of the increasing degree of cross-linking and number of Si-O bonds with a high heat resistance. The as-prepared foam was verified using Fourier-transform infrared spectroscopy (FTIR), energy-dispersive spectrometry (EDS) and foam residue (gel) analysis, which demonstrated that KH-561 was successfully grafted and cross-linked on the PVC chains. Finally, the effects of different KH-561 and NaHSO₃ additions on the mechanical properties and heat resistance of the foams were studied. The results showed that the mechanical properties of the rigid cross-linked PVC foam were raised after adding a certain amount of KH-561 and NaHSO₃. The residue (gel), decomposition temperature, and chemical stability of the foam significantly improved compared to the universal rigid cross-linked PVC foam (T_g = 72.2 °C). The T_g of the foam could reach 78.1 °C without any mechanical degradation. The results have important engineering application value regarding the preparation of lightweight, high-strength, heat-resistant, and rigid cross-linked PVC foam materials.

Bioinspired Natural Magnolol-Based Adhesive with Strong Adhesion and Antibacterial Properties for Application in Wet and Dry Environments

The development of environmentally friendly, green, and nontoxic adhesives with excellent dry and wet adhesion properties is of great attraction. In nature, barnacles and mussels exhibit strong adhesion by secreting a hydroxyl-rich dopa. Inspired by their adhesion mechanism, a simple biobased MAG-PETMP (MP) adhesive was prepared from magnolol (MAG) and pentaerythritol tetra (3-mercaptopropionate) (PETMP) by a thiol-ene click chemistry reaction. MP as an adhesive exhibits high bond strength with other substrates due to hydrogen bonds formed by the abundant hydroxyl groups at the interface and shows an inherent thermosetting network structure. Since MP has a thermosetting network, it exhibits excellent thermal stability, solvent resistance, and high mechanical strength, which make the adhesive stable in a humid environment. The cross-linking degree of MP can be easily controlled by adjusting the molar ratio of MAG and PETMP. Among the synthesized samples, the elongation at break of the MP 1 formulation is 174.27%, which makes it promising for use as a flexible adhesive. Moreover, the inherent antibacterial properties of MAG enable MP to exhibit antimicrobial properties and antibacterial adhesion to some extent. This work provides a simple biomimetic strategy that could enable the application of MAG for adhesives.

Efficient Coarse-Grained Superplasticity of a Gigapascal Lightweight Refractory Medium Entropy Alloy

Superplastic metals that exhibit exceptional ductility (>300%) are appealing for use in high-quality engineering components with complex shapes. However, the wide application of most superplastic alloys has been constrained due to their poor strength, the relatively long superplastic deformation period, and the complex and high-cost grain refinement processes. Here these issues are addressed by the coarse-grained superplasticity of high-strength lightweight medium entropy alloy (Ti_43.3 V₂₈ Zr₁₄ Nb₁₄ Mo_0.7 , at.%) with a microstructure of ultrafine particles embedded in the body-centered-cubic matrix. The results demonstrate that the alloy reached a high coarse-grained superplasticity greater than ≈440% at a high strain rate of 10^-2 s^-1 at 1173 K and with a gigapascal residual strength. A consecutively triggered deformation mechanism that sequences of dislocation slip, dynamic recrystallization, and grain boundary sliding in such alloy differs from conventional grain-boundary sliding in fine-grained materials. The present results open a pathway for highly efficient superplastic forming, broaden superplastic materials to the high-strength field, and guide the development of new alloys.

Fabrication of a High-Strength, Tough, Swelling-Resistant, Conductive Hydrogel via Ion Cross-Linking, Directional Freeze-Drying, and Rehydration

Conductive hydrogels have been in huge demand in biomedical and wearable electronics. However, the application of traditional conductive hydrogels is largely limited due to their poor mechanical properties. Here, a conductive hydrogel with excellent mechanical strength and swelling resistance properties is prepared by ion cross-linking, directional freeze-drying, and rehydration. First, the acrylamide and acrylic acid are polymerized in the κ-carrageenan solution to form the hydrogel. Then, the obtained hydrogel is cross-linked with Fe³⁺ by soaking in ferric chloride solution. Finally, the ionic cross-linked hydrogels are reinforced by directional freeze-drying and rehydration. The resulting hydrogel has excellent tensile strength (5.67 MPa) and high toughness (7.63 MJ/m³). It is worth noting that the hydrogel also had excellent anti-swelling properties. Its mechanical strength and volume almost show no changes after soaking in deionized water for 40 days. In addition, the hydrogel exhibits good ionic conductivity (0.091 S/m), high sensitivity, and excellent stability when applied as a strain sensor. This work proposes a simple method to fabricate a conductive hydrogel with great mechanical properties and swelling resistance, which displays huge potential in varied fields.

