Synthetic replication of biological materials like spider silk, cellulose, and collagen remains challenging owing to the entropic cost of aligning high-aspect-ratio chains into compact, load-bearing structures. These barriers cause misalignment, voids, and poor inter-fiber cohesion in macroscale materials. We report a scalable strategy for producing high-strength thread from poly(2,2'-disulfonyl-4,4'-benzidine terephthalamide) (PBDT), a rigid-chain aramid that forms double-helical supramolecular units, which further organize into nanofiber networks. Continuous PBDT threads are fabricated while retaining the solution-phase double-helix structure, enabling production over hundreds of meters. These nanofibers are processed into macroscale threads through wet-spinning and hydro-torsional compaction, which promotes densification and enhances inter-fiber contact. This hierarchical processing sequence yields compact, aligned fibers with improved structural coherence, supporting efficient interfacial load transfer and resulting in a tensile strength of 1.2 GPa and a Young's modulus of 103 GPa, corresponding to 5.8-fold and 6.3-fold improvements over bulk PBDT films, respectively. Among synthetic nanofibrous materials assembled in aqueous media, these threads demonstrate superior mechanical properties, with tensile strengths approaching those of spider silk. This study establishes a scalable framework for constructing high-strength, hierarchically organized aramid threads for aligned, robust architectures, ion-mediated transport pathways, and charged bioinspired systems.

Industrial fermentation relies on mechanically agitated submerged culture, in which impeller-driven mixing improves oxygen and nutrient transfer but imposes an energy penalty and a hydrodynamic shear field that stresses cells. Solid supports offer an agitation-free alternative, yet their surface is typically ill-defined and only a single polymer and a single organism have been examined. Here we treat the support material as a controllable process variable. Using an identical scaffold geometry 3D-printed by fused-deposition modeling in four thermoplastics—ABS, TPU, PLA, and PETG—we compared static cultivation of a model yeast (Saccharomyces cerevisiae) and a model lactic acid bacterium (Lactobacillus plantarum) against shaken and static controls, and related the outcomes to polymer surface wettability. For S. cerevisiae, embedding a matrix in static medium nearly doubled biomass relative to the static control and drove glucose to near-complete assimilation, raising ethanol titres ~1.7–1.8-fold to shaken-culture levels without any agitation. For L. plantarum, three of the four matrices (PLA, ABS, PETG) exceeded both the static and the aerated shaking controls in biomass (by ~15–21%) and in lactic acid production, while the elastomeric TPU behaved like the controls. Because L. plantarum is microaerophilic, these results suggest that factors other than improved aeration, including interactions at the scaffold–liquid interface, contribute to the observed enhancement. The polymer type thus emerges as a tunable parameter for scaffold-assisted cultivation, enabling fermentation without mechanical agitation while achieving performance comparable to, and in some cases greater than, that of shaken culture. The polymer type thus emerges as a tunable determinant of performance, defining an agitation-free cultivation strategy in which the interface—rather than bulk flow—is engineered to achieve, and in some cases surpass, the productivity of conventional stirred culture.

Polybenzoxazines (PBZs) are advanced thermosetting resins whose properties can be tuned by functional group substitution. In this study, the curing behaviors of bisphenol A-based benzoxazine monomers functionalized with nitrile and ethynyl groups at the ortho, meta, and para positions of the amine group were compared. Differential scanning calorimetry (DSC) revealed that nitrile substitution increased the onset and peak curing temperatures as well as the activation energy, thereby delaying the curing process. In contrast, ethynyl substitution significantly lowered these parameters, indicating a barrier-lowering effect that accelerates crosslinking. In situ FT-IR at 160 °C (air) confirmed slower ring-opening polymerization; nitrile conversion was minimal at this early stage, while ethynyl groups actively contributed to network formation. For nitrile-functionalized monomers, ortho, and para substitutions most severely hindered curing, whereas for ethynyl-functionalized monomers, meta-ethynyl provided the best balance when evaluated by lower Ea and higher network density. The results show the opposite directive influences of nitrile and ethynyl groups, which can serve as guidelines for controlling PBZs toward advanced thermal, structural, and electronic applications. All comparisons refer to identical early-stage FT-IR conditions (160 °C, air) and DSC-derived Ea; high-temperature trimerization of nitrile groups is discussed as a separate operating window.

