Dispersion Of Graphene Research Articles

Graphene Nanocomposites for Electromagnetic Interference Shielding—Trends and Advancements

Electromagnetic interference is considered a serious threat to electrical devices, the environment, and human beings. In this regard, various shielding materials have been developed and investigated. Graphene is a two-dimensional, one-atom-thick nanocarbon nanomaterial. It possesses several remarkable structural and physical features, including transparency, electron conductivity, heat stability, mechanical properties, etc. Consequently, it has been used as an effective reinforcement to enhance electrical conductivity, dielectric properties, permittivity, and electromagnetic interference shielding characteristics. This is an overview of the utilization and efficacy of state-of-the-art graphene-derived nanocomposites for radiation shielding. The polymeric matrices discussed here include conducting polymers, thermoplastic polymers, as well as thermosets, for which the physical and electromagnetic interference shielding characteristics depend upon polymer/graphene interactions and interface formation. Improved graphene dispersion has been observed due to electrostatic, van der Waals, π-π stacking, or covalent interactions in the matrix nanofiller. Accordingly, low percolation thresholds and excellent electrical conductivity have been achieved with nanocomposites, offering enhanced shielding performance. Graphene has been filled in matrices like polyaniline, polythiophene, poly(methyl methacrylate), polyethylene, epoxy, and other polymers for the formation of radiation shielding nanocomposites. This process has been shown to improve the electromagnetic radiation shielding effectiveness. The future of graphene-based nanocomposites in this field relies on the design and facile processing of novel nanocomposites, as well as overcoming the remaining challenges in this field.

Wet dispersion of graphene assisted constructing multiple interface pores of PVDF hollow fiber membranes via melt-spinning and stretching

In this work, in order to further improve the permeability of poly(vinylidene fluoride) (PVDF) hollow fiber microfiltration membranes through melt-spinning and stretching (MS-S), we doped graphene (GE) in the forming membrane system of the previous work via wet dispersion and successfully prepared PVDF hollow fiber microfiltration membranes with multiple interface pores. GE could be uniformly dispersed and embedded in the PVDF matrix through the wet dispersion, which could obviously improve the interface layer between the matrix phase (PVDF) and the dispersed phase (GE) due to their poor compatibility of organic/inorganic phases. In addition, the stress concentration would be generated at the interface between GE and PVDF, which resulted in PVDF forking to many tiny fibers. Thus, the multiple interface pores between organic/organic (PVDF/polysulfone(PSf)) and organic/inorganic (PVDF/GE) phases could occur and be controlled precisely through the further stretching. The results showed that GE could improve the pore size and porosity of the prepared membranes obviously. In addition, the pore size of the prepared membranes could be controlled from 0.258 to 1.066 µm by changing the stretching ratios. Accordingly, pure water flux increased from 174.5 to 2782.9 L m-2 h-1. Applied to filter the active sludge suspension, the prepared PVDF microfiltration membranes exhibited a high rejection (＞99.5%), and the turbidity decreased obviously (˂0.5 NTU). In particular, there were not any hazardous solvents used in the preparation process, which could achieve green preparation of PVDF membranes.

Graphene composite self-healing antifog/frost-resist transparent coatings with zwitter-wettability

Self-healing materials achieve both durability and simplified maintenance by restoring their structure and function. However, self-healing materials utilizing surface hydrophilicity are considered incompatible with zwitter-wettability properties. Therefore, further investigation is needed to fabricate antifogging coatings that combine zwitter-wettability and self-healing properties. In this study, we demonstrated that polymer multilayer graphene composite coatings exhibit simultaneous antifogging and self-healing properties. We achieved a uniform dispersion of an aqueous solution of graphene by directly dispersing in a strong acid polymer and a uniform dispersion of graphene in the membrane via layer-by-layer self-assembly without any post-treatment, enabling precise control of hydrophobicity and water absorption of the membrane. The fabricated layer-by-layer coatings exhibited zwitter-wettability and self-healing performances comparable to those of previously reported systems. The maximum water droplet contact angle on the surface was 99° The 20-bilayer coating also exhibited excellent self-healing performance, closing 100 μm scratches within approximately 60 s and flattening the surface within approximately 300 s of exposure to water. In the antifogging tests, the coatings demonstrated high resistance to harsh cooling environments and exhibited excellent antifogging performance. This study provides a new zwitter-wetting strategy that combines self-healing and antifogging properties, providing an exceptional option for the development of next-generation surface coatings.

