纳米力学材料，俞书弘院士的

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Owing to their outstanding comprehensive performance, polyimide (PI) composite films are widely used on the external surfaces of spacecraft to protect them from the adverse conditions of low Earth orbit (LEO). However, current PI composite films have inadequate mechanical properties and atomic oxygen (AO) resistance. Herein, this work fabricates a new PI‐based nanocomposite film with greatly enhanced mechanical properties and AO resistance by integrating mica nanosheets with PI into a unique double‐layer nacre‐inspired structure with a much higher density of mica nanosheets in the top layer. In addition, the unique microstructure and the intrinsic properties of mica also impart the nanocomposite film with favorable ultraviolet and high‐temperature resistance. The comprehensive performance of this material is superior to those of pure PI, single‐layer PI‐mica, and previously reported PI‐based composite films. Thus, the double‐layer nanocomposite film displays great potential as an aerospace material for use in LEO.

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Inspired by the hierarchically ordered "brick and mortar" (BM) architecture of natural nacre, in this study a rational assembly of boron nitride (BN) nanosheets was introduced into a mixture of trimethylolpropane triglycidyl ether (TTE) and soy protein isolate (SPI), and a strong and multifunctional SPI-based nanocomposite film with multinetwork structure was synthesized. At a low BN loading (<0.5%), the resulting multifunctional film was flexible, antiultraviolet, and nearly transparent and also displayed good thermal diffusion ability and exhibited an excellent combination of high tensile strength (36.4 MPa) and thermal conductivity (TC, 2.40 W·m-1·K-1), surpassing the performances of various types of petroleum-based plastics (displayed a tensile strength ranging from 1.9 to 21 MPa and TC ranging from 0.55-2.13 W·m-1·K-1), including nine different types of materials currently utilized for mobile phone shells, suggesting its vast potential in practical applications.

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Nacre, a natural nanocomposite with a brick-and-mortar structure existing in the inner layer of mollusk shells, has been shown to optimize strength and toughness along the laminae (in-plane) direction. However, such natural materials more often experience impact load in the direction perpendicular to the layers (i.e., out-of-plane direction) from predators. The dynamic responses and deformation mechanisms of layered structures under impact load in the out-of-plane direction have been much less analyzed. This study investigates the dynamic mechanical behaviors of nacre-inspired layered nanocomposite films using a model system that comprises alternating multi-layer graphene (MLG) and polymethyl methacrylate (PMMA) phases. With a validated coarse-grained molecular dynamics simulation approach, we systematically study the mechanical properties and impact resistance of the MLG-PMMA nanocomposite films with different internal nanostructures, which are characterized by the layer thickness and number of repetitions while keeping the total volume constant. We find that as the layer thickness decreases, the effective modulus of the polymer phase confined by the adjacent MLG phases increases. Using ballistic impact simulations to explore the dynamic responses of nanocomposite films in the out-of-plane direction, we find that the impact resistance and dynamic failure mechanisms of the films depend on the internal nanostructures. Specifically, when each layer is relatively thick, the nanocomposite is more prone to spalling-like failure induced by compressive stress waves from the projectile impact. Whereas, when there are more repetitions, and each layer becomes relatively thin, a high-velocity projectile sequentially penetrates the nanocomposite film. In the low projectile velocity regime, the film develops crazing-like deformation zones in PMMA phases. We also show that the position of the soft PMMA phase relative to the stiff graphene sheets plays a significant role in the ballistic impact performance of the investigated films. Our study provides insights into the effect of nanostructures on the dynamic mechanical behaviors of layered nanocomposites, which can lead to effective design strategies for impact-resistant films.

Summary Graphene-based substrates are emerging as a promising functional platform for biomedical applications. Although dispersible graphene sheets have been demonstrated to be biodegradable, their assembled macroscopic architectures are biopersistent because of strong π-π interactions. In this study, we developed a nacre-inspired graphene-silk nanocomposite film by vacuum filtration with a subsequent green chemical reduction procedure. The “brick-and-mortar” architecture not only ensures the mechanical and electrical properties of the film but also endows it with disintegrable and bioresorbable properties following rat subcutaneous implantation. Furthermore, covalent cross-linking leads to the formation of graphene with decreased interlayer spacing, which effectively prolongs the residence time in vivo. We found that enzymatic treatment created microcracks on the film surface and that the foreign-body reaction was involved in the deformation, delamination, disintegration, and phagocytosis processes of the nanocomposite films. This bioinspired strategy paves the way for the development of high-performance graphene-based macroscopic biomaterials with tunable bioresorbability.

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The detrimental effects of marine biofouling and metal corrosion on the functionality and maintenance of marine equipment are profound. Traditional protective coatings exhibit limited efficacy and are inadequate in addressing the evolving demands of the marine industry today. Inspired by the robust adhesion mechanisms employed by mussels and the distinctive "brick-and-mortar" architecture of their shells, a novel bioinspired nanocomposite coating boasting antifouling and anticorrosion capabilities was fabricated by integrating tannic acid (TA)/adipohydrazide (ADH)-modified graphene oxide (GO) (TDGO) as "brick" into an organosilane-modified epoxy (EPUR) serving as "mortar". The high-density hydrogen bonds formed at the TDGO/EPUR interface resulted in robust interfacial interactions to acquire composites with inverse nacre structures, while the intermolecular interactions significantly enhanced the strength and toughness of the composite material. The fouling release characteristics of low-surface-energy surfaces, combined with the antibacterial properties of TA, yield exceptional physicochemical antifouling synergy, demonstrating formidable resistance against biofoulings. The volume and labyrinth effect of TDGO and the coordination effect of TA effectively enhanced the anticorrosion performance of the coating. Additionally, the coating exhibits remarkable mechanical properties and substrate adhesion, satisfactory thermal stability, outstanding stability in acid and alkaline solutions, and exceptional self-healing capability under thermal stimulation, indicating substantial potential for the creation of bioinspired antifouling and anticorrosion coatings for marine applications.

Layered assemblies of polymers and graphene derivatives employ nacre’s tested strategy of intercalating soft organic layers with hard crystalline domains. These layered systems commonly display elastic properties that exceed simple mixture rule predictions, but the molecular origins of this phenomenon are not well understood. Here we address this issue by quantifying the elastic behavior of nanoconfined polymer layers on a model layered graphene-polymer nanocomposite. Using a novel, validated coarse-grained molecular dynamics simulation approach, here we clearly show that the elastic properties of layered nanocomposites cannot be described by volume fraction considerations alone and depend strongly on both interfacial energy and nanostructure. We quantify the relative importance of polymer nanoconfinement and interfacial energy on polymer structure and elasticity and illustrate the validity of our model for two polymers with different intrinsic elastic properties. Our theoretical model culminates in phase diagrams that accurately predict the elastic response of nacre-inspired nanocomposites by accounting for all material design parameters. Our findings provide widely applicable prescriptive guidelines for utilizing nanoconfinement to improve the mechanical properties of layer-by-layer nanocomposites. Our findings also serve to explain why the elastic properties of organic layers in nacre exhibit multifold differences from the native and extracted states.

The fabrication of mechanically robust multifunctional nanocomposite (NC) films using simple but effective strategies is a long-term challenge. Inspired by natural nacre, we designed and fabricated high-performance nacre-like NC films (Na-MTM/HBP) through the self-assembly of the hyperbranched poly(amido amine) (HBP) and montmorillonite (Na-MTM) using a vacuum filtration approach. The optimal Na-MTM/HBP NC film shows excellent mechanical strength (106 MPa), which can be attributed to the formation of numerous hydrogen bonds and the electrostatic interactions between hyperbranched HBP and Na-MTM nanosheets. Such films also exhibit excellent gas barrier and fire–fire-retardant owing to the high aspect ratio of the Na-MTM nanosheets. In this work, a class of high-performance NC films exhibiting good mechanical, gas barrier, and flame retardancy properties have been developed. These NC films have great potential in packing or coating materials.

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Nanoscale graphene oxide-lipid composites have shown wide applications in the field of biosensing and nanosafety. Macroscopic free-standing membranes of this combination potentially offer excellent mechanical properties which can be attributed to the inherent strength of graphene oxide(GO). Previous experimental studies have mostly dealt with monolayer or bilayer interactions of lipids with graphene and graphene oxide surfaces. In our study, we report for the first time, a simple and scalable fabrication method where Small Unilamellar Vesicles (SUVs) of 1,2-dioleoyl-sn-glycero-3-phosphocholine(DOPC) combine with graphene oxide to produce stable nanocomposites via self-assembly. Scanning Electron Microscopy (SEM) images of the composite revealed layer-by-layer structures, reconfirmed by X-Ray Diffraction(XRD) results which show a proportional increase in the interlayer separation with an increasing ratio of lipid in graphene oxide. The nanocomposite thus fabricated mimics naturally occurring nacre shell structures where graphene oxide substitutes the strong aragonite layers, and the intermediate lipid layers provide the necessary elasticity pertaining to protein chitin in nacre. The addition of lipids to graphene-based nanocomposites also serves as a biodegradable alternative to using polymers as a popular reinforcement agent. The ease of fabrication method reported facilitates the production of stable GO-Lipid membranes in variable scales and geometries.

In this work, a facile biomimetic method was proposed to enhance the interfacial adhesion between layered clay and polymer matrix inspired by strong adhesion of mussel adhesive proteins. Montmorillonite (MMT) was coated with a thin layer of polydopamine (PDA) through self-polymerization of dopamine (DA) and subsequently assembled with corn starch (CS) to generate CS/MMT-DA nanocomposite. FTIR, XPS, SEM and XRD results demonstrated that PDA coating benefited not only the intercalation and dispersion of the modified MMT (MMT-DA) in the polymer matrix but also the strong interfacial adhesion between filler and matrix. The tensile strength of CS/MMT-DA nanocomposites was largely enhanced by increasing the amount of DA or polymerization time. This work can largely expand the application of MMT and provide a new idea for preparing high performance starch nanocomposites.

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This study was inspired by the unique multi-scale and multi-level ‘brick-and-mortar’ (B&M) structure of nacre layers. We prepared the B&M, environmentally-friendly graphene oxide-carrageenan (GO-Car) nanocomposite films using the following steps. A natural polyhydroxy polymer, carrageenan, was absorbed on the surface of monolayer GO nanosheets through hydrogen-bond interactions. Following this, a GO-Car hybridized film was produced through a natural drying process. We conducted structural characterization in addition to analyzing mechanical properties and cytotoxicity of the films. Scanning electron microscope (SEM) and X-ray diffraction (XRD) analyses showed that the nanocomposite films had a similar morphology and structure to nacre. Furthermore, the results from Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and Thermogravimetric (TG/DTG) were used to explain the GO-Car interaction. Analysis from static mechanical testers showed that GO-Car had enhanced Young’s modulus, maximum tensile strength and breaking elongation compared to pure GO. The GO-Car nanocomposite films, containing 5% wt. of Car, was able to reach a tensile strength of 117 MPa. The biocompatibility was demonstrated using a RAW264.7 cell test, with no significant alteration found in cellular morphology and cytotoxicity. The preparation process for GO-Car films is simple and requires little time, with GO-Car films also having favorable biocompatibility and mechanical properties. These advantages make GO-Car nanocomposite films promising materials in replacing traditional petroleum-based plastics and tissue engineering-oriented support materials.

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Structural materials serving in extreme environments, such as offshore and desert, face persistent threats from impact damage and corrosion. While polyurethane (PU) coatings are widely used for protection (e.g., on wind turbine blades), their effectiveness is often limited by insufficient hardness, impact resistance, and long‐term corrosion performance. Inspired by the damage‐tolerant architectures of natural sponge and nacre, a bioinspired lamellar coating via alternating spray deposition and UV curing of rigid alumina/PU nanocomposite layers and soft polyurethane acrylate layers is developed. This approach enables conformal, large‐area application on complex geometries while featuring rapid preparation and overcoming scalability barriers. Compared to conventional PU coatings, the bioinspired film exhibits a 137% increase in flexural modulus, a 119% enhancement in penetration energy absorption, and a 17% reduction in penetration displacement under dynamic impact. Crucially, it maintains robust corrosion resistance post‐impact—microcracks are contained within individual layers, preventing catastrophic failure and electrolyte ingress, much like nacre's protective function in marine settings. Multiscale characterization and finite element analysis confirm that coordinated crack deflection and microcrack networks synergistically mitigate impact stress and preserve electrochemical barrier integrity. This spray‐based, UV‐cured platform offers a scalable route to multifunctional bioinspired coatings for demanding engineering applications.

Inspired by the "brick-and-mortar" structure and remarkable mechanical performance of nacre, many efforts have been devoted to fabricating nacre-mimicking materials. Herein, a class of graphene oxide (GO) based artificial nacre material with quadruple hydrogen-bonding interactions was fabricated by functionalization of polydopamine-capped graphene oxide (PDG) with 2-ureido-4[1 H]-pyrimidinone (UPy) self-complementary quadruple hydrogen-bonding units followed by supramolecular assembly process. The artificial nacre displays a strict "brick-and-mortar" structure, with PDG nanosheets as the brick and UPy units as the mortar. The resultant nanocomposite shows an excellent balance of strength and toughness. Because of the strong strengthening via quadruple hydrogen bonding, the tensile strength and toughness can reach 325.6 ± 17.8 MPa and 11.1 ± 1.3 MJ m-3, respectively, thus exceeding natural nacre, and reaching 3.6 and 10 times that of a pure GO artificial nacre. Furthermore, after further H2O treatment, the resulting H2O-treated PDG-UPy actuator displays significant bending actuations when driven by heat. This work provides a pathway for the development of artificial nacre for their potential applications in energy conversion, temperature sensor, and thermo-driven actuator.

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Graphene oxide (GO) has recently been highlighted as a promising multipurpose two-dimensional material. However, free-standing graphene oxide films suffer from poor strength and flexibility, which limits scaling-up of production and lifetime structural robustness in applications. Inspired by the relationship between the organic and inorganic components of the hierarchical structure of nacre found in mollusk shells, we have fabricated self-assembled, layered graphene-based composite films. The organic phase of our composite is produced via environmentally friendly and economical methods based on bacterial production of γ-poly(glutamic acid) (PGA). Composite films made of GO, PGA, and divalent cations (Ca2+) were prepared through a slow solvent evaporation method at ambient temperature, resulting in a nacre-like layered structure. These biobased nanocomposite films showed impressive mechanical properties, which resulted from a synergistic combination of hydrogen bonding with the bacterially produced PGA and ionic bonding with calcium ions (Ca2+). The GO/PGA/Ca2+ composite films possessed a high strength of 150 ± 51.9 MPa and a high Young’s modulus of 21.4 ± 8.7 GPa, which represents an increase of 120% and over 70% with respect to pure GO films. We provide rational design strategies for the production of graphene-based films with improved mechanical performance, which can be applied in filtration purification of wastewater in the paper, food, beverage, pigment, and pharmaceuticals industries, as well as for manufacturing of functional membranes and surface coatings.

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Mollusk nacre is a prototypical biological inorganic–organic composite that combines high toughness, stiffness, and strength by its brick‐and‐mortar microstructure, which has inspired several synthetic mimics. Its remarkable fracture toughness relies on inelastic deformations at the process zone at the crack tip that dissolve stress concentrations and stop cracks. The micrometer‐scale structure allows resolving the size and shape of the process zone to understand the fracture processes. However, for better scalability, nacre‐mimetic nanocomposites with aligned inorganic or graphene nanosheets are extensively pursued, to avoid the packing problems of mesoscale sheets like in nacre or slow in situ biomineralization. This calls for novel methods to explore the process zone of biomimetic nanocomposites. Here the fracture of nacre and nacre‐inspired clay/polymer nanocomposite is explored using laser speckle imaging that reveals the process zone even in absence of changes in optical scattering. To demonstrate the diagnostic value, compared to nacre, the nacre‐inspired nanocomposite develops a process zone more abruptly with macroscopic crack deflection shown by a flattened process zone. In situ scanning electron microscopy suggests similar toughening mechanisms in nanocomposite and nacre. These new insights guide the design of nacre‐inspired nanocomposites toward better mechanical properties to reach the level of synergy of their biological model.

In this study, inspired by nacre-like structural natural shells, novel three-dimensional (3D) nanocomposites based on natural nanoplatelets of montmorillonite (MMT) and polysaccharide of chitosan (CS) were prepared with solution intercalation and self-assembly process. The CS-intercalated-MMT nanoplatelets units acted as "bricks" and CS molecules acted as "mortar", arranging in fairly well-ordered layered structure. With addition of glutaraldehyde (GA) and Pd2+ cations, synergistic toughening and strengthening effects of covalent and ionic bonds could be achieved. The best mechanical properties of the prepared 3D nanocomposites were observed as 5.6 KJ/m2 (impact strength), 3.3 GPa (flexural modulus), and 65.8 MPa (flexural strength), respectively, which showed higher toughness but lower flexural properties than natural pearl mussel shells. Nevertheless, both the impact and flexural properties of the prepared 3D nanocomposite were much higher than the other natural shell, i.e. green grab shell. Besides conventional methods characterizations, the nacre-like structure of the artificial 3D nanocomposite was further evidenced with positron annihilation lifetime spectroscopy characterizations. This work might facilitate a versatile platform for developing green 3D bionanocomposites with fairly good mechanical properties.

Soy protein isolate (SPI) provides a potential alternative biopolymer source to fossil fuels, but improving the mechanical properties and water resistance of SPI composites remains a huge challenge. Inspired by the synergistic effect of natural nacre, we developed a novel approach to fabricate high-performance SPI nanocomposite films based on 2D graphene (G) nanosheets and 1D carbon nanotubes (CNTs) and nanofibrillated cellulose (NFC) using a casting method. The introduction of web-like NFC promoted the uniform dispersion of graphene/CNTs in the biopolymer matrix, as well as a high extent of cross-linkage combination between the fillers and SPI matrix. The laminated and cross-linked structures of the different nanocomposite films were observed by field-emission scanning electron microscope (FE-SEM) images. Due to the synergistic interactions of π–π stacking and hydrogen bonding between the nanofillers and SPI chains, the tensile strength of SPI/G/CNT/NFC film significantly increased by 78.9% and the water vapor permeability decreased by 31.76% in comparison to neat SPI film. In addition, the ultraviolet-visible (UV-vis) light barrier performance, thermal stability, and hydrophobicity of the films were significantly improved as well. This bioinspired synergistic reinforcing strategy opens a new path for constructing high-performance nanocomposites.