Natural ligaments are soft connective tissues that must simultaneously provide high stretchability to enable dexterous flexibility and high stiffness to protect the musculoskeletal system. These two functions cannot be independently tuned in conventional engineering materials with linear or hyperelasticity. Ligaments achieve this balance through a highly nonlinear tensile response characterized by a J-shaped curve, featuring an extended "toe region" of low force up to intermediate strains followed by an inflection, called the "heel region" which marks the onset of nonlinear stiffening. Here, we present a framework for characterizing the defining features of J-curve behavior. Based on these features, we define measures for protectiveness and mobility to quantitatively describe the effective stiffness and the level of nonlinearity, thereby elucidating how the J-curve enables decoupled fine-tuning of flexibility and damage protection. A simplified mathematical model, supported by experimental validation, reveals the performance advantages of J-curve materials in antagonistic arrangements and highlights their unique design space compared with linear elastic systems. Furthermore, we develop synthetic J-curve materials capable of self-strain sensing via piezoresistive transduction, enabling their integration into practical devices. Collectively, these materials, models, and insights advance the understanding of nonlinear mechanical mechanisms in natural systems and provide a foundation for harnessing J-curve behavior in engineering applications such as bio-inspired robots.

The yield stress of a viscoplastic material can stabilize an embedded fluid tunnel against capillarity-induced breakup, enabling remarkable technologies such as embedded 3D printing of intricate, freeform, and small components. However, there is persistent disagreement in the published literature between the observed minimum stable diameter, dmin, and the theoretical plastocapillary length Gp = 2r/ay, with interfacial tension r and bath yield stress ay, leading to a prior hypothesis that the apparent surface tension r is much smaller to enforce dmin = Gp. Here we introduce and experimentally test a new hypothesis that the critical diameter is set by the dimensionless plastocapaillary number, Yr = ayd/2r, having a non-trivial critical value different than one, Yr not equal 1, and therefore the prior hypothesis of adjusting r to enforce Gp = dmin is incorrect. We study several Newtonian inks (uncured polydimethylsiloxane (PDMS), highly refined mineral oil, silicone oil) extruded into a wide range of non-Newtonian viscoplastic bath materials (polyacrylic acid microgels, polysaccharide microgels, nanoclay gel, and micro-organogels). Across this wide parameter space, we observe a critical value of Yr = 0.21 +/- 0.03. We explain this being less than one by analogy to other critical dimensionless groups with yield stress fluids, such as the gravitational stability of a suspended sphere or bubble, where the yield stress acts upon an effective area larger than the na & iuml;ve estimate set only by embedded object diameter d. These results provide a new way to understand and predict the minimum stable diameter of embedded liquid filaments, as in embedded 3D printing, as dmin = Yr (2r/ay).

This study explores the capillarity-guided self-assembly of cyclo-diphenylalanine (FF) nanowires on surface defects with engineered topographies, emphasizing the interplay between geometric confinement and evaporation-driven flow. Evaporation on v-groove and trench substrates induces directional migration and alignment of FF nanowires, forming ordered, surface-adherent structures. Numerical simulations support these observations by illustrating flow behavior and deposition patterns. Guided by this mechanism, we fabricated nanowire-reinforced polyvinyl alcohol (PVOH) composite fibers with high stiffness (20.29 ± 6.57 GPa) and tensile strength (581.7 ± 34.69 MPa) at 10 wt % loading. Thermally treated, physically damaged fibers exhibited autonomous healing without external agents. Capillary migration and nanowire reassembly at fracture interfaces restored continuity and improved ductility, reflecting dynamic nanowire organization. These results present a geometric strategy for nanowire alignment and demonstrate the dual function of peptide nanowires in mechanical reinforcement and self-repair, highlighting their potential as active components in bioinspired, damage-tolerant materials.