Graphene Interlocking Carbon Nanotubes for High-Strength and High-Conductivity Fibers

Carbon nanotubes (CNTs) are promising building blocks for the fabrication of novel fibers with structural and functional properties. However, the mechanical and electrical performances of carbon nanotube fibers (CNTFs) are far lower than the intrinsic properties of individual CNTs. Exploring methods for the controllable assembly and continuous preparation of high-performance CNTFs is still challenging. Herein, a graphene/chlorosulfonic acid-assisted wet-stretching method is developed to produce highly densified and well-aligned graphene/carbon nanotube fibers (G/CNTFs) with excellent mechanical and electrical performances. Graphene with small size and high quality can bridge the adjacent CNTs to avoid the interfacial slippage under deformation, which facilitates the formation of a robust architecture with abundant conductive pathways. Their ordered structure and enhanced interfacial interactions endow the fibers with both high strength (4.7 GPa) and high electrical conductivity (more than 2 × 10⁶ S/m). G/CNTF-based lightweight wires show good flexibility and knittability, and the high-performance fiber heaters exhibit ultrafast electrothermal response over 1000 °C/s and a low operation voltage of 3 V. This method paves the way for optimizing the microstructures and producing high-strength and high-conductivity CNTFs, which are promising candidates for the high-value fiber-based applications.

Rapid Preparation of Novel Ionic Polymer-Metal Composite for Improving Humidity Sensing Effect

Ionic polymer-metal composites (IPMCs) have attracted attention in recent years due to their integration of actuation and sensing functions. As one of the main sensing functions of IPMCs, humidity sensing has been of consistent interest in wearable health monitors and artificial skin. However, there are still some technical challenges in that classical IPMCs have poor humidity sensing performance due to their dense surface electrode, and IPMCs are damaged easily due to an electrode/membrane mismatch. In this work, through the spraying and electrodepositing process, we developed an efficient method to rapidly prepare a Au-shell-Ag-NW (silver nanowire)-based IPMC with high strength, low surface resistance and excellent humidity sensing performance. Meanwhile, we optimized the preparation method by clarifying the influence of solvent type and electrodepositing time on the performance of the Au-shell-Ag-NW-based IPMC, thus effectively improving the humidity sensing effect and strength of the IPMC. Compared with previous research, the humidity electrical response (~9.6 mV) of the Au-shell-Ag-NW-based IPMC is at least two orders of magnitude higher than that of the classical IPMC (~0.41 mV), which is mainly attributed to the sparse gap structure for promoting the exchange of water molecules in the environment and Nafion membrane, a low surface resistance (~3.4 Ohm/sq) for transmitting the signal, and a seamless connection between the electrode and Nafion membrane for fully collecting the ion charges in the Nafion membrane. Additionally, the Au-shell-Ag-NW-based IPMC could effectively monitor the human breathing process, and the humidity sensing performance did not change after being exposed to the air for 4 weeks, which further indicates that the Au-shell-Ag-NW-based IPMC has good application potential due to its efficient preparation technology, high stability and good reproducibility.

New Class of Multifunctional Bioinspired Microlattice with Excellent Sound Absorption, Damage Tolerance, and High Specific Strength

Although mutually independent, simultaneous sound absorption and superior mechanical properties are often sought after in a material. One main challenge in achieving such a material will be on how to design it. Herein, we propose a bamboo-inspired design strategy to overcome the aforementioned challenges. Building on top of the basic octet-truss design, we introduce a hollow-tube architecture to achieve lightweight property and mechanical robustness and a septum-chamber architecture to introduce acoustic resonant cells. The concept is experimentally verified through samples fabricated using selective laser melting with the Inconel 718 alloy. High sound absorption coefficients (>0.99) with broadband spectra, damage-tolerant behavior, high specific strength (up to 81.2 MPa·cm3/g), and high specific energy absorption of 40.1 J/g have been realized in this design. The sound absorption capability is attributed to Helmholtz resonance through the pore-and-cavity morphology of the structure. Microscopically speaking, dissipation primarily occurs via the viscous frictional flow and thermal boundary layers on the air and microlattice interactions at the narrow pores. The high strength is in turn attributed to the near-membrane state of stress in the plate structures and the excellent strength of the base material. Overall, this work presents a new design concept for developing multifunctional metamaterials.

Photocurable Coatings to Improve the Mechanical Properties of 3D Printable Expanding Foams

Recent developments of highly expandable foaming pre-polymer resins for lithographic additive manufacturing have allowed for the creation of structures larger than a printer's build envelope. To fully utilize the capabilities of this technology, the mechanical properties of these foams must be improved. This manuscript presents one method for strengthening these lightweight polymeric structures via aerosol spray application of a high-strength, low-viscosity photocurable coating. This method is free from the reliance on often complex, large, or bulky on-site equipment ordinarily required by conventional high-strength spray coating. The newly formulated photocurable resin can be applied using an ordinary cordless paint sprayer and cured using sunlight in less than a minute, enabling the rapid production of large, load-bearing structures from a small volume of feedstock and low-cost portable equipment. A comprehensive screening process for resin formulations, detailed mechanical compression and tensile analysis of coated polymer structures, and an applied technical demonstration of the technology are described. The photocurable coating described herein greatly strengthens porous polymeric structures using a method that can be easily implemented.

