Nanofiber Composite Films Research Articles

Cross‐Scale Interface Engineering for Fabricating Super‐Strong and Super‐Tough Aramid nanofiber film

AbstractPoly (p‐phenylene terephthalamide) (PPTA), known for its exceptional mechanical properties under the brand name Kevlar, finds extensive use in high‐performance applications despite the challenges it presents in processing and integration with other materials. Existing top–down methods for preparing PPTA composites result in significantly reduced strength (<200 MPa) and toughness (<10 MJ·m−3) due to insufficient interfacial interactions, limiting their application. Here, a cross‐scale interface engineering strategy is reported for fabricating super‐strong and super‐tough PPTA composite films. At the microscale, a synergistic crosslinking strategy of physical entanglement and hydrogen bonding to crosslink PPTA nanofibers is employed. At the macroscale, the network using a cyclic freeze–thaw and the stretch‐drying method is reinforced. The PPTA nanofiber composite film is super‐strong (854.6 MPa), super‐tough (106.2 MJ·m−3), and has a high‐temperature resistance (300 °C). Moreover, the bottom–up approach enables the direct synthesis of PPTA nanofibers, significantly reducing the preparation time from 7 days to 0.5 h. Furthermore, it is demonstrated that the composite film can be integrated into a robust and intelligent sensing‐display device that responds to external mechanical and heat injuries for firefighter's protection. This work provides an efficient strategy for fabricating high‐performance PPTA composites, paving the way for their practical use as durable protective materials.

High-Quality Conductive Network Films Constructed from Carbon Nanotube/Carbon Nanofiber Composites via Electrospinning for Electrothermal Applications.

In this study, carbon nanotube (CNT)/carbon nanofiber (CNF) composite electrothermal films were prepared by electrospinning, and the effects of the CNT content and carbonization temperature on the electrothermal properties of the CNT/CNF composite films were investigated. The experimental results demonstrated that the conductivity of the CNT/CNF composite electrothermal film (0.006-6.89 S/cm) was directly affected by the CNT content and carbonization temperature. The electrothermal properties of the CNT/CNF positively correlated with the CNT content, carbonization temperature, and applied voltage. The surface temperature of CNT/CNF can be controlled within 30-260 °C, and continuously heated and cooled 100 times without any loss. The convective heat transfer with air is controllable between 0.008 and 31.75. The radiation heat transfer is controllable between 0.29 and 1.92. The prepared CNT/CNF exhibited a heat transfer efficiency of up to 94.5%, and melted a 1 cm thick ice layer within 3 min by thermal convection and radiation alone.

Electrothermal and humidity-responsive flexible actuator with asymmetric eutectic gallium-indium/cellulose nanofiber composite film printed by electrohydrodynamics

Electrothermal and humidity-responsive flexible actuator with asymmetric eutectic gallium-indium/cellulose nanofiber composite film printed by electrohydrodynamics

An MXene/cellulose nanofiber-based multi-parametric tactile sensor for object material identification

Abstract We propose a novel multi-parametric tactile sensor that can realize force and slip sensing during the contact between a manipulator and a target. The pressure-sensitive unit of this sensor is prepared by homemade MXene and cellulose nanofiber (CNF) composite conductive film, which has high sensitivity of pressure-sensitive response. The triboelectric unit is made of a chemically stable PTFE film with high electron-acquiring ability as the triboelectric sensing layer together with metal electrodes. Experiments have demonstrated that the prepared sensors have high sensitivity, fast response, and excellent durability and stability over 5000 cycles. Combined with the established machine learning algorithm model, the pressure and triboelectric signals of this multi-parametric tactile sensor were used to recognize 15 types of materials with similar characteristics and with 94.33% identification accuracy. This work shows the great potential of multi-parametric tactile sensors for applications in item sorting, human-machine interaction, and other fields.

Flexible sandwich-structured silver nanowire/exfoliated graphite platelet/aramid nanofiber composite films with excellent EMI shielding, thermal conduction and Joule heating performances

Multifunctional flexible sandwich-structured EMI shielding silver nanowire/exfoliated graphite platelet/aramid nanofiber (AgNW/EGP/ANF) composite films with excellent thermal conduction and Joule heating abilities were successfully prepared by a layer-by-layer vacuum filtration technique. The construction of EGP/ANF layer on the two sides is crucial in achieving outstanding thermal conductivity (TC) and contributes partial EMI shielding effectiveness (SE) for the composite films. The introduction of an ultrathin, dense, and sintered AgNW/ANF layer endows the composite films with significant enhancements in electrical conductivity and EMI SE. As a result, the optimal 30 μm-thick composite films with an AgNW loading of 35 wt% exhibit excellent EMI SE values of 69.0 dB in the X-band and 78.4 dB in the Ka-band and a superior in-plane TC of 48.7 W m−1 K−1. Besides, the prepared composite films present an outstanding Joule heating performance. Briefly, the sandwich-structured composite films show huge potential in advanced portable and wearable electronic applications.

