Composite Fibers Research Articles

Jet slipping mechanism and fabricating of composite fiber by multiple field coupling

AbstractThe rotary jet spinning process involves the joint action of centrifugal force, gravity, temperature, humidity, and flow fields on the spinning solution. The solution is ejected through the nozzle after flowing from the storage container and stretched in the air to form a composite fiber. At present, the investigation of rotary jet composite spinning primarily focused on the dynamics and kinematics of the spinning solution and jet within the container. However, there is still a lack of comprehensive exploration into the motion and slip phenomena exhibited by the composite spinning solution in air. This article investigates the slip phenomenon between the polymer and the gas contact surface after the spinning solution leaves the spinneret aperture. A slip model is established to analyze the motion and force of the polymer in air. Meanwhile, a mathematical model for the evaporation rate of composite spinning solution motion under the influence of multi‐field coupling is established through theoretical analysis. A numerical simulation of the rotary jet spinning process was conducted to obtain clouds of jet exit velocity. The morphology of composite fibers produced by rotary jet spinning was analyzed using scanning electron microscopy, enabling a comparison of diameter distribution and surface quality under different environmental and equipment parameters. This study provides a certain reference for the preparation of high‐quality composite fibers.

Fabrication of Magnetic Poly(L-lactide) (PLLA)/Fe3O4 Composite Electrospun Fibers.

Electrospinning technology is widely used for preparing biological tissue engineering scaffolds because of its advantages of simple preparation, accurate process parameters, and easy control. Poly(L-lactide) (PLLA) is regarded as a promising biomass-based polymer for use in electrospinning. The incorporation of Fe3O4 nanoparticles (NPs) could improve the osteogenic differentiation and proliferation of cells in the presence or absence of a static magnetic field (SMF). In this work, these two materials were blended together to obtain electrospun samples with better dispersibility and improved magnetic properties. First, composite PLLA and Fe3O4 NP fibers were prepared by means of electrospinning. The influence of electrospinning conditions on the morphology of the composite fibers was then discussed. Changes in magnetic properties and thermal stability resulting from the use of different PLLA/Fe3O4 mass ratios were also considered. Next, the morphology, crystal state, thermodynamic properties, and magnetic properties of the electrospun samples were determined using scanning electron microscopy (SEM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and vibration sample magnetization (VSM). The results showed that the fibers prepared using PLLA with Mn = 170,000 exhibited good morphology when electrospun at 12 KV. The magnetic properties of PLLA/Fe3O4 composite electrospun fibers increased with the NP content, with the exception of thermal stability. The results of the present study may help to promote the further development of PLLA/Fe3O4 composite materials in the biomedical field.

Fe3C@C composite fiber mats prepared by electrospinning with heat treatment and their application to Li-S batteries

The main challenges facing Li-S batteries stem from the low conductivity of sulfur and the dissolution of lithium polysulfides. This study addresses these issues by synthesizing Fe3C@C nanofibers through electrospinning followed by heat treatments, which are then applied as an interlayer in Li-S cells. The pre-oxidation temperature is adjusted to achieve the desired material properties, in which Fe3C nanoparticles are embedded in graphitic carbon nanofibers, resulting in a high specific surface area and mesopore volume. This configuration provides excellent polysulfide adsorption and catalytic properties for their further conversion. Consequently, when used as an interlayer, the electrochemical performance of the cell, including discharge capacity (first: 1174 vs. 850 mAh g−1 at 0.1 C), stability (852 vs. 400 mAh g−1 after 100 cycles), and rate-capability (620 vs. 100 mAh g−1 at 2 C), is significantly enhanced compared to cells without interlayer.

Development of Hollow Fiber Membranes Functionalized with Ionic Liquids for Enhanced CO2 Separation.

