Three-dimensional Fiber Networks Research Articles

A novel strategy for constructing active anti-corrosive coatings by embedding three-dimensional fiber networks

The corrosion protection effectiveness of micro/nanocontainer-based intelligent coatings significantly depends on their dispersion within the coating matrix. Inspired by the bionic concept of a ‘vascular network’ we designed a polylactic acid (PLA) three-dimensional fiber network incorporating the pH-responsive TiO2-8-hydroxyquinoline (TiO2-8HQ) nanotubes using electrospinning technology. These TiO2-8HQ@PLA networks are crosslinked and evenly dispersed on the Mg alloy surface, responsive to local pH variations. The encapsulated 8HQ inhibitors release rapidly in alkaline conditions, transporting through the network to enable continuous self-healing in multi-defect areas. An epoxy coating applied over the network forms a novel vascular network intelligent coating. Electrochemical and surface analysis tests reveal that 2 %TiO2-8HQ@PLA-EP provides the most enduring corrosion resistance over 50 days in a 3.5 wt% NaCl solution, with a coating resistance of 2.33 × 106 Ω cm2 and charge transfer resistance of 4.81 × 106 Ω cm2. Additionally, the network enhances adhesion strength (38.01 MPa) and surface wettability (104.25° ± 0.15°), significantly improving the coating’s physical barrier performance. The combination of the micro/nanocontainers technology and vascular network innovative design provides a unique insight into active corrosion control on diverse metals.

Multi-responsive novel phosphamide organogels dominated by a natural diterpene rigid backbone

Functional supramolecular organogels with unique properties and morphology can be obtained by designing gelators’s chemical structure. Rosin, an important natural renewable diterpene resource, consists of a rigid ring skeleton and chiral structure similar to triterpenoids and has excellent self-assembly ability in solution. In this paper, four novel rosin-based derivatives were proposed and synthesized in one step by introducing phosphamide groups by using natural rosin as raw material. They could form eleven types of monoamide and diamide organogels in specific solvents. The minimum gelatinization concentration is 50–180 mg/mL. In particular, by adjusting the number and type of phosphamide groups and rigid structures, the morphology and other properties of the gel could be modulated. Two-dimension lamellar and three-dimensional fiber network organogels were obtained and the hydrogen bond and π–π stack were proved to be the most important driving forces for the gelation. What is particularly important is that the gels exhibited multiple stimulus responsiveness, such as temperature, acid-base and anions. Thus, the four dehydroabietylamine phosphamide gelators synthesized by the one-step method provide new ways of designing novel gel-based soft materials for intelligent response, ion detection, etc.

Characterization and prediction of tensile properties of carbon fiber-reinforced thermoplastics composed of hybrid short carbon fiber/PA6 fiber nonwoven mats

Hybrid carbon fiber/resin fiber nonwoven mats are considered as a highly promising application of recycled carbon fibers due to their low cost and simple synthesis process. However, the mechanical properties of hybrid nonwoven mats are subject to uncertainties due to nonuniformity of fiber orientations during production procedures, which restricts their use in structural components. This study investigates the characteristics of various types of hybrid nonwoven mats with different volume fractions and fiber orientation distributions. Notably, the investigation yields noteworthy tensile properties, exemplified by a tensile strength of 367.20 MPa and a stiffness of 32.85 GPa, when the volume fraction is 28.9%. Tensile properties of the hybrid nonwoven mats and their fluctuations are then analyzed through statistical analyses. A three-dimensional microstructure-based fiber network model is established using the Monte Carlo method to represent the statistical and stochastic properties of the material. Furthermore, a prediction method of tensile properties based on microstructural properties in the model is proposed, which shows good agreement with all experimental results for adjustments of the volume fraction of carbon fibers, distribution of fiber lengths, and anisotropy of the materials, significantly reducing the experimental burden for optimization research. The tensile characteristics of composites are reliably anticipated with a nominal error margin below 10%. Additionally, this prediction method enables the prediction of scatter and stable standard deviation, making it possible to apply hybrid nonwoven mats in recycling and industrial processes.