High Strength and High Toughness Electrospun Multifibrillar Yarns with Highly Aligned Hierarchy Intended as Anisotropic Extracellular Matrix

Electrospun nanofibers can be effectively used as a surrogate for extracellular matrices (ECMs). However, in the context of cellular mechanobiology, their mechanical performances can be enhanced by using nanofibrous materials with a high level of structural organization. Herein, this work develops multifibrillar yarns with superior mechanical performance based on biocompatible polyacrylonitrile (PAN) as surrogate ECM. Nearly perfect aligned nanofibers along with the axis of the multifibrillar yarn are prepared. These highly aligned yarns exhibit high strength, high toughness, good stress relaxation behavior, and are robust enough for technical or medical applications. Further, this work analyzes the influence of the highly aligned-hierarchical topological structure of the material on cell proliferation and cell orientation using cells derived from epithelial and connective tissues. Compared to nonoriented electrospun multifibrillar yarns and flat films, the well-ordered topology in the electrospun PAN multifibrillar yarns triggers an improved proliferation of fibroblasts and epithelial cells. Fibroblasts acquire an elongated morphology analogous to their behavior in the natural ECM. Hence, this heterogeneous multifibrillar material can be used to restore or reproduce the ECM for tissue engineering applications, notably in the skeletal muscle and tendon.

Strength and Durability of Sustainable Self-Consolidating Concrete with High Levels of Supplementary Cementitious Materials

Self-consolidating concrete (SCC) has been used extensively in the construction industry because of its advanced characteristics of a highly flowable mixture and the ability to be consolidated under its own weight. One of the main challenges is the high content of OPC used in the production process. This research focuses on developing sustainable, high-strength self-consolidating concrete (SCC) by incorporating high levels of supplementary cementitious materials. The overarching purpose of this study is to replace OPC partially by up to 71% by using fly ash, GGBS, and microsilica to produce high-strength and durable SCC. Two groups of mixtures were designed to replace OPC. The first group contained 14%, 23.4%, and 32.77% fly ash and 6.4% microsilica. The second group contained 32.77%, 46.81%, and 65.5% GGBS and 6.4% microsilica. The fresh properties were investigated using the slump, V-funnel, L-box, and J-ring tests. The hardened properties were assessed using a compressive strength test, while water permeability, water absorption, and rapid chloride penetration tests were used to evaluate the durability. The innovation of this experimental work was introducing SCC with an unconventional mixture that can achieve highly durable and high-strength concrete. The results showed the feasibility of SCC by incorporating high volumes of fly ash and GGBS without compromising compressive strength and durability.

Rapid Fabrication of Porous Photothermal Hydrogel Coating for Efficient Solar-Driven Water Purification

Cost management and scalable fabrication without sacrificing the purification performance are two critical issues that should be addressed before the practical commercial application of solar-driven evaporators. To address this challenge, we report a porous photothermal hydrogel coating prepared by mixing the raw materials of sawdust (SD), carbon nanotubes (CNTs), and poly(vinyl alcohol) (PVA), which was applied to undergo a blading-drying-rehydration process to prepare the evaporator. In the coating, the crystallized PVA gives the coating a solid skeleton and the sawdust endows the coating with a loose structure to sufficiently enhance the water transportation capacity. As a result, the evaporator coated with the hydrogel coating displays a high water transport rate and efficient evaporation performance along with excellent mechanical properties and stability. Water migrates vertically upward 5 cm within 4 minutes. The compressive stress of the rehydrated hydrogel coating reaches as high as 14.28 MPa under 80% strain. The water evaporation rate of the hydrogel coating-based evaporator reaches 1.833 kg m^-2 h^-1 corresponding to an energy efficiency of 83.29% under 1 sun irradiation. What is more, the hydrogel coating retains its excellent evaporation performance and stability after immersion in acid or alkali solution, ultrasound treatment, and long-time immersion in water. Under outdoor conditions, the water evaporation rate of the hydrogel coating-based evaporator is about 5.69 times higher than that of pure water. This study proposes a rapid, cost-effective, and scalable strategy for preparing a high-performance photothermal hydrogel coating that will find sustainable and practical application in solar-driven water purification.

Bamboo-Inspired Renewable, Lightweight, and Vibration-Damping Laminated Structural Materials for the Floor of a Railroad Car

It is important for the floor of railroad cars to be fitted with vibration- and noise-reducing, fire-resistant, and durable materials. In this study, inspired by a delicate and ordered bamboo gradient structure and excellent multilevel interfaces, we fabricated a laminated composite with characteristics similar to those of the bamboo structure using a simple and effective "top-down" method by laminating fast-growing wood, waste rubber, and bamboo charcoal plastic sheets made of bamboo processing residues. This composite material combines the unique advantages of a laminated structure design and composite interface bionics. The low density (0.73 g/cm³) of the laminated composite results in a specific modulus of 13.03 GPa cm³/g, a vibration damping ratio of 6.61%, and an impact toughness of 14.16 J/cm², which is significantly higher than that of other wood-based composites used for high-speed rail floors, such as Birch plywood (BP). In addition, we also investigated the laminated composite bonding property, fire resistance, and fatigue performance. This biomimetic bamboo-wood composite material has great potential for application in fitting the floor of eco-friendly railway cars.

