Graphene Composite Film Research Articles

Poly(vinylidene fluoride-trifluoroethylene)/graphene composite pressure sensors and their potential applications in sports training

Pressure sensors based on advanced materials have gained high attention for their potential applications in various fields, including sports training. This study focuses on the development of poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE))/graphene composite films as high-performance pressure sensors. The composite films were fabricated using a casting method, and their morphological, structural, thermal, mechanical, and electrical properties were comprehensively characterized. The incorporation of graphene nanoplatelets (GnPs) into the P(VDF-TrFE) matrix led to the formation of a percolated conductive network, resulting in enhanced electrical conductivity and pressure sensitivity. The composite film containing 5 wt% GnP exhibited remarkable sensing capabilities, boasting an elevated sensitivity of 0.85 kPa−1, a rapid response time of 50 ms, and exceptional resilience over 1000 loading-unloading cycles. Moreover, the incorporation of GnP substantially augmented the mechanical properties, with a 65 % enhancement in tensile strength and a 92 % surge in Young's modulus when juxtaposed against pristine P(VDF-TrFE) films. The superior property of these P(VDF-TrFE)/graphene composite pressure sensors, along with their excellent mechanical properties, make them promising candidates for sports training applications, enabling the monitoring and analysis of various biomechanical parameters to optimize athletic performance and prevent injuries.

Nacre inspired supertough and flame-retardant reduced graphene oxide composite films

Nacre-like graphene composite films (GCFs) with high strength have been highly developed. However, the GCFs usually exhibit relatively poor toughness and poor flame resistance, seriously limiting their applications as structural materials. Here, reduced graphene oxide (rGO), halloysite nanotubes (HNTs), and flame-retarding modified lignin (F-lignin) were compounded to fabricate the rGO-HNTs-(F-lignin) film. In the rGO-HNTs-(F-lignin) film, the F-lignin binds the rGO sheets and HNTs, enhancing the entanglement of HNTs and the interactions between HNTs and rGO sheets, and the macromolecular F-lignin also improves the ductility of the rGO-HNTs-(F-lignin) film, while the entangled HNTs conversely reinforce the F-lignin to prevent the F-lignin from fracture when the rGO-HNTs-(F-lignin) film is under stress, further increasing the ductility of the rGO-HNTs-(F-lignin) film. The HNTs and F-lignin promote each other to enhance the strengthening and toughening effect on the rGO-HNTs-(F-lignin)-film, and endowing the rGO-HNTs-(F-lignin)-film with the superior mechanical properties of the tensile strength of 634 ± 38 MPa, tensile fracture strain of 8.17 ± 0.59 %, and toughness of 25.35 ± 2.95 MJ/m3, respectively. The rGO-HNTs-(F-lignin) film also exhibits improved flame-retardant properties due to the high flame retardancy of HNTs and F-lignin. These excellent integrated properties of the rGO-HNTs-(F-lignin) film will promote its potential applications as structural materials.

Sandwich-structure CNT-graphene film with covalent bond for high-performance electromagnetic shielding and thermal management

Macro-assembled graphene-based films can been considered as a potential material for the electromagnetic shielding (EMI) and thermal management in portable electronics. Here, a carbon nanotubes and graphene composite film with covalent bond (CNT-gGF) was fabricated through graphitized welding. The fabricated covalent-bonding CNT-gGF was featured with sandwich structure based carbon nanotubes welding graphene layers as the skeleton, resulting in an excellent conductivity of 13000 S cm−1 exceeding the pure graphene film. These unique structures endow CNT-gGF film with a prominent mechanical property and flexibility (folding resistant with 1000 cycles). Importantly, an outstanding EMI value is over 55 dB with a thickness of merely 20 μm in the broad frequency of 5–22 GHz. And the CNT-gGF was proven to exhibit a steady EMI property in a variety of extreme environments including high and low temperatures and burns. Moreover, the thermal conductivity of CNT-gGF could be up to 912 W m−1 K−1, then CNT-gGF presents well heat dissipation application for different voltages and mobile phone. Therefore, this large-size CNT-gGF film has a good application potential for high-performance EMI and thermal management, and this study provides favorable guidelines for the graphene-based films toward extreme demands in wearable electronics and 5G communication.