The combination of CO2-selective ionic liquids (ILs) with block copolymers, such as Pebax 1657, has demonstrated an enhancement of the gas separation capabilities of polymeric membranes. In the current work, the development of composite membranes by applying a thin, concentrated selective layer made of Pebax/imidazolium-based ionic liquids (ILs) is presented. The objective of the experiments was to determine the optimized IL loading and investigate how the alteration of the anion impacts the properties of the membranes. Two membrane configurations have been studied: coated flat sheet membranes, supported on a porous poly(ether sulfone) (PES) layer, as well as composite hollow fiber membranes, supported on commercial polypropylene (PP) hollow fibers. Coated hollow fiber composites were fabricated using a continuous coating method, offering a straightforward scalability in the manufacturing process. The determined mechanical pressure stability of hollow fiber composites reached up to 5 bar, indicating their potential for various industrial gas separation applications. It was found that the Pebax 1657-based coating containing 40 wt % [C6mim][NTf2] yielded membranes with the best gas separation properties, for both the coated flat sheet and the hollow fiber configurations. The CO2 permeance of hollow fibers reached 23.29 GPU, whereas the CO2/N2 ideal selectivity stood at 8.7, suggesting the necessity of the further enhancement of the coating technique, which can be achieved, for example, through application of multiple coatings. Nonetheless, the superior ideal selectivity of the CO2/CO separation, reaching 12.44, gave a promising outlook for further novel membrane applications, which involve the separation of the aforementioned gases.

Mechanically Robust Biopolymer Optical Fibers with Enhanced Performance in the Near-Infrared Region.

Polymer optical fibers (POFs) are lightweight, fatigue-tolerant, and suitable for local area networks, automobiles, aerospace, smart textiles, supercomputers, and servers. However, commercially available POFs are exclusively fabricated using synthetic polymers derived from nonrenewable resources. Recently, attempts have been made to fabricate biocompatible and biopolymeric optical fibers. However, their limitations in mechanical performance, thermal stability, and optical properties foil practical applications in waveguiding. Here, we report a comprehensive study of the preparation of biopolymer optical fibers with tailored mechanical strength, thermal properties, and their short-distance applications. Specifically, we use alginate as one of the key components with methylcelluloses to promote readily scalable wet spinning at ambient conditions to fabricate 21 combinations of composite fibers. The fibers display high maximum strain (up to 58%), Young's modulus (up to 11 GPa), modulus of toughness (up to 63 MJ/m3), and a high strength (up to 195 MPa), depending on the composition and fabrication conditions. The modulus of toughness is comparable to that of glass optical fibers, while the maximum strain is nearly 15 times higher. The mechanically robust fibers with high thermal stability allow rapid humidity, touch sensing, and complex shapes such as serpentine, coil, or twisted structures without losing their light transmission properties. More importantly, the fibers display enhanced optical performance and sensitivity in the near-infrared (NIR) region, making them suitable for advanced biomedical applications. Our work suggests that biobased materials offer innovative solutions to create short-distance optical fibers from fossil fuel-free resources with novel functionalities.

Sub-micron alkylated graphene oxide from coal

Sub-micron graphene oxide (GO) has emerged as a promising additive in the realms of composite films and fibers applications. Traditional GO preparation involves acid oxidation of high-purity graphite, yielding particles in micron scale. Achieving sub-micron dimensions typically demands rigorous conditions, leading to increased defects with low yield. In this study, the sp2 carbon domain from anthracite first undergoes graphitization, growing from nano to sub-micron scale, then sub-micron GO is extracted via oxidatively severing its bridging bonds. The resulting GO exhibits an average size of 800 nm, a thickness of 1-2 layers, and a yield of 107%. This methodology is applicable to bituminous and lignite as well. Furthermore, the broken bridging bonds act as alkyl danglings on sub-micron GO and serving as anchors in composites through hydrogen bonding. The reinforcing efficacy of sub-micron GO is demonstrated through the fabrication of composite films and fibers. This work pioneers cost-effective production of high-quality sub-micron GO, elevating coal’s value through advanced applications.

Curvature-ordered biomimetic helical ceramic composite fiber aerogel with shrinkage resistance, thermal insulation properties, and mechanical properties

Ceramic aerogel with high porosity and low thermal conduction was widely used in the field of thermal insulation. However, shrinkage and structural damage were produced by the ceramic precursors during pyrolysis. The shrinkage and mechanical properties of ceramic aerogels required to be improved. Herein, inspired by spiral grass and passionflower, curvature-ordered ceramic fiber aerogels were prepared by electrostatic spinning combined with polymer-derived ceramics (PDCs) route. Shrinkage resistance properties, thermal insulation properties, and mechanical properties of ceramic fiber aerogels were investigated. The shrinkage resistance property of aerogels was improved by the tensile deformation of helical fibers during pyrolysis. The path of heat transfer was extended through the helical fibers and heat conduction was reduced. The gas was confined in a porous network formed by helical fibers that lapped over each other, and thermal convection was minimized. Thermal radiation was attenuated due to reflection and scattering at the core-shell interface of the helical fibers. The mechanical properties of the aerogel were enhanced by the helical structure of the fibers and the stress diffusion mechanism. The tensile and compressive properties of the spiral ceramic aerogel were improved through the curvature structure by about 6 MPa and 3 MPa, respectively. The results showed that the helical ceramic composite fiber aerogel with ordered curvature exhibited shrinkage resistance, thermal insulation, and mechanical properties.