Zirconium ion ligand Cross-Linked carbon nanotubes and leather collagen fibers for Flexible, Stable, and highly efficient underwater sensors

Flexible sensing materials have recently found widespread applications in integrating various underwater sensors. In this study, we adopted oil-tanned sheepskin as a “structural template” and harnessed its distinctive three-dimensional collagen fiber network. By leveraging the coordination complexation of zirconium ions (Zr4+), we brided collagen fibers with carbon nanotubes (CNTs) to enhance the bonding fastness of the two. We finally constructed a double cross-linked network to produce a new flexible conductive leather called CNTs@Zr@OTL. This material is the basis for preparing leather bio-based piezoresistive sensors （LBPS） and further developing leather biosensing systems (LBS). Experimental outcomes revealed that when CNTs were employed at a concentration of 8.5 %, CNTs@Zr@OTL exhibited an electrical resistivity of approximately 7.4 Ω·cm and a shrinkage temperature of around 74.5 °C. Furthermore, this material demonstrated remarkable characteristics, including 24-hour biodegradability, a broad sensing range (20 %-120 %), and high sensitivity (with response and recovery times of 300 ms and 100 ms, respectively). Based on multiple cross-linked networks, we propose for the first time the underwater sensing mechanism of “Submarine Tunnel” to achieve strong stability in the water environment. Finally, we simulated the LBPS's response to minor external stimuli, including rainwater exposure, multiangle reactions, and water depth sensitivity. By interfacing with wireless modules and mobile phones, the LBS enabled the execution of emergency SOS signals, highlighting its potential applications in underwater motion monitoring and urgent rescue operations.

Microstructure and thermal properties of copper matrix composites reinforced by 3D carbon fiber networks

Three-dimensional (3D) carbon fiber (CF) networks were constructed by electrodeposition using Cu foam as template, and then 3D CF/Cu composites were prepared by hot pressing sintering. Experimental investigations revealed the successful formation of a well-connected 3D CF network embedded within the Cu matrix. The constructed 3D CF networks are conducive to establishing effective heat transfer channels in the composites. The thermal conductivity of the 3D CF/Cu composite with 20 vol% CF in the X–Y plane and Z plane are 418 ± 3 Wm−1K−1 and 415 ± 5 Wm−1K−1, respectively. The thermal conductivity of the composites is significantly enhanced, and the thermal conductivity becomes isotropic. Additionally, the construction of the 3D CF network promotes efficient heat transfer in CF/Cu composites, providing a promising strategy for the development of advanced CF/metal thermal management materials.

High thermal insulation and high strength SiBCN@SiC double network ceramic composite aerogel

Silicon carbide (SiC) fiber materials prepared by precursor conversion method have attracted extensive attention in recent years due to their excellent high temperature resistance and thermal insulation properties. Herein, a novel SiBCN/SiC dual network ceramic composite aerogel with the three-dimensional (3D) porous SiC fiber network obtained by direct electrospinning as the first network and SiBCN aerogel as the second network was prepared by combining electrospinning with sol-gel technology and supercritical drying technology. The microstructure, phase composition, pore size distribution, compressive resistance, thermal insulation and related mechanisms of the 3D SiC fiber network and composite aerogel at different heat treatment temperatures were investigated in detail. The results show that the constructed double-network structure can make up for the heat transfer problem of a single SiC fiber network and further reduce its thermal conductivity, so that the prepared composite aerogel exhibits a lower thermal conductivity (∼0.0316 W m−1 K−1). In addition, the unique double network structure endows the composite aerogel with excellent compressive properties (2.56–2.89 MPa).

Flexible strain sensor based on PU film with three-dimensional porous network

Flexible strain sensors are widely used in wearable applications such as human motion and health detection, but it is challenging to prepare sensors with excellent performance, such as a wide sensing range and high sensitivity with a simple process and low cost. By taking the advantages of the electrostatic spinning technique that can prepare micro-structured films with fibrous porous networks, and this paper investigated the effect of the distance between the electrostatic spinning needle and the collection drum on the mechanical properties of the PU films produced. Then, the most mechanically excellent three-dimensional porous PU fiber film was selected as the substrate, and Carbon Black (CB) particles were selected as the conductive filler to prepare the CB/PU/Ecoflex strain sensor (CPESS) with a three-dimensional porous fiber network structure by spraying CB on the PU fiber film for the sensitive layer and applying a layer of biocompatible Ecoflex on the surface as the encapsulation layer. Owing to the substrates of this three-dimensional network microstructure with excellent mechanical properties such as high Young's modulus and elongation at break, the CPESS has an excellent sensing performance, with a detection range of 200 %, a sensitivity of up to 1443.95, rapid dynamic response of 50 ms, a low detection limit of (0.3 % strain), favorable repeatability, and excellent dynamic response at a large-scale tensile strain of 150 % − 200 %. The CPESS can be used to detect human joint movements and fine motion changes, and it exhibits great potential for smart wearable applications.