Hagfish produce extraordinary slime as a defense mechanism, releasing exudate from glands that rapidly form a fibrous, soft, ultra-dilute, water-capturing network upon contact with seawater (up to 10 000 times its original volume). The gland thread cell (GTC) produces high-strength protein threads (filament diameter df = 1-3 µm) meticulously coiled into skeins (coil diameter Do ∼ 150 µm) that rapidly unravel upon deployment to reveal their hidden length (Lf = 15 cm), forming a cohesive fibrous slime network through interaction with mucin vesicles and seawater. To date, no engineered material is able to replicate the fiber uncoiling mechanics observed in slime, which are responsible for the unique set of mechanical properties that slime exhibits. Focusing on fundamental physical mechanisms rather than specific biochemistry or biomaterials, it is demonstrated that how existing materials and manufacturing processes can be used to achieve comparable functional performance. To engineer rapidly deployable soft materials inspired by hagfish slime, this work establishes design principles for synthetic skeins used to create the first-ever deployable synthetic skeins. Four design principles are revealed for engineering synthetic skeins: (1) the mechanics of high-strain fiber coiling and uncoiling, (2) adhesives to maintain elastic energy in non-equilibrium deformed states, (3) fluid-mediated deployment of coiled fibers, and (4) the individual fiber stiffness and size needed to result in a soft, deformable fibrous network. As proof of concept, the first successful fabrication of synthetic skeins with tightly coiled threads arranged in controlled packing geometries is demonstrated. These synthetic structures undergo fluid-mediated unraveling under flow, replicating the deployment behavior of their biological counterparts and demonstrating the feasibility of engineered, deployable fibrous networks.

Nature uses fibrous structures for sensing and structural functions as observed in hairs, whiskers, stereocilia, spider silks, and hagfish slime thread skeins. Here, we demonstrate multi-nozzle printing of 3D hair arrays having freeform trajectories at a very high rate, with fiber diameters as fine as 1.5 µm, continuous lengths reaching tens of centimeters, and a wide range of materials with elastic moduli from 5 MPa to 3500 MPa. This is achieved via 3D printing by rapid solvent exchange in high yield stress micro granular gel, leading to radial solidification of the extruded polymer filament at a rate of 2.33 μm/s. This process extrudes filaments at 5 mm/s, which is 500,000 times faster than meniscus printing owing to the rapid solidification which prevents capillarity-induced fiber breakage. This study demonstrates the potential of 3D printing by rapid solvent exchange as a fast and scalable process for replicating natural fibrous structures for use in biomimetic functions. Soft hair arrays anchored to a substrate are useful for bio-inspired engineering applications. Here, the authors demonstrate a rapid 3D printing technique for creating fine, continuous, biomimetic hair arrays using solvent exchange. Fibers as small as 1.5 µm are printed at high speeds, offering scalability for biomimetic and structural applications.

Hagfish slime is a unique biological material composed of mucus and protein threads that rapidly deploy into a cohesive network when deployed in seawater. The forces involved in thread deployment and interactions among mucus and threads are key to understanding how hagfish slime rapidly assembles into a cohesive, functional network. Despite extensive interest in its biophysical properties, the mechanical forces governing thread deployment and interaction remain poorly quantified. Here, we present the first direct in situ measurements of the micromechanical forces involved in hagfish slime formation, including mucus mechanical properties, skein peeling force, thread-mucus adhesion and thread-thread cohesion. Using a custom glass-rod force sensing system, we show that thread deployment initiates when peeling forces exceed a threshold of approximately 6.8 nN. To understand the flow strength required for unravelling, we used a rheo-optic setup to impose controlled shear flow, enabling us to directly observe unravelling dynamics and determine the critical shear rate for unravelling of the skeins, which we then interpreted using an updated peeling-based force balance model. Our results reveal that thread-mucus adhesion dominates over thread-thread cohesion and that deployed threads contribute minimally to bulk shear rheology at constant flow rate. These findings clarify the physics underlying the rapid, flow-triggered assembly of hagfish slime and inform future designs of synthetic deployable fibre-gel systems.