Multifiller carbon nanotube, graphene, and carbon black composite filaments: A path to versatile electromaterials

Abstract Addressing the growing demand for conductive and flexible composites, this research focuses on producing thermoplastic composite fibers made of polyurethane and carbon nanomaterials featuring the highest possible electrical conductivity. Based on a recently developed methodology enabling the formation of very high filler contents of 40% w/w, this work presents a systematic investigation of the role of all the materials used during the manufacturing process and selects the materials that ensure the best electrical performance. The results show that the highest electrical conductivity and current-carrying capacities are obtained when dimethylformamide is used as a solvent, and small amounts of AKM surfactant aid the de-agglomeration of carbon nanomaterials. It is also shown that the hybridization of MWCNTs filler with graphene nanoplatelets and small amounts of carbon black is beneficial for the electrical properties. However, the highest performance is achieved with SWCNTs as fillers, exhibiting two orders of magnitude higher electrical conductivities of 6.17 × 104 S/m. Impact statement The article presents a pioneering exploration into the synthesis and application of a novel composite material. This research significantly impacts the field of electromaterials by introducing a cutting-edge approach that leverages the synergistic properties of carbon nanotubes, graphene, and carbon black within a single filament. The impact of this research extends beyond the laboratory, influencing the development of next-generation materials that bridge the gap between conventional materials and advanced nanomaterials. The presented composite filaments open avenues for the creation of innovative devices and systems that demand good mechanical strength, electrical conductivity, and thermal stability. Moreover, the versatility of these filaments allows for the optimization of materials properties, enabling customization based on specific application requirements. In addition to its technological significance, the paper contributes to sustainability efforts by facilitating the production of lightweight, energy-efficient materials. The insights provided by this research have the potential to reshape the landscape of materials science, inspiring further exploration and innovation in the quest for versatile and high-performance electromaterials. Graphical abstract

Ultra-fast light repair, ultrasensitive, large strain detection range PDA@RGO/EVA composites fiber flexible strain sensor

The sensor fabricated from high-molecular polymer is soft, lightweight, and biocompatible; however, traditional high-molecular polymers suffer from viscoelasticity and poor cycle stability. To address these issues, it is essential to develop flexible matrix materials that can overcome viscoelasticity, ensuring high sensitivity and long-term use under large strains for next-generation wearable intelligent devices. In this study, ethylene-vinyl acetate (EVA) with a shape memory effect was utilized as the substrate for a flexible sensor，the shape memory effect of EVA can eliminate the residual strain generated by each long time of use to improve its service life. A polydopamine@reduced graphene oxide (PDA@RGO)/EVA fiber flexible strain sensor was fabricated through melt extrusion, swelling ultrasound, and in-situ polymerization techniques. The resulting sensor exhibits high sensitivity (gauge factor=1801.21), a wide strain detection range (strain = 193 %), and excellent stability and durability (2000 cycles). Notably, the PDA@RGO/EVA fiber flexible strain sensor demonstrates exceptional dual thermal and light repair functions, with light repair achieving a repair speed of 5 seconds, 100 % electrical performance repair efficiency, and perfect consistency in relative resistance response before and after repair. Furthermore, the PDA@RGO/EVA strain sensor can monitor finger and wrist movements in real-time with high accuracy, highlighting its significant potential application in the wearable technology field.