Inspired by the nacre layered multistage structure and high toughness and strength of the unity of mechanical properties, a graphene oxide/carboxyl functionalized single-walled carbon nanotubes/konjac glucomannan (GO-SC-KGM) nanocomposite is successfully fabricated through a vacuum filtration method for the first time. The GO nanosheets with carboxyl and hydroxyl groups, SC with carboxyl groups, and the KGM molecule chains with abundant hydroxyl groups could easily form hydrogen bonding networks, resulting in a strong interface interaction. The tensile strength of prepared GO-SC-KGM nanocomposites reaches 311.4 ± 9.2 MPa. At the same time, it can maintain toughness up to 11.1 ± 0.5 MJ m-3. Its strength and toughness are much higher than nacres and other nacre-like GO-base composites. Thus, this kind of SC enhances high tensile strength and toughness, and the bioinspired nanocomposite exhibits promising potential applications for food packaging, aerospace, tissue engineering, or as a replacement for conventional chemical synthetic organic based materials.

Stiff yet room‐temperature self‐healing polymers are designed using molecularly engineered hydrogen bonds (H‐bonds). However, they often suffer from high brittleness, moisture sensitivity, and limited functionality. To overcome these challenges, high‐performance biomimetic nanocomposites inspired by inverse nacre structures are developed. A layered boron nitride nanosheet (BNNSs) skeleton is embedded within a previously synthesized room‐temperature self‐healing glassy polyurethane network, leveraging a solvent exchange‐induced self‐assembly strategy. This approach resolved the problem of BNNSs agglomeration and reconstructed robust yet dynamic noncovalent interfacial interactions, maximizing the reinforcing and toughening effects of BNNSs. Consequently, the nanocomposite exhibited significant mechanical enhancements, including 6.6‐fold, 14.4‐fold, 490‐fold, and 35.7‐fold increases in flexural modulus, strength, toughness, and fracture toughness, respectively, achieving a balance between stiffness and toughness. Furthermore, the nanocomposite retained room‐temperature self‐healing properties through the secondary relaxation of H‐bonds. The impermeability of BNNSs effectively shielded H‐bonds from moisture, fundamentally altering the hygroscopic nature of self‐healing glassy polyurethanes. Additionally, the highly oriented and interconnected BNNSs skeleton endowed the nanocomposite with an in‐plane thermal conductivity of up to 11.54 W m−1 K−1, making it a promising candidate for next‐generation high‐performance intelligent thermal interface materials.

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Constructing flexible and robust thermally conductive but electrically insulating composite films for efficient and safe thermal management has always been a sought-after research topic. Herein, a nacre-inspired high-performance poly(p-phenylene-2,6-benzobisoxazole) (PBO)/MXene nanocomposite film was prepared by a sol-gel-film conversion method with a homogeneous gelation process. Because of the as-formed optimized brick and mortar structure, and the strong bridging and caging effects of the fine PBO nanofibre network on the MXene nanosheets, the resulting nanocomposite film is electrically insulating (2.5 × 109 Ω cm), and exhibits excellent mechanical properties (tensile strength of 416.7 MPa, Young’s modulus of 9.1 GPa and toughness of 97.3 MJ m−3). More importantly, the synergistic orientation of PBO nanofibres and MXene nanosheets endows the film with an in-plane thermal conductivity of 42.2 W m−1 K−1. The film also exhibits excellent thermal stability and flame retardancy. This work broadens the ideas for preparing high-performance thermally conductive but electrically insulating composites.

As one of the materials having a bionic structure, nacrelike layered composites, inspired by their natural hybrid structures, have been studied via a variety of approaches. Graphene oxide (GO), which differed from inert graphene, was used as a new building block because it could be readily chemically functionalized. Rather than natural polymers, synthetic polymers were most commonly used to fabricate nacrelike GO–polymer materials. However, naturally occurring polymers complied more easily with the requirements of biocompatibility, biodegradability, and nontoxicity. Here, a simple solution-casting method was used to mimic natural nacre and fabricate a self-assembled and aging-resistant binary natural polymer, (κ-carrageenan (κ-CAR)–Konjac glucomannan (KGM))–GO nanocomposites, with varying GO concentrations. The investigation results revealed that κ-CAR–KGM and GO mostly self-assemble via the formation of intermolecular hydrogen bonds to form a well-defined layered structure. The mechanical properties of the natural polymer–GO films were improved significantly compared to those of pure natural polymer films. With the addition of 7.5 wt % GO, the tensile strength (TS) and Young’s modulus were found to increase by 129.5 and 491.5%, respectively. In addition, the composite films demonstrated high reliability and aging resistance as well as a definite TS after cold and hot shock and ozone aging tests, especially showing a superior ozone resistance. The composite films can potentially be used as biomaterials or packing materials.

High-strength, flexible, and multifunctional characteristics are highly desirable for electromagnetic interference (EMI) shielding materials in the field of electric devices. In this work, inspired by natural nacre, we fabricated large-scale, layered MXene/amarid nanofiber (ANF) nanocomposite papers by blade-coating process plus sol-gel conversion step. The as-synthesized papers possess excellent mechanical performance, that is, exceptional tensile strength (198.80 ± 5.35 MPa), large strain (15.30 ± 1.01%), and good flexibility (folded into various models without fracture), which are ascribed to synergetic interactions of the interconnected three-dimensional network frame and hydrogen bonds between MXene and ANF. More importantly, the papers with extensive continuous conductive paths formed by MXene nanosheets present a high EMI shielding effectiveness of 13188.2 dB cm2 g-1 in the frequency range of 8.2-12.4 GHz. More interestingly, the papers show excellent Joule heating performance with a fast thermal response (<10 s) and a low driving voltage (≤4 V). As such, the large-scale MXene/ANF papers are considered as promising alternatives in a wide range of applications in electromagnetic shielding and thermal management.

Strength and toughness have traditionally been regarded as mutually exclusive, but simultaneously achieving both high strength and high toughness in organic‒inorganic nanocomposites remains a significant challenge. Inspired by natural nacre and bone, inorganic ionic oligomers and organic molecular chains are employed to achieve multiscale crosslinking assembly, advancing from the ionic‐molecular level to nanolines, nanorods, nanofibers, microfibers, and ultimately to nanocomposite films and bulk nanocomposite materials. This process results in a highly integrated organic‒inorganic hierarchical ordered structure, imparting exceptional record‐breaking ultrahigh toughness (558.90 ± 34.84 MJ m−3), excellent tensile strength (353.84 ± 18.77 MPa), and fracture energy (2.93 MJ m−2) to the nanocomposite films. The resulting bulk nanocomposite exhibits outstanding bending mechanical properties (a maximum bending stress of 207.17 ± 12.37 MPa, and a bending energy of 37.62 ± 7.33 MJ m−3 without fracture), exceptional fatigue resistance, and remarkable toughness in extreme environments (e.g., −196 and 200 °C). Furthermore, the nanocomposites can undergo hydrothermal‐induced recycling and regeneration owing to their noncovalent crosslinking nature. Consequently, these nanocomposites exhibit significant potential for applications in high‐performance structural engineering materials. The proposed organic‒inorganic multiscale crosslinking assembly tactic based on inorganic ionic oligomers presents a promising approach for the fabrication of ultrahigh‐toughness nanocomposites.

Integration, being lightweight, and intelligence are important orientations for the future advancement of soft robots. However, existing soft robots are generally hydrogels or silicone rubber, which are inherently mechanically inferior and easily damaged and difficult to integrate functions. Here, inspired by nacre, an elastomer actuator with sulfonated graphene-based gradient nanostructures is constructed via supramolecular multiscale assembly. The resulting nanocomposite possesses an ultrahigh toughness of 141.19 MJ/m3 and high room-temperature self-healing efficiency (89%). The proof-of-concept robot is demonstrated to emphasize its maximum swimming speed of 2.67 body length per second, whose speed is comparable to that of plankton, representing the outperformance of most artificial soft robots. Furthermore, the robot can stably absorb pollutants and recover its robustness and functionality even when damaged. This study breaks the mutual exclusivity of functional execution and fast locomotions, and we anticipate that our nanostructural design will offer an effective extended path to other integrated robots that required multifunction integration.

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With increasing concern about the environmental pollution of petrochemical plastics, people are constantly exploring environmentally friendly and sustainable alternative materials. Compared with petrochemical materials, cellulose has overwhelming superiority in terms of mechanical properties, thermal properties, cost, and biodegradability. However, the flammability of cellulose hinders its practical application to a certain extent, so improving the fire‐retardant properties of cellulose nanofiber‐based materials has become a research focus. Here, cellulose nanofiber and alginate are extracted from abundant natural sargassum as high‐strength nanoscale building blocks, and then a sargassum cellulose fire‐retardant structural material is prepared through a bottom‐up hydrogel layer‐by‐layer method. The structural materials obtained incorporate excellent mechanical properties (≈297 MPa), thermal stability (≈200 °C), low thermal expansion coefficient (≈7.17 × 10−6 K−1), and fire‐retardant properties. This work largely improves the utilization of seaweed residue and natural polymers, providing a bio‐based fire‐retardant strategy, and has a wide range of development prospects in the field of fiber‐based high‐performance structural materials in the future.

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A sustainable bulk structural material is fabricated with great dimensional stability and mechanical properties. Sustainable structural materials with light weight, great thermal dimensional stability, and superb mechanical properties are vitally important for engineering application, but the intrinsic conflict among some material properties (e.g., strength and toughness) makes it challenging to realize these performance indexes at the same time under wide service conditions. Here, we report a robust and feasible strategy to process cellulose nanofiber (CNF) into a high-performance sustainable bulk structural material with low density, excellent strength and toughness, and great thermal dimensional stability. The obtained cellulose nanofiber plate (CNFP) has high specific strength [~198 MPa/(Mg m−3)], high specific impact toughness [~67 kJ m−2/(Mg m−3)], and low thermal expansion coefficient (<5 × 10−6 K−1), which shows distinct and superior properties to typical polymers, metals, and ceramics, making it a low-cost, high-performance, and environmental-friendly alternative for engineering requirement, especially for aerospace applications.

The honeycomb structure stands out as an exemplary material, characterized by its remarkable combination of lightweight and superior mechanical strength. Drawing inspiration from the roles of cellulose nanofiber and lignin in natural wood, a novel high‐stiffness biomass honeycomb nanocomposite is developed. This composite is engineered by incorporating lignin into bacterial cellulose, followed by the self‐polycondensation of lignin at elevated temperature. The nanocomposite architecture features intricately interwoven nanofibers to provide a robust long‐range framework, while the self‐polymerized lignin through coniferyl alcohol radicals serves as a rigid binder that interlinks the nanofibers. The dual mechanisms endow the material with exceptional tensile strength and rigidity. Molding this nanocomposite into a honeycomb structure yields a material with outstanding mechanical properties that outperform commercial alternatives, including those derived from Nomex paper and aluminum alloys. Given its characteristics, this nanocomposite holds great promise as a substrate for the next generation of high‐performance structural materials.

Preparing a lightweight yet high-strength bio-based structural material with sustainability and recyclability is highly desirable in advanced applications for architecture, new energy vehicles and spacecraft. In this study, we combined cellulose scaffold and aramid nanofiber (ANF) into a high-performance bulk material. Densification of cellulose microfibers containing ANF and hydrogen bonding between cellulose microfibers and ANF played a crucial role in enhanced physical and mechanical properties of the hybrid material. The prepared material showed excellent tensile strength (341.7 MPa vs. 57.0 MPa for natural wood), toughness (4.4 MJ/m3 vs. 0.4 MJ/m3 for natural wood) and Young’s modulus (24.7 GPa vs. 7.2 GPa for natural wood). Furthermore, due to low density, this material exhibited a superior specific strength of 285 MPa·cm3·g−1, which is remarkably higher than some traditional building materials, such as concrete, alloys. In addition, the cellulose scaffold was infiltrated with ANFs, which also improved the thermal stability of the hybrid material. The facile and top-down process is effective and scalable, and also allows one to fully utilize cellulose scaffolds to fabricate all kinds of advanced bio-based materials.

Bio-resources have carved a unique niche for the ever-increasing thrust of the global scientific community to impart green credentials to various research outputs along with the demands for advanced materials. In this milieu, the authors wish to fabricate a fully bio-based waterborne polyester nanocomposite as an advanced material using different bio-based reactants and cellulose nanofibers as the nanomaterial. Three different compositions of the nanocomposite were prepared at different loadings of cellulose nanofibers (0.25, 0.5 and 1 weight%) which were isolated from waste brewed green tea leaves. The structural attributes of the nanocomposites were evaluated by Fourier transform infrared spectroscopic, X-ray diffraction, scanning electron microscopic and transmission electron microscopic studies. The nanocomposites were further cured with glycerol based epoxy and fatty acid based poly(amido amine) as the hardener to obtain the respective thermosets. The significant improvements in mechanical properties including tensile strength (13.71–22.33 MPa), elongation at break (128–290%), toughness (15.65–45.18 MJ m−3) and scratch hardness (8 to >10 kg) were observed for the thermosetting nanocomposites and the thermogravimetric analysis supports their high thermostability (234–265 °C). Further, the thermosetting nanocomposites were found to be highly biodegradable by Bacillus subtilis and Pseudomonas aeruginosa bacterial strains, hemocompatible with the erythrocytes present in RBCs and showed antioxidant properties. Thus, this nanocomposite could be used as a promising eco-friendly material for different related applications.

Thin cellulose nanofiber (CNF) nanostructured substrates with varying roughness, stiffness (Young's modulus), porosity, and swelling properties were produced by varying the conditions used during fabrication. It was shown that with increased heat exposure, CNF substrate porosity in an aqueous state decreased while Young's modulus in a water submerged state increased. In this study, the adhesion and viability of mesenchymal stem cells (MSCs) cultured on this CNF substrate will be presented. Viability of D1/BALBc MSCs were assessed for 24 and 48 h, and it was shown that depending on the CNF substrate the viability varied significantly. The adhesion of MSCs after 6 and 24 h was conditional on material mechanical properties and porosity of the CNF in cell culture conditions. These results suggest that material properties of CNF nanostructured substrate within the aqueous state can be easily tuned with curing step without any chemical modification to the CNF and that these changes can affect MSC viability in cell culture.

Cellulose nanofibers (CNFs), which are plant-derived materials, have recently garnered considerable attention owing to their excellent mechanical properties, such as their low weight and high Young’s modulus. Novel methods for producing 100% CNF bulk structural materials have been developed. However, the tribological properties of CNFs have not been investigated thus far although their mechanical properties are known and are comparable to those of some conventional structural materials. In this study, the tribological properties of a novel biomass material, 100% CNF molding, were investigated based on CNF/steel contacts under dry and boundary lubrication conditions at various temperatures. The friction test results showed that the friction coefficient and wear volume of the CNF molding increased with the test temperature of the CNF/steel tribopair under dry-sliding conditions. Conversely, no significant temperature dependence of the friction and wear properties was observed upon lubrication with a pure polyalfaolefin. The surface analytical results revealed that the amorphization of the CNF molding progressed on the worn surface, especially under dry-sliding conditions at a high temperature. All the results suggested that the friction and wear performance of the 100% CNF moldings strongly depends on the sliding test conditions, and the amorphization process of the CNF molding can affect its friction and wear performance.

Constructing structural materials from sustainable raw materials is considered an efficient way to reduce the potential threat posed by plastics. Nevertheless, challenges remain regarding combining excellent mechanical and thermal properties, especially the balance of strength and toughness. Here, we report a 3D nanofiber network interfacial design strategy to strengthen and toughen all-natural structural materials simultaneously. The introduced protonated chitosan at the interface between the surface oxidized 3D nanonetwork of bacterial cellulose forms the interfacial interlocking structure of nanonetworks, achieving a robust physical connection and providing enough physical contact sites for chemical crosslinking. The obtained sustainable structural material successfully integrates excellent mechanical and thermal properties on the nanoscale of cellulose nanofibers, such as light weight, high strength, and superior thermal expansion coefficient. The relationship between structural design and comprehensive mechanical property improvement is analyzed in detail, providing a universal perspective to design sustainable high-performance structural materials from nanoscale building blocks.

Cellulose nanofiber (CNF) possesses excellent intrinsic properties, and many CNF-based high-performance structural and functional materials have been developed recently. However, the coordination of the mechanical properties and functionality is still a considerable challenge. Here, a CNF-based structural material is developed by a bioinspired gradient structure design using hollow magnetite nanoparticles and the phosphorylation-modified CNF as building blocks, which simultaneously achieves a superior mechanical performance and electromagnetic wave absorption (EMA) ability. Benefiting from the gradient design, the flexural strength of the structural material reached ∼205 MPa. Meanwhile, gradient design improves impedance matching, contributing to the high EMA ability (-59.5 dB) and wide effective absorption width (5.20 GHz). Besides, a low coefficient of thermal expansion and stable storage modulus was demonstrated as the temperature changes. The excellent mechanical, thermal, and EMA performance exhibited great potential for application in stealth equipment and electromagnetic interference protecting electronic packaging materials.

Widely used disposable plastic tableware is usually buried or directly discharged into the natural environment after using, which poses potential threats to the natural environment and human health. To solve this problem, nondegradable plastic tableware needs to be replaced by tableware composed of biodegradable structural materials with both food safety and the excellent mechanical and thermal properties. Here, a food‐safe sargassum cellulose nanofiber (SCNF) is extracted from common seaweed in an efficient and low energy consuming way under mild reaction conditions. Then, by assembling the SCNF into a dense bulk material, a strong sargassum cellulose nanofiber structural material (SCNSM) with high strength (283 MPa) and high thermal stability (>160 °C) can be prepared. The SCNSM also possesses good machinability, which can be processed into tableware with different shapes, e.g., knives and forks. The overall performance of the SCNSM‐based tableware is better than commercial plastic, wood‐based, and poly(lactic acid) tableware, which shows great application potential in the tableware field.

Developing sustainable and lightweight structural materials is a promising strategy for reducing carbon emissions in transportation and buildings. However, producing high‐performance bulk structural materials from sustainable biomass materials while maintaining excellent mechanical strength remains a major challenge, especially for further scale‐up. Herein, a scalable and robust bottom‐up strategy is reported to fabricate bulk wooden plate (W‐plate) with a typical “brick‐and‐mortar” structure from engineered wood particles via moderate delignification and in situ LiCl/DMAc treatment followed by hot‐pressing. The W‐plate constructed by delignified wood particles and regenerated cellulose nanofibers can achieve a confluence of mechanical strengthening and toughening by the ordered lamination structure and multiscale cellulose micro/nanofiber crosslinking interactions, resulting in high flexural strength (225.17 ± 12.18 MPa) and high fracture toughness (4.01 ± 0.53 MPa m0.5) while maintaining a low density (1.34 g cm−3), superior to typical metals and ceramics. Moreover, the W‐plate exhibits advantageous thermal properties, including a low thermal expansion coefficient (<19 × 10−6 K−1) and a high storage modulus (>7.5 GPa) compared to those of petroleum‐based polymers. Coupled with abundant and renewable raw materials, all‐cellulose components, and scalable and recyclable fabrication, the W‐plate can potentially be used as a high‐performance, cost‐effective, and environmentally friendly alternative for engineering applications.