Biomimetic Gradient Hydrogel Actuators with Ultrafast Thermo-Responsiveness and High Strength

Most current hydrogel actuators suffer from either poor mechanical properties or limited responsiveness. Also, the widely used thermo-responsive poly-(N-isopropylacrylamide) (PNIPAM) homopolymer hydrogels have a slow response rate. Thus, it remains a challenge to fabricate thermo-responsive hydrogel actuators with both excellent mechanical and responsive properties. Herein, ultrafast thermo-responsive VSNPs-P(NIPAM-co-AA) hydrogels containing multivalent vinyl functionalized silica nanoparticles (VSNPs) are fabricated. The ultrafast thermo-responsiveness is due to the mobile polymer chains grafted from the surfaces of the VSNPs, which can facilitate hydrophobic aggregation, inducing the phase transition and generating water transport channels for quick water expulsion. In addition, the copolymerization of NIPAM with acrylic acid (AA) decreases the transition temperature of the thermo-responsive PNIPAM-based hydrogels, contributing to ultrafast thermo-responsive shrinking behavior with a large volume change of as high as 72.5%. Moreover, inspired by nature, intelligent hydrogel actuators with gradient structure can be facilely prepared through self-healing between the ultrafast thermo-responsive VSNPs-P(NIPAM-co-AA) hydrogel layers and high-strength VSNPs-PAA-Fe³⁺ multibond network (MBN) hydrogel layers. The obtained well-integrated gradient hydrogel actuators show ultrafast thermo-responsive performance within only 9 s in 60 °C water, as well as high strength, and can be used for more practical applications as intelligent soft actuators or artificial robots.

High-Strength, Conductive, Antifouling, and Antibacterial Hydrogels for Wearable Strain Sensors

Conductive hydrogels have shown great potential in the field of flexible strain sensors. However, their application is greatly limited due to the poor antifouling and low mechanical strength. Unfortunately, it is still a challenge to improve these two distinct properties simultaneously. Herein, a hydrogel with high strength, good conductivity, and excellent antifouling and antibacterial properties was prepared through the synergistic effect of physical and chemical cross-linking. First, acrylic acid (AA), acrylamide (AM), and 2-methacryloyloxyethyl phosphorylcholine (MPC) monomers were polymerized in the presence of chitosan chains to form the hydrogel. Then, the prepared hydrogel was immersed in a ferric ion solution to further strengthen the hydrogel through ion coordination. The obtained CS-P(AM-MPC-AA_0.2)-Fe_0.1³⁺ hydrogel showed outstanding tensile strength (1.03 MPa), excellent stretchability (1075%), good toughness (7.03 MJ/m³), and fatigue resistance. The CS-P(AM-MPC-AA_0.2)-Fe_0.1³⁺ hydrogel also demonstrated good ion conductivity (0.42 S/m) and excellent antifouling and antibacterial properties. In addition, the strain sensor constructed by the CS-P(AM-MPC-AA_0.2)-Fe_0.1³⁺ hydrogel showed high sensitivity and good stability. This work presented a facile method to construct a zwitterionic hydrogel with high-strength, conductive, antifouling, and antibacterial properties, which suggested a promising gel platform for flexible wearable sensors.

Effect of Curing Temperature on High-Strength Metakaolin-Based Geopolymer Composite (HMGC) with Quartz Powder and Steel Fibers

Geopolymer is a new type of synthesized aluminosilicate material. Compared with ordinary Portland cement, it has better fire resistance and durability, and is more environmentally friendly. In this paper, a high-strength metakaolin-based geopolymer composite (HMGC) has been developed by utilizing quartz powder and steel fibers. The optimization compositions and effect of curing temperatures (from ambient temperature to 90 °C) on the strength performance of the HMGC is studied. The optimized 1-day compressive strength of the HMGC can reach 80 MPa, and the 3-day compressive strength is close to 100 MPa (97.49 MPa). Combined with XRD, FTIR, SEM and MIP characterization, the mechanisms behind the strength development under different curing temperatures are analyzed. The results show that heat curing can significantly speed up the process of geopolymerization and increase the early strength of the HMGC. However, long-term heat curing under high temperature (such as 90 °C, 7 days) would reduce the mechanical strength of the HMGC. Prolonged high-temperature curing increases the pores and micro-defects in the gel phase of the HMGC, which may be attributed to chemical shrinkage. Thus, the curing temperature should be carefully controlled to make a HMGC with better performance.