Development of a cellulose nanofiber composite film containing CuO/ZnO nanoparticles and its human norovirus inactivation properties in clams

Human norovirus (HuNoV) threatens human health worldwide, highlighting the critical need for antiviral materials. In this study, copper and zinc nanoparticles (NPs) as inorganic antiviral materials and a cellulose nanofiber (CNF) were selected to construct a hybrid inorganic-organic composite film (CuO/ZnO NPs-CNF) against MS2 and murine norovirus 1 (MNV-1) (surrogates for HuNoV) viruses. Selected NPs concentrations (50 µM of CuO NPs and 5 mM of ZnO NPs) showed non-toxicity (89.88 % of cell viability) through the MTT assay. Upon the development and characterization of the CuO/ZnO NPs-CNF film, high compatibility between CuO/ZnO NPs and CNF was identified, along with consistent thickness, low moisture content, and water solubility. A synergistic antiviral effect was exhibited in vitro and on the film against MS2 and MNV-1 in the mentioned co-treated inorganic matrix within 1 h. The antiviral stability of the film was also maintained at various temperatures (−18 °C, 5 °C, and 25 °C) and humidities (20–30 %, 50–60 %, and 70–80 %). When a synergistic antiviral effect was exhibited on the CuO/ZnO NPs-CNF film against both MS2 and MNV-1, mechanisms analysis by SDS-PAGE and RT-qPCR revealed that there were damages to both capsid protein and RdRP. The application of CuO/ZnO NPs-CNF film on clams resulted in a significant decrease in the survival rate of MS2 by up to 65.67 % and MNV-1 by up to 78.62 % when treated at low temperatures compared to the CNF film. Taken together, these results suggest that the CuO/ZnO NPs-CNF film could be used as potential anti-HuNoV agent in the food industry.

Gradient structured MoS2@MXene/MXene/aramid nanofiber composite film with excellent electromagnetic interference shielding performance

Developing high-performance electromagnetic interference (EMI) shielding materials with robust microwave attenuation capabilities and structural stability remains a formidable challenge to enhance their practical adaptability in everyday scenarios. In this study, we have successfully fabricated a gradient structured MXene-based composite film tailored for high-performance EMI shielding. Initially, a hybrid MoS2@MXene material featuring heterointerfaces is synthesized, which exhibits exceptional electromagnetic wave (EMW) absorption capabilities. Subsequently, a gradient structured multi-layer film is engineered using a layer-by-layer casting approach, gradually increasing the MXene content in the MoS2@MXene/MXene/aramid nanofiber composite. This composite film is purposefully designed to employ an “absorb-reflect-reabsorb” EMI shielding mechanism, resulting in reduced reflection power. The resultant composite film achieves an impressive EMI SE of 50.9 dB, coupled with remarkable structural stability persisting through 500 folding cycles. This study presents a viable and potent strategy for developing flexible, absorption-dominant EMI shielding materials.

Mica/nylon composite nanofiber film based wearable triboelectric sensor for object recognition

The wearable sensors have essential impacts on the progress of intelligent technology, while the traditional sensors cannot meet the sensitivity requirements. Here, we propose a high performance intelligent triboelectric wearable sensor (HITWS) by Mica/Nylon composite nanofiber film (MCNF), which is fabricated by the electrospinning and dielectric particle doping process. The addition of Mica particles effectively improves the dielectric constant, surface charge density and functional group properties of MCNF and further optimizes its positive triboelectric properties. Therefore, the HITWS demonstrates significantly higher signal-to-noise ratio, sensitivity and power density (11.82 W/m2) compared to previous similar studies. Furthermore, based on HITWS, 4-channel STM32 signal acquisition and deep learning algorithm, an intelligent tactile sensing system is achieved. Combined with the structurally optimized VGG16 network model, the recognition of 7 kinds of objects can reach an average accuracy of 96.57 %. This work provides new idea and method for the development of applications based on object recognition, such as remote interaction, medical prosthetics and smart robots.