Petroleum-based plastics are useful but they pose a great threat to the environment and human health. It is highly desirable yet challenging to develop sustainable structural materials with excellent mechanical and thermal properties for plastic replacement. Here, inspired by nacre’s multiscale architecture, we report a simple and efficient so called “directional deforming assembly” method to manufacture high-performance structural materials with a unique combination of high strength (281 MPa), high toughness (11.5 MPa m1/2), high stiffness (20 GPa), low coefficient of thermal expansion (7 × 10−6 K−1) and good thermal stability. Based on all-natural raw materials (cellulose nanofiber and mica microplatelet), the bioinspired structural material possesses better mechanical and thermal properties than petroleum-based plastics, making it a high-performance and eco-friendly alternative structural material to substitute plastics. It is desirable yet challenging to develop sustainable structural materials to replace petroleum-based plastics. Here, the authors report a facile assembly method for manufacturing high-performance structural materials with a unique combination of high strength, toughness and stiffness.

All-cellulose composites are usually prepared by removing impurities and surface selective dissolution approach, which detract significantly from their environment-friendly properties. In this paper, we report an environment-friendly approach to fabricate all-cellulose nanofiber composites from stack-up bacterial cellulose (BC) hydrogels via self-aggregation forces of the hydrogen bond by water-based processing. Structural and mechanical properties of BC laminated composites have been investigated. The results indicated that BC composites possess the structure of all nanofibers, a tensile strength of 116 MPa and a storage modulus of 25 GPa. Additionally, the interfacial shear strength and the tensile strength of piece-hot-press BC demonstrate the strong self-aggregation forces of BC nanofibers. Thus, BC laminated composites will be attractive in structural material.

While tremendous efforts have been dedicated to developing environmentally friendly films made from natural polymers and renewable resources, in particular, multifunctional films featuring extraordinary mechanical properties, optical performance, and ordered nanostructure, challenges still remain in achieving all these characteristics in a single material via a scalable process. Here, we designed a green route to fabricating strong, super tough, regenerated cellulose films featuring tightly stacked and long-range aligned cellulose nanofibers self-assembled from cellulose solution in alkali/urea aqueous systems. The well-aligned nanofibers were generated by directionally controlling the aggregation of cellulose chains in the hydrogel state using a preorientation-assisted dual cross-linking approach; i.e., a physical cross-linking was rapidly introduced to permanently reserve the temporarily aligned nanostructure generated by preorienting the covalent cross-linked gels. After a structural densification in air-drying of hydrogel, high strength was achieved, and more importantly, a record-high toughness (41.1 MJ m-3) in anisotropic nanofibers-structured cellulose films (ACFs) was reached. Moreover, the densely packed and well-aligned cellulose nanofibers significantly decreased the interstices in the films to avoid light scattering, granting ACFs with high optical clarity (91%), low haze (<3%), and birefringence behaviors. This facile and high-efficiency strategy might be very scalable in fabricating high-strength, super tough, and clear cellulose films for emerging biodegradable next-generation packaging, flexible electronic, and optoelectronic applications.

Natural trabecular bone is typically a complex 3D honeycomb-like material, which can influence the behavior of bone marrow mesenchymal stem cells (BMSCs), particularly their migration and differentiation direction. However, engineering such biomimetic hydrogels with an orthogonal anisotropic structure similar with trabecular bone via a universal and scalable manner still poses a great challenge. This study develops a cellulose nanofiber (CNF) reinforced composite hydrogel with an orthogonal anisotropic structure, which exhibits a highly aligned fibrous configuration and structural densification, endowing it with excellent mechanical properties and damage-tolerant architectures. Moreover, compared with the composite hydrogel with uniaxially anisotropic structure, this as-developed composite hydrogel with orthogonal anisotropic structure utilizes the interactions between rigid and flexible components to form an anisotropic network structure in orthogonal directions, mimicking the microscopic interactions between collagen fibers and proteoglycans in natural ECMs. It could not only facilitate the physical alignment and directional migration of BMSCs, but also enhance their proliferation and differentiation into osteoblasts. Overall, replicating the structure and properties of natural trabecular bone enhances insights into cellular mechanisms, but also improves the efficiency of bone regenerative medicine treatments.

Electromagnetic interference (EMI) shielding materials with excellent EMI shielding efficiency (SE), lightweight property, and superb mechanical performance are vitally important for modern society, but it is still a challenge to realize these performances simultaneously on one material. Here, we report a sustainable bioinspired double-network structural material with excellent specific strength (146 MPa g-1 cm3) and remarkable EMI SE (100 dB) from cellulose nanofiber (CNF) and carbon nanotubes (CNTs), which demonstrates remarkable and outstanding performance to both typical metal materials and reported polymer composites. In particular, the bioinspired double-network structure design simultaneously achieves an extremely high electrical conductivity and mechanical strength, which makes it a lightweight, high shielding efficiency, and sustainable structural material for real-life electromagnetic wave shielding applications.

Superelastic and fatigue‐resistant materials that can work over a wide temperature range are highly desired for diverse applications. A morphology‐retained and scalable carbonization method is reported to thermally convert a structural biological material (i.e., bacterial cellulose) into graphitic carbon nanofiber aerogel by engineering the pyrolysis chemistry. The prepared carbon aerogel perfectly inherits the hierarchical structures of bacterial cellulose from macroscopic to microscopic scales, resulting in remarkable thermomechanical properties. In particular, it maintains superelasticity without plastic deformation even after 2 × 106 compressive cycles and exhibits exceptional temperature‐invariant superelasticity and fatigue resistance over a wide temperature range at least from −100 to 500 °C. This aerogel shows unique advantages over polymeric foams, metallic foams, and ceramic foams in terms of thermomechanical stability and fatigue resistance, with the realization of scalable synthesis and the economic advantage of biological materials.

We used cellulose and a non-classical mineralization process to fabricate a bioinspired nanohybrid material that exhibited structural features and properties similar to those of human hard tissues. We made a hydrogel with highly compacted and aligned cellulose nanofibers. We thoroughly mineralized the cellulose hydrogel with hydroxyapatite nanocrystals, using polyacrylic acid as a soluble template for precursor minerals, which infiltrated the nanocompartments of the aligned cellulose nanofiber network. The ultrastructure and mechanical properties of the mineralized gels were strikingly similar to those of bone and dentin, which supports further use of cellulose-based fibrillary materials as affordable, biocompatible scaffolds for repair and regeneration of hard tissues. The versatility of the bioinspired mineralization processes used here can broaden the applications of these cellulosic nanohybrids.

No abstract available

Introducing natural Bouligand structure into synthetics is expected to develop high-performance structural materials. Interfibrous interface is critical to load transfer, and mechanical functionality of bioinspired Bouligand structure yet receives little attention. Here, we propose one kind of hierarchical and reconfigurable interfibrous interface based on moderate orderliness to mechanically reinforce bioinspired Bouligand structure. The interface imparted by moderate alignment of adaptable networked nanofibers hierarchically includes nanofiber interlocking and hydrogen-bonding (HB) network bridging, being expected to facilitate load transfer and structural stability through dynamic adjustment in terms of nanofiber sliding and HB breaking-reforming. As one demonstration, the hierarchical and reconfigurable interfibrous interface is constructed based on moderate alignment of networked bacterial cellulose nanofibers. We show that the resultant bioinspired Bouligand structural material exhibits unusual strengthening and toughening mechanisms dominated by interface-microstructure multiscale coupling. The proposed interfibrous interface enabled by moderate orderliness would provide mechanical insight into the assembly of widely existing networked nanofiber building blocks toward high-performance macroscopic bioinspired structural assemblies.

No abstract available

Bioinspired unidirectional porous materials have emerged as a unique class of scaffolds for the fabrication of macroscopic nanomaterial assemblies. However, these scaffolds usually served simply as mechanical carriers to support various building blocks. Here, we report that the unidirectional silk fibroin scaffold could not only act as a carrier, but also serve as a controllable multiscale reactor to achieve in situ synthesis of Ag3PO4 nanowire network anchored to ordered channels. Both silk fibroin matrix and the interface were revealed to play important roles in the nucleation and growth of Ag3PO4 nanowires. Such a unidirectional composite scaffold exhibits efficient water disinfection property. Furthermore, unidirectional silk-Ag2S nanowire composite scaffold was obtained via the facile chemical transformation of Ag3PO4 into Ag2S, leading to both efficient solar water evaporation effect and antibacterial activity. It is expected that this method can be extended to fabricate a series of silk-based unidirectional composite scaffolds with varying functionalities.

No abstract available

The expanding use of carbon fiber-reinforced polymer (CFRP), valued for its high specific strength and modulus, in joining dissimilar materials has heightened the need to understand the mechanical behavior of these connections. Inspired by the microstructural morphology of beetle elytra, this study proposes a Bioinspired CFRP Mortise-Tenon Structure (BCMTS) and establishes a two-dimensional continuous shell model using the Abaqus platform. Numerical simulations reveal that the load-bearing capacity of BCMTS is nonlinearly influenced by key geometric parameters and layup configuration. An optimal geometric configuration maximizing structural strength was identified. Furthermore, a quadratic model for predicting the tensile strength of BCMTS was developed using Kriging interpolation and the Levenberg-Marquardt optimization algorithm. The bioinspired layup design achieved an ultimate tensile strength of 1807 MPa and a corresponding peak load of 22.01 kN—representing enhancements of 108% and 136%, respectively, over conventional [0/90] 5 layup. Furthermore, the study maps failure modes and stress concentrations across different geometries and layups, offering a foundation for targeted structural optimization.

Introduction Joint injuries, a major type of human musculoskeletal disorder, are often accompanied by soft tissue damage, and restoring ligament integrity is a key strategy for reconstructing joint function. However, existing artificial ligaments face a critical challenge: reconciling robust biomechanical performance with intrinsic self-healing capability, especially under cyclic loading and accidental overload conditions. Conventional materials like polyethylene terephthalate (PET) and polytetrafluoroethylene (PTFE) struggle with long-term durability, while emerging self-healing designs are limited by poor mechanical robustness and slow healing kinetics. Methods This study developed a self-healing artificial ligament via 3D braiding of shape memory alloy (SMA, Ni50.71Ti49.29) wires and polyethylene (PE) fishing lines, mimicking the hierarchical structure of natural ligaments. The ligament was fabricated with a 1-over-1-under interlock configuration (6 carriers, 180° braid angle) and pre-tensioned (5% strain at 60 °C for 12 h) for structural stabilization. Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA), and mechanical tests (hysteresis, stress relaxation, cyclic loading) were conducted to characterize its thermal and mechanical properties. Electrothermal recovery tests (3–5.5 W power input) evaluated self-healing performance, and a 3D-printed artificial hip joint was used to validate in-situ functionality. Results DSC showed the SMA had a thermal hysteresis window of 24.8 °C (Ms=46.5 °C, Mf=27.2 °C, As=58.3 °C, Af=71.3 °C), and DMA revealed an “S”-type storage modulus curve during heating . After 1,000 s of cyclic loading, the self-healing ligament retained ∼73% of initial stress (vs. 37% for conventional ligaments) and had a lower energy dissipation ratio due to SMA’s low damping. Electrothermal tests showed maximum contraction rate increased with pre-strain, and 3–5.5 W power input enabled proportional contraction strain. In artificial hip tests, SMA activation restored ∼95% of initial joint laxity, reducing excessive rotational/translational motion by 26% and 12% respectively. Discussion The hybrid SMA-PE design resolves the trade-off between biomechanical performance and self-healing: PE provides foundational tensile strength, while SMA enables electrothermal self-healing via phase transformation. The 3D braided structure replicates natural ligaments’ J-shaped stress-strain behavior, ensuring adaptability to dynamic joint movements. Compared to piezoelectric nanomaterial (PENM)-based designs (focused on proprioception), this ligament prioritizes mechanical stability and rapid self-healing, making it suitable for clinical rehabilitation and assistive devices. Future work will address limitations like wired power supply (via wireless modules) and long-term stability (via anti-degradation coatings).

No abstract available

Mineralization is a long-lasting method commonly used by biological materials to selectively strengthen in response to site specific mechanical stress. Achieving a similar form of toughening in synthetic polymer composites remains challenging. In previous work, we developed methods to promote chemical reactions via the piezoelectrochemical effect with mechanical responses of inorganic, ZnO nanoparticles. Herein, we report a distinct example of a mechanically-mediated reaction in which the spherical ZnO nanoparticles react themselves leading to the formation of microrods composed of a Zn/S mineral inside an organogel. The microrods can be used to selectively create mineral deposits within the material resulting in the strengthening of the overall resulting composite.

Lightweight structural materials with a unique combination of high stiffness, strength, toughness, and hardness, are highly desired yet challenging to be artificially fabricated. Biological structural materials, on the other hand, ingeniously integrate multiple mutually exclusive mechanical properties together relying on their hierarchically heterogeneous structures bonded with gradient interfaces. Here, a scalable bottom‐up approach combining continuous nanofiber‐assisted evaporation‐induced self‐assembly with laminating, pressure‐less sintering and resin infiltration is reported to fabricate bioinspired heterogeneous ceramic–resin composites with locally tunable microstructure to fulfill specific properties. A gradient interlayer is introduced to provide a gradual transition between adjacent heterogeneous layers, effectively alleviating their property mismatch. The optimized heterogeneous nacre‐like composite, as a demonstration, exhibits an attractive combination of low density (≈2.8 g cm−3), high strength (≈292 MPa), toughness (≈6.4 MPa m1/2), surface hardness (≈1144 kgf mm−2) and impact‐resistance, surpassing the overall performance of engineering alumina. This material‐independent approach paves the way for designing advanced bioinspired heterogeneous materials for diverse structural and functional applications.

Energy‐absorbing materials are widely used under certain high‐frequency scenarios, such as cargo packaging or sport protection. Though negative stiffness mechanical metamaterials have many distinctive advantages, fairly low strength and poor specific energy absorption unfortunately limit their present industrial applications. Inspired by the excellent cushioning performance of the paw pads of mammals, a novel flexible energy‐absorbing negative stiffness mechanical metamaterial is proposed herein. Results show that the presented metamaterial outperforms traditional packaging materials with respect to cushion performance. Moreover, a performance programming strategy is proposed to achieve multistage tuning between large energy absorption and high rebound properties.

No abstract available

Bioinspired materials are among the most durable materials known to man. Mimicking solutions and structures observed in nature is a modern approach to modeling materials in line with sustainable development. Designers of mechanical structures are continually seeking new applications and materials that replicate natural effects. This article presents the primary natural sources of bioinspiration in the production of advanced composite materials. The focus is on discussing current advances in the production of impact-resistant composite materials. The main sources of bioinspiration for impact-resistant materials are pearl structures, insect exoskeletons, and fruit shells. Insect cuticles offer a sustainable alternative due to their exceptional stiffness, unique properties, and mechanical parameters. The use of biocomposites in the production of mechanical structures is expected to grow in the coming years due to the continuous development of new composite technologies.

Elegant design principles in biological materials such as stiffness gradients or sophisticated interfaces provide ingenious solutions for an efficient improvement of their mechanical properties. When materials such as wood are directly used in high‐performance applications, it is not possible to entirely profit from these optimizations because stiffness alterations and fiber alignment of the natural material are not designed for the desired application. In this work, wood is turned into a versatile engineering material by incorporating mechanical gradients and by locally adapting the fiber alignment, using a shaping mechanism enabled by reversible interlocks between wood cells. Delignification of the renewable resource wood, a subsequent topographic stacking of the cellulosic scaffolds, and a final densification allow fabrication of desired 3D shapes with tunable fiber architecture. Additionally, prior functionalization of the cellulose scaffolds allows for obtaining tunable functionality combined with mechanical gradients. Locally controllable elastic moduli between 5 and 35 GPa are obtained, inspired by the ability of trees to tailor their macro‐ and micro‐structure. The versatility of this approach has significant relevance in the emerging field of high‐performance materials from renewable resources.

Concepts that draw inspiration from soft biological tissues have enabled significant advances in creating artificial materials for a range of applications, such as dry adhesives, tissue engineering, biointegrated electronics, artificial muscles, and soft robots. Many biological tissues, represented by muscles, exhibit directionally dependent mechanical and electrical properties. However, equipping synthetic materials with tissue-like mechanical and electrical anisotropies remains challenging. Here, we present the bioinspired concepts, design principles, numerical modeling, and experimental demonstrations of soft elastomer composites with programmed mechanical and electrical anisotropies, as well as their integrations with active functionalities. Mechanically assembled, 3D structures of polyimide serve as skeletons to offer anisotropic, nonlinear mechanical properties, and crumpled conductive surfaces provide anisotropic electrical properties, which can be used to construct bioelectronic devices. Finite element analyses quantitatively capture the key aspects that govern mechanical anisotropies of elastomer composites, providing a powerful design tool. Incorporation of 3D skeletons of thermally responsive polycaprolactone into elastomer composites allows development of an active artificial material that can mimic adaptive mechanical behaviors of skeleton muscles at relaxation and contraction states. Furthermore, the fabrication process of anisotropic elastomer composites is compatible with dielectric elastomer actuators, indicating potential applications in humanoid artificial muscles and soft robots. Many biological tissues exhibit directionally dependent properties. Here, authors develop tissue-like elastomer composites with programmed mechanical and electrical anisotropy and discuss potential applications in bioelectronics and humanoid artificial muscles.