Layered membranes assembled from two-dimensional (2D) building blocks such as graphene oxide (GO) are of significant interest in desalination and osmotic power generation because of their ability to selectively transport ions through interconnected 2D nanochannels between stacked layers. However, architectural defects in the final assembled membranes (e.g., wrinkles, voids, and folded layers), which are hard to avoid due to mechanical compliant issues of the sheets during the membrane assembly, disrupt the ionic channel pathways and degrade the stacking geometry of the sheets. This leads to degraded ionic transport performance and the overall structural integrity. In this study, we demonstrate that introducing in-plane nanopores on GO sheets is an effective way to suppress the formation of such architectural imperfections, leading to a more homogeneous membrane. Stacking of porous GO sheets becomes significantly more compact, as the presence of nanopores makes the sheets mechanically softer and more compliant. The resulting membranes exhibit ideal lamellar microstructures with well-aligned and uniform nanochannel pathways. The well-defined nanochannels afford excellent ionic conductivity with an effective transport pathway, resulting in fast, selective ion transport. When applied as a nanofluidic membrane in an osmotic power generation system, the holey GO membrane exhibits higher osmotic power density (13.15 W m(-2)) and conversion efficiency (46.6%) than the pristine GO membrane under a KCl concentration gradient of 1000-fold.

MXenes are a class of two-dimensional materials with potential applications in the fields such as thermal management and high-temperature materials. In this study, the transitions of Ti3C2Tx MXene are investigated during thermal annealing via x-ray photoelectron spectroscopy and two-dimensional correlation spectroscopy. The thermal evolution of MXene samples occurs as two distinct processes in different temperature regions: process I (from 25 to 500 °C) and process II (from 500 to 777 °C). In process I, the terminal groups of MXene are reduced, and fluorine (–F) terminal groups are released. Four different pathways are identified with C–Ti–O and C–C as probable final products. In process II, the reaction resulting in the removal of –F species and decomposition of the Ti3C2 region in the MXene is observed. These results provide insight into the thermal decomposition behavior of Ti3C2Tx MXene, which can assist in the design of MXene-based materials with specific functionalities.

Two-dimensional Ti3C2Tx MXenes are promising candidates for a wide range of film- or fiber-based devices owing to their solution processability, high electrical conductivity, and versatile surface chemistry. The surface terminal groups (Tx) of MXenes can be removed to increase their inherent electrical performance and ensure chemical stability. Therefore, understanding the chemical evolution during the removal of the terminal groups is crucial for guiding the production, processing, and application of MXenes. Herein, we investigate the effect of chemical modification on the electron-transfer behavior during the removal of the terminal groups by annealing Ti3C2Tx MXene single sheets under argon (Ar-MXene) and ammonia gas (NH3-MXene) conditions. Annealing in ammonia gas results in surface nitridation of MXenes and preserves the electron-abundant Ti3C2 structure, whereas annealing MXene single sheets in Ar gas results in the oxidation of the titanium layers. The surface-nitrided MXene film exhibits an electrical conductivity two times higher than that of the Ar-MXene film. The oxidation stability is quantified by calculating the oxidation rate constants for severe reactions with H2O2. The surface-nitrided MXene is 13 times more stable than Ar-MXene. The investigation of MXene single sheets provides fundamental insights that are valuable for designing electrically conductive and chemically stable MXenes.

The conversion of the electrokinetic energy arising from evaporation-induced water flow through nanoporous materials has great potential for renewable energy production. In this study, we prepare a nanocapillary membrane containing both nanopores and nanochannels based on an assembly of holey graphene oxide (HGO) nanosheets, which enables water molecules to permeate and simultaneously evaporate from the nanostructure. In particular, we find that the performance of our HGO membrane-based water evaporation-induced energy harvester (WEEH) can be significantly improved by ensuring (1) a high capillary flow of water through lowfriction nanochannels and (2) a high rate of evaporation, which is achieved by the presence of large nanoscale pores with a broad size distribution. Our WEEH yields a maximum voltage of 0.44 V, current of 200 nA, and output energy density of 2.2 mu Wh cm-2. Furthermore, the use of multiple WEEHs allows for the generation of sufficient energy to charge a 1-F supercapacitor and power a light-emitting diode (2 V x 20 mA). Thus, our proposed nanocapillary, thin-membrane-based WEEH has great practical potential for energy generation, as well as other membrane-based technologies such as water purification.