Improving passive daytime radiative cooling via incorporation of composite nanoparticles into sheath of PU-PVDF core-sheath nanofiber film

Climate change has recently caused more severe temperatures, increasing demand for personal thermal management outdoors. Radiative cooling fabrics, known for their potent cooling ability, play a crucial role in regulating the thermal balance of the human body in high-temperature environments. In this study, an innovative PU (polyurethane)-SiO2/TiO2@PVDF (polyvinylidene fluoride) core-sheath nanofiber film was developed by incorporating SiO2/TiO2 composite nanoparticles (STNs) into the sheath of the nanofibers through coaxial electrospinning. The PU-STNs@PVDF composite nanofiber film with thickness of ∼100 μm achieved a reflectance of 92 % in the visible to near-infrared spectral range and an emittance of 91 % within the atmospheric transparent window. The temperature of the PU-STNs@PVDF core-sheath nanofiber film was reduced by 6.9 °C and 4.7 °C compared with that of the cotton fabric and PU-PVDF nanofiber film, respectively. Under direct solar radiation in summer, the temperature of the PU-STNs@PVDF core-sheath nanofiber film was 7.7 °C lower than that of cotton fabric. The PU-STNs@PVDF core-sheath nanofiber film elongated at a break of 127.5 % and a tensile strength of 4.3 MPa, implying it promising flexibility. The PU-STNs@PVDF core-sheath nanofiber film possesses huge potential in personal thermal management.

Carbon Nanofiber-Based Sandwich Free-Standing Cathode for High-Performance Lithium-Sulfur Batteries.

Challenges including rapid capacity degradation and reduced Coulombic efficiency due to the shuttle effect have hindered the commercial viability of lithium-sulfur (Li-S) batteries. A novel sandwich-structured electrode with an optimized electrode structure and current collector interface design was presented as a free-standing positive electrode for Li-S batteries. Fabricated via a simple slurry coating process, the electrode embedded multiwalled carbon nanotubes within carbon nanofiber composite films (PCNF/T). Owing to the superior conductivity and reduced weight in comparison to both carbon nanofibers (PCNF) and the conventional aluminum foil current collector (Al), the PCNF/T electrode exhibited diminished polarization and accelerated redox reaction kinetics. Thus, it delivers an initial discharge capacity of 990.23 mA h g-1 at 0.5 C. Even after 400 cycles, while retains a reversible capacity of 707.45 mA h g-1, corresponding to a minimal capacity degradation rate of merely 0.07% per cycle. Notably, the electrode exhibits a capacity retention of 619.81 mA h g-1 after 400 cycles at 1 C, with a capacity decay rate of only 0.08% per cycle. This study presents an innovative approach to developing a new free-standing cathode for high-performance Li-S batteries.

High strength and transparent polyvinyl alcohol/nanocellulose film with encoding fluorescence properties

Fluorescent anti-counterfeiting films have garnered significant attention due to their advantages of tunable emission, strong concealment, high difficulty of imitation, and good processability. In this work, two zinc sulfide quantum dots (ZnS QDs) with different fluorescence wavelengths were loaded to construct polyvinyl alcohol (PVA)/cellulose nanofiber (CNF) composite films with encoding anti-counterfeiting fluorescence properties. By controlling the loading ratio of the two ZnS QDs, coded signals with different fluorescence intensity ratios at emission wavelengths of 400 nm and 600 nm were achieved. The fluorescence intensity ratio of the film can be adjusted between 1.3 × 105 and 1 × 10−4, resulting in a wide range of blue to orange color changes under ultraviolet light. The fluorescence intensity ratio corresponds to the color change of the film, which can be used for fluorescence coding design. By fine-tuning the addition ratio of the two types of QDs, the fluorescence intensity ratio and the color of the film can be precisely controlled, enhancing the anti-counterfeiting performance of the film. PVA is employed as a carrier to maintain high transmittance (> 80 %). The strength of the film was elevated up to 90 MPa due to the reinforcing effect of CNF, and the hydrophobic property was significantly improved with a contact angle higher than 113° through modification with diphenyl diisocyanate (MDI). This type of fluorescent PVA/CNF composite film, with its high mechanical strength and transparency, holds great potential in the field of anti-counterfeiting.

