Atomistic Investigation of Load Transfer Between DWNT Bundles “Crosslinked” by PMMA Oligomers

The production of carbon nanotube (CNT) yarns possessing high strength and toughness remains a major challenge due to the intrinsically weak interactions between “bare” CNTs. To this end, nanomechanical shear experiments between functionalized bundles of CNTs are combined with multiscale simulations to reveal the mechanistic and quantitative role of nanotube surface functionalization on CNT‐CNT interactions. Notably, the in situ chemical vapor deposition (CVD) functionalization of CNT bundles by poly(methyl methacrylate) (PMMA)‐like oligomers is found to enhance the shear strength of bundle junctions by about an order of magnitude compared with “bare” van der Waals interactions between pristine CNTs. Through multiscale simulations, the enhancement of the shear strength can be attributed to an interlocking mechanism of polymer chains in the bundles, dominated by van der Waals interactions, and stretching and alignment of chains during shearing. Unlike covalent bonds, such synergistic weak interactions can re‐form upon failure, resulting in strong, yet robust fibers. This work establishes the significance of engineered weak interactions with appropriate structural distribution to design CNT yarns with high strength and toughness, similar to the design paradigm found in many biological materials.     

Novel,Robust, and Versatile Bijels of Nitromethane,Ethanediol, and Colloidal Silica: Capsules,Sub‐Ten‐Micrometer Domains,and Mechanical Properties

Bicontinuous, interfacially jammed emulsion gels (bijels) are a class of soft solid materials in which interpenetrating domains of two immiscible fluids are stabilized by an interfacial colloidal monolayer. Such structures form through the arrest of the spinodal decomposition of an initially single‐phase liquid mixture containing a colloidal suspension. With the use of hexalmethyldisilazane, the wetting character of silica colloids, ranging in size and dye content, can be modified for fabricating a novel bijel system comprising the binary liquid ethanediol–nitromethane. Unlike the preceding water‐lutidine based system, this bijel is stable at room temperature and its fabrication and resultant manipulation are comparatively straightforward. The new system has facilitated three advancements: firstly, we use sub 100 nm silica particles to stabilize the first bijel made from low molecular weight liquids that has domains smaller than ten micrometers. Secondly, our new and robust bijel permits qualitative rheological work which reveals the bijel to be significantly elastic and self healing whilst its domains are able to break, reform and locally rearrange. Thirdly, we encapsulate the ethanediol–nitromethane bijel in Pickering drops to form novel particle‐stabilized bicontinuous multiple emulsions that we christen bijel capsules. These emulsions are stimuli responsive – they liberate their contained materials in response to changes in temperature and solvency, and hence they show potential for controlled release applications.     

Design of the interfacial shear strength between the glass fiberand primary coating in double-coated optical fibers

The design of the interfacial shear strength between the glass fiber and primary coating in double-coated optical fibers is investigated. An optical fiber with higher interfacial shear strength possesses a better ability to prevent the delamination of polymeric coatings, but it makes the strip of coating materials more difficult. Based on the consideration of the stripping ability and delamination of polymeric coatings, the optimal value of the interfacial sheer strength is dependent on the tensile strength of the glass fiber, the damping condition of the tensile force applied on the optical fiber, the fiber's length, and material's properties of polymeric coatings. In the real applications of optical fibers, the tensile strength of the glass fiber can be regarded as the allowable external load induced axial stress in the glass fiber which usually is a fraction of the proof-test setting value. The clamping condition of the optical fiber can be regarded that the tensile force is only applied on the both ends of the secondary coating. The fiber's length can be regarded as the minimum operating length, for example, 10 mm. A higher value of the interfacial shear strength is required for optical fibers with higher Young's modulus of the primary coating, lower Poisson's ratio of the primary coating, and lower radius and Young's modulus of the secondary coating. Finally, the limitation of the lateral load on the optical fibers to prevent the delamination of polymeric coatings is also discussed     

Functional Polysaccharide Sutures Prepared by Wet Fusion of Interfacial Polyelectrolyte Complexation Fibers