A simple and low-cost method of sulfur functionalization and aqueous dispersion of graphene driven by gas-liquid non-thermal plasma discharge

A simple and low-cost method of sulfur functionalization and aqueous dispersion of graphene driven by gas-liquid non-thermal plasma discharge

Thermo-elastic buckling behaviors of advanced fluid-infiltrated porous shells integrated with GPLs-reinforced nanocomposite patches

In the existing paper, thermo-mechanical buckling performance of three-layered advanced fluid-infiltrated porous shells that are embedded between two GPLs-reinforced composite layers is investigated. The influence of the fluids in the pores is investigated using Skempton coefficient. Imperfection types and ratio effects are also considered. Moreover, for the face layers, Graphene nanoplatelets (GPLs) weight fraction and dispersion patterns are studied. After deriving the governing equations employing virtual displacement method, they are solved analytically via Navier’s approach. Finally, the impact of different factors on the critical buckling loads (CBLs) and temperatures (CBTs) of cylindrical, spherical, and doubly-curved shells is assessed.

Preparation of a graphene/silicone modified polyester composite coating and its corrosion resistance

Tetramethoxysilane polyester was prepared via hydrosilylation of Tetramethoxysilane with acryl-terminated polyester (Si-PET). GO dispersed Si-PET fluids (GO/Si-PET) were cured on a tinplate surface as coatings for tinplate via room temperature vulcanization with an applicable curing time. The mechanical properties, thermal stability, chemical resistance, and anticorrosion properties of the coatings were assessed. The mechanical properties of the material depend on the GO dispersion, and the best dispersed GO sheets lead to the highest flexibility and the lowest adhesive force to tinplate. Electrochemical impedance spectroscopy (EIS) confirmed that dispersions of graphene (GE), as barriers for molecular permeation, were also important. The coatings with the best dispersed GE, not those with the highest GE loadings, gave the highest Z′, |Z′′|, Rc and arc radii.

Nanocomposite Nanofibers of Graphene—Fundamentals and Systematic Developments

Research on polymer nanocomposite nanofibers has seen remarkable growth over the past several years. One of the main driving forces for this progress is the increasing applicability of polymer nanocomposite nanofibers for technological applications. This review basically aims to present the current state of manufacturing polymer/graphene nanofiber nanocomposites, using appropriate techniques. Consequently, various conducting and thermoplastic polymers have been processed with graphene nano-reinforcement to fabricate the nanocomposite nanofibers. Moreover, numerous methods have been adopted for the fabrication of polymer/graphene nanocomposites and nanofibers including interfacial polymerization, phase separation, freeze drying, template synthesis, drawing techniques, etc. For the formation of polymer/graphene nanocomposite nanofibers, electrospinning can be preferable due to various advantages such as the need for simple equipment, control over morphology, and superior properties of the obtained material. The techniques such as solution processing, melt spinning, and spin coating have also been used to manufacture nanofibers. Here, the choice of manufacturing techniques and parameters affects the final nanofiber morphology, texture, and properties. The manufactured nanocomposite nanofibers have been examined for exceptional structural, microstructure, thermal, and other physical properties. Moreover, the properties of polymer/graphene nanofiber rely on the graphene content, dispersion, and matrix–nanofiller interactions. The potential of polymer/graphene nanocomposite nanofibers has been investigated for radiation shielding, supercapacitors, membranes, and the biomedical field. Hence, this review explains the literature-driven significance of incorporating graphene in polymeric nanofibers. Conclusively, most of the studies focused on the electrospinning technique to design polymer/graphene nanofibers. Future research in this field may lead to advanced innovations in the design and technical applications of nanocomposite nanofibers. To the best of our knowledge, research reports are available on this topic; however, the stated literature is not in a compiled and updated form. Therefore, field researchers may encounter challenges in achieving future advancements in the area of graphene-based nanocomposite nanofibers without first consulting the recent literature, such as an assembled review, to gain necessary insights, etc. Consequently, this state-of-the-art review explores the manufacturing, properties, and potential of polymer/graphene nanocomposite nanofibers.