A Graphene Composite Film Based Wearable Far-Infrared Therapy Apparatus (GRAFT) for Effective Prevention of Postoperative Peritoneal Adhesion.

Postoperative peritoneal adhesion (PPA) is the most frequent complication after abdominal surgery. Current anti-adhesion strategies largely rely on the use of physical separating barriers creating an interface blocking peritoneal adhesion, which cannot reduce inflammation and suffers from limited anti-adhesion efficacy with unwanted side effects. Here, by exploiting the alternative activated macrophages to alleviate inflammation in adhesion development, a flexible graphene-composite-film (F-GCF) generating far-infrared (FIR) irradiation that effectively modulates the macrophage phenotype toward the anti-inflammatory M2 type, resulting in reduced PPA formation, is designed. The anti-adhesion effect of the FIR generated by F-GCF is determined in the rat abdominal wall abrasion-cecum defect models, which exhibit reduced incidence and area of PPA by 67.0% and 92.1% after FIR treatment without skin damage, significantly superior to the clinically used chitosan hydrogel. Notably, within peritoneal macrophages, FIR reduces inflammation reaction and promotes tissue plasminogen activator (t-PA) level via the polarization of peritoneal macrophages through upregulating Nr4a2 expression. To facilitate clinical use, a wirelessly controlled, wearable, F-GCF-based FIR therapy apparatus (GRAFT) is further developed and its remarkable anti-adhesion ability in the porcine PPA model is revealed. Collectively, the physical, biochemical, and in vivo preclinical data provide compelling evidence demonstrating the clinical-translational value of FIR in PPA prevention.

Carboxylated cellulose composite film fabricated via layer‐by‐layer self‐sssembly for thermal management material with ultra‐high thermal conductivity

AbstractWith the development of 5G equipment, aerospace, sensors, thermal management devices and other fields in the direction of high power, high performance and miniaturization, the heat released during usage increases significantly, leaving great application prospects for heat dissipation materials. In spite of great attention paid to film materials due to their light weight and flexibility, they have the obvious disadvantage of poor thermal conductivity. In this work, carboxylated cellulose (CNF‐C)/dopamine‐coated nickel‐coated graphene (PDA‐Ni@GNS) composite films with high in‐plane thermal conductivity (in‐plane TC) have been fabricated by a simple vacuum‐assisted filtration method. In the prepared composite films, the flaky packing layers were found to be stacked orderly and form an excellent thermally conductive network, resulting in an increase in in‐plane TC by 322.1% (sample W4) as compared with that of neat films. By comparing the in‐plane TCs of the composite films with that of a commercial gasket, it was readily seen that the present composite films had fairly excellent heat dissipation properties. The composite exhibits not only sufficiently high in‐plane TC and tensile strength of 149.02 MPa but also exhibits hydrophobic property, imparting the composite films good working stability under extreme conditions, which ensured of their potential applications in thermal management materials.Highlights The introduction of Ni promotes the construction of heat conduction path. High in‐plane TC is obtained through layer‐by‐layer self‐assembly. The modification of filler enhanced the mechanical properties of the films. The modification of fillers led to the hydrophobicity of the film. The introduction of PDA made the films have insulating properties.

Three-dimensional surface strain sensor based on PDMS/LIG composite film with adjustable electromechanical performance

Flexible strain sensors play a crucial role in health monitoring, smart wearable devices, and human–machine interaction. Three-dimensional surface evaluation methods for strain sensors offer advantages by being closer to actual strain, featuring a larger working range, and being more suitable for multidirectional strain. In this study, a three-dimensional (3D) surface strain sensor based on polydimethylsiloxane/laser-induced graphene (PDMS/LIG) composite films has been developed. The electromechanical properties of this sensor, encompassing 3D strain range and sensitivity, can be adjusted by manipulating laser parameters and LIG patterns. The key to attaining these specific characteristics lies in the intentional design of crack types and orientations on the sensor's surface. Remarkably, the line-vertical (LV) sensor exhibits outstanding sensitivity with a GF of 211.3. The line-parallel (LP) sensor achieves a GF of 115.1. Additionally, it demonstrates a stretching range of 25% and maintains stable performance over an extensive number of strain/release test cycles (more than 3000 cycles). With these advantages, the 3D strain sensor can not only be applied in human activity monitoring but also monitoring pressure within microchannels in microfluidic chips, suggesting promising applications in the health and medical fields.