This study reports polysaccharide‐based fibers that can be utilized as biocompatible functional sutures. Fibers are spontaneously formed by spinning at the interface between two oppositely charged polysaccharide solutions. Unlike the common belief that polysaccharide fibers prepared by electrostatic interactions would exhibit weak mechanical strength, it is demonstrated that fibers spun at the interface between two droplets of positively charged chitosan and negatively charged heparin can exhibit high mechanical strength through spontaneous wet‐state fusion of interfiber strands at a spinning wheel. Dry solidification results in multistranded fibers that were ≈100 µm in diameter with a tensile strength of ≈220 MPa. Post fibrous manipulation yields various morphology with straight or twisted fibers, fabrics, or springs. To demonstrate application of the fiber, it is applied as a medical suture. As heparin has a unique ability to bind adeno‐associated virus (AAV), a therapeutic, biocompatible suture exhibiting localized AAV‐mediated gene delivery function can be prepared. This study shows that multistrand fusion of fibers, formed by weak, electrostatic interactions and followed by drying solidification counterintuitively results in mechanically strong, functional fibers with various potential applications.     

Hybrid functional microfibers for textile electronics and biosensors

Fibers are low-cost substrates that are abundantly used in our daily lives.This review highlights recent advances in the fabrication and application of multifunctional fibers to achieve fibers with unique functions for specific applications ranging from textile electronics to biomedical applications.By incorporating various nanomaterials such as carbon nanomaterials,metallic nanomaterials,and hydrogel-based biomaterials,the functions of fibers can be precisely engineered.This review also highlights the performance of the functional fibers and electronic materials incorporated with textiles and demonstrates their practical application in pressure/tensile sensors,chemical/biosensors,and drug delivery.Textile technologies in which fibers containing biological factors and cells are formed and assembled into constructions with biomimetic properties have attracted substantial attention in the field of tissue engineering.We also discuss the current limitations of functional textile-based devices and their prospects for use in various future applications.     

Reinforced Wool Keratin Fibers via Dithiol Chain Re-bonding

Regenerated wool keratin fibers (RWKFs) have heretofore attracted tremendous interest according to environmental friendliness, ample resource, and intrinsic biocompatibility for broad applications. In this realm, both uncontrollable keratin fibril assembly procedure and resultant insufficient mechanical strength, have greatly hindered their large-scale manufacture and commercial viability. Herein, a continuous wet-spinning strategy is put forward to rebuild wool keratin into compact regenerated bio-fibers with improved strength via disulfide re-bonding. Dithiothreitol (DTT) has been introduced to renovate disulfide linkage inside keratin polypeptide chains, and bridge keratin fibrils via covalent thiol bonding to form a continuous backbone as mechanical support. A thus-derived RWKF manifests a tensile strength of 186.1 ± 7.0 MPa and Young's modulus of 7.4 ± 0.2 GPa, which exceeds those of natural wool, feathers, and regenerated wool or feather keratin fibers. The detailed wet-spinning technical parameters, such as coagulation, oxidation, and post-treatment, have been systematically optimized to guarantee the continuous preparation of high-strength regenerated keratin fibers. This work offers insight into solving the concurrent challenges for continuous manufacture of regenerated protein fibers and sustainability concerns about biomass waste.     

Printing Reconfigurable Bundles of Dielectric Elastomer Fibers

Active soft materials that change shape on demand are of interest for a myriad of applications, including soft robotics, biomedical devices, and adaptive systems. Despite recent advances, the ability to rapidly design and fabricate active matter in complex, reconfigurable layouts remains challenging. Here, the 3D printing of core-sheath-shell dielectric elastomer fibers (DEF) and fiber bundles with programmable actuation is reported. Complex shape morphing responses are achieved by printing individually addressable fibers within 3D architectures, including vertical coils and fiber bundles. These DEF devices exhibit resonance frequencies up to 700 Hz and lifetimes exceeding 2.6 million cycles. The multimaterial, multicore-shell 3D printing method opens new avenues for creating active soft matter with fast programable actuation.     

Giving Direction to Motion and Surface with Ultra‐Fast Speed Using Oriented Hydrogel Fibers

Thermoresponsive hydrogel fibrous membranes showing directionally controlled movements and surface change with ultra‐fast speed are presented for the first time. They show reversible coiling, rolling, bending, and twisting deformations in different controllable directions for many cycles (at least 50 cycles tried) with inside‐out change in surfaces and shapes. Speed, reversibility, large‐scale deformations and, most importantly, control over the direction of deformation is required in order to make synthetic actuators inspired from natural materials or otherwise. A polymeric synthetic material combining all these properties is still awaited. This issue is addressed and provide a very simple system fulfilling all these requirements by combining porosity and asymmetric swelling/shrinking via orientation of hydrogel fibers at different angles in a fibrous membrane. Electrospinning is used as a tool for making membranes with fibers oriented at different angles.     