Preparation of UiO-66-NH2@cellulose nanofiber composite film and its adsorption performance study towards Cd(II)

Preparation of UiO-66-NH2@cellulose nanofiber composite film and its adsorption performance study towards Cd(II)

A robust, eco-friendly, and biodegradable cellulose nanofiber composite film for highly effective formaldehyde removal at room temperature

Formaldehyde (HCHO) poses a significant threat as a common indoor air pollutant, leading to various health issues. However, effectively addressing HCHO removal at room temperature remains a considerable challenge. This paper presents the preparation of a robust, eco-friendly, and biodegradable composite cellulose nanofiber film, incorporating CeO2-Ag@MnO2 catalysts and TEMPO-oxidized cellulose nanofiber (TOCNF), for high-efficiency HCHO removal at room temperature. A CeO2-Ag@MnO2 ternary catalyst with a core–shell structure was constructed to enhance the catalytic oxidation activity and stability. This structure increased the number of active sites on the catalyst surface and enhanced the interfacial synergistic effect of Ce-Ag-Mn. The TOCNF physically adsorbed HCHO in the composite film, while the catalyst oxidized it to CO2 and water. The composite films, particularly those with 20 wt% CeO2-Ag@MnO2 catalyst, exhibited high HCHO removal rates of 91.2 % at 20 °C and 99.6 % at 60 °C. Furthermore, the TOCNF/20 CAM composite films demonstrated excellent mechanical properties and degradability. This composite film offers an efficient and eco-friendly solution for the catalytic oxidation of HCHO at room temperature.

Mussel-inspired structure based CsPbBr3/Aramid nanofiber composite film for lightweight, flexible and superior X-ray shielding

Excessive exposure to X-rays risks human health and the proper functioning of precision instruments. Conventional materials have high atomic numbers, but their unsatisfactory mechanical properties hinder commercial application. Currently, X-ray shielding materials must fulfill the characteristics of high strength, lightweight, flexibility, high shielding efficiency, and low secondary radiation to alleviate urgent radiation risks. Here, this work introduces a mussel-inspired structure into the construction of the lightweight and flexible CsPbBr3/aramid nanofiber (ANF) composite films to enhance the ability of X-ray absorption. The CsPbBr3 provides effective X-ray shielding in millimeter thickness and addresses the challenge of absorption zone matching by containing both Cs and Pb elements. The interlayer reflection caused by the mussel-inspired structure increases the photon travel distance in the film, which synergizes with the absorption of X-rays by the elements, significantly improving shielding performance and weakening secondary radiation. The CsPbBr3/ANF composite film with 60 wt% CsPbBr3 content demonstrates robust tensile stress (57.6 MPa), lightweight (0.87 g/cm3), superior heat resistance, exceptional flexibility with a notable mass attenuation coefficient (58.2–65.6 cm2/g in the 20–70 kV range), which is much higher than Pb plate. Considering its comprehensive performance advantages, the CsPbBr3/ANF composite film significantly impacts the landscape of X-ray shielding.

Optimized performance of self-driven piezoelectric sensors through KNN/Nb2CTx synergistic effect

Flexible high-performance piezoelectric nanogenerator (PENG) excel in converting mechanical energy into electrical energy and exhibit remarkable sensitivity, a feature that is paramount for the development of self-driven piezoelectric sensors. In this study, electrospinning technology was used to prepare poly (vinylidene fluoride-co-trifluoroethylene) [P(VDF-TrFE)] based piezoelectric nanofiber composite films containing potassium-sodium niobate nano particles (KNN NPs) and Nb2CTx co-doping, as well as single-component doping. The co-doped composite film attained an optimal β-phase content of 91.33%. Owing to the enhanced dipole alignment and interface charge polarization, the piezoelectric performance of the co-doped composite film was significantly enhanced compared to that of single-component doping. The co-doped piezoelectric composite film displayed a stable maximum output voltage of 20 V and an output current of 1.46 μA. The peak instantaneous power output was measured at 9.9 μW under the optimal resistive load of 10 MΩ. Durability testing over 2000 cycles affirmed the excellent mechanical stability of the piezoelectric composite film. Moreover, the fabricated piezoelectric composite film showed considerable potential in applications such as monitoring human activities and serving as an early warning system for natural disasters such as landslides, as indicated by the test results.