Ethylcellulose and bismuth sodium titanate-barium zirconate titanate (BNT-BZT) composite fibers for triboelectric energy harvesting

Green cellulose and toxic-free/rare earth-free nanomaterials are promising towards the development of triboelectric nanogenerators (TENGs) as energy harvesters for sustainable electronics. In this study, ethylcellulose (EC) and bismuth sodium titanate-barium zirconate titanate (BNT-BZT) are used as raw materials. An EC and BNT-BZT composite fiber mat was prepared by electrospinning and used as a positive triboelectric layer in a friction nanogenerator, while fluorinated ethylene propylene (FEP) was used as a negative triboelectric layer. After optimizing the electrospinning parameters and characterizing the materials, the developed TENG output power was studied as a function of the BNT-BZT doping concentration in the EC. At 2 wt% of doping, the output voltage of the TENG has a 3-fold increase compared with that obtained with a pure EC mat as the positive triboelectric layer. In addition, the TENG showed good output performance and operating stability after exposure to high temperature (70 ºC) and relative humidity (90 %). The maximum output power density of 134 μW/cm2 was obtained at a load resistance of 210 MΩ, showing good prospects in powering Internet of Things (IoT) sensor nodes.

Core-sheath PVDF hollow porous fibers via coaxial wet spinning for energy harvesting

Flexible piezoelectric nanogenerators (PENGs), as a promising sustainable power source in smart electronics, have attracted much attention for their potential applications in the Internet of Things. In this paper, poly(vinylidene fluoride) (PVDF) fibers with core-sheath hollow porous structure were prepared by coaxial wet spinning process, serving as the dielectric layer, which were perfused internally by liquid metal (LM) as the inner electrode layer and wrapped outside by copper-silver nanoparticles (Cu@AgNP) as the outer electrode layer, thus constructing high-performance PVDF/LM/Cu@AgNP composite fibers. The composite PVDF fibers have a layered pore structure and arbitrarily deformable LM electrodes, which can significantly reduce the effective electric constant and thus enhance the piezoelectric properties. The results reveal that PVDF/LM/Cu@AgNP-PENG yields an optimal voltage output of 410 mV, providing a clear advantage over PENG by using alternative fibers. Moreover, the PVDF/LM/Cu@AgNP-PENG shows an excellent charging capability for energy storage devices, being able to charge 1 μF capacitors to 10 V within 30 s and directly power commercial LEDs. This study demonstrates the significant potential for utilizing composite PVDF piezoelectric fibers in flexible wearable electronic devices.

Revisit the Efficacy of Transformation‐Induced Plasticity Mechanism and Martensite‐Austenite Composite Fiber Effect on the Increase of Uniform Elongation in Steel

The ductility of a retained austenite (RA)‐bearing steel is conventionally correlated with the gradual transformation of RA into martensite during straining, i.e., transformation‐induced plasticity (TRIP) mechanism. Nevertheless, current experiments and mathematical calculations illustrate that most of the RA transformed into martensite at quite an early stage of tensile straining. The result shows that only 4% of leftover RA exists after the initial tensile loading. It looks like enough RA is not available to operate TRIP to obtain successive ductility in the steel. Inexplicably, current work exhibits the maximum uniform tensile elongation after the major martensite transformation, which contradicts the conventional TRIP‐driven ductility theory. Thus, only 4% RA could be one of the prime factors that operate unfailingly to impart ductility in the steel. This work has created an understanding of the possible factors responsible for the observed ductility in the current steel while TRIP is not operating.

Preparation of photothermal alginate/chitosan derivative/CuS@polydopamine composite fibers and application in desalination

A polyelectrolyte system consisting of sodium alginate (SA) and quaternary ammonium chitosan (QAC) blended with polydopamine-coated copper sulfide particles (CuS@PDA) was chosen to investigate the function of CuS@PDA in the uniform binary blending of anionic and cationic polyelectrolytes in detail. A smart composite fiber SA/QAC/CuS@PDA was prepared via a dry-wet spinning technique. With the addition of CuS@PDA (about 4.3 % in fiber), the as-prepared SA/QAC/CuS@PDA-0.50 fibers (SQCuS@P-0.50 SCFs) showed notably enhanced intensity 359.2 MPa, excellent moisture response, and photothermal conversion performance, with the temperature increasing from 25.9 to 80.7 °C as irradiated under a 980 nm infrared lamp at distance 20 cm away for 120 s. The photothermal performance was maintained after 6 lighting on-and-off cycles. The tensile strength decreased ~23.8 % after 4 cycles, then remained fixed. The diameter increases to ~480 % in wet state but decreases to the original size in dry state for 10 cycles. When the fabric with 90 wt% SQCuS@P-0.50 SCFs was used as a water evaporator, the water evaporation rate and efficiency were 1.68 kg·m−2·h−1 and 102 % under 1 sun irradiation. This work provides a simple and ecofriendly strategy for fabricating photothermal fabrics by designing and preparing composite fibers.