Scalable Nano Building Blocks of Waterborne Polyurethane and Nanocellulose for Tough and Strong Bioinspired Nanocomposites by a Self-Healing and Shape-Retaining Strategy

Nature has given us significant inspiration to reproduce bioinspired materials with high strength and toughness. The fabrication of well-defined three-dimensional (3D) hierarchically structured nanocomposite materials from nano- to the macroscale using simple, green, and scalable methods is still a big challenge. Here, we report a successful attempt at the fabrication of multidimensional bioinspired nanocomposites (fiber, films, plates, hollow tubes, chair models, etc.) with high strength and toughness through self-healing and shape-retaining methods using waterborne polyurethane (WPU) and nanocellulose. In our method, the prepared TEMPO oxide cellulose nanofiber (TOCNF)-WPU hybrid films show excellent moisture-induced self-healing and shape-retaining abilities, which can be used to fabricate all sorts of 3D bioinspired nanocomposites with internal aligned and hierarchical architectures just using water as media. The tensile and flexural strength of the self-assembled plate can reach 186.8 and 193.2 MPa, respectively, and it also has a high toughness of 11.6 MJ m^-3. Because of this bottom-up self-assembly strategy, every multidimensional structure we processed has high strength and toughness. This achievement would provide a promising future to realize a large-scale and reliable production of various sorts of bioinspired multidimensional materials with high strength and toughness in a sustainable manner.

Biomimetic Swallow Nest Structure: A Lightweight and High-Strength Thermal Insulation Material

A common method for reducing carbon emissions and the load-bearing pressure of buildings, and while also achieving improved energy conservation is to prepare porous magnesium-based lightweight composites to reduce waste and environmental hazards. However, due to internal stress, the pores of traditional lightweight composites crack easily and collapse, resulting in composites that are brittle with poor water resistance. These materials cannot achieve both low density and high strength, which limits their application in advanced functional materials. Thus, learned from nature, inspired by swallow's nest, a solution has been proposed, which is a simple and fast chemical arrangement and assembly method. Using bamboo scraps as the supporting framework and methylcellulose (MC) molecular chains as the templates, 5-phase crystals are grown and arranged on the MC. These crystals are arranged on the bamboo scraps by chemical means with MC acting as a bridge. At the same time, using the high viscosity and flexibility of the vinyl acetate/ethylene (VAE) copolymer emulsion and the formation of magnesium acetate chelate from VAE and hydration products, crystals and bamboo scraps can be assembled. Through these organic-inorganic copolymers, an intercalated and integrated biomimetic swallow nest structure is formed. The biomimetic swallow nest structure composites (BSNSC) imitated the formation process of a natural swallow nest. It is a lightweight material with a thick wall, low connectivity rate, and regular shape. Its density is 0.42 g/cm³, which is still in the density class of ultralight inorganic foam materials, and its compressive strength reaches 6.5 MPa, three times that of ordinary composites. The structure has a strength-to-weight ratio 3.5 times that of ordinary composites and a thermal conductivity much lower than of other thermal insulation materials. In the future, this type of lightweight composites with high strength, high heat insulation, and low density not only functions as a good energy-saving material for buildings but also a good thermal insulation material in the aerospace field.

Bamboo-Based Biomaterials for Cell Transportation and Bone Integration

The construction of hierarchical porous structure in biomaterials is of great significance for improving nutrient transport and biological performance. However, it is still challenging to design porous bone substitutes with high strength and biological properties, which limits their clinical applications in load-bearing bone regeneration. Herein, based on hierarchical porous structure of renewable bamboo, the mineralized calcium phosphate/bamboo composite scaffolds with high strength and excellent transport performance are successfully prepared in combination of biotemplated approach and biomimetic mineralization. The mineralized biomaterials have simultaneously achieved high mechanical strength and low modulus, similar to those of cortical bone. Furthermore, the mineralized biomaterials exhibit good liquid transport capacity and can transport cells along anti-gravity direction. Based on density functional theory (DFT) calculations, the mineralized calcium phosphate reveals the optimal H₂ O adsorption energy (-0.651 eV) and low diffusion energy barrier (0.743 eV), which is conducive to enhance hydrophilicity and liquid transport performance. Moreover, owing to the synergistic effect of the porous structure of biotemplate and bioactive mineralized components, the mineralized biomaterials possess enhanced bone integration and osteoconduction properties. The present study shed light on deeper understanding of mineralized biosourced materials, offering a strategy of combining green chemistry with tissue engineering to prepare eco-friendly biomaterials.