Vertical Graphene on Graphene Composite Film for Heat Dissipation and Electromagnetic Shielding

Vertical Graphene on Graphene Composite Film for Heat Dissipation and Electromagnetic Shielding

A conjugated microporous polymer–graphene composite porous sandwich-like film for highly efficient flexible supercapacitors

A conjugated microporous polymer–graphene composite porous sandwich-like film has been developed for flexible supercapacitors with highly efficient electrochemical performance.

Graphene and graphene–cellulose nanocrystal composite films for sustainable anodes in biophotovoltaic devices

This work demonstrates the innovative utilisation of sheer exfoliated few-layer graphene and graphene–CNC films as eco-friendly electrodes for efficient current extraction from cyanobacteria, promising advancements in biophotovoltaic applications.

Application of graphene gas sensor technological convergence PSO-SVM in distribution transformer insulation condition monitoring and fault diagnosis

This study aims to improve the real-time monitoring and fault diagnosis of distribution transformers by utilizing a combination of five thin film gas detectors, these detectors include metal-modified graphene composite films and SnO2/RGO humidity sensors, which were prepared using the hydrothermal method. The experiment focused on investigating humidity and main fault characteristic gases that can reflect the insulation status of transformers. Additionally, a gas sensor array was constructed using a deep confidence neural network model. Based on the analysis of dissolved gas in transformer oil, the study extensively discusses the insulation fault diagnosis model and constructs the transformer fault diagnosis model using various methods including TRM, Particle swarm optimization support vector machine. The results demonstrated that the SnO2/RGO thin film humidity sensor exhibited high humidity sensitivity, and the other thin film gas sensors also exhibited good sensitivity. The average accuracy of the three classification methods mentioned is 80%, 92%, and 96%, respectively. These findings highlighted that the vector machine model not only improved the fault diagnosis accuracy but also possessed the characteristics of fewer parameters and a fast rate of convergence. Consequently, it effectively addressed the issue of early diagnosis of potential transformer faults. This study was of significant practical importance for ensuring the secure operation of the power grid.

High-performance carbon-based nanomaterial composites for ultrafast lasers based on stretch processing

Carbon-based nanomaterials, and specifically carbon nanotube and graphene, have been widely used as saturable absorber (SA) in ultrafast fiber laser. However, the performance of these SAs is limited due to the low damage threshold or self-starting capability. In our work, we have proposed a novel and straightforward method for enhancing the optical performance of polyvinyl alcohol-based carbon nanotube and graphene composite film. By mechanical stretching the composite films, the damage threshold of carbon nanotube-based SA and the self-starting capability of graphene-based SA can be obviously improved. The distinct nonlinear optical properties of carbon nanotube and graphene are analyzed, and the mode-locking performance is compared. Our finding provides a new insight and experimental basis for the development of high-performance carbon-based nanomaterial mode locker for ultrafast fiber lasers.

Irradiation-cured graphene composite films: a comparison between UV and EB curing

Irradiation-cured graphene composite films: a comparison between UV and EB curing

Fabrication of ZnO@Fe2O3 superhydrophobic coatings with high thermal conductivity