Superior enhancement in thermal conductivity of epoxy/graphene nanocomposites through use of dimethylformamide (DMF) relative to acetone as solvent

This method article describes the fabrication of graphene-epoxy nanocomposites using two different solvents, dimethylformamide (DMF) and acetone, and validates the resulting thermal conductivity improvements. The study compared the two solvents at a filler composition of 7 wt% and found that DMF resulted in more uniform dispersion of graphene nanoparticles in the epoxy matrix, leading to a 44% improvement in thermal conductivity compared to acetone. Laser scanning confocal microscopy (LSCM) imaging showed that DMF-based composites had more evenly dispersed graphene nanoplatelets than acetone-based composites, which exhibited larger graphene agglomerations. Effective medium theory calculations showed that DMF led to almost 35% lower interface thermal resistance between graphene and epoxy compared to acetone. The validated fabrication method and findings provide new possibilities for developing high thermal conductivity graphene-epoxy nanocomposites for various thermal management applications.•This article describes methods for fabricating graphene-epoxy composites using acetone and DMF as solvents, and validates that DMF is better for achieving higher thermal conductivity in the composite.

Cutting-Edge Graphene Nanocomposites with Polythiophene—Design, Features and Forefront Potential

Among conducting polymers, polythiophene has gained an important stance due to its remarkable physical features. Graphene is a unique, two-dimensional, nanocarbon nanomaterial. As in other polymers, graphene has been reinforced in polythiophene to form advanced nanocomposites. This comprehensive review covers the design, essential features, and methodological potential of significant polythiophene and graphene-derived nanocomposites. In this context, various facile approaches, such as in situ processing, the solution method, and analogous simplistic means, have been applied. Consequently, polythiophene/graphene nanocomposites have been investigated for their notable electron conductivity, heat conduction, mechanical robustness, morphological profile, and other outstanding properties. Studies have revealed that graphene dispersion and interactions with the polythiophene matrix are responsible for enhancing the overall characteristics of nanocomposites. Fine graphene nanoparticle dispersal and linking with the matrix have led to several indispensable technical applications of these nanocomposites, such as supercapacitors, solar cells, sensors, and related devices. Further research on graphene nanocomposites with polythiophene may lead to remarkable achievements for advanced engineering and device-related materials.

Straightforward Strategy Toward In Situ Water-Phase Exfoliation and Improved Interfacial Adhesion to Fabricate High-Performance Polypropylene/Graphene Nanocomposites.

Graphene is a potential candidate for achieving high-performance and multifunctional polypropylene (PP) composites. However, the complex manufacturing process and low dispersibility of graphene, as well as poor interfacial adhesion between graphene and polypropylene chains, stifle progress on large-scale production and applications of graphene/polypropylene composites. Here, we develop a strategy of maleic anhydride grafted polypropylene (MAPP) latex-assisted graphene exfoliation and melt blending to address the key challenges facing in industrial production. The surface property of the graphitic precursor is well-designed to achieve a high graphene exfoliation yield of ∼100% and induce abundant hydrogen bonding between the obtained mild-oxidized graphene (MOG) sheets and MAPP chains. Therefore, the MAPP-modified MOG can homogeneously disperse in the PP matrix and exhibits an excellent interfacial compatibility with the polymer. The addition of 5 wt % MOG results in simultaneous increase in the initial decomposition temperature, crystallization temperature, tensile strength, and Young's modulus by 43.2, 11.4 °C, 21.5, and 50.7%, respectively, and the electrical conductivity increases to 0.02 S·m-1. This work illustrates a practical solution to low-cost, eco-friendly, and feasible industrial production of graphene/PP composites through synchronous exfoliation and interfacial modification of graphene.