What are the key mechanical mechanisms governing integrin-mediated cell migration in three-dimensional fiber networks?

Cell migration plays a vital role in numerous processes such as development, wound healing, or cancer. It is well known that numerous complex mechanisms are involved in cell migration. However, so far it remains poorly understood what are the key mechanisms required to produce the main characteristics of this behavior. The reason is a methodological one. In experimental studies, specific factors and mechanisms can be promoted or inhibited. However, while doing so, there can always be others in the background which play key roles but which have simply remained unattended so far. This makes it very difficult to validate any hypothesis about a minimal set of factors and mechanisms required to produce cell migration. To overcome this natural limitation of experimental studies, we developed a computational model where cells and extracellular matrix fibers are represented by discrete mechanical objects on the micrometer scale. In this model, we had exact control of the mechanisms by which cells and matrix fibers interacted with each other. This enabled us to identify the key mechanisms required to produce physiologically realistic cell migration (including advanced phenomena such as durotaxis and a biphasic relation between migration efficiency and matrix stiffness). We found that two main mechanisms are required to this end: a catch-slip bond of individual integrins and cytoskeletal actin-myosin contraction. Notably, more advanced phenomena such as cell polarization or details of mechanosensing were not necessary to qualitatively reproduce the main characteristics of cell migration observed in experiments.

Flexible CoFe2O4 nanoparticles/N-doped carbon nanofibers membrane as self-standing anode for lithium-ion batteries

The development of new generation wearable electronic devices requires the power supply with high power density, long-term cycling performance, and excellent flexibility and mechanical stability that would enhance the durability of flexible devices during use. Herein, we designed a novel strategy for the preparation of flexible self-supporting nanofiber membrane with highly dispersed CoFe2O4 nanoparticles embedded in one-dimensional (1D) N-doped carbon nanofibers (denoted as [email protected]) by electrospinning and subsequent thermal treatment process, which possesses unique hierarchical structure containing zero-dimensional [email protected] carbon nanospheres and cross-linked three-dimensional (3D) fiber network. The rational combination of the nano-sized CFO particles with high theoretical capacity and a N-doped carbon nanofiber conductive skeleton with interconnected 3D open microstructure facilitates the robust penetration of electrolyte into the electrode, improves the overall electrical conductivity of the electrode, shortens the diffusion pathways of Li+ ions, and buffers the volume change of active materials during lithiation/delithiation. As a consequence, the optimized [email protected] exhibits relatively high electrochemical reversible capacity (611.4 mA h g−1 at 100 mA g−1 after 100 cycles) and good cycling stability, as well as satisfactory rate capability.

Novel poly(ionic liquid)s reinforced with three-dimensional electrospun fiber network as electrolyte for all solid state lithium batteries

Solid polymer electrolytes have been identified lately as the most pragmatic research area towards the development of safe and reliable lithium batteries with zero electrolyte leakage. In this work, ionene oligomers based on 1,4-Diazabicyclo [2.2.2] octane (DABCO) bearing oxyethylene spacers with varying –CH2CH2O- units and having bis (trifluoromethanesulfonyl) imide (TFSI−) counter anion were synthesized. The ionene oligomers exhibited excellent thermal stability up to 300 °C with glass transition below room temperature. Interestingly, the presence of oxyethylene linkers between the cationic moieties in the oligomer backbone significantly affected the Li+ ion coordination and ionic conductivity as explained by Raman spectroscopy and electrochemical impedance spectroscopy (EIS) studies carried out on binary mixtures of POnTFSI/LiTFSI (where ‘P’ indicates the oligomer and ‘On’ denotes the number ‘n’ of oxyethylene units in the spacer). The oxygen atoms present in the spacer backbone of the ionene can interact with the Li+ ions and prevent the formation of aggregates with the anions while the mobility of the TFSI−anions is restricted by the polar nature of the ionene backbone. Such binary mixtures were incorporated in an electrospun nanofibrous framework, to form a free-standing solid polymer electrolyte and the electrochemical performance was evaluated in a Li/LiFePO4 (LFP) battery.