Wearable device‐based gait data analysis is being used in medical research to prevent and treat serious diseases such as dementia beyond modern health management strategies. For gait‐related data collection and analysis, it is advantageous to place the sensor on the sole of the foot as a foot‐pressure, it is advantageous to use a piezoelectric generator‐based electronic textile (E‐textile) that can supply its own power by converting mechanical energy from the foot into electrical energy. In order to apply E‐textile materials to the sole of the foot, excellent durability, flexibility, and high signal accuracy through noise minimization are required. In this study, a piezoelectric polymer was used to coat the surface of a conductive fiber using the reverse dip coating technique. This method is easily scalable, feasible for large‐scale processing with a continuous process. The electrodes of this process are placed inside a piezoelectric fiber to minimize noise from the electrodes. The inner‐electrode piezoelectric yarn (IEPY) used during the process has excellent tensile strength (maximum stress and strain value: 54.2 MPa, 54%) and strong durability, maintaining its performance over 105 cycles under pushing force of 60 kg and generating excellent piezoelectric output (292 mVmax, 16.2 µW). The IEPY can drive the sensor for gait data, with the sensors being capable of continuous and large‐scale operation and feasible for the manufacturing of custom sensors.

High torsional strength fibers are of practical interest for applications such as artificial muscles, electric generators, and actuators. Herein, we maximize torsional strength by understanding, measuring, and overcoming rheological thresholds of nanocarbon (nanotube/graphene oxide) dopes. The formed fibers show enhanced structure across multiple length scales, modified hierarchy, and improved mechanical properties. In particular, the torsional properties were examined, with high shear strength (914 MPa) attributed to nanotubes but magnified by their structure, intercalating graphene sheets. This design approach has the potential to realize the hierarchical dimensional hybrids, and may also be useful to build the effective network structure of heterogeneous materials.

Controlling the microstructures in fibers, such as crystalline structures and microvoids, is a crucial challenge for the development of mechanically strong graphene fibers (GFs). To date, although GFs graphitized at high temperatures have exhibited high tensile strength, GFs still have limited the ultimate mechanical strength owing to the presence due to the structural defects, including the imperfect alignment of graphitic crystallites and the presence of microsized voids. In this study, we significantly enhanced the mechanical strength of GF by controlling microstructures of fibers. GF was hybridized by incorporating polyacrylonitrile (PAN) in the graphene oxide (GO) dope solution. In addition, we controlled the orientation of the inner structure by applying a tensile force at 800 °C. The results suggest that PAN can act as a binder for graphene sheets and can facilitate the rearrangement of the fiber's microstructure. PAN was directionally carbonized between graphene sheets due to the catalytic effect of graphene. The resulting hybrid GFs successfully displayed a high strength of 1.10 GPa without undergoing graphitization at extremely high temperatures. We believe that controlling the alignment of nanoassembled structure is an efficient strategy for achieving the inherent performance characteristics of graphene at the level of multidimensional structures including films and fibers.

Rechargeable sodium-ion batteries (SIBs) have received significant attention as a promising alternative to traditional lithium-ion counterparts for large-scale energy storage applications owing to the low cost and abundance of sodium resources. Herein, we demonstrate the photonic irradiated mesoporous reduced graphene oxide (rGO)-TiO2 nanocomposite architectures using environmentally benign, ultrafast splitsecond (millisecond) intense pulsed light (IPL) process at room temperature. The photonic IPL irradiation spontaneously triggers the deoxygenation of graphene oxide (GO) and the simultaneous structural engineering of TiO2 nanocomposites. The precisely controlled IPL irradiation (energy density of 10 J cm(-2)) exhibits excellent conductivity, high surface area, and outstanding electrochemical performance as a green anode material for SIBs. The photonic IPL irradiated rGO-TiO2 nanocomposite delivers a high reversible capacity of 244 mAh g(-1) at 0.1 Ag-1, a high rate performance of 112 mAh g(-1) at 1 Ag-1, and high cycling stability compared to pristine GO-TiO2 and conventional furnace annealed rGO-TiO2 (FHrGO-TiO2) nanocomposites. The detailed electrochemical analysis suggests that the improved capacitance contribution results from the fast kinetics of the IPL irradiated rGO-TiO2 nanocomposite anode. This work provides new insight into the fabrication of versatile, cost-effective techniques for developing advanced electrode materials for energy applications. (C) 2021 Elsevier Ltd. All rights reserved.