A strategy to integrate the preparation of graphene with the preparation of electrode slurry for lithium-ion batteries

Because of its unique structure and superior properties, graphene has been used a lot in lithium-ion batteries. The common way of adding graphene not only increases the preparation process but also makes it easy to stack graphene. This paper proposes a strategy to integrate the preparation process of graphene with the preparation process of electrode slurry for lithium-ion batteries. In this paper, graphene dispersions were prepared by the liquid-phase shearing method. On this basis, the centrifugal process was removed and a one-step method was proposed to prepare graphite conductive slurry. The initial capacity of the battery was increased by 8% when the graphene dispersion prepared by the liquid-phase method was used as the graphite anode conductive agent for lithium-ion batteries. The graphite conductive slurry prepared by the one-step method can replace acetylene black, the conductive agent in conventional graphite electrodes. And the initial capacity of the battery was improved by 22% and 12.8% compared to that of the battery with acetylene black and the prepared graphene dispersion as the conductive agent, respectively. The graphene conductive slurry as graphite anode conductive agent can increase the graphite capacity and improve the cycling and multiplicity performance of the anode material. The conductive agent is easy to prepare, low cost, and can effectively improve graphite anode's electrochemical charge and discharge performance.

Evaluation of electrical properties of graphene nanopowder-dispersed propylene glycol-water solutions

Nanofluids, which are suspensions of nanoparticles in base fluids, have gained significant attention in recent years due to their enhanced thermal and electrical properties. In particular, propylene glycol-water nanofluids have been extensively investigated for their electrical properties. The primary goal of this study is to evaluate the electrical characteristics of nanofluids containing graphene powder distributed in propylene glycol-water. Compositions containing 100:0, 75:25, as well as 50:50 of Propylene Glycol as well as Water were created, along with other nano fluids. Both types of base fluids were infused with graphene at quantities of 0.25 as well as 0.5 percent, respectively. The assessment of electrical characteristics in nanofluids includes the analysis of parameters like breakdown voltage, permittivity, resistivity, and electrical conductivity. With the increase in the diameter there is an increase in the value of resistivity with the dispersion of graphene nano powder whereas breakdown voltage, permittivity and electrical conductivity have been decreased with the increase in the diameter. Overall with the dispersion of graphene in nano powder the electrical properties have been enhanced. Furthermore, it discusses the underlying mechanisms and provides insights into potential applications of propylene glycol-water nanofluids in electrical and electronic systems.

Research on the application of new functional materials in concrete

The self-made polycarboxylic acid water reducer was used as a dispersant to investigate its influence on the dispersion property of new functional material graphene slurry. The dispersion technology in the preparation process of new functional material and the influence of the dosage of new functional material on the performance of concrete were studied. The results showed that the self-made polycarboxylic acid water reducer as a dispersant can improve the dispersibility of the new functional material graphene in water. When the ultrasonic dispersion time is 40min, it can be used to discharge bubbles in the graphene dispersion solution and improve the strength of concrete. By means of manual mixing, the concrete containing the dispersible liquid of the new functional material has less slump and less expansion loss at 1h, and higher compressive strength at 3 d, 7 d, and 28 d. The 7 d and 28 d compressive strength of concrete can be significantly improved when the content of new functional material graphene dispersion is 0 ∼ 0.23 %, and the optimal content of graphene dispersion is 0.05 %.

Experimental investigation and characterization of the tensile and flexural properties of amine functionalized graphene enhanced nanocomposite prepregs

Graphene has drawn tremendous scientific and commercial interest because of its outstanding properties. It is extensively researched as a reinforcement in composite materials. Graphene is the most significant reinforced filler because of its outstanding mechanical, electrical, and thermal properties. On the other hand, epoxy resin is highly utilized in practical applications such as laminates, coatings, and composites because of its simplicity of processing, firm adherence to various substrates, and chemical resistance. The distribution and interplay of graphene nanoparticles with the polymer determine the composite's performance. Several approaches are used to integrate Graphene into graphene-enhanced composites, including graphene dispersion in the polymer matrix. Prepregs are used in high-performance applications where weight and mechanical qualities are more important than price. Prepreg constructions frequently employ premium epoxy resins, carbon fiber, or other cutting-edge fibers. This research aims to experimentally investigate the tensile and flexural properties of epoxy prepreg composite with a varied weight percentage of amine-functionalized Graphene. In this research, to have good dispersion of Amine functionalized Graphene, the developed methodology with a combination of different stages for better dispersion. The Effect of different concentrations of weight fractions (wt. %) of Amine functionalized Graphene (AFG) was tested through tensile strength, and flexural strength surface fractures were investigated through Scanning Electron Microscope (SEM). The result of the tensile test and flexural test exhibited the enhancement of Tensile strength by 12.33% at one wt. % of AFG as a reinforcement and flexural strength, no change was seen compared to neat Epoxy.