Biomimetic and flexible high-performance carbon paper prepared by welding three-dimensional carbon fiber network with polyphenylene sulfide spherical sites for fuel cell gas diffusion layer

High-performance carbon fiber paper (CFP) is usually an important part of the fuel cell gas diffusion layer (GDL). However, the preparation of CFP for GDL is still a challenge due to its arduous preparation process. Here, inspired by the structure of bird's nest in nature, we present the original design of PPS spherical sites welding three-dimensional (3D) carbon fiber network to produce high-performance CFP by facile wet papermaking and heat treatment. With a 3D CF network as the skeleton and PPS spherical sites as the welding points, CFs/PPS composite paper exhibits good mechanical strength and outstanding flexibility. Meanwhile, the excellent conductivity (6.8 S/cm) is integrated with super-hydrophobic performance, electrothermal performance (Tmax = 365 °C), heat resistance (DTGmax>575 °C), and corrosion resistance, becoming a high-performance multifunctional CFP. The mythical combination of these properties makes CFs/PPS composite paper an ideal candidate in the field of fuel cell GDL. In addition, the evolution of chemical structure of CF/PPS during carbonization is emphasized, which is of great significance for the properties of composite paper. This work presents a leap forward in the preparation of multi-property high-performance CFP in a simple method and is a key step toward exploring how the structural changes of CFs/PPS composite paper can be understood during carbonization.

A 3D Corncob-based interfacial solar evaporator enhanced by environment energy with salt-rejecting and anti-corrosion for seawater distillation

Biomass-derived, carbon converted from renewable biomass materials via the carbonization process, has been widely investigated for interfacial solar evaporators and is deemed a promising choice for solar desalination. However, salt accumulation at the evaporation interface is a great challenge. Studies show that the surface wetting and antifouling ability of carbonized-biomass, affects solar absorption, water supply, and water evaporation. In this paper, a simple two-step strategy completely different from carbonization is proposed for efficient solar evaporation and seawater desalination. In this regard, an interfacial solar evaporator is prepared based on the corn cob. The evaporator makes the best use of the raw three-dimensional interconnected fiber network structure, which extremely promotes the collection of solar energy, sufficient water supply, and vapor escape at the evaporation interface. Owing to the decrease in evaporation enthalpy and drawing energy from the environment, the evaporation rate and the photothermal conversion efficiency of proposed the evaporator reached 1.68 kg·m−2·h−1 and 99.32 % under solar irradiation intensity of 1 kW·m−2, respectively. The performance of the proposed scheme was investigated under various salinity levels and a great salt-rejecting and anti-corrosion performance was achieved. This simple strategy is a promising candidate for preparing biomass-based interfacial solar evaporators in practical applications.

Removal of Cd2+ from wastewater to form a three-dimensional fiber network using Si-Mg doped industrial lignin-based carbon materials

In this study, SiMg doped industrial lignin-based carbon materials (SLCs) were prepared by water bath silicification and MgCl2 activation to remove Cd2+ from aqueous solutions. What’s more, the doping of SiMg jointly promoted the excellent physicochemical properties of the material, e.g., high specific surface area, good pore volume, and numerous oxygen-containing groups. The Cd2+ batch adsorption experiments proved that SLCs have good Cd2+ removal capacity within pH 3–7, and the adsorption model demonstrated the adsorption process as a physicochemically complex process. The maximum adsorption of Cd2+ in the SLC was 665.35 mg/g, and the contributing factors to the removal of Cd2+ were as follows: ion exchange (59.36 %) > Cd2+ precipitation (24.93 %) > oxygen-containing functional group complexation (14.79 %) > Cd2+–π interactions (0.92 %). In addition, the complexation of SiO, MgO, and Cd precipitates allowed the formation of a three-dimensional fiber mesh structure. The application of SLCs has the potential to eliminate Cd2+ pollution in water bodies, and its preparation is simple and environmentally friendly. Finally, this study provides a theoretical basis for an in-depth understanding of the mechanism of heavy metal adsorption by inorganic nonmetals in combination with metal oxides.