Highlights A self-grinding exfoliation strategy that depends on mutual shear friction between flake graphite particles is successfully developed to prepare pristine graphene with largely enhanced yield and productivity. Bioinspired assembly of pristine graphene nanosheets to an interconnected aramid nanofiber network is achieved by a continuous sol-gel-film transformation strategy and generates a flexible yet highly thermoconductive film. Abstract Flexible yet highly thermoconductive materials are essential for the development of next-generation flexible electronic devices. Herein, we report a bioinspired nanostructured film with the integration of large ductility and high thermal conductivity based on self-exfoliated pristine graphene and three-dimensional aramid nanofiber network. A self-grinding strategy to directly exfoliate flake graphite into few-layer and few-defect pristine graphene is successfully developed through mutual shear friction between graphite particles, generating largely enhanced yield and productivity in comparison to normal liquid-based exfoliation strategies, such as ultrasonication, high-shear mixing and ball milling. Inspired by nacre, a new bioinspired layered structural design model containing three-dimensional nanofiber network is proposed and implemented with an interconnected aramid nanofiber network and high-loading graphene nanosheets by a developed continuous assembly strategy of sol–gel-film transformation. It is revealed that the bioinspired film not only exhibits nacre-like ductile deformation behavior by releasing the hidden length of curved aramid nanofibers, but also possesses good thermal transport ability by directionally conducting heat along pristine graphene nanosheets. Graphical abstract

No abstract available

Self-healing efficiency and mechanical strength are always a pair of mechanical contradictions of a polymer. Herein, a series of novel mussel-inspired modified graphene oxide/polyurethane composites were successfully fabricated via rational molecular design and introducing hyperbranched polymer-modified graphene oxide. The composites exhibit outstanding self-healing performances with a self-healing efficiency of 87.9%. Especially, their self-healing properties possess exceptional water-insensitivity, which presents a high self-healing efficiency of 92.5% under 60 °C water for 2 h and 74.6% under 25 °C water for 6 h. Furthermore, the tensile strength of the composites increased by 107.7% with a high strain of 2170%. In addition, the composites show a remarkable recovery capability of 76.3% and 83.7% under tensile and compression loading, respectively, after 20 cycles. This strategy shows prominent application potential in high-performance solid propellants, protective coating, electronic skin, soft sensors and other water-insensitive devices.

The fabrication of bone regeneration biomaterials, which simultaneously possess superior mechanical performances and excellent bioactivity, remains challenging because these properties are usually mutually exclusive. Herein, inspired by the brick‐and‐mortar architecture of nacre, lamellar silicate‐based bioceramic composites are successfully prepared by constructing orderly layered bioceramics infiltrated with a biomedical resin interlayer via the bidirectional freezing technique. The lamellar composites possess high strength and proper Young's moduli, which match with human cortical bone. Furthermore, the lamellar composites can release bioactive ions with a controlled profile, which significantly enhance the cell proliferation of both rabbit bone mesenchymal stem cells and periodontal ligament cells in vitro. Moreover, with the degradation of silicate bioceramics in vivo, newly formed bone tissue can grow into the materials to present the bioceramic/new bone/resin sandwich‐like lamellar microstructure. The silicate‐based bioceramic composites with brick‐and‐mortar architecture represent an excellent biomaterial in combination of superior mechanical performances matching that of human cortical bone, and excellent bioactivity for potential load‐bearing bone regeneration.

Natural structural materials often possess unique combinations of strength and toughness resulting from their complex hierarchical assembly across multiple length scales. However, engineering such well-ordered structures in synthetic materials via a universal and scalable manner still poses a grand challenge. Herein, a simple yet versatile approach is proposed to design hierarchically structured hydrogels by flow-induced alignment of nanofibrils, without high time/energy consumption or cumbersome postprocessing. Highly aligned fibrous configuration and structural densification are successfully achieved in anisotropic hydrogels under ambient conditions, resulting in desired mechanical properties and damage-tolerant architectures, for example, strength of 14 ± 1 MPa, toughness of 154 ± 13 MJ m^−3, and fracture energy of 153 ± 8 kJ m^−2. Moreover, a hydrogel mesoporous framework can deliver ultra-fast and unidirectional water transport (maximum speed at 65.75 mm s^−1), highlighting its potential for water purification. This scalable fabrication explores a promising strategy for developing bioinspired structural hydrogels, facilitating their practical applications in biomedical and engineering fields. Natural materials can combine strength and toughness, but achieving similar well-ordered structures for synthetic materials is challenging. Here, the authors report hydrogels prepared by flow-induced alignment of nanofibrils, with anisotropic structure and good mechanical properties.

Inspired by the catechol and amine rich adhesive proteins of mussels, polydopamine (pDA) has become one of the most widely employed methods for functionalizing material surfaces, powered in part by the versatility and simplicity of pDA film deposition that takes place spontaneously on objects immersed in an alkaline aqueous solution of dopamine monomer. Despite the widespread adoption of pDA as a multifunctional coating for surface modification, it exhibits poor mechanical performance. Attempts to modify the physical properties of pDA by incorporation of oxidizing agents, crosslinkers or carbonization of the films at ultra-high temperatures have been reported; however, improving mechanical properties with mild post-treatments without sacrificing the functionality and versatility of pDA remains a challenge. Here, we demonstrate thermal annealing at a moderate temperature (130 ˚C) as a facile route to enhance mechanical robustness of pDA coatings. Chemical spectroscopy, x-ray scattering, molecular force spectroscopy and bulk mechanical analyses indicate that monomeric and oligomeric species undergo further polymerization during thermal annealing, leading to fundamental changes in molecular and bulk mechanical behavior of pDA. Considerable improvements in scratch resistance were noted in terms of both penetration depth (32% decrease) and residual depth (74% decrease) for the annealed pDA coating, indicating the enhanced ability of the annealed coating to resist mechanical deformations. Thermal annealing resulted in significant enhancement in the intermolecular and cohesive interactions between the chains in the pDA structure, attributed to cross-linking and increased entanglements, preventing desorption and detachment of the chains from the coating. Importantly, improvements in pDA mechanical performance through thermal annealing did not compromise the ability of pDA to support secondary coating reactions as evidenced by electroless deposition of a metal film adlayer on annealed pDA.

Natural structural materials, such as bone, can autonomously modulate their mechanical properties in response to external loading to prevent failure. These material systems smartly control the addition/removal of material in locations of high/low mechanical stress by utilizing local resources guided by biological signals. On the contrary, synthetic structural materials have unchanging mechanical properties limiting their mechanical performance and service life. Inspired by the mineralization process of bone, a material system that adapts its mechanical properties in response to external mechanical loading is reported. It is found that charges from piezoelectric scaffolds can induce mineralization from surrounding media. It is shown that the material system can adapt to external mechanical loading by inducing mineral deposition in proportion to the magnitude of the stress and the resulting piezoelectric charges. Moreover, the mineralization mechanism allows a simple one‐step route for fabricating functionally graded materials by controlling the stress distribution along the scaffold. The findings can pave the way for a new class of self‐regenerating materials that reinforce regions of high stress or induce deposition of minerals on the damaged areas from the increase in mechanical stress to prevent/mitigate failure. It is envisioned that the findings can contribute to addressing the current challenges of synthetic materials for load‐bearing applications from self‐adaptive capabilities.

Currently, multifunction has become an essential direction of personal protective equipment (PPE), but achieving the protective effect, flexibility, physiological comfort, and intelligent application of PPE simultaneously is still a challenge. Herein, inspired by the meso-structure of rhinoceros skin, a novel strategy is proposed by compounding an ammonium sulfate ((NH4)2SO4) solution soaked gelatin hydrogel with the high weight fraction and vertically interwoven Kevlar fibers to manufacture a flexible and wearable composite with enhanced puncture resistance and strain-sensing properties. After (NH4)2SO4 solution immersion, the hydrogel's tensile strength, toughness, and fracture strain were up to 3.77 MPa, 4.26 MJ/m3, and 305.19%, respectively, indicating superior mechanical properties. The Kevlar/hydrogel composites revealed excellent puncture resistance (quasi-static of 132.06 N and dynamic of 295.05 N), flexibility (138.13 mN/cm), and air and moisture permeability (17.83 mm/s and 2092.73 g m-2 day-1), demonstrating a favorable balance between the protective effect and wearing comfort even after 7 days of environmental exposure. Meanwhile, salt solution immersion endowed the composite with excellent strain-sensing properties at various bending angles (30-90°) and frequencies (0.25-1 Hz) and allowed it to monitor different human motions directly in real-time. The rhinoceros-skin-inspired Kevlar/hydrogel composites provide a simple and economical solution for antipuncture materials that combine high protective effects, a comfortable wearing experience, and good strain-sensing properties, promising multifunctional PPE in the future.

Natural biopolymeric materials often possess properties superior to their individual components. In mussel byssus, reversible histidine (His)–metal coordination is a key feature, which mediates higher-order self-assembly as well as self-healing. The byssus structure, thus, serves as an excellent natural blueprint for the development of self-healing biomimetic materials with reversibly tunable mechanical properties. Inspired by byssal threads, we bioengineered His–metal coordination sites into a heterodimeric coiled coil (CC). These CC-forming peptides serve as a noncovalent cross-link for poly(ethylene glycol)-based hydrogels and participate in the formation of higher-order assemblies via intermolecular His–metal coordination as a second cross-linking mode. Raman and circular dichroism spectroscopy revealed the presence of α-helical, Zn2+ cross-linked aggregates. Using rheology, we demonstrate that the hydrogel is self-healing and that the addition of Zn2+ reversibly switches the hydrogel properties from viscoelastic to elastic. Importantly, using different Zn2+:His ratios allows for tuning the hydrogel relaxation time over nearly three orders of magnitude. This tunability is attributed to the progressive transformation of single CC cross-links into Zn2+ cross-linked aggregates; a process that is fully reversible upon addition of the metal chelator ethylenediaminetetraacetic acid. These findings reveal that His–metal coordination can be used as a versatile cross-linking mechanism for tuning the viscoelastic properties of biomimetic hydrogels.

Suffering weak mechanical properties, hydrogels are generally limited to be applied as load-bearing materials. Previously, we introduced methods to fabricate high-strength hydrogels using chitin nanofibers (ChNFs) under alkali or calcium chloride conditions. This work provides an alternative approach for the preparation of quinone-crosslinked ChNF-based hydrogels using amino groups, which inspired by the quinone hardening process during insect cuticle sclerotization. By increasing the number of amino groups on the chitin crystalline surface through deacetylation, the resulting surface-deacetylated chitin nanofiber (S-ChNF) transformed to a dark hydrogel when reacted in hydroquinone (HQ)/copper (Cu(II)) solutions. The results show that the S-ChNF-based hydrogel displayed almost 10-fold higher tensile strength than the ChNF-based hydrogel due to the extended crosslinking effect between quinone and amino groups. Given the natural sustainability of chitin and the demonstrated improved mechanical strength, this work offers a promising strategy to fabricate a bioinspired S-ChNF-based hydrogel for potential applications in bio-medical engineering fields.

Biological materials, although composed of meager minerals and biopolymers, often exhibit amazing mechanical properties far beyond their components due to hierarchically ordered structures. Understanding their structure–properties relationships and replicating them into artificial materials would boost the development of bulk structural nanocomposites. Layered microstructure widely exists in biological materials, serving as the fundamental structure in nanosheet‐based nacres and nanofiber‐based Bouligand tissues, and implying superior mechanical properties. High‐efficient and scalable fabrication of bioinspired bulk structural nanocomposites with precise layered microstructure is therefore important yet remains difficult. Here, one straightforward bottom‐up film‐to‐bulk assembly strategy is focused for fabricating bioinspired layered bulk structural nanocomposites. The bottom‐up assembly strategy inherently offers a methodology for precise construction of bioinspired layered microstructure in bulk form, availability for fabrication of bioinspired bulk structural nanocomposites with large sizes and complex shapes, possibility for design of multiscale interfaces, feasibility for manipulation of diverse heterogeneities. Not limited to discussing what has been achieved by using the current bottom‐up film‐to‐bulk assembly strategy, it is also envisioned how to promote such an assembly strategy to better benefit the development of bioinspired bulk structural nanocomposites. Compared to other assembly strategies, the highlighted strategy provides great opportunities for creating bioinspired bulk structural nanocomposites on demand.

No abstract available

No abstract available

Plastic pollution is one of most daunting sustainability challenges. Multi-functional and biodegradable plastics are critical for both desirable end-of-life outcomes and petrochemical plastics replacement. Current bioplastics are either: short of mechanical properties, like polyhydroxybutyrate (PHB); lack room temperature biodegradability, like polylactic acid (PLA); or lack the functionality to create additional values. Here, we present the bioinspired Layered, Ecological, Advanced, and multi-Functional Film (LEAFF), for sustainable plastic packaging. This biomimetic composite, based on the structure of the natural plant leaf, synergistically improves mechanical strength while empowering PLA for rapid ambient soil biodegradability, achieving complete degradation in 5 weeks. The film is also highly transparent and water stable, and achieves high gas barrier properties to improve food shelf life and reduce waste. The biomimetic design showcases the synergistic advantage leveraged by the LEAFF’s multilayer structure to enhance mechanical performance while simultaneously retaining biodegradability and achieving multifunctionality for broad applications. Designing biodegradable plastics is highly desirable, though it has been a challenge to balance mechanical properties with biodegradability. Here the authors design a multilayered biodegradable composite without compromising the mechanical properties.

Porous bone implants have been extensively studied, with gradient structures receiving increasing attention due to their superior compatibility with bone tissue. However, comparative studies between gradient and uniform structures remain relatively scarce. In this study, selective laser melting (SLM) technology was employed to fabricate a gradient composite Ti6Al4V humeral bone plate, utilizing rhombic dodecahedron and its derived structures as unit cells. By adjusting the porosity parameter range to 22.02–94.37% using the Ashby Gibson formula, the mechanical properties of the porous bone plate were analyzed by varying the porosity parameters and conducting compression tests. The experimental results show that after preparing and compressing the structure, the elastic modulus of the model is controlled between 0.09–5.43 GPa, and the maximum yield strength is 216.1 Mpa. The experimental results demonstrate that, under shear loading, the gradient structure generates stress from the center of mass, with the phenomenon becoming more pronounced as the number of struts aligned with the direction of the applied load increases. This results in the model exhibiting characteristics of good resilience on the outside and a certain degree of rigidity on the inside. Compared to non-gradient models, gradient structures are more effective in controlling the direction of force transmission. Moreover, the elastic modulus of the bone plate is closer to that of natural bone tissue. These findings provide valuable insights for further research into gradient structure models of other rod-shaped unit cells, highlighting the mechanical advantages of gradient structures over uniform ones.

Despite an increasing number of tissue-engineered scaffolds have been developing for bone regeneration, simple and universal fabrication of biomimetic bone microstructure to repair full-thickness bone defects remains a challenge and an acute clinical demand due to the negligence of microstructural differences within the cortex of cancellous bone. In this work, a biomimetic sandwich-layered PACG-CS@Mn(III) hydrogel (SL hydrogel) was facilely fabricated in an end-tail soaking strategy by simply post-crosslinking of poly(acryloyl 2-glycine)-chitosan (PACG-CS) composite hydrogel using trivalent manganese solutions. Taking the merits of in-situ formation and flexible adjustment of chain entanglements, hydrogen bonds and metal chelate interactions, SL hydrogel with sandwich-like three-layered structures and anisotropic mechanical performance was easily customized through control of the manganese concentration and soaking time in fore-and-aft sides, simulating the structurally and mechanically biomimetic characteristics of cortical and cancellous bone. Furthermore, the produced SL hydrogel also demonstrated favorable biocompatibility and enhanced MnSOD activity via a peroxidase-like reaction, which enabled the excellent radical scavenging efficiency and anti-inflammatory regulation for facilitating the activity, proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs). In vivo studies further revealed that these SL hydrogels achieved restrictive pro-vascular regeneration through their stratified structure, thereby promoting the differentiation of osteoblasts. Simultaneously, the mechanical cues of stratified structure could mediate macrophage phenotype transitions in accordance with stem cell-osteoblast differentiation process via the PI3K-AKT pathway, resulting in robust osteogenesis and high-quality bone reconstruction. This facile yet efficient strategy of turning anisotropic hydrogel offers a promising alternative for full-thickness repair of bone defects, which is also significantly imperative to achieve high-performance scaffolds with specific usage requirements and expand their clinic applicability in more complex anisotropic tissues.

Developing an engineered scaffold inspired by structural features of healthy articular cartilage (AC) has attracted much attention. In this study, the design and fabrication of a three-layered fiber/hydrogel scaffold in which each layer replicates the organization of a pertinent layer of AC tissue is aimed. To this end, electrospun poly-L-lactic acid (PLLA) nanofibers are prepared and fragmented into nano/micro cylinders via aminolysis. Three-layers of the scaffold, a fibrin coated fibrous layer, a fibrin gel (FG) layer incorporating chopped fibers and a FG embedding cylindrical aligned fibrous mat perpendicular to articulating surface, respectively served as an upper, middle and bottom layers, are prepared. The layers’ physicomechanical characteristics are comprehensively evaluated. Results show that optimized electrospinning set up results in the smallest fibers diameter of 367 ± 317 nm and successful aminolysis provides amine-functionalized chopped nanofibers with a mean length of 1.46 ± 0.9 µm. Static mechanical analysis of the layers demonstrates that tensile Young’s modulus of the upper layer is 152 ± 17 MPa while compressive moduli of the middle and bottom layers are 9.8 ± 3.8 and 25.3 ± 5.2 KPa, respectively and the compressive modulus of three-layered scaffold is 13.7 ± 2.5 KPa. Assessing mechanical parameters under dynamic loading also shows that adding fibrous part in the composite scaffold layers enhances viscoelastic behavior of FG. Also, incorporation of 0.25% chopped fibers into the fibrin matrix notably enhances the equilibrium water content; however, it increases in-vitro weigh loss rate from 6% to 10.5% during a seven-day period. Cytocompatibility analysis confirms that all layers possess acceptable cytocompatibility. In a conclusion, the designed three-layered composite structure successfully mimics the physicomechanical as well as microstructural features of AC and could be suggested as a potential scaffold for this tissue regeneration.

Dura mater defect and subsequent cerebrospinal fluid (CSF) leakage usually appear in trauma or neurosurgical procedures and are followed by a series of serious complications and even death. The use of a qualified dura mater substitute with multifunction of leakage blockade, adhesion prevention, and dura reconstruction is one of the promising treatment methods. However, even though some products have been used in the clinic, none of the substitutes achieved the required multifunction. In this study, we aimed to design and fabricate a dura repair composite with the ideal multifunction. By biomimicking the structure and component of natural dura, we applied L-polylactic acid (PLLA), chitosan (CS), gelatin, and acellular small intestinal submucosa (SIS) powders to successfully prepare a triple-layered composite. Then, a series of specific devices and techniques were developed to investigate the performance. The results revealed that satisfactory structural stability could be realized under good synergistic interactions among the components. In addition, all the findings suggested that the bionic triple-layered composite showed satisfactory multifunction of leakage blockade, adhesion prevention, antibacterial property, and dura reconstruction potential, and thus, it might be a promising candidate for dura repair. STATEMENT OF SIGNIFICANCE: : Developing qualified dura mater substitutes with multifunction of leakage blockade, adhesion prevention, and dura reconstruction is crucial for treating dura mater defect and subsequent cerebrospinal fluid (CSF) leakage that appear in trauma or neurosurgical procedures. In this study, we designed and fabricated a triple-layered dura repair biocomposite with satisfactory structural stability and desired multifunction based on biomimicking of the structure and component of natural dura. Moreover, a series of specific devices and techniques were developed to investigate the relevant performance. Overall, the developed hydrogel electrospinning system exhibited excellent advantages in achieving multifunction and could be applied widely in the future to achieve multifunctional tissue repair materials.