In English

In presented work we have reported that polyvinylpyrrolidone (PVP) is suitable organic solvent for mechanical exfoliation of crystalline graphite to graphene in aqueous solution through kitchen blender technique. Morphological, structural and optical, properties of graphene samples were characterized by scanning electron microscopy, Raman scattering and UV-Visible spectroscopy. Scanning electron microscopy demonstrates folded morphology of graphene flakes with ~4 nm thickness. Raman scattering was revealed the high-quality graphene with low levels of defects after the exfoliation process of graphite/PVP dispersions. The G band at ~1582 cm−1 on Raman spectra is related with stretching vibrations of carbon atoms. The broadening of the G band is not observed, that indicated on absence of the basal plane defects in the graphene structure, which can be introduced during exfoliation by the kitchen blender. The ratio of the intensity of 2D and G bands equal to 1.66 (I2D/IG>1) and the value of 2D band full width at half maximum is 79.88 cm–1, indicated a few-layer graphene (FLG) structure. The defects quantity identified by the intensity ratio of the D and G bands, ID/IG is 0.18, significantly lower than that reported for graphene oxide with basal plane defects (> 1) and for sonication dispersed graphene (~ 0.6). The graphene dispersions were characterized by UV–Vis spectroscopy, minimum transmittance observed at around 270 nm is attributed to the π→π* transitions of aromatic C–C bonds in graphene. The optical transmittance minimum and the overall high transmittance decreasing values observed between 270 and 800 nm strongly suggest the presence of two-dimensional material in the dispersion, thus confirming the successful exfoliation of graphite to graphene by blending. We demonstrate the simple and nontoxic method to product high-quality FLG sheets, free from defects, using a kitchen blender and eco-friendly polyvinylpyrrolidone as an organic exfoliant.

Experimental characterization optimizing the alignment parameter for GNP epoxy base nanocomposite via a weak DC magnetic field

AbstractGraphene has been hailed by scientists as the “wonder material” of the 21st century. Despite the impressive mechanical and electrical qualities of graphene in its unprocessed state, graphene‐based epoxy nanocomposites can only be used as a structural material on a small scale. The random dispersion and orientation of graphene in epoxy cause the failure. Magnetite Fe3O4 nanoparticles are synthesized and solvo‐thermally attached to the graphene nanoplatelets (GNP) surfaces in order to utilize our recently model's suggested optimized alignment parameters. Solution with properly dispersed nanoparticles, that is, Fe3O4‐GNP within epoxy, is exposed to the magnetic field (0.05 T). Morphology, microstructure, and magnetic properties of GNP, Fe3O4, and Fe3O4‐GNP nanoparticles have been characterized by X‐ray diffraction, Fourier‐transform infrared spectroscopy, Raman spectroscopy, thermogravimetric analysis, differential scanning calorimetry, atomic force microscopy, X‐ray photoelectron spectroscopy, Brunauer–Emmett–Teller, transmission electron microscopy, scanning electron microscopy, energy‐dispersive X‐ray microanalysis, and vibrating sample magnetometry. The aforementioned characterization method, optical microscopy, and studying the fracture surface morphology confirmed the alignment. The fabricated aligned Fe3O4‐GNP nanocomposite is best used as a functional material.

Prying or pushing? The dispersion mechanism of amphiphilic molecules on graphene in aqueous solution: A molecular dynamics simulation

Amphiphilic molecule aqueous solutions are widely used in the dispersion of graphene. Previous experimental studies have focused on selecting amphiphilic molecules with high dispersion yield and stability through a large number of “trial and error” methods, without delving into their dispersion mechanism. In this study, the graphene dispersing processes in aqueous solutions of three amphiphilic dispersants with different structures, flavin mononucleotide sodium, polyvinyl pyrrolidone and the oligomer of poly(pyrenemethyl acrylate)-b-poly[(polyethylene glycol) acrylate], were investigated by molecular dynamics simulation. By characterizing the influence of three dispersants on the intercalation effect of water molecules, their distribution relative to graphene, and their influence on the equilibrium conformation of graphene, the simulation conclusion was drawn that the arrangement of hydrophilic and hydrophobic structures of amphiphilic molecules is the decisive factor in their mechanism of dispersing graphene. Two different dispersion mechanisms have been concluded and the relationship between them and the structure of amphiphilic molecules was elaborated. This article also explored the driving forces of two mechanisms and the influence of graphene lateral area on the dispersion effectiveness. This investigation provided theoretical clues to design the amphiphilic molecules with suitable structure and select appropriate mechanical operations to achieve higher dispersion yield.