Self-Healable, Strong, and Tough Polyurethane Elastomer Enabled by Carbamate-Containing Chain Extenders Derived from Ethyl Carbonate

Commercial diol chain extenders generally could only form two urethane bonds, while abundant hydrogen bonds were required to construct self-healing thermoplastic polyurethane elastomers (TPU). Herein, two diol chain extenders bis(2-hydroxyethyl) (1,3-pheny-lene-bis-(methylene)) dicarbamate (BDM) and bis(2-hydroxyethyl) (methylenebis(cyclohexane-4,1-diy-l)) dicarbamate (BDH), containing two carbamate groups were successfully synthesized through the ring-opening reaction of ethylene carbonate (EC) with 1,3-benzenedimetha-namine (MX-DA) and 4, 4′-diaminodicyclohexylmethane (HMDA). The two chain extenders were applied to successfully achieve both high strength and high self-healing ability. The BDM-1.7 and BDH-1.7 elastomers had high comprehensive self-healing efficiency (100%, 95%) after heated treatment at 60 °C, and exhibited exceptional comprehensive mechanical performances in tensile strength (20.6 ± 1.3 MPa, 37.1 ± 1.7 MPa), toughness (83.5 ± 2.0 MJ/m³, 118.8 ± 5.1 MJ/m³), puncture resistance (196.0 mJ, 626.0 mJ), and adhesion (4.6 MPa, 4.8 MPa). The peculiar mechanical and self-healing properties of TPUs originated from the coexisting short and long hard segments, strain-induced crystallization (SIC). The two elastomers with excellent properties could be applied to engineering-grade fields such as commercial sealants, adhesives, and so on.

Ultrahigh-Strength Porous Ceramic Composites via a Simple Directional Solidification Process

Porous ceramics possess great application potential in various fields. However, the contradiction between their pores and their strength have significantly hampered their applications. In this study, we present a simple directional solidification process that relies on its in situ pore forming mechanism to fabricate Al₂O₃/Y₃Al₅O₁₂/ZrO₂ porous eutectic ceramic composites with a highly dense and nanostructured eutectic skeleton matrix and a lotus-type porous structure. The flexural strength of this porous ceramic composite with a porosity of 34% is 497 MPa at ambient temperature, which is a new record of the strength of all current porous ceramics. This strength can remain at 324 MPa when the temperature increases up to 1773 K because of its refined lamellar structure and strong bonding interface. We demonstrate an interesting application of the directional solidification in efficiently preparing the ultrahigh-strength porous ceramic with high purity. The findings will open a window to the strength of porous ceramics.

Interphase in Polymer Nanocomposites

The lightweight and high-strength functional nanocomposites are important in many practical applications. Natural biomaterials with excellent mechanical properties provide inspiration for improving the performance of composite materials. Previous studies have usually focused on the bionic design of the material's microstructure, sometimes overlooking the importance of the interphase in the nanocomposite system. In this Perspective, we will focus on the construction and control of the interphase in confined space and the connection between the interphase and the macroscopic properties of the materials. We shall survey the current understanding of the critical size of the interphase and discuss the general rules of interphase formation. We hope to raise awareness of the interphase concept and encourage more experimental and simulation studies on this subject, with the aim of an optimal design and controllable preparation of polymer nanocomposite materials.

Unprecedented Strength Polysiloxane-Based Polyurethane for 3D Printing and Shape Memory

Thermoplastic polysiloxane-based polyurethane (Si-TPU) has been attracting a great deal of attention because of the dual advantages of polysiloxane and polyurethane. However, the strength of Si-TPU with a traditional structure is low, and improvement is urgently needed for diverse applications. Herein, we design a polysiloxane-based soft segment (SS) with two urethane groups at the end of the polysiloxane chain, and then we prepare a series of Si-TPUs through a designed SS, isophorone diisocyanate and 1,4-butanediol. Such structural design improves the polarity of the SS and endows more regular hydrogen bonds to the polymer molecular chain. As a result, the prepared Si-TPUs exhibit a good microphase separation structure, unprecedentedly high strength, repeatable processing, noncytotoxicity, shape memory properties, and three-dimensional printing capabilities. Moreover, a maximum tensile strength of Si-TPUs can reach 20.3 MPa, exceeding that of other existing Si-based polymer materials. Si-TPUs show great potential for biomedical applications.

High-Strength Regenerated Cellulose Fiber Reinforced with Cellulose Nanofibril and Nanosilica

In this study, a novel type of high-strength regenerated cellulose composite fiber reinforced with cellulose nanofibrils (CNFs) and nanosilica (nano-SiO₂) was prepared. Adding 1% CNF and 1% nano-SiO₂ to pulp/AMIMCl improved the tensile strength of the composite cellulose by 47.46%. The surface of the regenerated fiber exhibited a scaly structure with pores, which could be reduced by adding CNF and nano-SiO₂, resulting in the enhancement of physical strength of regenerated fibers. The cellulose/AMIMCl mixture with or without the addition of nanomaterials performed as shear thinning fluids, also known as "pseudoplastic" fluids. Increasing the temperature lowered the viscosity. The yield stress and viscosity sequences were as follows: RCF-CNF² > RCF-CNF²-SiO₂² > RCF-SiO₂² > RCF > RCF-CNF¹-SiO₂¹. Under the same oscillation frequency, G' and G" decreased with the increase of temperature, which indicated a reduction in viscoelasticity. A preferred cellulose/AMIMCl mixture was obtained with the addition of 1% CNF and 1% nano-SiO₂, by which the viscosity and shear stress of the adhesive were significantly reduced at 80 °C.