Dielectric materials with excellent thermally conductive and mechanical properties can enable disruptive performance enhancement in the areas of advanced electronics and high-power devices. However, simultaneously achieving high thermal conductivity and mechanical strength for a single material remains a challenge. Herein, we report a new strategy for preparing mechanically strong and thermally conductive composite films by combining aramid nanofibers (ANFs) with graphene oxide (GO) and edge-hydroxylated boron nitride nanosheet (BNNS-OH) via a vacuum-assisted filtration and hot-pressing technique. The obtained ANF/GO/BNNS film exhibits an ultrahigh in-plane thermal conductivity of 33.4 Wm−1 K−1 at the loading of 10 wt.% GO and 50 wt.% BNNS-OH, which is 2080% higher than that of pure ANF film. The exceptional thermal conductivity results from the biomimetic nacreous “brick-and-mortar” layered structure of the composite film, in which favorable contacting and overlapping between the BNNS-OH and GO is generated, resulting in tightly packed thermal conduction networks. In addition, an outstanding tensile strength of 93.3 MPa is achieved for the composite film, owing to the special biomimetic nacreous structure as well as the strong π−π interactions and extensive hydrogen bonding between the GO and ANFs framework. Meanwhile, the obtained composite film displays excellent thermostability (Td = 555 °C, Tg > 400 °C) and electrical insulation (4.2 × 1014 Ω·cm). We believe that these findings shed some light on the design and fabrication of multifunctional materials for thermal management applications.

No abstract available

Polysaccharide-based adhesives, especially chitosan (CS)-derived adhesives, serve as promising sustainable alternatives to traditional adhesives. However, most demonstrate a poor adhesive strength. Inspired by the inherent layered structure of marine arthropods (lobsters), a core-shell structure (SiO2-NH2@OPG) with amine-functionalized silica (SiO2-NH2) as the core and oxidized pyrogallol (OPG) as the shell is prepared in this study. The compound is blended with CS to produce a structural biomimetic wood adhesive (SiO2-NH2@OPG/CS) with excellent performance. In addition to thermocompressive curing, this adhesive exhibits a water-evaporation-induced curing behavior at room temperature. With reference to the design mechanism of the lobster cuticle, this microphase-separated structure consists of clustered nanofibers with varying amounts of SiO2-NH2@OPG particles between the fibers. This intriguing microphase structure and its mechanical effects could offer a powerful solution for improving the functional modification of wood composites.

Conductive hydrogels have broad application in flexible electronics, soft robotics, and human-machine interaction. However, the limited mechanical properties and complex fabrication processes hinder further development. This study proposes a biomimetic hierarchical fabrication strategy to create MXene (2D transition metal carbides)/polyvinyl alcohol (PVA) composite conductive hydrogels with a layered microstructure (LMP) via evaporation-induced self-assembly. The joint action of multiple energy dissipation mechanisms significantly enhances the mechanical properties of the hydrogel, achieving a tensile strength of 6.11 MPa, toughness of 20.57 MJ m- 3, and elongation at break of 730.73%. Meanwhile, the high conductivity of Ti3C2Tx MXene endows the hydrogel with excellent sensing capabilities, including strain sensitivity (GF = 1.96), fast response time (≈100 ms), and temperature sensitivity (TCR = -3.468%/°C). This study provides a simple and efficient strategy for developing strong, tough, and multifunctional conductive hydrogels.

Lightweight structural composite materials are widely used in automobiles, aerospace, and other fields. However, achieving the integration of structural and functional properties, such as the ability to monitor external forces, remains a significant challenge. Nacre and turtle shells in nature are strong and tough due to their unique ordered structure of alternating soft and hard phases. Inspired by this, an interface anchoring strategy is proposed which leverages hyphae (filamentous structure forming the vegetative part of fungi) to fix the hard‐phase graphene nanosheets (GNs) and the soft‐phase intertwined polymer matrix to form theree‐dimentional (3D) layered bulk composites (LBCs). The growth pattern of fungi is utilized to place GNs and assemble polyethylene glycol‐polyvinyl alcohol (PEG‐PVA) to fabricate the LBCs, which is different from most existing preparation methods of bulk biomimetic composites. The LBCs exhibit self‐regenerative capabilities and are amenable to scalable manufacturing. These composites demonstrate impressive mechanical properties, including a specific strength of 92.8 MPa g cm−3, fracture toughness of 6.5 MPa m−1/2, and impact resistance of ∼3.1 kJ m−2, outperforming both natural nacre and other biomimetic layered composites. Furthermore, the LBCs display effective protective warning functions under external force stimulations, making them a promising material for anti‐collision applications in industries such as sports and aerospace.

Humidity-responsive actuators, which can directly convert ambient humidity changes into controllable mechanical deformation, exhibit broad application potential in fields such as bionic robotics, smart wearable devices, and human-machine interactive systems. MXenes have emerged as ideal humidity-responsive materials due to their unique two-dimensional layered structure, exceptional surface hydrophilicity and electrical conductivity. However, their poor environmental stability severely limits their application in humidity-driven actuators. In this study, we designed a composite film (MXBC) based on MXene-Nb2CTx and bacterial cellulose (BC), where a three-dimensional layered-fiber interwoven structure synergistically enhances humidity-driven performance through a hydrogen-bonding network. The MXBC film demonstrates an ultrafast response of 536° within 0.5 s under ΔRH = 50%, along with remarkable cycling stability over 3000 cycles, while maintaining robust mechanical properties. Leveraging these advantages, we successfully developed various intelligent bionic devices, including biomimetic flytraps, artificial flowers, smart switches, and adaptive clothing. This study not only provides a new strategy for developing highly stable and multifunctional smart actuating materials but also expands the application of MXenes in environmentally adaptive soft robotics and interactive wearable systems.

Owing to the evolution of 5G technology, new energy vehicles, flexible electronics, miniaturization and integration of microelectronic devices, high-frequency and high-power devices, and thermal management of materials must consider additional limitations such as electrical insulation, excellent transverse heat transfer, flexibility, and weight. Boron nitride nanosheets (BNNSs) are ideal insulating materials with high thermal conductivity. However, the problem of the 3D thermal conductivity pathway and toughness strength of nanocomposite paper loaded with inorganic thermal conductivity fillers remains a huge challenge. In this study, we propose a new method for preparing ultrathin, large, and uniformly thick BNNS for quantitative production. Bulk hexagonal boron nitride (hBN) layers were exfoliated using a simple and low-cost hydrothermal reaction, and large-scale fewer-layered BNNSs were efficiently prepared by ball milling with a high yield (up to 80%). Based on the aforementioned step, a flexible insulating composite film with high thermal conductivity and a natural "brick-mud" shell structure was constructed via the sol-gel-film conversion method. After prestretching and hot-pressing treatment, the hydrogels became denser, and the modified BNNS formed a three-dimensional (3D) network structure with an ordered orientation and interconnections in the bacterial cellulose (BC) matrix. After 100 folding cycles, the tensile strength of the nanofiber composite film reached 53 MPa, and the strength retention rate exceeded 42%. By optimizing the modified BNNS content, the thermal conductivity reached 24 W/(m·K). This simple approach has wide application potential in the next-generation electronic devices, providing options for designing thermal interface materials with excellent electrical insulation, high thermal stability, and flexibility.

Although responsive actuators have been intensively investigated, it remains challenging to enable rapid and self-oscillating actuation under ambient circumstances without human intervention analogous to living organisms. By hybridizing a unique type of two-dimensional nanomaterials (i.e., MXene) with a particular hydrophilic polymer, a smart and flexible conductive composite was produced with rapid actuation and spontaneous oscillation near a moist surface. Due to the presence of layered microstructures and the moisture-sensitivity improved by surface roughness and intercalated polymeric layers, the composites could reversibly bend up to 180° in 2 s or 210° in 10 s on demand when the circumstantial humidity was varied, being superior or comparable to many actuators in the literature. More importantly, the composite was capable not only of flipping upside down repeatedly on the moist surface but also of self-oscillating ceaselessly under ambient gradient humidity without human intervention, e.g., an oscillation between 30 and 100° with an oscillation frequency of 0.08 Hz. This self-oscillation resulted from the occurrence of rapid asymmetrical hydration and dehydration of the composite between the regions of high and low humidity, which could further be modulated both by different hydrophilic polymers and by photoradiation owing to the photothermal effect of MXene nanosheets. Because of the ubiquitous presence of humidity gradient near the moist surface, this type of smart composite may not only offer a strategy for designing artificial materials that are capable of spontaneous actuation under ambient circumstance without human intervention but also promise potential applications in artificial muscles, autonomous robotics, and energy harvesting from environments.

The rapid development of modern electrical engineering puts forward urgent demand for high-performance electrical insulating materials. In this study, inspired by the layered structure of natural nacre, we present a novel biomimetic composite insulating film (referred to as M/C film) that is derived from agricultural waste corncobs and industrial waste mica tailings through a sol-gel-film transformation process. The novel insulating film has excellent tensile strength (94 MPa), high dielectric strength (68 kV mm-1), low dielectric loss, good heat resistance (T0 = 235 °C), and excellent UV shielding properties. Meanwhile, the M/C film presents environmental impacts much lower than those petrochemical-based plastic film as it can be 100 % recycled in a closed-loop recycling process and easily biodegraded in the environment (lignocellulose goes back to the carbon cycle and the mica return to the geological cycle). It is a potential alternative for petrochemical plastics and provides a possible way to utilize agricultural waste and mica tailings.

No abstract available

No abstract available

Organic-inorganic hybrid layer-by-layer (LBL) composite structures can not only increase the strength and ductility of materials but also well disperse nanomaterials for better-conducting pathways. Here, we discovered the self-assembly process of an organic and silver (Ag) LBL hybrid structure having excellent sustainability during the long-term bending cycle. During the assembly process, the organic and Ag hybrid structure can be self-assembled into a layered structure. Unlike other conventional LBL fabrication processes, we applied the hydrogel scaffold of a biological polymer, which can spontaneously phase separate into an LBL structure in a water/alcohol solvent system. This new hydrogel-based Ag LBL patterns can successfully be printed on a flexible polyimide film without nozzle-clogging problem. Although these Ag LBL patterns cracked during the bending cycle, carbonized organic compounds between the Ag layers help to self-heal within few minutes at a low temperature (<80 °C). On the basis of our new hydrogel-based Ag ink, we could fabricate a fully printed reliable microscale flexible heater. We expect that our self-layering phenomenon can expand to the broad research field of flexible electronics in the near future.

Throughout millions of years of biological evolution, shell structures have developed a highly complex layered organic–inorganic structure that makes them effective against a wide range of external impacts, including mechanical stress and chemical corrosion. Therefore, shell-like biomimetic materials are considered to possess high strength and toughness. Nevertheless, although shell structures have exhibited superior performance across multiple domains, understanding of their structural complexities and corrosion protection mechanisms remains relatively limited within the scope of human knowledge. In this study, alternating ZnO–graphene/epoxy coatings featuring shell-like structures were synthesized, and their anticorrosion properties were evaluated through the incorporation of ZnO to enhance the dispersion of graphene. Electrochemical impedance spectroscopy (EIS) tests showed that with an increased number of ZnO–graphene layers, the coating resistance of the bionic composite coating also increased: from 8.21 × 107 Ω·cm2 of the pure epoxy coating to 7.64 × 108 Ω cm2. The composite coating, comprising three alternating layers of zinc oxide and four layers of epoxy resin, exhibited an electrochemical impedance two orders of magnitude greater than that of pure epoxy resin following immersion in a 3.5% sodium chloride solution, demonstrating excellent corrosion resistance. The results showed that with increased ZnO–graphene layers, ZnO–graphene disperses more uniformly in water and has greater rigidity.

No abstract available

Amorphous alumina is hard but brittle like all ceramic type materials which affects durability under impact or scratch. Here we show that alumina layers below 100 nm thickness when stacked with aluminum interlayers exhibit exceptional performances including toughness equal to 300 J.m−2 determined by on chip nanomechanics. This is almost two orders of magnitude higher than bulk alumina and higher than any other thin hard coatings. In addition, a hardness above 8 GPa combines with a fracture strain above 5%. The origin of this superior set of properties is unravelled via in-situ TEM and mechanical models. The combination of constrained alumina layers with ductile behavior, strong “accommodating” interfaces, giant shear deformability of Al layers, and plasticity-controlled crack shielding cooperate to stabilize deformation, dissipate energy and arrest cracks. These performances unlock several options of applications of Al2O3 in which brittleness under contacts prevents benefiting from remarkable functional properties and chemical stability. Alumina layers below 100 nm thickness stacked with aluminum interlayers combine exceptional properties including high toughness, strength and ductility. The origin of this optimal tryptic is unraveled by advanced nanomechanics and in-situ TEM.

Architected lattice metamaterials offer tunable, exceptional mechanical performance through precisely engineered microarchitectures, yet an intrinsic trade‐off between strength and toughness remains a fundamental design challenge. Here, a class of aperiodic architected metamaterials guided by the golden ratio ‐ a geometric principle emblematic of natural balance and structural harmony—is introduced to overcome this limitation. The concept is validated via additive manufacturing of conventional periodic, hierarchical periodic, and golden‐ratio‐guided aperiodic lattices, along with their interpenetrating phase composite (IPC) counterparts. The aperiodic architectures exhibit significantly enhanced damage tolerance under monotonic loading, with increases of 84.24% and 42.45% in ultimate load, and 277.43% and 128.13% in initial fracture energy, for the lattice and IPC metamaterials, respectively. Under cyclic loading, only the aperiodic IPC withstands five tensile cycles at 350 N before incurring damage, whereas all other architectures fail during the initial cycle. These improvements stem from the unification of local geometric heterogeneity and global order in the golden‐ratio‐guided aperiodic architecture, which alleviates stress concentrations and promotes spatial delocalization of damage‐tolerence regions. As a result, crack paths become more tortuous and adaptive, enhancing energy dissipation and resistance to fracture. These findings establish golden‐ratio‐guided aperiodicity as a robust design paradigm for next‐generation damage‐tolerant metamaterials.

High mechanical strength, toughness, and fatigue resistance are essential to improve the reliability of conductive hydrogels for self‐powered sensing. However, achieving mutually exclusive properties simultaneously remains challenging. Hence, a novel directed interlocking strategy based on topological network structure and mechanical training is proposed to construct tough hydrogels by optimizing the network structure and modulating the orientation of molecular chains. Combining Zn2+ crosslinked cellulose nanofibers (CNFs) and a polyacrylamide‐poly(vinyl alcohol) double‐network, the unique interlocked‐network structure exhibits an enhanced toughening effect due to hydrogen bonding and metal‐ligand interactions. The aligned nanocrystalline domains achieved by training further contribute to an increase in the toughness and fatigue thresholds. This innovative approach synergistically enhances the mechanical properties of the nano‐conductive hydrogel, achieving a maximum tensile strength of 4.98 MPa and a toughness of 48 MJ m−3. Notably, the CNFs template with anchored polyaniline, when oriented through mechanical training, forms a unique directional conductive pathway, which significantly enhances the power output performance. Besides, a motion recognition system based on a self‐powered sensing device is designed with the assistance of deep learning techniques to accurately identify human motion behaviors. This work showcases a potentially transformative flexible electronic material for self‐powered sensing systems and intelligent recognition systems.

No abstract available

Characterized by periodic cellular unit cells, microlattices offer exceptional potential as lightweight and robust materials. However, their inherent periodicity poses the risk of catastrophic global failure. To address this limitation, a novel approach, that is to introduce microlattices composed of aperiodic unit cells inspired by Einstein's tile, where the orientation of cells never repeats in the same orientation is proposed. Experiments and simulations are conducted to validate the concept by comparing compressive responses of the aperiodic microlattices with those of common periodic microlattices. Indeed, the microlattices exhibit stable and progressive compressive deformation, contrasting with catastrophic fracture of periodic structures. At the same relative density, the microlattices outperform the periodic ones, exhibiting fracture strain, energy absorption, crushing stress efficiency, and smoothness coefficients at least 830%, 300%, 130%, and 160% higher, respectively. These improvements can be attributed to aperiodicity, where diverse failure thresholds exist locally due to varying strut angles and contact modes during compression. This effectively prevents both global fracture and abrupt stress drops. Furthermore, the aperiodic microlattice exhibits good damage tolerance with excellent deformation recoverability, retaining 76% ultimate stress post-recovery at 30% compressive strain. Overall, a novel concept of adopting aperiodic cell arrangements to achieve damage-tolerant microlattice metamaterials is presented.

Its excellent renewability and biodegradability make cellulose an attractive resource to prepare fossil-based plastic alternatives. However, cellulose itself exhibits strong intermolecular hydrogen bond (H-bond) interactions, significantly restricting the mobility of cellulose chains, thus leading to poor thermo-processing performance. Here, we reconstructed the intermolecular interactions of cellulose chains via replacing the original H-bonds with dynamic covalent bonds. By this, cellulose can be easily thermo-processed into a cellulosic plastic under mild conditions (70 °C). Through adjusting the chemical structure of dynamic covalent networks, the cellulosic plastic shows tunable mechanical strength (3.0-33.5 MPa) and toughness (43-321 kJ m-2). The cellulosic plastic also exhibits excellent resistance to water, organic solvent, acid solution, alkali solution, and high temperature (>400 °C). Moreover, it owns good chemical and biological degradability and recyclability. This work provides an effective method to develop high-performance cellulosic plastics for fossil-based plastic substitution.

Photocurable 3D printing technology has outperformed extrusion-based 3D printing technology in material adaptability, resolution, and printing rate, yet is still limited by the insecure preparation and selection of photoinitiators and thus less reported. In this work, we developed a printable hydrogel that can effectively facilitate various solid or hollow structures and even lattice structures. The chemical and physical dual-crosslinking strategy combined with cellulose nanofibers (CNF) significantly improved the strength and toughness of photocurable 3D printed hydrogels. In this study, the tensile breaking strength, Young's modulus, and toughness of poly(acrylamide-co-acrylic acid)D/cellulose nanofiber (PAM-co-PAA)D/CNF hydrogels were 375 %, 203 % and 544 % higher than those of the traditional single chemical crosslinked (PAM-co-PAA)S hydrogels, respectively. Notably, its outstanding compressive elasticity enabled it to recover under 90 % strain compression (about 4.12 MPa). Resultantly, the proposed hydrogel can be utilized as a flexible strain sensor to monitor the motions of human movements, such as the bending of fingers, wrists, and arms, and even the vibration of a speaking throat. The output of electrical signals can still be collected through strain even under the condition of energy shortage. In addition, photocurable 3D printing technology can provide customized services for hydrogel-based e-skin, such as hydrogel-based bracelets, fingerstall, and finger joint sleeves.