Prediction of the pipe buckling by using broadening factor with distributed Brillouin fiber sensors

We successfully measured longitudinal strains in two full-scale steel pipe specimens subjected to loading combinations of internal pressure, axial tensile force and bending moments undergoing local buckling under controlled laboratory conditions. Carbon-coated fibers, for the first time, and standard communication fibers were used. By using the broadening factor of the Brillouin spectrum width, we can successfully predict the location and progression sequence of buckling patterns, prior their visual detection in the laboratory. The broadening factor processing time is more efficient than multiple-peak fitting of the Brillouin spectrum method. Thus, it is capable of proving real-time deformation progression in structural health monitoring applications. High strength carbon-coated fibers are found to be superior to standard communication fibers in two respects: they provide more accurate readings and are able to measure significantly larger strains.     

A multiplicative damage model for strength of fibrous compositematerials

Knowledge of the tensile strength properties of a fibrous composite material is essential in the design of reliable structures from that material. Determination of statistical models for the tensile strength of a composite material which provide good fits to experimental data from tensile tests on material specimens is therefore important for engineering design. Perhaps the most commonly used statistical model is the Weibull distribution, based on `weakest link of a chain' arguments. However, in many cases the usual Weibull distribution does not adequately fit experimental data on tensile strength for composite materials made from brittle fibers such as carbon. Here, an alternative model is developed for tensile strength of carbon composites, which is based on a multiplicative cumulative-damage approach. This approach results in a 3-parameter extension of the Birnbaum-Saunders fatigue model and incorporates the material specimen size (size effect) as a known variable. This new distribution can also be written as an inverse Gaussian-type distribution, which can be interpreted as the first passage of the accumulated damage past a damage threshold, resulting in material failure. The new model fits experimental tensile-strength data, for carbon micro-composites better than existing models, providing more accurate estimates of material strength     

Unified Bundling and Registration of Brain White Matter Fibers

Magnetic resonance diffusion tensor imaging is being widely used to reconstruct brain white matter fiber tracts. To characterize structural properties of the tracts, reconstructed fibers are often grouped into bundles that correspond to coherent anatomic structures. For further group analysis of fiber bundles, it is desirable that corresponding bundles from different studies are coregistered. To address these needs simultaneously, a unified fiber bundling and registration (UFIBRE) framework is proposed in this work. The framework is based on maximizing a posteriori Bayesian probabilities using an expectation maximization algorithm. Given a set of segmented template bundles and a whole-brain target fiber set, the UFIBRE algorithm optimally bundles the target fibers and registers them with the template. The bundling component in the UFIBRE algorithm simplifies fiber-based registration into bundle-to-bundle registration, and the registration component in turn guides the bundling process to find bundles consistent with the template. Experiments with in vivo data demonstrate that the estimated bundles have an $sim$ 80% consistency with ground truth and the root mean square error between their bundle medial axes is less than one voxel. The proposed algorithm is highly efficient, offering potential routine use for group analysis of white matter fibers.      

Drawing influence on the lifetime of optical fibres

Strength and lifetime measurements carried out on optical fibers with different residual tensile stress at the surface are discussed. This stress was optically measured and included in the theory of fiber strength and lifetime. The strength results were compared with measurements done on pure silica fibers without residual stress. In lifetime predictions, this residual tensile stress in the outside region of the fiber has to be taken into account. However, the decrease in intrinsic strength was much larger than the increase in residual stress in the outside region of the fiber. This phenomenon, which is not well understood, depends on drawing conditions     

Making a Robust Interfacial Scaffold: Bijel Rheology and its Link to Processability

Confocal microscopy and rheology studies of two bijel systems are presented to elucidate relationships between the physicochemical properties of bijels and their ability to be utilized as soft matter templates for materials synthesis. For the first time, the origins of viscoelasticity in these systems are investigated using conventional rheometry and a direct correspondence between the elastic storage modulus, particle loading, and the departure from criticality is observed. Further, the rheological transitions that accompany fluid re‐mixing in bijels are characterized, providing key insights into the synergistic role of interfacial tension and interparticle interactions in mediating their mechanical robustness. Bijels that are predominantly stabilized by interfacial tension are also highly sensitive to gradients in chemical composition and more easily prone to mechanical failure during processing. Despite this increased sensitivity, a modified strategy for processing these more delicate systems is developed and its efficacy is demonstrated by synthesizing a bicontinuous macroporous hydrogel scaffold.     