Sodium alginate/guar gum/multi-walled carbon nanotubes-based hydrophobic Joule thermal textiles for enhanced body thermal management and dehumidification

A sodium alginate (SA), guar gum, and multi-walled carbon nanotube composite solution was prepared using a simple blending method, followed by the construction of alginate/guar gum/multi-walled carbon nanotube fibers and fabrics through complexation with various metal ions (zinc, copper, calcium), featuring multiple hydrogen bonds and ionic complex structures. Specifically, the sodium alginate zinc/guar gum/multi-walled carbon nanotube (SA/GG/Zn2+/MWCNTs) composite fibers exhibited a significant Joule heat effect. By integrating with electronic components such as a temperature control switch, a wearable device capable of operating in cold and humid environments for dehumidification and warming was fabricated. The SA/GG/Zn2+/MWCNTs composite fabric demonstrated excellent hydrophobicity, with a contact angle reaching 145.4°, significantly enhancing its resistance to droplet penetration. Under a 5V voltage, the composite fabric rapidly generated Joule heat, increasing the surface temperature by 5∼7 °C (sensible heat) within just 40 s. Additionally, part of its energy (latent heat) transformed the tiny droplets adhering to the fabric's surface from liquid to gas, achieving dehumidification. This research provides an important theoretical and practical foundation for enhancing the performance and energy efficiency of personal thermal management textiles.

GO/MoS2@PVA composite membrane-based optical fiber Mach-Zehnder interferometer for humidity sensing and its non-contact sensing application.

A humidity sensor based on an optical fiber Mach-Zehnder interferometer (MZI) coated with a GO/MoS2@PVA composite membrane was investigated for non-contact sensing. MoS2 was used as a nanospacer to enhance the humidity-sensitive properties of GO, and the adhesion and stability of the composite membrane on the fiber surface could be increased by PVA. The proposed sensor shows a maximum sensitivity of 0.26 dB/%RH with average response and recovery times of 1.62 and 1.11 s, respectively. In non-contact sensing applications, the sensor can effectively recognize a maximum distance of 10 mm for the proximity of a human finger with a distance variation interval of 3 mm. The proposed sensor is expected to be applied in non-contact distance detection and localization or as a non-contact human-computer interaction panel.

Flexural performance of seawater sea sand concrete composite beams enhanced by dual-functional C-FRCM jackets

The flexural performance of seawater sea sand concrete (SSC) composite beams enhanced by the dual-functional carbon-fabric reinforced cementitious matrix (C-FRCM) jackets was experimentally investigated. Five SSC composite beams were constructed and tested in flexure under four-point loading, including one control specimen, one C-FRCM enhanced beam without the presence of the impressed current cathodic protection (ICCP) system, and three C-FRCM jacketed beams implementing the ICCP system (three different current densities: 25, 75 and 125 mA/m2). The failure modes observed and the performance of the strengthened beams with the dual-functional C-FRCM jackets were discussed in details. The results indicated that the C-FRCM jacketing effectively increased the cracking load up to 46.43 % and delayed yielding. The C-FRCM jacket had a relatively small impact on the initial stiffness of the specimens but significantly increased the load-carrying capacity (up to 18 %) and improved ductility. With the increase in current density, the load-carrying capacity gradually decreased, the crack inhibitory effect gradually weakened, but the ductility coefficient increased notably (up to 98 %). Regarding the failure modes of the composite beams, both fiber fracture and fiber slippage coexisted, and with the increase of current density, the latter became more predominant. Based on the design guidelines provided by ACI 549.4R-13, an analytical formula for bending moment was proposed and compared with the experimental results, providing a reference for the design of such components.

Robust and ultra-sensitive self-powered fire warning sensor based on polyimide thermoelectric fibers for temperature sensing and intelligent fire safety monitoring