Facile Preparation of High Strength Silica Aerogel Composites via a Water Solvent System and Ambient Pressure Drying without Surface Modification or Solvent Replacement

To further reduce the manufacturing cost and improve safety, silica aerogel composites (SAC) with low density and low thermal conductivity synthesized via ambient pressure drying (APD) technology have gradually become one of the most focused research areas. As a solvent, ethanol is flammable and needs to be replaced by other low surface tension solvents, which is dangerous and time-consuming. Therefore, the key steps of solvent replacement and surface modification in the APD process need to be simplified. Here, we demonstrate a facile strategy for preparing high strength mullite fiber reinforced SAC, which is synthesized by APD using water as a solvent, rather than using surface modification or solvent replacement. The effects of the fiber density on the physical properties, mechanical properties, and thermal conductivities of SAC are discussed in detail. The results show that when the fiber density of SAC is 0.24 g/cm³, the thermal conductivity at 1100 °C is 0.127 W/m·K, and the compressive strength at 10% strain is 1.348 MPa. Because of the simple synthesis process and excellent thermal-mechanical performance, the SAC is expected to be used as an efficient and economical insulation material.

High strength pure chitosan hydrogels via double crosslinking strategy

Chitosan (CS) hydrogels have been widely used throughout basic tissue engineering and regenerative medicine research and it is very desirable to develop advanced CS materials with superior mechanical and topographical properties for more extensive applications. Herein, we present the design of a double crosslinking pure CS hydrogel material via the synergic effect of the chemical covalent network, hydrophobic interactions, enhanced intermolecular hydrogen bonding and the formation of the CS crystallite. The resultant pure CS hydrogel possesses increases in strength and toughness by two orders of magnitude (fracture energy ∼7.733 J m^-2; maximal compression stress ∼10.81 MPa, elastic modulus ∼1.33 MPa). We utilize¹H NMR and FT-IR to prove the success of chemical modification. The results of Raman spectra and WXRD have proved the existence of physical interaction between CS hydrogels and microcrystals, thus explaining the enhancement mechanism of mechanical strength of CS hydrogel. The live and death results also show that MSCs can grow well on CS hydrogels, and the results of CCK-8 indicate low cytotoxicity of CS hydrogels. This CS hydrogel shows great potential applications in tissue engineering and regenerative medicine.

Facile Preparation of Continuous and Porous Polyimide Aerogel Fibers for Multifunctional Applications

High-performance aerogel fibers with high porosity, ultralow density and thermal conductivity, and good flexibility are attractive candidates for the next generation of effective thermal insulation, efficient personal thermal management, and other functional applications. However, most previously reported aerogel fibers suffered from either limited working temperatures, weak mechanical properties, or complex manufacturing processes. In the present work, a facile wet-spinning technique combined with freeze-drying was developed to fabricate strong polyimide aerogel fibers (PAFs) based on organo-soluble polyimide. Attributed to the unique "porous core-dense sheath" morphology, the PAFs exhibited excellent mechanical properties with an optimum tensile strength of 265 MPa and an initial modulus of 7.9 GPa at an ultimate elongation of 65%, representing the highest value for aerogel fibers reported so far. Moreover, the PAFs possess high porosity (>80%) and high specific surface area (464 m² g^-1), which render the woven PAF fabrics with excellent thermal insulation properties within a wide temperature range (-190 to 320 °C) and potential applications for thermal insulation under harsh environments. Additionally, a series of functionalized aerogel fibers or their fabrics based on PAFs, including phase-change fabrics with a thermoregulation function and electromagnetic shielding (EMI) textiles with a high EMI SE value, have been successfully fabricated for expanding their potential applications. Overall, this novel aerogel fiber sheds light on a promising direction for developing the next generation of high-performance thermal insulation and multifunctional fibers and textiles.

Composite Aramid Membranes with High Strength and pH-Response

The pH-responsive membrane is a new wastewater treatment technology developed in recent years. In this paper, a novel film with intelligent pH-responsiveness was first prepared by blending functional gates comprised of hydrolyzed aramid nanofibers (HANFs) into aramid nanofiber (ANF) membranes via a vacuum filtration method. Those as-prepared membranes exhibited dual pH-responsive characteristics, which were featured with a negative pH-responsiveness in an acidic environment and a positive pH-responsiveness in basic media. These dual pH-responsive membranes also exhibited a high tensile strength which could still reach 55.74 MPa (even when the HANFs content was as high as 50 wt%), a high decomposition temperature at ~363 °C, and good solvent resistance. The membranes described herein may be promising candidates for a myriad of applications, such as the controlled release of drugs, sensors, sewage treatment, etc.