Reactive Spinning of Cyanate Ester Fibers Reinforced with Aligned Amino‐Functionalized Single Wall Carbon Nanotubes

We report a new approach of reactive spinning to fabricate thermosetting cyanate ester micro‐scale diameter fibers with aligned single walled carbon nanotubes (SWNTs). The composite fibers were produced by first dispersing the SWNTs (1 wt %) in cyanate ester (CE) via solvent blending, followed by pre‐polymerization, spinning and then multiple‐stage curing. The pre‐polymerization, spinning and post‐spinning cure temperatures were carefully controlled to achieve good spun crosslinked fibers. Both pristine and amino‐functionalized SWNTs were used for the reinforced fiber spinning. Amino‐functionalized SWNTs (f‐SWNTs) were prepared by reacting acid‐treated SWNTs with toluene 2,4‐diisocyanate and then ethylenediamine (EDA). FTIR, optical microscopy and scanning electron microscopy (SEM) showed that the amino‐functionalized SWNTs were covalently and uniformly dispersed into the cyanate ester matrix and aligned along the fiber axis. The alignment was further confirmed using polarized Raman spectroscopy. The composite fibers with aligned amino‐functionalized SWNTs possess improved tensile properties with respect to neat CE fibers, showing 85, 140, and 420% increase in tensile strength, elongation and stress‐strain curve area (i.e., toughness), respectively. NH₂‐functionalization of SWNTs improves their dispersibility, alignment and interfacial strength and hence tensile properties of composite spun fibers. Fiber spinning to align SWNTs using thermosetting resin is novel. Others have reported fiber spinning to align SWNTs in thermoplastics. However, thermosetting CE resins offer the advantages of low and controllable viscosity during spinning and reactivity with amino functional groups to enable f‐SWNT/CE covalent bonding.     

Controlled Synthesis of Ag2S,Ag2Se,and Ag Nanofibers by Using a General Sacrificial Template and Their Application in Electronic Device Fabrication

Nanofiber bundles of Ag₂S, Ag₂Se, and Ag have been successfully synthesized by making use of Ag₂C₂O₄ template nanofiber bundles, utilizing both anion‐exchange and redox reactions. The obtained bundles were polycrystalline nanofibers composed of nanoparticles in which the precursor morphology was well‐preserved, indicating that Ag₂C₂O₄ nanofiber bundles acted as a general sacrificial template for the synthesis of silver‐based semiconductor and metal nanofibers. Dispersing media and transforming reactants were found to be key factors influencing the chemical transformation in the system. In particular, separate single‐crystalline Ag nanofibers were obtained via a nontemplate route when ascorbic acid was used as a relatively weak reductant. An electrical transfer and switching device was built with the obtained Ag₂S and Ag nanofiber bundles, utilizing the unique ion‐conductor nature of Ag₂S and revealing their potential applications in electronics.     

Ultra-High Toughness Fibers Using Controlled Disorder of Assembled Aramid Nanofibers

Assembling nanoscale building blocks with reduced defects has emerged as a promising approach to exploit nanomaterials in the fabrication of simultaneously strong and tough architectures at larger scales. Aramid nanofibers (ANFs), a type of organic nanobuilding block, have been spotlighted due to their superior mechanical properties and thermal stability. However, no breakthrough research has been conducted on the high mechanical properties of a structure composed of ANFs. Here, assembling ANFs into macroscale fiber using a simultaneous protonation and wet-spinning process is studied to reduce defects and control disorder. The ANF-assembled fibers consist of hierarchically aligned nanofibers that behave as a defective law structure, making it possible to reach a Young's modulus of 53.15 ± 8.98 GPa, a tensile strength of 1,353.64 ± 92.98 MPa, and toughness of 128.66 ± 14.13 MJ m⁻³. Compared to commercial aramid fibers, the fibers exhibit ≈1.6 times greater toughness while also providing specific energy to break as 93 J g⁻¹. Furthermore, this shows recyclability of the ANF assembly by retaining ≈94% of the initial mechanical properties. This study demonstrates a facile process to produce high stiffness and strength fibers composed of ANFs that possess significantly greater toughness than commercial synthetic fibers.     