High performance multifunctional piezoelectric PAN/UiO-66-NO2/MXene composite nanofibers for flexible touch sensor

In this study, a flexible piezoelectric sensor based on polyacrylonitrile (PAN), zirconium-based MOF (UiO-66) with nitro (NO2) and two-dimensional material MXene composite nanofiber film was proposed. When pressure was applied, the three-dimensional structural nanopores were compressed, increasing the intercalation structure between the MXene nanosheets coated in the fibers. The double-packed system produced a higher resistance change under the same pressure load, which can be explained by the fact that the low-conductivity octahedral UiO-66-NO2 particles acted as a similar “buffer” between the highly conductive MXene. At the same time, a large number of hydrogen bonds between the surfaces of the two fillers enhanced the synergistic effect and promoted the interfacial coupling effect, so that more 31-helical conformation in the PAN matrix was converted into a planar zigzag conformation. This improved the piezoelectric performance and enabled the sensor to have a voltage output of about 200 V in the detection range. And because the polyhedral form of UiO-66-NO2 particles provided a rougher surface structure, the piezoelectric sensor can achieve a high sensitivity of 5.62 V/N. The other results showed that the dielectric constant of the designed flexible piezoelectric sensor was increased to 2.67, the dielectric loss was kept at a low level of 0.026, and the maximum elongation was 56.03 %. This multi-functional sensor shows great potential in the fields of health and medical treatment, human-computer interaction, etc.

Aramid Nanofiber and Boron Nitride Nanosheet Composite Films for Mechanical and Dielectric Insulation Application

Aramid Nanofiber and Boron Nitride Nanosheet Composite Films for Mechanical and Dielectric Insulation Application

Flexible piezoelectric sensor based on PAN/MXene/PDA@ZnO composite film for human health and motion detection with fast response and highly sensitive

Polyacrylonitrile (PAN) nanofiber-based flexible piezoelectric sensors are recognized for their applicability in wearable electronic devices, personal health monitoring, and motion detection. This research explores the impact of dual fillers, MXene and polydopamine-modified zinc oxide (PDA@ZnO), on the characteristics of PAN-based piezoelectric composite nanofiber films, including planar zigzag conformation content, dielectric, ferroelectric, piezoelectric, and mechanical properties. By integrating PDA@ZnO as a filler, PAN/MXene/PDA@ZnO-5 (PMPO) piezoelectric sensors were developed, showcasing enhanced piezoelectric sensing capabilities. These sensors achieved a sensitivity of 28.56 V/N across a broad linear range, with superior mechanical stability and durability across 3000 loading–unloading cycles, and exhibited swift response and recovery times of 49 ms and 40 ms, respectively. Furthermore, their unique fiber structure and flexibility, when interfaced with the human body, enable the detection of minute physiological movements and the conversion of varied motions into distinct voltage outputs. Thus, these sensors offer considerable promise for applications in human health monitoring and motion posture correction.

Highly Thermally Conductive Flexible Biomimetic APTES-BNNS/BC Nanocomposite Paper by Sol-Gel-Film Technology.

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

High-temperature flexible electric Piezo/pyroelectric bifunctional sensor with excellent output performance based on thermal-cyclized electrospun PAN/Zn(Ac)2 nanofiber mat

High-temperature sensors are critical in petrochemical, aerospace, and automotive industries. However, the inorganic piezoelectric materials for high-temperature sensors are usually rigid and only can work in low temperatures due to their low Curie temperature (< 200 °C), which restricts these sensors for high-temperature application. Herein, we report a high-temperature piezoelectric sensor based on PAN/Zn(Ac)2 composite nanofiber mat created via electrospinning and thermal-oxidative stabilization process, which can continuously work over 500 °C. Moreover, the heat-treatment PAN is first found to be pyroelectric. The effects of the different heat-treatment temperatures on the mechanical and electrical performance of PAN/Zn(Ac)2 composite nanofiber mats are studied systematically. The maximum voltage output of the PAN/Zn(Ac)2 composite film sensor is 14.13 V at room temperature, and the voltage output of the composite film (450 ℃ heat-treated) sensor is about 14.86 V at high temperature. Besides, it has durability for over 10000 cycles (room temperature), and it has durability for over 5000 cycles and stability after 60 days (400 ℃). The PAN/Zn(Ac)2 composite nanofiber film also showed a linear voltage response to the thermal gradient, but the pyroelectric output of the PAN/Zn(Ac)2 composite nanofiber film is independent of the heat treatment temperature. The PAN/Zn(Ac)2 composite film sensor can charge a capacitor and can instantly drive small electronic devices when the capacitor discharges, and the PAN/Zn(Ac)2 composite film sensor can be applied to fire safety. Overall, good flexibility, high-temperature resistance, and bifunctional sensing ability make PAN/Zn(Ac)2-type sensors expected to be widely used in the high-temperature field of fire safety, the automotive industry, and other harsh environment.