Enhanced Water Resistance of Recycled Newspaper/High Density Polyethylene Composite Laminates via Hydrophobic Modification of Newspaper Laminas

A high strength recycled newspaper (NP)/high density polyethylene (HDPE) laminated composite was developed using NP laminas as reinforcement and HDPE film as matrix. Herein, NP fiber was modified with stearic acid (SA) to enhance the water resistance of the NP laminas and NP/HDPE composite. The effects of heat treatment and SA concentration on the water resistance and tensile property of NP and composite samples were investigated. The chemical structure of the NP was characterized with X-ray diffractometer, X-ray photoelectron spectroscopy and attenuated total reflectance Fourier transform infrared spectra techniques. The surface and microstructure of the NP sheets were observed by scanning electron microscopy. An expected high-water resistance of NP sheets was achieved due to a chemical bonding that low surface energy SA were grafted onto the modified NP fibers. Results showed that the hydrophobicity of NP increased with increasing the stearic acid concentration. The water resistance of the composite laminates was depended on the hydrophobicity of the NP sheets. The lowest value of 2 h water absorption rate (3.3% ± 0.3%) and thickness swelling rate (2.2% ± 0.4%) of composite were obtained when the SA concentration was 0.15 M. In addition, the introduction of SA can not only enhance the water resistance of the composite laminates, but also reduce the loss of tensile strength in wet conditions, which shows potential in outdoor applications.

Recent Progress in 3D Printing of Elastic and High-Strength Hydrogels for the Treatment of Osteochondral and Cartilage Diseases

Despite considerable progress for the regenerative medicine, repair of full-thickness articular cartilage defects and osteochondral interface remains challenging. This low efficiency is largely due to the difficulties in recapitulating the stratified zonal architecture of articular cartilage and engineering complex gradients for bone-soft tissue interface. This has led to increased interest in three-dimensional (3D) printing technologies in the field of musculoskeletal tissue engineering. Printable and biocompatible hydrogels are attractive materials for 3D printing applications because they not only own high tunability and complexity, but also offer favorable biomimetic environments for live cells, such as porous structure, high water content, and bioactive molecule incorporation. However, conventional hydrogels are usually mechanically weak and brittle, which cannot reach the mechanical requirements for repair of articular cartilage defects and osteochondral interface. Therefore, the development of elastic and high-strength hydrogels for 3D printing in the repairment of cartilage defects and osteochondral interface is crucial. In this review, we summarized the recent progress in elastic and high-strength hydrogels for 3D printing and categorized them into six groups, namely ion bonds interactions, nanocomposites integrated in hydrogels, supramolecular guest-host interactions, hydrogen bonds interactions, dynamic covalent bonds interactions, and hydrophobic interactions. These 3D printed elastic and high-strength hydrogels may provide new insights for the treatment of osteochondral and cartilage diseases.

Towards Ultrahigh Performance Concrete Produced with Aluminum Oxide Nanofibers and Reduced Quantities of Silica Fume

Ultrahigh performance concrete (UHPC), which is characterized by dense microstructure and strain hardening behavior, provides exceptional durability and a new level of structural response to modern structures. However, the design of the UHPC matrix often requires the use of high quantities of supplementary cementitious materials, such as silica fume, which can significantly increase the cost and elevate the production expenses associated with silica fume handling. This paper demonstrates that a fiber-reinforced composite with properties similar to conventional UHPC can be realized with very low quantities of silica fume, such as 1% by mass of cementitious materials. The proposed UHPC is based on reference Type I cement or Type V Portland cement with very low C₃A (<1%) that also complies with Class H oil well cement specification, silica fume, small quantities of Al₂O₃ nanofibers, and high-density polyethylene or polyvinyl alcohol macro fibers. Previous research has demonstrated that nanofibers act as a seeding agent to promote the formation of compact and nanoreinforced calcium silicate hydrate (C-S-H) clusters within the interparticle and nanofiber spaces, providing a nanoreinforcing effect. This approach produces a denser and stronger matrix. This research expands upon this principle by adding synthetic fibers to ultrahigh strength cement-based composites to form a material with properties approaching that of UHPC. It is indicated that the developed material provides improved strain hardening and compressive strength at the level of 160 MPa.

Nanoglass-Nanocrystal Composite-a Novel Material Class for Enhanced Strength-Plasticity Synergy

The properties of a material can be engineered by manipulating its atomic and chemical architecture. Nanoglasses which have been recently invented and comprise nanosized glassy particles separated by amorphous interfaces, have shown promising properties. A potential way to exploit the structural benefits of nanoglasses and of nanocrystalline materials is to optimize the composition to obtain crystals forming within the glassy particles. Here, a metastable Fe-10 at% Sc nanoglass is synthesized. A complex hierarchical microstructure is evidenced experimentally at the atomic scale. This bulk material comprises grains of a Fe₉₀ Sc₁₀ amorphous matrix separated by an amorphous interfacial network enriched and likely stabilized by hydrogen, and property-enhancing pure-Fe nanocrystals self-assembled within the matrix. This composite structure leads a yield strength above 2.5 GPa with an exceptional quasi-homogeneous plastic flow of more than 60% in compression. This work opens new pathways to design materials with even superior properties.