Traditional oxide ceramics are inherently brittle and highly sensitive to defects, making them vulnerable to failure under external stress. As such, endowing these materials with high strength and high toughness simultaneously is crucial to improve their performance in most safety‐critical applications. Fibrillation of the ceramic materials and further refinement of the fiber diameter, as realized by electrospinning, are expected to achieve the transformation from brittleness to flexibility owing to the structural uniqueness. Currently, the synthesis of electrospun oxide ceramic nanofibers must rely on an organic polymer template to regulate the spinnability of the inorganic sol, whose thermal decomposition during ceramization will inevitably lead to pore defects, and seriously weaken the mechanical properties of the final nanofibers. Here, a self‐templated electrospinning strategy is proposed for the formation of oxide ceramic nanofibers without adding any organic polymer template. An example is given to show that individual silica nanofibers have an ideally homogeneous, dense, and defect‐free structure, with tensile strength as high as 1.41 GPa and toughness up to 34.29 MJ m−3, both of which are far superior to the counterparts prepared by polymer‐templated electrospinning. This work provides a new strategy to develop oxide ceramic materials that are strong and tough.

Plant based proteins are green, sustainable, and renewable materials that show the potential to replace traditional formaldehyde resin. High performance plywood adhesives exhibit high water resistance, strength, toughness, and desirable mildew resistance. Adding petrochemical-based crosslinkers is not economically viable or environmentally benign; this chemical crosslinking strategy makes the imparted high strength and toughness less attractive. Herein, a green approach based on natural organic-inorganic hybrid structure enhancement is proposed. The design of soybean meal-dialdehyde chitosan-amine modified halloysite nanotubes (SM-DACS-HNTs@N) adhesive with desirable strength and toughness enhanced by covalent bonding (Schiff base) crosslinking and toughened by surface-modified nanofillers is demonstrated. Consequently, the prepared adhesive showed a wet shear strength of 1.53 MPa and work of debonding of 389.7 mJ, which increased by 146.8 % and 276.5 %, respectively, due to the cross-linking effect of organic DACS and toughening effect of inorganic HNTs@N. The introduction of DACS and Schiff base generation enhanced the antimicrobial property of the adhesive and increased the mold resistance of the adhesive and plywood. In addition, the adhesive has good economic benefits. This research creates new opportunities for developing biomass composites with desirable performance.

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.

Nanocellulose films possess numerous merits ascribing to their inherent biocompatibility, non-toxic and biodegradability properties. The potential for practical applications would be improved if their mechanical strength and toughness requirements could be met simultaneously. Herein, dual cross-linked nanocellulose (DC) film was fabricated by the treatments of chemical and physical cross-linking, which was mechanically superior to pure nanocellulose (CNF) films. To further increase the toughness of DC films, spherical cellulose (Sph) was incorporated into DC film (DC-Sph film), and analyzed under different humidity conditions (RH) (from 10 % to 90 %). The changes of functional groups of CNF, DC and DC-Sph films were detected by FTIR and XPS spectrum. The epichlorohydrin and Sph content were optimized, followed by the investigation of RH on the toughness of films. The highest tensile strength (146.6 ± 4.6 MPa) was obtained in DC film at 50 % RH, while the DC-Sph film showed the largest toughness (40.3 ± 3.7 kJ/m2) at 70 % RH. Furthermore, the possible toughening mechanism of DC-Sph film was also discussed.

The energy dissipative features of hydrogen bonds under conditions of mechanical strain have provided an ongoing incentive to explore hydrogen bonding units for the purpose of controlling and customizing the mechanical properties of polymeric materials. However, there remains a need for hydrogen bond units that (1) possess directionality, (2) provide selectivity, (3) dissipate energy effectively, and (4) can be incorporated readily into polymeric materials to regulate their mechanical properties. Here, we report mechanically interlocked hydrogen bond units that incorporate multiple hydrogen bonds within a [2]catenane structure. The conformational flexibility and associated spatial folding characteristics of the [2]catenane units allow for molecular scale motion under external stress, while the interlocked structure serves as a pivot that maintains the directionality and selectivity of the resultant hydrogen bonding units. When incorporated into polymers, these interlocked hydrogen bond motifs serve to strengthen and toughen the resulting materials. This study not only presents a novel hydrogen bond unit for creating polymeric materials with improved mechanical properties but also underscores the unique opportunities that mechanically interlocked hydrogen bond structures may provide across a diverse range of applications.

Poly(ε-caprolactone)/poly(lactic acid) (PCL/PLA) blends are promising biomaterials with biodegradable characteristics. However, poor compatibility of the two components may lead to undesirable mechanical properties. In this work, the effect of combining carboxyl multi-walled carbon nanotubes (CNTs) and organically modified montmorillonite (MMT) on the morphology and properties of PCL/PLA blend was investigated. The morphological observations and rheological analysis showed that exfoliated MMT platelets enhanced interfacial adhesion of the two phases, whereas CNTs formed a percolating network in PCL matrix. The addition of CNTs/MMT (0.5 wt% : 0.5 wt%) led to an increase by 137.4% in elongation at break, 79.6% in tensile strength, and 14 oC in decomposition temperature without sacrificing its rigidity apparently for the PCL/PLA matrix. Obvious synergistic effect was demonstrated in comparison to the blends containing single nanofiller. This study demonstrated that combining CNTs and MMT is a facile way to preparing immiscible PCL/PLA blends based nanocomposites with interesting structure and properties.

The development of intrinsic self-healing elastomers with simultaneous high mechanical strength, toughness and room-temperature reparability remains a formidable challenge. Herein, we report a mechano-responsive strategy, known as strain induced crystallization, to address the above issue, whereby synthesized elastomers with unprecedented high mechanical performances are bestowed with room-temperature self-healing materials, achieving tensile strength, toughness and fracture energy values of 29.0 MPa, 121.8 MJ m-3 and 104.1 kJ m-2, respectively.

Glass transition temperature (Tg) always deteriorates while improving the strength of epoxy resins which inherently suffer from brittleness. Herein, novel linear polyhedral oligomeric silsesquioxane (POSS)-epoxy nano-modifiers are synthesized with variable contents of POSS. The thermomechanical properties and chemical structure study of the POSS-epoxy indicates significant differences of the rigid POSS content in the linear nano-modifiers. By taking advantage of the synergistic effect of nanofillers and linear polymers, the modifiers disperse at the molecular level when POSS-epoxy is utilized as a co-curing agent for epoxy resins, allowing the applied force to be transferred into the polymer matrix. A good balance of Tg, stiffness, and fracture toughness can be obtained. At 5 wt% of the nano-modifier, the resultant epoxy resins showed 27% enhancement in the Young's modulus relative to the neat epoxy. In addition, the Tg and strength of epoxy thermosets are improved due to the increased cross-linking density, rough surface and tortuous path that resulted in good dispersion of energy during crack propagation.

Natural polymeric hydrogels are expected to serve as potential structural biomaterials, but, most of them are usually soft and fragile. Herein, a polyphenol-mediated self-assembly (PMS) strategy was developed to significantly enhance the chitin hydrogel strength and toughness at the same time, which is distinctive from the rigid-soft double-network energy-dissipation approaches. A polyphenol (tannic acid, TA as a model compound) was introduced to compete with the chitin chains self-assembly for simultaneously forming the weak chitin-TA and strong chitin-chitin networks. High-density noncovalent crosslinking involving hydrogen bonding and ionic and hydrophobic interactions endowed the PMS hydrogels with a high modulus and strength. The relatively weaker chitin-TA crosslinking acted as the sacrificial bonds to dissipate the energy, leading to the high toughness. The mechanical properties of the PMS chitin hydrogels depended on the TA concentration and ethanol aqueous coagulation, which mainly contributed to the hydrophobic and hydrophilic interactions formation, respectively. The fully naturally robust chitin-TA hydrogels exhibited considerable antibacterial properties, stomach acid solubility, and excellent biocompatibility and degradability, enabling their potential in food, biomedical, and sustainable applications.

Owing to their anisotropic and hierarchical structure, tendons exhibit an outstanding mechanical performance despite the low polymer concentration and softness of the constituent materials. Here, we propose a tendon-mimicking, strong, and tough hydrogel with a multiscale hierarchical and anisotropic structure. An isotropic, precursor double-network hydrogel is transformed into an anisotropic hydrogel by stretching, solvent exchange, and subsequent fixation via ionic crosslinking. Solvent exchange induces densification of the stretched polymer network, enhancement of linear alignment of polymer chains, and microphase separation, leading to anisotropic toughening of the hydrogel. The resulting anisotropic hydrogels show high strength and toughness, which vary over a wide range (1.2-3.3 MPa of strength and 4.9-8.8 MJ/m3 of toughness, respectively), controlled by the degree of pre-stretching. Furthermore, a hierarchical architecture is constructed by braiding the anisotropic hydrogel strands into a rope, resulting in an improved mechanical performance (4.7 MPa of strength in a four-strand hydrogel rope) compared to separated unbraided strands of a hydrogel (2.3 MPa of strength). The higher hierarchical hydrogel cable, prepared by braiding four hydrogel ropes, can withstand a heavy load even up to 13 kg. These results represent that a hierarchical assembly of anisotropic hydrogels exhibits high mechanical performance and a hierarchically anisotropic structure, which are reminiscent of tendons.

No abstract available

A bioinspired PEEK material with hard “bricks” of nanoscale lamellae and micron-scale deformed spherulites bonded by soft “mortar” of a rigid amorphous fraction was produced with a pressure-induced flow (PIF) processing applied in the solid-state. Novel mechanisms were proposed for the marked and simultaneous improvement in the strength and toughness, where the tensile strength and impact strength could be increased to ∼200% and ∼450%, respectively. On one hand, the rotation, recombination and restacking of the crystalline blocks formed an oriented and stratified morphology similar to the “brick-and-mortar” structure in nacre, and resulted in the confined crack propagations and the tortuous energy dissipating paths. On the other hand, the PIF-relaxation due to the newly generated rigid amorphous fraction further contributed to the improvement of the impact strength. The efficiency of enhancement could be controlled by the molding temperature, the compression ratio, and the volume fraction of chopped carbon fiber. As a result, PIF-processing might endow the PEEK material with improved mechanical matching with the surrounding tissues and extended service life in biomedical applications while retaining excellent biocompatibility with no external substances introduced.

Interconnected macro-porous cryogels with robust and pore-tunable structures have been fabricated using chemically crosslinked microfibrillated cellulose (MFC). Periodate oxidation was initially conducted to introduce aldehyde groups into the MFC surface, followed by the freeze-induced chemical crosslinking via the formation of hemiacetal bonds between aldehyde and hydroxyl at -12 °C. The cryogels with pore-tunable structures and sharply enhanced mechanical strengths were finally achieved by re-assembly of MFCs through soaking in NaIO4 solution. Furthermore, the MFC cryogels were post-crosslinked by polyethyleneimine (PEI), bestowing the cryogels with the capability of adsorbing anionic dyes. The stress of the PEI-MFC cryogel at the 80% strain was determined to be 304.5 kPa, which is the maximum value for the nanocellulose-based cryogels reported so far. Finally, the adsorption performances of PEI-MFC cryogels for methyl orange (MO) were evaluated. Maximum adsorption capacity of 500 mg/g could be obtained by the Langmuir model, outperforming that of previous absorbent materials. Reuse experiments indicated that over 90% of adsorption capacity was retained after 6 cycles. Continuous clean-up experiments demonstrated excellent MO removal abilities of the PEI-MFC cryogel. This study shows that the novel, green strategy to fabricate the robust cryogel extends the practical applications of nanocellulose adsorbents for environmental remediation.

No abstract available

One-dimensional cellulose nanofiber (CNF) is prone to constructing connected nanofiber networks in vacuum-assisted self-assembly due to intense hydrogen bonds, which exhibits great superiority in fabricating electromagnetic interference (EMI) shielding composite membranes. However, time-consuming vacuum-assisted assembly process creates vast bottlenecks for spreading EMI shielding CNF composites. Herein, a Calcium ion (Ca2+)-precomplexed vacuum-assisted self-assembly strategy is first proposed to high-efficiently assemble robust CNF&Carbon nanotube/Polyethylene oxide (CNF&CNT/PEO) composite membranes with alternating multilayer architectures. The introduction of Ca2+ pre-complexation can not only largely improve the fabrication efficiency but also immensely enhance the mechanical properties of alternating multilayered CNF&CNT/PEO membranes. The self-assembly time of CNF-5&CNT/PEO-4 is greatly decreased to 756 min at 0.45 mmol/L Ca2+, in comparison with the common vacuum-assisted filtration (i.e., without Ca2+) of 1192 min, owing to the hydrogen bonds between CNF and water broken down by Ca2+ complexation in aqueous dispersion. With the Ca2+ concentration increasing from 0 to 0.23 further to 0.45 mmol/L, the tensile strength of CNF-3&CNT/PEO-2 is gradually reinforced from 40.2 to 43.2 and to 47.6 MPa, as a consequence of the excellent Ca2+ crosslinking and hierarchical “Zigzag” crack paths. The favorable electrical conductivity and unique alternating multilayered structures endow CNF-5&CNT/PEO-4 membrane with the maximal EMI shielding effectiveness (SE) of 43.3 dB. The Ca2+-precomplexed strategy sheds new light on high-efficient self-assembly of multilayered CNF composite membranes with pretty EMI shielding performances, which has prospective application in advanced electronics and microelectronic packaging.

No abstract available

Delicately aligned structures of two-dimensional (2D) MXene nanosheets have demonstrated positive effects on applications, especially in electromagnetic interference (EMI) shielding and infrared (IR) stealth. However, precise regulation of structural assembly by theory-guided solution processing is still a great challenge. Herein, one-dimensional (1D) cellulose nanofibers (CNFs) with a high aspect ratio are applied as a reinforcing agent and a rheological modifier for MXene/CNF colloids to fabricate aligned MXene-based materials for EMI shielding and IR stealth. Notably, a systematical rheological study of the MXene/CNF colloids is proposed to determine the optimal solution-processing conditions for finely oriented component arrangement requirements and provides in-depth information on the interactions between the components. The delicately regulated orientation structure assembled by shear inducement is convincingly demonstrated through micro-CT and wide-angle X-ray diffraction/small-angle X-ray scattering (WAXD/SAXS), which endows the MXene/CNF film with a significantly enhanced electrical conductivity of 46 685 S m-1, a tensile strength of 281.7 MPa, and Young's modulus of 14.8 GPa. Furthermore, the highly aligned structure of the ultrathin film possesses a great enhancement in EMI shielding effectiveness (50.2 dB) and IR stealth (0.562 emissivity). These findings provide a fruitful understanding of the optimized fabrication in solution processing of high-performance MXene-based functional composite films and open up a great opportunity for the development of multifunctional stealth materials.

Liquid hot water (LHW) pretreatment is an environmentally friendly that uses hot water under certain pressure to break down biomass in the absence of chemicals. In this paper, bamboo was used as the substrate to prepare the lignin-containing cellulose nanofibers (LCNFs) and xylo-oligosaccharides (XOS) using LHW strategy. The results showed that a total xylose yield of 63.95 % was achieved in only 20 min, with a high total xylose selectivity of 96.6 %. Meanwhile, a cellulose retention rate of 99.7 % was also achieved. The optimal conditions obtained from the 100 mL reactor were validated through three parallel experiments using the 2 L reactor, and the residue was treated with 1.5 wt% NaOH to reduce the lignin content. LCNF was obtained through ball milling and ultrasonic treatment, and the LCNF film was prepared using an evaporation-induced self-assembly approach, which showed excellent mechanical properties, including tensile strength (109.4 MPa), Young's modulus (1.4 GPa) and elongation at break (28.3 %). Additionally, the LCNF films exhibited effective UV-shielding capacity. This study achieved the full component utilization of bamboo for the co-production of high value-added chemicals and biomass-based materials. Graphical abtsract.

In abdominal wall defect repair, current mainstream polypropylene (PP)-based patches face challenges such as chronic inflammation, mismatched degradation rates, and insufficient anti-deformation properties. While natural biomaterials offer good biocompatibility and degradability, their clinical application is limited by insufficient mechanical strength. To overcome this challenge, we engineered a chitosan (CS) and cellulose nanofiber (CNF)-reinforced collagen membrane. This design leveraged dual polysaccharide functionalities: CNF provided nanoscale reinforcement, while CS enabled multi-point cross-linking with collagen, synergistically enhancing the membrane's structural stability. To further enhance performance, a sequential approach involving the layer-by-layer blade-coating and induced assembly was employed, producing stacked and oriented lamellar structures. The optimized membrane exhibited raised tensile strength (49.00 MPa) and fracture energy (121.22 MJ/m3), prolonged degradation period (52.7 % weight retention at 28 days), and reduced swelling rate (135.5 %). In vitro biocompatibility assays confirmed the material's non-cytotoxicity and excellent blood compatibility. Moreover, in vivo rat abdominal defect models demonstrated superior tissue regeneration, minimized inflammation, and effective mechanical support when using the developed membrane compared to PP meshes and pure collagen membranes (COL). These findings highlight the potential of this green strategy to provide a balanced solution for hernia repair, addressing both mechanical and biological requirements.

Cellulose nanofiber (CNF) is often incorporated as reinforcements into various matrices to optimize the mechanical properties of composites. However, the role of CNF in structural design interface components has been mostly neglected. Inspired by the architectural structure of "straw and clay", CNF and polydopamine (PDA) were used as the "straw phase" and "clay phase", respectively, to construct PDA/CNF self-assembled coatings on the carbon fiber (CF) surface via covalent bonding and non-covalent self-assembly. The organic coatings endowed the CF with high specific surface area, roughness and polarity, as well as a broad and gentle interfacial layer of the CF/epoxy resin composites. After self-assembly, the monofilament tensile strength (TS) of the fiber and the interlaminar shear strength (ILSS) of the CF/epoxy resin composites were increased by 13.44 % and 31.88 %, respectively. This investigation furnishes ideas for improving the mechanical performances of composites from the viewpoint of surface structure design and interface modulation.