Surface iodine modification inducing robust CEI enables ultra-stable Li-Se batteries

Lithium-selenium batteries (LSeBs) have attracted increasing attention due to their excellent electronic conductivity and high theoretical specific capacity. However, there are still difficult problems such as low utilization rate and fast capacity decay in the actual application process. Herein, a surface iodine modified three-dimensional (3D) nano hollow carbon fiber (I-NHCF) network is designed and synthesized as Se host (Se@I-NHCF) for highly stable LSeBs. The surface iodine species induce the formation of robust cathode electrolyte interface (CEI), thus preventing the transformation of amorphous selenium to low-activity crystalline selenium and enabling stable electrochemical performance. Moreover, the surface iodine species promote rapid charge transfer, enhancing the chemical reaction kinetics and improving the utilization of the active Se species. As a result, the Se@I-NHCF cathode exhibits superior specific capacity of 581.8 mAh g−1 with a high stability (0.0054% capacity decay per cycle) after 500 cycles at 1C, and an excellent rate performance of 567.6 mAh g−1 at 2C. This work addresses the problem of rapid capacity decay by the formation of uniform and robust CEI to conserve highly reactive amorphous Se species, improve Se utilization, and achieve ultra-stable Li-Se batteries with high energy and long cycle life.

Densely packed ultrafine SnO2 nanoparticles grown on carbon cloth for selective CO2 reduction to formate

Electrochemical reduction of CO2 to fuels and chemicals is a viable strategy for CO2 utilization and renewable energy storage. Developing free-standing electrodes from robust and scalable electrocatalysts becomes highly desirable. Here, dense SnO2 nanoparticles are uniformly grown on three-dimensional (3D) fiber network of carbon cloth (CC) by a facile dip-coating and calcination method. Importantly, Zn modification strategy is employed to restrain the growth of long-range order of SnO2 lattices and to produce rich grain boundaries. The hybrid architecture can act as a flexible electrode for CO2-to-formate conversion, which delivers a high partial current of 18.8 mA cm−2 with a formate selectivity of 80% at a moderate cathodic potential of −0.947 V vs. RHE. The electrode exhibits remarkable stability over a 16 h continuous operation. The superior performance is attributed to the synergistic effect of ultrafine SnO2 nanoparticles with abundant active sites and 3D fiber network of the electrode for efficient mass transport and electron transfer. The sizeable electrodes hold promise for industrial applications.

A computational framework for biomaterials containing three-dimensional random fiber networks based on the affine kinematics.

Understanding the structure-function relationship of biomaterials can provide insights into different diseases and advance numerous biomedical applications. This paper presents a finite element-based computational framework to model biomaterials containing a three-dimensional fiber network at the microscopic scale. The fiber network is synthetically generated by a random walk algorithm, which uses several random variables to control the fiber network topology such as fiber orientations and tortuosity. The geometric information of the generated fiber network is stored in an array-like data structure and incorporated into the nonlinear finite element formulation. The proposed computational framework adopts the affine fiber kinematics, based on which the fiber deformation can be expressed by the nodal displacement and the finite element interpolation functions using the isoparametric relationship. A variational approach is developed to linearize the total strain energy function and derive the nodal force residual and the stiffness matrix required by the finite element procedure. Four numerical examples are provided to demonstrate the capabilities of the proposed computational framework, including a numerical investigation about the relationship between the proposed method and a class of anisotropic material models, a set of synthetic examples to explore the influence of fiber locations on material local and global responses, a thorough mesh-sensitivity analysis about the impact of mesh size on various numerical results, and a detailed case study about the influence of material structures on the performance of eggshell-membrane-hydrogel composites. The proposed computational framework provides an efficient approach to investigate the structure-function relationship for biomaterials that follow the affine fiber kinematics.