Efficient thermal management materials are an integral part of electronic devices and can quickly contribute to their heat dissipation, thereby greatly improving their reliability, stability and service life. However, the inherent hygroscopicity of the film surface sets obstacles to the reliability and structural stability of electronic devices. To address these issues, a bionic structural design was obtained by spraying a polyurethane/stearic acid/zinc oxide‑iron oxide composite powder (TPU/STA/ZnO@Fe2O3) on the surface of graphene composite films. At the same time, the graphene composite film has a high in-plane thermal conductivity (up to 533 W−1·m−1·K−1) and is able to reduce the film surface temperature to room temperature within 5 s due to its highly ordered layered design and strong hydrogen bonding interactions. In addition, the composite film offers a range of advantages such as good hydrophobicity and electrical conductivity. With a water contact angle of up to 159.5 ± 2° and an electrical conductivity of up to 3 × 103 S/m in steady state, the results show that the superhydrophobic graphene composite film has good physical, chemical and mechanical stability, as well as self-cleaning capabilities. It also retains good flexibility and reliability under 350 bending cycles. In this regard, the development of graphene composite films with high thermal conductivity, high superhydrophobicity, good electrical conductivity and flexibility is expected to be used as thermally conductive materials, opening up a new path in the field of thermally conductive heat dissipation materials for electronic components.

Network structural carbon nanotubes covalently linked graphene composite film for flexible electro-thermal heater with enhanced performance

Network structural carbon nanotubes covalently linked graphene composite film for flexible electro-thermal heater with enhanced performance

Poly(L-lactic acid)/graphene composite films with asymmetric sandwich structure for thermal management and electromagnetic interference shielding

The blowout growth of the power density and transmission efficiency of microelectronic devices makes the problems of “overheating” and electromagnetic pollution of electronic devices increasingly prominent, and it is raising an urgent demand to improve the thermal conductivity and electromagnetic interference (EMI) shielding performance of packaging materials. Additionally, the environmental damage caused by fossil-based electronic waste should not be ignored. Hence, a scalable production strategy was proposed to prepare sandwich structure poly(L-lactic acid) (PLLA) composite films with high thermal conductivity and excellent EMI shielding efficiency (SE), which was achieved via solution pouring method and stacking hot-pressing process, in which PLLA/graphene nanoplatelets (PLLA/GNPs) with different GNPs contents was the top and substrate layers, and PLLA/poly(D-lactic acid)/Fe3O4 (PLLA/PDLA/Fe3O4) with a small amount of PDLA and Fe3O4 was the middle layer. Owing to the asymmetric distribution of filler and the successful introduction of magnetic particles, when the GNPs and Fe3O4 contents of the whole film are respectively only 5.61 wt% and 4.39 wt%, and the asymmetric ratio is 1:9, the in-plane thermal conductivity (K‖) and EMI SE of the composite film reaches 7.49 W m−1 K−1 and 41.7 dB, respectively, higher than those of PLLA film with symmetric structure (3.31 W m−1 K−1 and 33.0 dB) at the same contents of fillers. Furthermore, a small amount of PDLA (4.39 wt%) promotes the formation of stereocomplex (SC) crystallites in the middle layer and further induces the interlayer SC microcrystals during the stacking hot-pressing process, enhancing the interlayer interaction to maintain the mechanical robustness of the PLLA film. This work provides a new direction for the manufacture of polymer based composite films with high thermal conductivity and directional EMI shielding, and has broad application potential in the field of large-scale production of green electronic products.

Fabrication of Carbon Coated Nickel/Nitrogen Doped Graphene Composite Film and as Enhancer for Sensitive and Rapid Determination of Sunset Yellow

The innovative glassy carbon electrode used in the determination of sunset yellow is modified using a carbon-coated nickel/nitrogen doped graphene composite film. (C-Ni/NGE/GCE). The morphology and structure of different materials (C-Ni and NG) were characterized by transmission electron microscope. When HAc-NaAc (pH=4) was selected as the electrolyte solution, the maximum current of C-Ni/NGE/GCE oxidation peak was reached when the electrolyte concentration was 0.15 mol·L−1, which was a reversible redox peak. The maximum linear range is 1.0×10−4 mol·L−1 and the minimum is 4.0×10−6 mol·L−1. Taking the peak current as the vertical coordinate and SY concentration as the horizontal coordinate, the working standard curve equation obtained by differential pulse voltammetry is Ip(μA)=0.187+56.91c (μmol·L−1 )(R2=0.9992). The detection limit was 5.0×10−8 mol·L−1. The electrochemical behavior of SY shows proton number (X=1) and electron transfer number (n=1). The recovery rate of SY in beverage was 101.5%-103.3%. The following research of sensor to nitrite was the linear range, recovery rate and uL, produced in small experiments.