Graphene's effect and mechanism on the properties of alkali-activated slag coating

Using alkali-activated slag to prepare coatings is an alternative solution for concrete repair and protection. However, shrinkage cracking limits the application of alkali-activated slag, which also increases the risk of coating peeling. Graphene dispersions (content of 0.2%, 0.4%, 0.6% and 0.8%) were added to the alkali-activated slag coatings. The drying time, apparent circumstance (thicknesses of 1 mm, 2 mm, 3 mm and 5 mm) and the tensile bond strength with 1 mm thickness coating were determined. The mechanism of action was analyzed in terms of both product and interfacial properties. The experimental results showed that the graphene dispersion would shorten the drying time of the coatings. The drying time was reduced by 57.1% (from 116 min to 52 min). Moreover, the graphene dispersion improves the cracking of the coating. The larger the coating thickness is, the better it improves the cracking effect. The surface cracking of the coating with 5 mm thickness was reduced by 60.7% (from 1.6751% to 0.6583%). Graphene can significantly improve the bond strength of the coating. When the graphene content is 0.8%, the bonding strength with a thickness of 1 mm is 0.502 MPa at 7 days and 1.577 MPa at 28 days. The bond strength increased by 280.3% and 175.2%, respectively, XRD, FTIR and SEM analysis showed that the increase in bond strength was caused by two factors. (1) Graphene can promote the generation of zeolite phase in alkali-activated slag. This is conducive to enhancing the interlayer adhesion of the coating itself. (2) Graphene is beneficial to reduce the pores in the transition zone between the coating and the substrate and enhance the contact area between the coating and the substrate and makes the transition zone denser.

Influence of surface groups on the properties of disperse systems

Published data on the influence of surface groups on various properties of disperse systems are integrated and analyzed. The preparation of these systems is considered in relation to activated carbon. The discussion addresses the effect of redox reactions of surface groups on the energy efficiency of electrochemical supercapacitors, operation of capacitive deionization units for water desalination, and functioning of redox capacitors based on organic monomers. It is shown that very high energy and power characteristics of lithium ion capacitors are based on the redox reactions of lithium-containing surface groups of highly dispersed graphene electrodes. The effect of surface groups on the self-discharge of electrochemical supercapacitors with activated carbon-based electrodes is demonstrated. The prospects for the production of drinking water by capacitive deionization using mosaic cation/anion exchange membranes are evaluated. The practically important inversion of sulfo groups relative to the polymer chain in the catalyst layers of fuel cells with proton exchange membranes is noted.<br> The bibliography includes 181 references.

Insights into the Mechanism of Graphene Acting on Water and Chloride Ion Permeability of Cement-Based Materials.

Due to its excellent mechanical properties and high aspect ratio, graphene can significantly improve the water and chloride ion permeability resistance of cementitious materials. However, few studies have investigated the effect of graphene size on the water and chloride ion permeability resistance of cementitious materials. The main issues are as follows: How do different sizes of graphene affect the water and chloride ion permeability resistance of cement-based materials, and by what means do they affect these properties? To address these issues, in this paper, two different sizes of graphene were used to prepare graphene dispersion, which was then mixed with cement to make graphene-reinforced cement-based materials. The permeability and microstructure of samples were investigated. Results show that the addition of graphene effectively improved both the water and chloride ion permeability resistance of cement-based materials significantly. The SEM (scanning electron microscope) images and XRD (X-ray diffraction) analysis show that the introduction of either type of graphene could effectively regulate the crystal size and morphology of hydration products and reduce the crystal size and the number of needle-like and rod-like hydration products. The main types of hydrated products are calcium hydroxide, ettringite, etc. The template effect of large-size graphene was more obvious, and a large number of regular flower-like cluster hydration products were formed, which made the structure of cement paste more compact and thus significantly improved the resistance to the penetration of water and chloride ions into the matrix of the concrete.