Aqueous Processed Ni-Rich Li(Ni0.8Co0.1Mn0.1)O2 Cathodes Along with Water-Based Binders and a Carbon Fabric as 3-D Conductive Host

A carbon fabric with three-dimensional carbon fiber network is proposed as a conductive framework instead of Al current collector, in order to fabricate a LiNi0.8Co0.1Mn0.1O2 (NCM811) cathode using an environmentally friendly water-based process. Water-based NCM811 slurries prepared without binder, with poly(acrylic acid) (PAA) binder, and with poly(acrylonitrile) (PAN) binder have the equilibrium pH values of 12.4, 6.7, and 12.6, respectively. Without a binder, the cathode materials are poorly dispersed in the slurry, which hinders smooth casting on the carbon fabric. The addition of either PAA or PAN improves the uniform dispersion of particles and the loading capability of slurries, leading to a lower impedance of the cast cathodes. Compared to PAA, PAN performs better with the carbon fabric as a conductive framework, due to the better dispersion of electrode materials, lower impedance in the fabricated electrode, and good chemical stability of PAN to the electrolyte. The cell constructed with PAN-added cathode exhibits a high specific capacity of 150–160 mAh g−1 at a charge/discharge rate of 0.5 C, and nearly 100% capacity retention after 100 cycles. Nevertheless, PAA is soluble in the electrolyte and has some negative effects on the capacity performance of the constructed cell.

Transformation of electrospun Keratin/PVA nanofiber membranes into multilayered 3D Scaffolds: Physiochemical studies and corneal implant applications

In this study, we engineered an electrospun keratin/polyvinyl alcohol (PVA) nanofiber membrane with a three-dimensional (3D) fiber network. Both keratin and PVA are known as biocompatible materials, and the 3D assembly of these two led to a transparent membrane with superior mechanical properties. The as-prepared three-dimensionally assembled keratin/PVA nanofiber (3D keratin/PVA NFs) membrane was characterized by state-of-the-art techniques and used as a corneal implant in rabbit eyes. The transparency, mechanical properties, and biocompatibility of the electrospun keratin/PVA NFs were highly enhanced after 3D modification which is mainly attributed to its unique three-dimensional morphology. The performance of 3D keratin/PVA NFs membrane was compared with horse amniotic membrane (AM), and the results obtained from the clinical and histological evaluations showed that it could be considered as an alternative material to the AM. Furthermore, this study provides an emerging approach for converting a two-dimensional electrospun nanofiber membrane to three-dimensional fiber networks that resemble the structure of the extracellular matrix (ECM).

Shear-induced phase transition and critical exponents in three-dimensional fiber networks.

When subject to applied strain, fiber networks exhibit nonlinear elastic stiffening. Recent theory and experiments have shown that this phenomenon is controlled by an underlying mechanical phase transition that is critical in nature. Growing simulation evidence points to non-mean-field behavior for this transition and a hyperscaling relation has been proposed to relate the corresponding critical exponents. Here, we report simulations on two distinct network structures in three dimensions. By performing a finite-size scaling analysis, we test hyperscaling and identify various critical exponents. From the apparent validity of hyperscaling, as well as the non-mean-field exponents we observe, our results suggest that the upper critical dimension for the strain-controlled phase transition is above three, in contrast to the jamming transition that represents another athermal, mechanical phase transition.

High thermal conductivity and low leakage phase change materials filled with three-dimensional carbon fiber network

As one of the most effective energy storage compounds, phase change materials (PCMS) play an important role in energy conservation and storage. However, the inherent poor thermal conductivity and liquid leakage of PCMS seriously limit their practical application. Polyethylene glycol·calcium chloride (PEG·CaCl2) phase change materials filled with three-dimensional carbon fiber network were prepared by liquid phase impregnation and hot pressing molding method. The experimental results show that carbon fiber network (CF felt) and PEG·CaCl2 complex structure increase the thermal conductivity and stability. The in-plane thermal conductivity of PEG·CaCl2/CF composite (47.73% carbon content) is 0.97 W/mK, about 103% higher than that of PEG. PEG·CaCl2/CF composite does not present leakage even heating at 80 °C for 45 min (35 °C higher than the melting point of pure PEG), showing low leakage ability. High thermal conductivity, low leakage and low density of this composite suggest a promising route for thermal storage applications.