The interfacial assembly and rearrangement of nanomaterials are critical for stabilizing air-water/oil-water interfaces. Cellulose nanofibers (CNFs) are promising renewable bio-based solid surfactants that form stable interfacial layers separating the fluid interface. However, the correlations between microstructural features (e.g., defects, orientation, buckling) and physicochemical properties of the interfacial layer remain unclear. This study attempted to understand the interfacial behaviors of CNFs with different hydrophobicity through a common mechanism. First, nanofiber monolayers were fabricated on the water surface of a Langmuir trough. Three different regions corresponding to gaseous, liquid expanded, and liquid condensed films were determined from the characteristic points of surface pressure isotherms. The film structures and their surface dilatational storage/loss moduli exhibited significant changes across these three regions. Overall, we propose that the interfacial behaviors of nanofiber monolayers can be organized by macroscopic wettability of nanofibers which is readily measurable. These results provide insights into the interfacial stabilization mechanism of fibrous nanomaterials and pave the way for applications in functional Pickering emulsions/foams.

The self-assembly of nanocellulose and graphene oxide into highly porous biohybrid materials has inspired the design and synthesis of multifunctional membranes for removing water pollutants. The mechanisms of self-assembly, metal ion capture, and cluster formation on the biohybrids at the nano- and molecular scales are quite complex. Their elucidation requires evidence from the synergistic combination of experimental data and computational models. The AFM-based microscopy studies of (2,2,6,6-tetramethylpiperidine-1-oxylradical)-mediated oxidized cellulose nanofibers (TOCNFs), graphene oxide (GO), and their biohybrid membranes provide strong, direct evidence of self-assembly; small GO nanoparticles first attach and accumulate along a single TOCNF fiber, while the long, flexible TOCNF filaments wrap around the flat, wide GO planes, thus forming an amorphous and porous biohybrid network. The layered structure of the TOCNFs and GO membrane, derived from the self-assembly and its surface properties before and after the adsorption of Cu(II), is investigated by advanced microscopy techniques and is further clarified by the ReaxFF molecular dynamics (MD) simulations. The dynamics of the Cu(II)-ion capture by the TOCNF and GO membranes in solution and the ion cluster formation during drying are confirmed by the MD simulations. The results of this multidisciplinary investigation move the research one step forward by disclosing specific aspects of the self-assembly behavior of biospecies and suggesting effective design strategies to control the pore size and robust materials for industrial applications.

In-depth understanding of interfacial behavior between biopolymer and semiconductor metal oxides is crucial to developing potential applications of their composites. A structure-ordered cellulose/zinc oxide composite was synthesized and systematically examined by a relativistic density functional theory. The prepared composite shows a hierarchical structure. ZnO nanoparticles of around 30 nm in size are found to uniformly grow along the cellulose fiber, which together construct the primary-structure unit. Associated with experimental characterizations, calculations unravel that the electrostatic attraction between cellulose and ZnO is the main driving force to form the primary structure and the subsequent electron transfer from cellulose to ZnO enhances their interfacial interaction; moreover, an exothermic process was computed. The interfacial interaction is mainly contributed by Zn-Oc (Oc denotes the cellulose oxygen atom), which is intrinsically of a dative bond; the interaction was calculated between -1.39 and -1.83 eV in strength and dominated by orbital attractions.

Polyacrylamides of different molecular weight, charges and dosages allow to control the retention and distribution of nanoparticles (NPs) in composites, and optimise composite properties and functionality. Our aim is to evaluate the effect of high molecular weight (13 MDa) cationic polyacrylamide (CPAM) charge and dosage on SiO2 (74 nm) NP's assembly in cellulose nanofibers composites. Engineered cellulose/SiO2 composites were investigated by SEM, SAXS and DLS. SEM images show the local area retention of NPs into the cellulose matrix. SAXS provides an average NPs distribution and inter-NPs distance over complete volume of composite. DLS gives the hydrodynamic radius of CPAM adsorbed onto SiO2 NPs in a suspension. SAXS analysis reveals a structure conformation made of spherical SiO2 NPs core of diameter 74 nm surrounded by a CPAM polyelectrolyte shell 2.5 nm thick. Surprisingly, CPAM induced assembly of SiO2 NPs with constant inter-nanoparticle distance, which is irrelevant of polymer charge density. However, NPs retention in the cellulose fibre network increases with CPAM dosage. The assembly mechanism is governed by the balance of electrostatic and steric forces following CPAM coverage onto NPs and the inter-nanoparticle CPAM bridging conformation. This maintains the constant inter-nanoparticle distance and the assembly of NPs in the cellulose network.

Natural polymer-based adhesive hydrogels have garnered significant interest for their outstanding strength and versatile applications, in addition to being eco-friendly. However, the adhesive capabilities of purely natural products are suboptimal, which hampers their practical use. To address this, we engineered carboxymethyl cellulose (CMC) surfaces with complementary bases, adenine (A) and thymine (T), to facilitate the self-assembly of adhesive hydrogels (CMC-AT) with a nanofiber configuration. Impressively, the shear adhesive strength reached up to 6.49 MPa with a mere 2% adhesive concentration. Building upon this innovation, we conducted a comparative analysis of the shear adhesion properties between CMC and CMC-AT hydrogel adhesives when applied to delignified and non-delignified wood chips. We examined the interplay between the adhesives and the substrate, as well as the role of mechanical interlocking in overall adhesion performance. Our findings offer a fresh perspective on the development of new biodegradable polymer hydrogel adhesives.

Polyvinyl alcohol (PVA) film, a promising alternative to non-biodegradable plastic packaging films for food and medical packaging, is limited by poor water resistance. In this work, a simple solvent evaporation self-assembly was used to construct a nanophase separation structure to establish dense interfacial hydrogen bonding, covalent bonding and iron metal ion coordination interactions between lignin-containing cellulose nanofibers (LCNFs) and PVA matrix to improve the interfacial force and solve the problem of poor compatibility of LCNFs in PVA. The iron ion (Fe3+) coordination tended to combine with the more active lignin phenolic hydroxyl group to construct the nanophase separation structure. Covalent crosslinking of glutaraldehyde (GA) improved the interfacial compatibility of PVA/LCNF films, enhanced the interfacial bonding and formed a homogeneous structure. The multi-nanophase structures improved the strength and elastic modulus of the PVA/LCNF film and provided the films with extremely low water absorption, water vapor transmission rate and excellent UV-shielding. Compared with pure PVA film, PVA-10L-5Fe-3GA film had about 106.9 % higher tensile strength, 93.9 % lower water absorption and 93.4 % lower mass loss, 69.8 % lower water vapor transmission coefficient, and was able to shield UV at 200-400 nm, which is highly expected to be used in packaging films.

The extensive use of petroleum-based plastics has led to severe environmental pollution and resource depletion issues, driving an urgent need for sustainable material alternatives. In this work, we present an environmentally friendly approach to fabricating bioinspired composite films by integrating cellulose nanofibers with brushite microplates via blade assisted assembly. The resulting nacre-like brick-and-mortar architecture is stabilized through hydrogen bonding and dynamic Ca2+-carboxyl coordination, leading to a combination of exceptional mechanical and functional properties. The composite films exhibit a tensile strength of 288.15 MPa, a Young's modulus of 7.4 GPa, a fracture toughness of 19.82 MJ·m-3, and a wet strength of 22.97 MPa, outperforming most previously reported cellulose-based and bioinspired composites. The incorporation of brushite microplates delayed thermal degradation and conferred intrinsic flame retardancy, while also reducing surface hydrophilicity and enhancing long-term water resistance. Furthermore, these films can be easily patterned or printed into complex geometries and have been demonstrated to function reliably as sensors, showing stable and reproducible electrical response under repeated loading and instantly changing humidity.

Cellulose nanofiber was an ideal candidate for humidity actuators based on its wide availability, biocompatibility and excellent hydrophilicity. However, conventional cellulose nanofiber-based actuators faced challenges like poor water resistance, flexibility, and sensitivity. Herein, water-resistant, flexible, and highly sensitive cross-linked cellulose nanofibers (CCNF) single-layer humidity actuators with remarkable reversible humidity responsiveness were prepared by combining the green click chemistry modification and intercalation modulated plasticization (IMP). The incorporation of phenyl ring and the crosslinked network structure in CCNF films contributed to its improved water resistance and mechanical properties (with a stress increased from 85.9 ± 3.1 MPa to 141.2 ± 21.5 MPa). SEM analysis confirmed enhanced interlaminar sliding properties facilitated by IMP. This resulted in increased flexibility and toughness of CCNF films, with a strain of 11.5 % and toughness of 9.9 MJ/m3. These improvements efficiently enhanced humidity sensitivity for cellulose nanofiber, with a 4.8-fold increase in bending curvature and a response time of only 3.4 ± 0.1 s. Finally, the good humidity sensitivity of modified CNF can be easily imparted to carbon nanotubes (CNTs) via simple self-assembly method, thus leading to a high-performance humidity-responsive actuator. The click chemistry modification and IMP offer a new avenue to fabricate tough, reversible and highly sensitive humidity actuator based on cellulose nanofiber.

Nanoellulose-based mechanochromic materials represent a frontier in sustainable optics, offering a renewable platform for advanced functional materials. However, the precise manipulation of cellulose nanofibers (CNFs) into intelligent optical systems remains challenging due to their inherent variability in size and the difficulty of achieving controlled orientation. Herein, we developed a straightforward and scalable strategy to construct mechanochromic CNF hydrogels (MCNFHs) with engineerable interference colors (ranging from yellow, red, blue, green) under compressive stress by exploiting their response to acidic vapor, that is, via simple and feasible gas phase coagulation. Remarkably, MCNFHs displayed excellent solvent resistance, mechanochromic reversibility and mechanochromic sensitivity, which could achieve the switch from black to yellow, red, blue and green under only a load of 0.36 N, a stress of 1.2 KPa, and a strain of 15 %, offering a robust platform for pressure sensing or micro-strains detecting. We also demonstrated that these new MCNFHs can be smoothly applied in optical coding systems for optical encryption. This work highlighted a versatile strategy for creating high performance CNF-based mechanochromic materials, without the need for complicated pre-assembly or precise manipulation of CNF, underscoring their potential in pressure sensing, encryption, and beyond.

The ingenious design of sustainable thermoplastic elastomers (STPEs) is of great significance for the goal of the sustainable development. However, the preparation of STPEs with good mechanical performance is still complicated and challenging. Herein, to achieve a simple preparation of STPEs with strong mechanical properties, two biobased monomers (tetrahydrofurfuryl methacrylate (THFMA) and lauryl methacrylate (LMA)) were copolymerized into poly (THFMA-co-LMA) (PTL) and grafted onto TEMPO oxidized cellulose nanofiber (TOCN) via one-pot surface-initiated atom transfer radical polymerization (SI ATRP). The grafting modified TOCN could be self-assembled into nano-enhanced phases in STPEs, which are conducive to the double enhancement of the strength and toughness of the STPEs, and the size of nano-enhanced phases is mainly affected by TOCN fiber length and molecular weight of grafting chains. Especially, with the addition of 7 wt% TOCN, tensile strength, tensile strain, toughness, and glass transition temperature (Tg) of TOCN based STPEs (TOCN@PTL) exhibited 140 %, 36 %, 215 %, and 6.8 °C increase respectively, which confirmed the leading level in the field of bio-based elastomers. In general, this work constitutes a proof for the chemical modification and self-assembly behavior of TOCN by one-pot SI ATRP, and provides an alternative strategy for the preparation of high-performance STPEs.

The design of humidity actuators with high response sensitivity (especially actuation time) while maintaining favorable mechanical properties is important for advanced intelligent manufacturing, like soft robotics and smart devices, but still remains a challenge. Here, we fabricate a robust and conductive composite film-based humidity actuator with synergetic benefits from one-dimensional cellulose nanofibers (CNFs) and carbon nanotubes (CNTs) as well as two-dimensional graphene oxide (GO) via an efficient vacuum-assisted self-assembly method. Owing to the excellent moisture sensitivity of CNF and GO, the hydrophobic CNT favoring rapid desorption of water molecules, and the unique porous structure with numerous nanochannels for accelerating the water exchange rate, this CNF/GO/CNT composite film delivers excellent actuation including an ultrafast response/recovery (0.8/2 s), large deformation, and sufficient cycle stability (no detectable degradation after 1000 cycles) in response to ambient gradient humidity. Intriguingly, the actuator could also achieve a superior flexibility, a good mechanical strength (201 MPa), a desirable toughness (6.6 MJ/m3), and stable electrical conductivity. Taking advantage of these benefits, the actuator is conceptually fabricated into various smart devices including mechanical grippers, crawling robotics, and humidity control switches, which is expected to hold great promise toward practical applications.

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Biological materials, such as bamboo, are naturally optimized composites with exceptional mechanical properties. Inspired by such natural composites, traditional methods involve extracting nanofibers from natural sources and applying them in composite materials, which, however, often results in less ideal mechanical properties. To address this, this study develops a bottom-up nanofiber assembly strategy to create strong fiber-reinforced composite hydrogels inspired by the hierarchical assembly of bamboo. Self-assembled chitosan-sodium alginate nanofibers (CSNFs) are combined with tannic acid (TA) and poly(vinyl alcohol) (PVA) as the interfacial crosslinker and hydrogel matrix, respectively, to emulate the fundamental cellulose-lignin-hemicellulose composition unit of bamboo. Strong interfacial electrostatic interactions and hydrogen bonding form between the functional groups of these components. These molecular interactions can be further reinforced by constructing higher-order structure through stretch-induced orientation. The resulting composite hydrogel achieves good mechanical performance, including a high tensile strength of up to 60.2 MPa and a simultaneous high strength of 48.0 MPa and ultimate strain of 470%. This approach demonstrates a hierarchical bottom-up strategy to construct strong and robust composite hydrogels by effectively leveraging fundamental molecular interactions. By mimicking bamboo’s highly integrated structural composition, it offers a promising solution for creating advanced bioinspired materials with excellent mechanical properties. There is interest in mimicking the properties of biological composites in artificial materials, but the hierarchical structures can be challenging to replicate. Here, the authors report the development of a bamboo-inspired hydrogel with favourable mechanical performance.

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Developing multimodal sensors with human‐like tactile perception is highly desirable for wearable devices, electronic skins (e‐skins), and human‐machine interfaces. However, realizing decoupled signal output and high‐precision measurement remains challenging. Superelastic conductive aerogels are ideal materials for fabricating multimodal sensors as they can convert pressure and temperature stimuli into different electrical signals. Herein, inspired by the microstructure of lightweight and robust avian bones, a biomimetic lamellar silica nanofiber/MXene aerogel (LSMA) sensor for decoupled pressure and temperature sensing is first developed. The avian bone‐like lamellae‐strut structure endows the ultralight LSMA with superb fatigue resistance of 99.1% height retention after 10 000 compression cycles, which is second to none in the reported MXene‐based aerogels. Meanwhile, benefiting from the advantages of the aerogel structure, the LSMA sensor integrating piezoresistive and thermoelectric effects has an ultrahigh temperature resolution of 0.07 K and the lowest pressure detection limit of 0.20 Pa in the reported pressure‐temperature sensors. The unique performance renders it a promising platform for wearable physiological monitoring and tactile e‐skin. Furthermore, an innovative multilevel encryption protection system assisted by machine learning is designed based on the LSMA sensing array as the interactive terminal. This study provides novel insights into the design and application of multimodal sensors.

The rapid development of aerospace, artificial intelligence, and flexible wearable electronics has led to an increasing demand for multifunctional electromagnetic interference (EMI) shielding materials, especially for lightweight and high-strength biomimetic intelligent actuators. In this study, we present polyolefin elastomer/aramid nanofiber/carbon nanotube (POE/ANF/CNT) composites with a sandwich architecture fabricated via layer-by-layer technology. Actuation is achieved by exploiting the differential thermal expansion coefficients among the layers, where the POE functions as the active layer, while ANFs and CNTs serve as inert reinforcement layers. The bird's-nest-like CNT layer imparts the actuators with repeatable programming capabilities. These intelligent actuators exhibit rapid responses to light, electrical, and thermal stimuli, featuring a low activation energy, high actuation speed, significant deformation, and exceptional fatigue resistance. Inspired by paper cutting and origami techniques, the actuators achieve repeatable morphological programming and complex actuation behaviors. The POE/ANF/CNT composites also demonstrate effective EMI shielding (35.7 dB at 40 wt % CNTs), high tensile strength (39.1 MPa), superior Joule heating performance (301 °C at 20 V voltage), and excellent thermal stabilities (with a maximum decomposition temperature reaching 473 °C). These multifunctional intelligent materials hold significant potential for applications in flexible wearable electronic devices, EMI shielding, and soft robotics.

Innovation in the ionotronics field has significantly accelerated the development of ultraflexible devices and machines. However, it is still challenging to develop efficient ionotronic‐based fibers with necessary stretchability, resilience, and conductivity due to inherent conflict in producing spinning dopes with both high polymer and ion concentrations and low viscosities. Inspired by the liquid crystalline spinning of animal silk, this study circumvents the inherent tradeoff in other spinning methods by dry spinning a nematic silk microfibril dope solution. The liquid crystalline texture allows the spinning dope to flow through the spinneret and form free‐standing fibers under minimal external forces. The resultant silk‐sourced ionotronic fibers (SSIFs) are highly stretchable, tough, resilient, and fatigue‐resistant. These mechanical advantages ensure a rapid and recoverable electromechanical response of SSIFs to kinematic deformations. Further, the incorporation of SSIFs into core–shell triboelectric nanogenerator fibers provides outstanding stable and sensitive triboelectric response to precisely and sensitively perceive small pressures. Moreover, by implementing a combination of machine learning and Internet of Things techniques, the SSIFs can sort objects made of different materials. With these structural, processing, performance, and functional merits, the SSIFs prepared herein are expected to be applied in human–machine interfaces.

Nature with its abundant source offers numerous inspirations for structural and engineering designs. The oriented membranes stacked with bouligand structures in the fish scales show an outstanding combination of high strength and crack-resistance. Although the applications of hard biomimetic composites have been reported, the structures have not been utilized in soft materials. Inspired by the scales of various fishes, we use and stack electrospun membranes to fabricate bouligand elastomers, including orthogonal-plywood, single-bouligand, and double-bouligand structures. We systematically investigated the effects of different structures on the properties of elastomers and explained possible mechanism using finite element analysis. The stiffness and fatigue characteristics of these biomimetic elastomers with the above structures were improved compared with the original membranes, especially the elastomers with a single-bouligand structure, which can undergo 5000 cycles at a maximum strain of 35% without complete failure. The crack only propagates to half of the width of the elastomer with a remaining strength of 50% of its original strength. Moreover, the mechanical performance can be adjusted by regulating the proportion of the components. The excellent crack-resistant properties and transparency promote its various potential applications. This article is protected by copyright. All rights reserved.