Polymer Fiber Scaffolds for Bone and Cartilage Tissue Engineering

Successful regeneration of weight‐bearing bone defects and critical‐sized cartilage defects remains a major challenge in clinical orthopedics. In the past decades, biodegradable polymer materials with biomimetic chemical and physical properties have been rapidly developed as ideal candidates for bone and cartilage tissue engineering scaffolds. Due to their unique advantages over other materials of high specific‐surface areas, suitable mechanical strength, and tailorable characteristics, scaffolds made of polymer fibers have been increasingly used for the repair of bone and cartilage defects. This Review summarizes the preparation and compositions of polymer fibers, as well as their characteristics. More importantly, the applications of polymer fiber scaffolds with well‐designed structures or unique properties in bone, cartilage, and osteochondral tissue engineering have been comprehensively highlighted. On the whole, such a comprehensive summary affords constructive suggestions for the development of polymer fiber scaffolds in bone and cartilage tissue engineering.     

Discrete‐Continuum Duality of Architected Materials: Failure,Flaws, and Fracture

3D nano‐ and micro‐architected materials are resilient under compression; their susceptibility to flaws and fracture remain unexplored. This work reports the fabrication and tensile‐to‐failure response of hollow alumina nanolattices arranged into 5 µm octet‐truss unit cells. Some specimens contained through‐thickness center notches oriented at different angles to the loading direction, with a length‐over‐sample‐width ratio of 0.45. In situ tensile experiments reveal that for all orientations, failure initiates at the notch root, followed by instantaneous crack propagation along lattice planes orthogonal to extension. A tensile strength of 27.4 ± 0.7 MPa is highest for unnotched samples and decreases as notch orientation varies from 0° to 90° to its minimum, 7.2 ± 0.4 MPa; their specific tensile strength is ≈4 × higher than that for all other low‐density materials. Finite element simulations reproduce observed strengths and failure mechanisms: initial cracks always initiate at the nodal junctions with highest stress concentrations by tearing of alumina walls at the nodes. Subsequent crack propagation shifts maximum stress concentration to the nodes along lattice plane orthogonal to the loading direction. A modified analytical fracture model based on the effective notch length predicts tensile strengths consistent with experiments. These findings imply that continuum fracture mechanics can predict failure in nano‐architected materials, which helps develop advanced materials through informed architectural design.     

Ultra-Strong Regenerated Wool Keratin Fibers Regulating via Keratin Conformational Transition

By virtue of remarkable biocompatibility and their promising applications in biomedical fields, biomass-regenerated fibers, such as wool keratin fiber and cellulose fiber, have attracted extensive attention. However, the insufficient mechanical performance still hinders their yarn manufacturing capability and further large-scale applications. Herein, an ultra-strong and ultra-tough regenerated wool keratin fiber by regulating keratin conformation with high-quality small-size graphene (HQSGr) and mechanical training treatment (M-HQSGr-RWKF) is fabricated. With the assistance of mechanical training, a small addition of HQSGr (0.1 wt.%) remarkably augments the secondary structure transition from α-helix to β-sheet of the keratin, which delivers a tensile strength of 215.4 ± 5.2 MPa, surpassing all reported natural wool and regenerated wool or even poultry fibers. Benefiting from the excellent mechanical strength, wet-state toughness (158.9 MJ m⁻³), and recoverable strain (205.0%), M-HQSGr-RWKF has been demonstrated as a biocompatible artificial muscle to drive the biomimetic motion, which manifests ultrahigh actuation strain greater than 100.0% and stress of 16.7 MPa. The derived ultra-strong and ultra-tough keratin fiber opens a new avenue for developing smart fiber from biomass resources.     

镀镍光纤抗拉强度及其影响因素

针对以硫酸镍为主盐所得镀镍光纤表面质量较差、镀层内应力大和抗拉强度低等问题,采用氨基磺酸镍为主盐在化学镀镍后的光纤表面电镀镍。对比研究了两种工艺所得镀镍光纤的表面质量和抗拉强度,与FiberGuide所售镀金光纤进行了对比。结果表明:以氨基磺酸镍为主盐所得镀镍光纤表面比以硫酸镍为主盐所得镀镍光纤表面更加光滑致密;氨基磺酸镍镀镍光纤的抗拉强度(877.20 MPa)比硫酸镍镀镍光纤的抗拉强度(511.11 MPa)提高41.73%,与FiberGuide所售镀金光纤的抗拉强度(718.99 MPa)相当;光纤表面有机物涂层的去除方法,包括光纤钳和化学浸泡去除方法,可能影响最终镀层表面质量。