Fabrication and excellent properties of polyvinylidene fluoride/graphene composite films as thermal interface materials

The growing concern about thermal conductivity and electromagnetic shielding m electronic equipment has promoted the development of interfacial film materials. In this work, polyvinylidene fluoride (PVDF)/graphene composite films with different graphene contents were fabricated by high-energy ball milling, cold isostatic pressing, scraping and coating, successively. High-energy ball milling is beneficial to the dispersion of graphene powder, while cold isostatic pressing can greatly enhance thermal conductivity and mechanical strength by reducing the voids in the film and increasing the contact area of graphene sheets. The thermal conductivity, tensile strength and electromagnetic shielding properties of the films were carefully investigated and compared. It was demonstrated that the thermal conductivity increased from 0.19 W·m-1·K-1 for pure PVDF to 103.9 W·m-1·K-1 for the composite film with PVDF:graphene=l:3. Meanwhile the electromagnetic shielding efficiency can reach 36.55 dB. The prepared PVDF/ graphene composite films exhibit outstanding overall performance and have the potential for practical applications.

Highly sensitive broadband terahertz modulator based on MAPbI<sub>3</sub>/Graphene/Si composite structure

A high-performance silicon-based terahertz modulator is one of the key devices for building an ultrawideband terahertz-fiber hybrid communication system. In this paper, an ultrawideband terahertz modulator with large modulation depth based on a chalcogenide/graphene/silicon (MAPbI<sub>3</sub>/Graphene/Si) composite structure driven by near-infrared light (NIR) is proposed. The experimental results show that the graphene thin film and the chalcogenide hole transport layer can effectively promote the interfacial charge separation, increase the carrier complex lifetime, significantly enhance the surface conductivity of the device, further modulate the terahertz wave transmission amplitude, and realize the function of the light-controlled terahertz wave modulator under the NIR light drive. The terahertz transmission characteristics of the device are characterized by an 808 nm NIR modulation excitation source, and a large modulation depth of up to 88.3% is achieved in an ultra-wide frequency range of 0.2–2.5 THz and a low power density of 6.1 mW/mm<sup>2</sup> driven by NIR light, which is much higher than that of the bare silicon substrate (14.0%), with the significant advantages of high sensitivity, broadband, and large modulation depth. The corresponding semi-analytical device model is established and the experimental results are verified by simulation. The proposed MAPbI<sub>3</sub>/Graphene composite thin film is effective in enhancing the silicon-based modulator performance and provides a new strategy for the future integration of silicon-based terahertz modulators in NIR terahertz-fiber hybrid communication systems.

Enhanced electrically and thermally conductive free-standing graphene films with two-dimensional copper sheets as the catalyst and bridge.

Two-dimensional copper sheets were introduced as the catalyst and bridge to enhance the electrical and thermal conductivity of graphene films prepared from graphene oxide nanosheets via a thermal reduction method. The effects of adding different amounts of copper sheets in the composite films were investigated, and the results show that the electrical and thermal conductivity of the graphene films could be increased by 3 times and 64.9%, respectively. The two-dimensional copper sheets not only play an important role as a catalyst toward improving the graphitization degree of reduced graphene oxide, but also act as a bridge and promote the interconnection of the electrical and thermal conduction paths in the composite films due to the good electrical and thermal conductivity of copper. Moreover, the heat dissipation experiment shows that this enhanced graphene composite film has potential applications in the heat management of electronics.

Deep eutectic solvent assisted preparation of cellulose nanofibers and graphene composite films for supercapacitors

Cellulose nanofibers have been prepared directly from rice biomass with green solvent DES for graphene/CNF composite electrodes of high-performance supercapacitors.