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Biological tissues hinge on blood perfusion and mechanical toughness to function. Injectable hydrogels that possess both high permeability and toughness have profound impacts on regenerative medicine but remain a long‐standing challenge. To address this issue, injectable, pore‐forming double‐network hydrogels are fabricated by orchestrating stepwise gelation and phase separation processes. The interconnected pores of the resulting hydrogels enable direct medium perfusion through organ‐sized matrices. The hydrogels are amenable to cell encapsulation and delivery while promoting cell proliferation and spreading. They are also pore insensitive, tough, and fatigue resistant. When tested in biomimetic perfusion bioreactors, the hydrogels maintain physical integrity under prolonged, high‐frequency biomechanical stimulations (>6000 000 cycles at 120 Hz). The excellent biomechanical performance suggests the great potential of the new injectable hydrogel technology for repairing mechanically dynamic tissues, such as vocal folds, and other applications, such as tissue engineering, biofabrication, organs‐on‐chips, drug delivery, and disease modeling.

Developing hydrogels with high conductivity and toughness via a facile strategy is important yet challenging. Herein, we proposed a new strategy to develop conductive hydrogels by growing metal dendrites. Water-soluble Sn2+ ions were soaked into the gel and then converted to Sn dendrites via an electrochemical reaction; the excessive Sn2+ ions were finally removed by water dialysis, accompanied by dramatic shrinkage of the gel. Based on in situ transformation from metal ions to dendrites, the method integrated the advantages of ionic conductive fillers, such as LiCl (uniform dispersion), and electrical fillers, such as metal particles (high conductivity). Additionally, the morphology of metal dendrites combined advantages of 1D nanowires (large aspect ratio of the branches) and 2D nanosheets (large specific surface area of the skeleton). The strategy was found to be effective across diverse gel systems (non-ionic, anionic, cationic and zwitterionic). The dense, highly conductive and branched Sn dendrites not only formed a conductive pathway but also interacted with the polymer network to transfer stress and dissipate energy. The resultant gel exhibited a high conductivity of 12.5 S m-1, fracture energy of 1334.0 J m-2, and fatigue threshold of 720 J m-2. Additionally, the gel exhibited excellent sensitivity when used as a wearable strain sensor and bioelectrode. We believe this strategy offers new insights into the development of conductive hydrogels.

It is highly desirable but still remains challenging to develop high‐performance hydrogels with satisfactory mechanical properties for tissue engineering. Here, anisotropic yet transparent hydrogels (AHs) are prepared for tendon repair via a facile “poor solvent evaporation assisted hot‐stretching” strategy. AHs have great mechanical properties with tensile strength, toughness, and fracture energy as high as 33.14 ± 2.05 MPa, 44.1 ± 3.5 MJ m−3, and 106.18 ± 7.2 kJ m−2, respectively. Especially, AHs show unique flaw‐insensitive characteristics, and cracks can only deflect along the fiber alignment direction rather than propagate transverse to this direction, showing an interesting self‐protection function. The high strength, toughness, and fatigue resistance originate from the hierarchal structure of AHs, i.e., the densified polymeric network comprising fiber bundles and nanofibrils with aligned macromolecular chains, crystalline domains, and intermolecular hydrogen bonds. AHs with superior biocompatibility and swelling resistance can be used to repair rat tendons, and implantation of AHs can promote collagen regeneration for the tendon repair. This study provides a new method to fabricate strong and anti‐fatigue hydrogels as a new class of promising materials for soft tissues.

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The fabrication of highly elastic, fatigue-resistant and conductive hydrogels with antibacterial properties is highly desirable in the field of wearable devices. However, it remains challenging to simultaneously realize the above properties within one hydrogel without compromising excellent sensing ability. Herein, we fabricated a highly elastic, fatigue-resistant, conductive, antibacterial and cellulose nanocrystal (CNC) enhanced hydrogel as a sensitive strain sensor by the synergistic effect of biosynthesized selenium nanoparticles (BioSeNPs), MXene and nanocellulose. The structure and potential mechanism to generate biologically synthesized SeNPs (BioSeNPs) were systematically investigated, and the role of protease A (PrA) in enhancing the adsorption between proteins and SeNPs was demonstrated. Additionally, owing to the incorporation of BioSeNPs, CNC and MXene, the synthesized hydrogels showed high elasticity, excellent fatigue resistance and antibacterial properties. More importantly, the sensitivity of hydrogels determined by the gauge factor was as high as 6.24 when a high strain was applied (400-700 %). This study provides a new horizon to synthesize high-performance antibacterial and conductive hydrogels for soft electronics applications.

Outstanding overall mechanical properties are essential for the successful utilization of hydrogels in advanced applications such as human-machine interfaces and soft robotics. However, conventional hydrogels suffer from fracture toughness-stiffness conflict and fatigue threshold-stiffness conflict, limiting their applicability. Simultaneously enhancing the fracture toughness, fatigue threshold, and stiffness of hydrogels, especially within a homogeneous single network structure, has proven to be a formidable challenge. In this work, we overcome this challenge through the design of a loosely cross-linked hydrogel with slight dehydration. Experimental results reveal that the slightly-dehydrated, loosely cross-linked polyacrylamide hydrogel, with an original/current water content of 87%/70%, exhibits improved mechanical properties, which is primarily attributed to the synergy between the long-chain structure and the dense dehydration-induced entanglements. Importantly, the creation of these microstructures does not require intricate design or processing. This simple approach holds significant potential for hydrogel applications where excellent anti-fracture and fatigue-resistant properties are necessary. For use in a range of applications, hydrogel properties are vital, but it can be challenging to balance different aspects. Here, the authors report the use of a dehydration strategy to prepare hydrogels with desirable fracture toughness, fatigue threshold, and modulus.

Fatigue-resistant functional bioadhesion is desired in diverse applications ranging from wound management to wearable devices. Nanoparticle-based bioadhesives offer versatile functionality but suffer from weak adhesion and fatigue vulnerability due to tissue barriers and poor tissue interactions. Polymer chain-based bioadhesives can form tough bioadhesion but remain vulnerable to fatigue fracture. Here we demonstrate that rationally designed chitosan nanowhiskers glues achieve fatigue-resistant bioadhesion and interfacial functionalization via the combined high aspect ratio, rigidity, polymer-binding and network-forming properties. We deploy these glues using chemical enhancers, microneedle rollers, and ultrasound, enabling strong tissue anchorage despite tissue barriers. At low concentrations, the nanowhisker glue paired with a tough hydrogel achieves an interfacial fatigue threshold of 382 J m−2 and adhesion energy exceeding 1000 J m−2. Transmission electron microscopy reveals a sandwiched nanowhisker layer interpenetrated with both hydrogels and tissues, creating an interface of high stiffness and strength that kinks and arrests interfacial cracks, ensuring unprecedented fatigue resistance. Further, the nanowhisker glue allows for versatile functionalization at the interface such as photothermal and sonodynamic effects. This work expands the performance and functionality of bioadhesives, opening new possibilities for medical and engineering applications. Fatigue-resistant functional bioadhesion is desired in diverse applications ranging from wound management to wearable devices but remains elusive. Here, the authors report the design, deployment, and mechanism of nanowhisker glues for fatigue-resistant functional bioadhesion.

A hydrogel that is expected as a biomedical load‐bearing material remains a substantial challenge. In this work, a multi‐solvent‐induced gradient aggregation state strategy is developed to construct lignin‐based supramolecular hydrogels that feature superstrong, tough, stretchable, and fatigue‐resistant properties. The multi‐solvent high‐temperature annealing induces the gradient crystallization of polyvinyl alcohol and the self‐assembly of lignin. The interior strong hydrogen‐binding and the external weak non‐covalent‐binding forms a gradient aggregation state microstructure and compact macrostructure, where lignin acts as an interfacial molecular bridge. By sharing interconnection points to collaboratively dissipate energy, the developed hydrogels demonstrate high modulus (74.4 MPa), toughness (90 MJ m−3), tear (34,000 J m−2), tensile (24.8 MPa), and compressive strength (60 MPa). Moreover, such lignin‐based supramolecular hydrogels also exhibit extraordinary fatigue resistance, biocompatibility, and reactive oxygen species scavenging activity. This gradient non‐covalent conjoined‐network caused by multi‐solvent high‐temperature annealing provides a new design strategy and potential for developing biomaterials that mimic biomedical load‐bearing materials (e.g., natural tendons and ligaments).

As a common natural phenomenon, phase separation is exploited for the development of high‐performance hydrogels. Using supersaturated salt to create microphase‐separated hydrogels with strengthened mechanical properties has gained widespread attention. However, such strengthened hydrogel loses its intrinsic flexibility, making the phase separation strategy unsuitable for the fabrication of stretchable and tough hydrogels. Here, a phase‐engineering design strategy is introduced to produce stretchable yet tough hydrogels using supersaturated NaAc salt, by leveraging the hydration effect of cellulose nanocrystal (CNC) to mitigate microphase separation. The CNC‐mitigated microphase‐separated hydrogel presents unprecedented mechanical properties, for example, tensile strength of 1.8 MPa with a fracture strain of 4730%, toughness of 43.1 MJ m−3, fracture energy of 75.4 kJ m−2, and fatigue threshold up to 3884.7 J m−2. Furthermore, this approach is universal in synthesizing various microphase separation‐enhanced polymer gels, including polyacrylic acid, poly(acrylic acid‐co‐acrylamide), gelatin, and alginate. These advancements provide insights into the incorporation of CNC‐mediated microphase separation structures in hydrogels, which will foster the future development of high‐performance soft materials.

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Mechanoresponsive color‐changing materials that can reversibly and resiliently change color in response to mechanical deformation are highly desirable for diverse modern technologies in optics, sensors, and robots; however, such materials are rarely achieved. Here, a fatigue‐resistant mechanoresponsive color‐changing hydrogel (FMCH) is reported that exhibits reversible, resilient, and predictable color changes under mechanical stress. At its undeformed state, the FMCH remains dark under a circular polariscope; upon uniaxial stretching of up to six times its initial length, it gradually shifts its color from black, to gray, yellow, and purple. Unlike traditional mechanoresponsive color‐changing materials, FMCH maintains its performance across various strain rates for up to 10 000 cycles. Moreover, FMCH demonstrates superior mechanical properties with fracture toughness of 3000 J m−2, stretchability of 6, and fatigue threshold up to 400 J m−2. These exceptional mechanical and optical features are attributed to FMCH's substantial molecular entanglements and desirable hygroscopic salts, which synergistically enhance its mechanical toughness while preserving its color‐changing performance. One application of this FMCH as a tactile sensoris then demonstrated for vision‐based tactile robots, enabling them to discern material stiffness, object shape, spatial location, and applied pressure by translating stress distribution on the contact surface into discernible images.

The development of highly effective chitosan-based hemostatic materials that can be utilized for deep wound hemostasis remains a considerable challenge. In this study, a hemostatic antibacterial chitosan/N-hydroxyethyl acrylamide (NHEMAA)/Ti3C2Tx (CSNT) composite cryogel was facilely prepared through the physical interactions between the three components and the spontaneous condensation of NHEMAA. Because of the formation of strong crosslinked network, the CSNT cryogel showed a developed pore structure (~ 99.07 %) and superfast water/blood-triggered shape recovery, enabling it to fill the wound after contacting the blood. Its capillary effect, amino groups, negative charges, and affinity with lipid collectively induced rapid hemostasis, which was confirmed by in vitro and in vivo analysis. In addition, CSNT cryogel showed excellent photothermal antibacterial activities, high biosafety, and in vivo wound healing ability. Furthermore, the presence of chitosan effectively prevented the oxidation of MXene, thus enabling the long-term storage of the MXene-reinforced cryogel. Thus, our hemostatic cryogel demonstrates promising potential for clinical application and commercialization, as it combines high resilience, rapid hemostasis, efficient sterilization, long-term storage, and easy mass production.

Conductive organohydrogels-based flexible pressure sensors have gained considerable attention in health monitoring, artificial skin, and human-computer interaction due to their excellent biocompatibility, wearability, and versatility. However, hydrogels' unsatisfactory mechanical and unstable electrical properties hinder their comprehensive application. Herein, an elastic, fatigue-resistant, and antifreezing poly(vinyl alcohol) (PVA)/lipoic acid (LA) organohydrogel with a double-network structure and reversible cross-linking interactions has been designed, and MXene as a conductive filler is functionalized into organohydrogel to further enhance the diverse sensing performance of flexible pressure sensors. The as-fabricated MXene-based PVA/LA organohydrogels (PLBM) exhibit stable fatigue resistance for over 450 cycles under 40% compressive strain, excellent elasticity, antifreezing properties (<-20 °C), and degradability. Furthermore, the pressure sensors based on the PLBM organohydrogels show a fast response time (62 ms), high sensitivity (S = 0.0402 kPa-1), and excellent stability (over 1000 cycles). The exceptional performance enables the sensors to monitor human movements, such as joint flexion and throat swallowing. Moreover, the sensors integrating with the one-dimensional convolutional neural networks and the long-short-term memory networks deep learning algorithms have been developed to recognize letters with a 93.75% accuracy, representing enormous potential in monitoring human motion and human-computer interaction.

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Hydrogels as skin wound dressings have been extensively studied owing to their good flexibility and biocompatibility. Nevertheless, the mechanical performance, adhesive capability, antifouling and antibacterial properties of conventional hydrogels are still unsatisfactory, which hinder the application of hydrogel for cutaneous healing. Here, we developed a novel biocompatible multifunctional hydrogel with super flexible, fatigue resistant, antifouling and self-adhesive capability for effective wound healing, where naturally rigid polymers including quaternized chitosan (QCS) and Tunicate cellulose nanocrystals (TCNCs) are used as bioactive cross-linkers and reinforcers to endow the hydrogel with excellent mechanical and antibacterial property, and the synergistic contributions from the poly(acrylic acid/methacrylate anhydride dopamine/sulfobetaine methacrylate) (poly(AA/DMA/SBMA)) chains and QCS endow the hydrogel with excellent adhesive property, antioxidant, antifouling and pH-responsive sustained drug release capabilities. The optimized hydrogel exhibited high tensile strength (77.69 KPa), large tensile strain (889.9 %), large toughness (307.51KJ.m-3), high adhesive strength (35.57 KPa) and ideal compressive property. The in vivo infected full-thickness skin model demonstrated that the hydrogel with vanvomycin sustained release ability efficiently improved the granulation tissue formation, facilitating collagen deposition and reducing inflammatory expression, thus effectively accelerating wound healing. This superiorly skin-adhesive antibacterial biocompatible hydrogel appears to be a promising candidate for wound therapy.

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Hydroxyapatite-based materials have been widely used in countless applications, such as bone regeneration, catalysis, air and water purification or protein separation. Recently, much interest has been given to controlling the aspect ratio of hydroxyapatite crystals from bulk samples. The ability to exert control over the aspect ratio may revolutionize the applications of these materials towards new functional materials. Controlling the shape, size and orientation of HA crystals allows obtaining high aspect ratio structures, improving several key properties of HA materials such as molecule adsorption, ion exchange, catalytic reactions, and even overcoming the well-known brittleness of ceramic materials. Regulating the morphogenesis of HA crystals to form elongated oriented fibres has led to flexible inorganic synthetic sponges, aerogels, membranes, papers, among others, with applications in sustainability, energy and catalysis, and especially in the biomedical field.

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Structural materials used for safety critical applications require high strength and simultaneously high resistance against crack growth, referred to as damage tolerance. However, the two properties typically exclude each other and research efforts towards ever stronger materials are hampered by drastic loss of fracture resistance. Therefore, future development of novel ultra-strong bulk materials requires a fundamental understanding of the toughness determining mechanisms. As model material we use today’s strongest metallic bulk material, namely, a nanostructured pearlitic steel wire, and measured the fracture toughness on micron-sized specimens in different crack growth directions and found an unexpected strong anisotropy in the fracture resistance. Along the wire axis the material reveals ultra-high strength combined with so far unprecedented damage tolerance. We attribute this excellent property combination to the anisotropy in the fracture toughness inducing a high propensity for micro-crack formation parallel to the wire axis. This effect causes a local crack tip stress relaxation and enables the high fracture toughness without being detrimental to the material’s strength.

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This paper describes a nickel-based cellular material, which has the strength of titanium and the density of water. The material’s strength arises from size-dependent strengthening of load-bearing nickel struts whose diameter is as small as 17 nm and whose 8 GPa yield strength exceeds that of bulk nickel by up to 4X. The mechanical properties of this material can be controlled by varying the nanometer-scale geometry, with strength varying over the range 90–880 MPa, modulus varying over the range 14–116 GPa, and density varying over the range 880–14500 kg/m3. We refer to this material as a “metallic wood,” because it has the high mechanical strength and chemical stability of metal, as well as a density close to that of natural materials such as wood.

Abstract Although a variety of nanoparticles with better-than-bulk material performances can be synthesized, it remains a challenge to scale the extraordinary properties of individual nanoscale units to the macroscopic level for bulk nanostructured materials. Here, we report a general and scalable biosynthesis strategy that involves simultaneous growth of cellulose nanofibrils through microbial fermentation and co-deposition of various kinds of nanoscale building blocks (NBBs) through aerosol feeding on solid culture substrates. We employ this biosynthesis strategy to assemble a wide range of NBBs into cellulose nanofibril-based bulk nanocomposites. In particular, the biosynthesized carbon nanotubes/bacterial cellulose nanocomposites that consist of integrated 3D cellulose nanofibril networks simultaneously achieve an extremely high mechanical strength and electrical conductivity, and thus exhibit outstanding performance as high-strength lightweight electromagnetic interference shielding materials. The biosynthesis approach represents a general and efficient strategy for large-scale production of functional bulk nanocomposites with enhanced performances for practical applications. Industrial-scale production of these bulk nanocomposite materials for practical applications can be expected in the near future.

Recently, a novel dental restorative composite based on nanostructured micro-fillers of anodic porous alumina has been proposed. While its bulk properties are promising thanks to decreased aging and drug delivery capabilities, its surface properties are still unknown. Here we investigated the surface morphology and the adhesion to tooth dentin of this composite as prepared. For comparison, we used two commercial composites: Tetric EVO Flow (Ivoclar) and Enamel HRi Plus (Micerium). The surface morphology was characterized by atomic force microscopy and the adhesion strength by tensile tests. The experimental composite is rougher than the commercial composites, with root mean square roughness of ~549 nm against 170–511 nm, and presents an adhesion strength of ~15 MPa against 19–21 MPa. These results show at the same time some proximity to the commercial composites, but also the need for optimization of the experimental material formulation.

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