In recent years, the “Kirigami” have been exploited to engineer stretchable electronics that exhibit enhanced deformability without sacrificing their mechanical and electrical properties. However, kirigami‐inspired engineering is often limited to passive mechanical stretching for 3D shape morphing. To counter this problem, in this study, azobenzene‐functionalized liquid crystalline polymer networks (azo‐LCNs) are monolithically integrated with patterned reduced graphene oxide (rGO), called azo‐LCN/rGO, to achieve on‐demand shape reconfiguration in response to external stimuli (UV, NIR, solar rays, and portable light); in addition, the azo‐LCN/rGO exhibit highly enhanced mechanical and electrical properties. The cross‐sectional area and thickness of rGO patterns are controlled using a masking technique and evaporative self‐assembly. By the spatial patterning of rGO, insulating azo‐LCNs are converted into electrically conducting structures (381.9 S cm−1). The elastic modulus of <2 µm thick azo‐LCN can be tailored in the range of 1.3–6.4 GPa by integration with rGO layers of thickness less than 2 µm. Upon UV irradiation, azo‐LCN/rGO exhibit both for/backward in‐plane bending as well as out‐of‐plane chiral twisting, thus overcoming the typical trade‐off relationship between elastic modulus and deformability. Finally, an on‐demand contactless shape reconfiguration in azo‐LCN/rGO by UV irradiation in conjunction with passive mechanical strain is demonstrated.

Self-assembly of two-dimensional MXene sheets is used in various fields to create multiscale structures due to their electrical, mechanical, and chemical properties. In principle, MXene nanosheets are assembled by molecular interactions, including hydrogen bonds, electrostatic interactions, and van der Waals forces. This study describes how MXene colloid nanosheets can form self-supporting MXene hydrogels. Three-dimensional network structures of MXene gels are strengthened by reinforced electrostatic interactions between nanosheets. Stable gel networks are beneficial for fabricating highly aligned fibers because MXene gel can endure structural deformation. During wet spinning of highly concentrated MXene colloids in a coagulation bath, MXene sheets can be transformed into perfectly aligned fibers under a mechanical drawing force. Oriented MXene fibers exhibit a 1.5-fold increase in electrical conductivity (12 504 S cm-1) and Young's modulus (122 GPa) compared with other fibers. The oriented MXene fibers are expected to have widespread applications, including electrical wiring and signal transmission.

Noble metal/metal-oxide-based hybrid gas sensors exhibit a low operating temperature, remarkable sensitivity, and fast recovery. As additives, noble metals induce a catalytic sensitization effect, which promotes charge transfer from the metal oxide to the analyte molecules, the so-called spillover mechanism. This suggests that metal catalysts can improve gas sensing performance. Herein, for the first time, non-noble metals are introduced on hybrid metal oxide/graphene fibers as sensitizers to fabricate high-performance chemiresistive sensors. The formation of metal components can be effectively controlled by annealing the metal oxide on graphene. Remarkably, compared with the corresponding metal oxide/graphene fiber sensors without metal components, the metal/metal oxide/graphene fiber sensors exhibit over a 16-fold higher response to NO2 gas as well as effective recovery characteristics. Specifically, the Cu/Cu2O/graphene and Ni/NiO/graphene fiber sensors operating at 150 degrees C exhibit sensitivities of 18.90 % and 0.82 %, respectively, for 5 ppm NO2 gas. The proposed strategy to achieve flexible graphene fiber chemiresistors by decorating them with non-noble metal and metal oxide nanoparticles opens a new avenue for realizing high-performance devices, such as photovoltaic devices, photocatalysts, and chemical catalysts.