Fire warning sensors is crucial to effectively prevent fire accidents in a variety of modes and meet the needs of the connected age. Nevertheless, there is still a formidable challenge in fabricating self-powered fire warning sensors that are flexible and can be integrated in combustible materials. In this work, flexible high-fireproof polyimide (PI)/hydroxyapatite (HAP)/Ag2Se composite aerogel fiber (PHA-AF) was fabricated by specific wet spinning technology. The extraordinary thermoelectric effect of Ag2Se enabled PHA-AF to achieve precise temperature sensing over a wide temperature range of 100 °C–500 °C. Simultaneously, the PHA-AF-based fire alarm sensor could trigger a fire alarm system in 1.9 s and respond continuously for 14 s under flame attack, while generating output voltage of up to 5.9 mV in self-powered mode. Notably, PI as a flame-retardant material could be formed the 3D networks with HAP, as well as the skeleton support effect provided by Ag2Se nanorods enabled PHA-AF based fire alarm sensors with superior breaking tenacity (2.9 MPa), strong heat stability (maximum weight loss rate at 550 °C) and flame retardancy (LOI = 35.8 %), further highlighting its authenticity, repeatability, and reliability in fire. This work offers potential for the preparation of fiber-based self-powered early fire alarm sensors for long-term continuous using in harsh fire environment.

Temperature Effects on GaN/AlN Heterojunction in a Piezomagnetic and Piezoelectric Semiconductor Composite Fiber

In this article, considering the thermal effects, a PN GaN/AlN heterojunction in a piezomagnetic and piezoelectric semiconductor composite fiber driven by dynamic magnetic loads is studied. The true nonlinear constitutive equations of the electric current density for the composite heterojunction are employed. Thus, a nonlinear finite‐element method (FEM) is adopted to obtain dynamic responses of the composite heterojunction, including the mechanical displacement, electric potential, and electron and hole concentrations. By comparing dynamic responses with those derived by COMSOL Multiphysics, the nonlinear FEM is verified. Based on numerical results, regulation effects of the temperature on distributions of the mechanical displacement, electron and hole concentrations, and temperature–current–voltage characteristics are discussed.

Construction of spherical heterogeneous interface on ZnFe2O4@C composite nanofibers for highly efficient microwave absorption

Enriching the electromagnetic wave loss mechanism and improving the impedance matching are the keys to improve the electromagnetic wave absorption performance of carbon fibers. In this study, beaded ZnFe2O4@C absorbing composite fibers (ZFCF) with synergistic effects of magnetic loss and dielectric loss was prepared by electrospinning and heat treatment. ZnFe2O4 magnetic particles effectively improve the impedance matching and increase the loss mechanism of carbon nanofibers. The optimal ZFCF composite has excellent absorption performance, with a minimum reflection loss of −53.6 dB at 2.64 mm and the widest effective absorption bandwidth of 4.32 GHz. The excellent absorption performance is attributed to significant magnetic losses from eddy currents and magnetic resonance generated by ZnFe2O4, and strong interfacial polarization from the numerous heterogeneous interfaces. Additionally, the one-dimensional carbon nanofibers create a conductive network and structural defects that enhance conductive loss and dipole polarization effects. Moreover, the RCS of ZFCF composite was significantly reduced by −32.85 dBm2. The combination of simulation technology and material design is of great significance for the study of electromagnetic wave absorption mechanism and the rational design of electromagnetic wave absorbing coatings.

Manufacturing of Continuous Core–Shell Hydrated Salt Fibers for Room Temperature Thermal Energy Storage

The encapsulation ofsalt hydrate phase change materials (PCMs) in uniform microscale bodies has yetbeen reported in research due in part to the delicate relationship betweenthermal performance and water‐to‐salt ratios which are easily altered duringmanufacturing. Herein, core–shell composite fibers comprised of a salt hydratePCM core and a poly(acrylonitrile) (PAN) shell are wet spun in a continuousprocess using a syringe pump and coaxial die. The PCM phase comprises calciumchloride hexahydrate (CaCl2·6H2O) with strontium chloride hexahydrate(SrCl2·6H2O) (3 wt%) and fumed silica(SiO2) (2 wt%) as additive, acomposition that is prepared from homogenous melt at 40 °C. 15 wt% PAN indimethylsulfoxide solvent is used to prepare the shell‐forming polymer gel. PCM and polymer gel injectionrates of 10–40 mL h−1 are used tospin coaxial fibers through a coagulation bath, yielding continuousmicrotubules with diameters in the range of 850–1500 μm. Cyclic testing showsthat after 1000 cycles, melting enthalpies incurred only a 3.5% decline from 131.46 to 126.9 J g−1. Success hereovercomes several coincidental drawbacks of PCM fiber performance andmanufacturing and delivers the first example of scalable roll‐to‐roll PCM fiber produced by wet spinning forbuilding material applications.