Author: Energeia Graphenemex

Graphene Oxide Versatile Applications

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Graphene Oxide Versatile Applications:

From Sensing Technologies to Environmental Solutions

Graphene and its derivatives such as graphene oxide (GO) and reduced graphene oxide (rGO) are two-dimensional, sheet-like carbon nanomaterials with a wide range of opportunities for numerous applications due to their thinness, transparency, conductivity, flexibility, chemical stability, impermeability, and mechanical strength. In the case of GO and rGO, in addition to their large surface area with hydrophilic and hydrophobic regions inherent to graphene, they allow the adsorption of organic aromatic molecules, ions, and polymers through π-π stacking, hydrogen bonding, and electrostatic interactions. These properties make them suitable materials for constructing sensors or biocatalytic and photocatalytic platforms. According to various reports, the surface-to-volume ratio of graphene materials enhances the surface charge of the desired molecules, while their excellent electrical conductivity, especially at room temperature, favors electron transfer to the surface of electrodes for analysis or photocatalysis.

On the other hand, graphene sheets are not perfectly flat; they exhibit undulations formed as a result of the bonding between their carbon atoms or thermal fluctuations, which can ultimately induce magnetic fields and alter their electronic properties for designing sensors, biosensors, or electronic devices in general. Thus, through more than ten years of research and exploration of their remarkable multifunctionality, the study of graphene has transcended to the development of highly sensitive devices for monitoring, for example, the presence of harmful gases, medically relevant molecules, or proteins, and even water decontamination.

Detection Systems

Metamaterials are a type of compound with the ability to produce useful electromagnetic responses for designing sensors or non-destructive detection devices. Generally, these sensors consist of an insulating material and a conductive material, sensitive to the refractive index of the analyte’s upper layer. In the presence of graphene, it has been observed that this interaction (sensor-analyte) is enhanced by changes in resonance intensity, leading to amplitude changes that further favor detection sensitivity.

In a study conducted in 2023 by the School of Electronic and Information Engineering at Zhejiang University of Science and Technology, Hangzhou, China, a sensor was designed comprising a polyimide (PI) film as an insulating layer, an aluminum structure as a conductive layer, and a monolayer of graphene as the detection interface. Simulation results indicated that graphene could modulate the entire electric field and produce an amplitude change that significantly increases detection limits.

In another study conducted at the Laboratory of Nanostructured Materials of the Institute of Physics at UASLP, functionalized graphene oxide with gold nanoparticles was used as a SERS (Surface Enhanced Raman spectroscopy) biodetection platform, an important technique for biological detection due to its high sensitivity, low sample requirements, relatively low cost, and real-time detection. Crystal violet was used as the standard molecule and flavin adenine dinucleotide as the experimental coenzyme for its participation in numerous redox processes of metabolic reactions and biological electron transport. The results showed that graphene oxide hybrids with gold nanoparticles substantially enhance SERS signals compared to individual nanoparticles. Additionally, the results are consistent with other research on identifying significant improvements for molecule stabilization and fluorescence reduction during measurements, which is often a major drawback of such techniques, supporting its potential as a diagnostic or monitoring tool.

Toxic Gas Removal

Advances in nanoengineering allow graphene and GO sheets to be manipulated for the detection and separation of certain gases. According to the results of a study conducted by the Department of Energy Engineering at Hanyang University, Seoul, Korea, selective diffusion can be achieved by controlling the gas flow channels and pores through different stacking methods, demonstrating that GO’s functional groups provide a unique adsorption behavior towards CO2.

CO2 Conversion

The photocatalytic properties of GO can also be harnessed for converting CO2 into hydrocarbons such as methanol for solar energy capture and CO2 reduction. In 2018, at the Advanced Technology Laboratory for Materials Synthesis and Processing, Wuhan University of Technology, China, silver chromate (Ag2CrO4) nanoparticles were used as a photosensitizer and GO as a co-catalyst for the photocatalytic reduction of CO2 into methanol and methane. The study concluded that this synergy between nanoparticles could enhance conversion activity up to 2.3 times under solar irradiation due to better light absorption, increased CO2 adsorption, and improved charge separation efficiency.

Water Decontamination

Water technologies have various areas of opportunity, particularly in improving filtration or membrane systems. In this regard, it has been found that using hybrid graphene nanostructures, for example, with ruthenium or magnetite, can allow the removal of microorganisms and organic matter present in water. However, research continues to advance to perfect graphene-based methodologies for the removal and reduction of metal ions such as zinc, copper, lead, cadmium, cobalt, among others.

At Energeia-Graphenemex®, we recognize and admire the advancements that research centers have achieved in various areas of knowledge, starting from basic science to applied science results. We firmly believe that in the short or medium term, these technologies will materialize into real products that are useful to society and the environment.

Redaction: EF/ DHS   

References

  1. A. Fasolino, J.H. Los, M.I. Katsnelson, Intrinsic ripples in graphene, Nat. Mater. 6 (2007) 858;
  2. W. Bao, F. Miao, Z. Chen, H. Zhang, W. Jang, C. Dames, C.N. Lau, Controlled ripple texturing of suspended graphene and ultrathin graphite membranes, Nat. Nanotechnol. 4 (2009) 562; 3. G. Yildiz, M. Bolton-Warberg and F. Awaja. Graphene and graphene oxide for bio-sensing: General properties and the effects of graphene ripples. Acta Biomaterialia 131 (2021) 62;
  3. Lang, T.; Xiao, M.; Cen,W. Graphene-Based Metamaterial Sensor for Pesticide Trace Detection. Biosensors 2023, 13, 560;
  4. D. Hernández- Sánchez, E. G. Villabona Leal, I. Saucedo-Orozco, V. Bracamonte, E. Pérez, C. Bittencourt and M. Quintana, Phys. Chem. Chem. Phys., 2017;
  5. Kim, H.W.; Yoon, H.W.; Yoon, S.-M.; Yoo, B.M.; Ahn, B.K.; Cho, Y.H.; Shin, H.J.; Yang, H.; Paik, U.; Kwon, S. Selective gas transport through few-layered graphene and graphene oxide membranes. Science 2013, 342, 91;
  6. Kim, D.; Kim, D.W.; Lim, H.-K.; Jeon, J.; Kim, H.; Jung, H.-T.; Lee, H. Intercalation of gas molecules in graphene oxide interlayer: The role of water. J. Phys. Chem. C 2014, 118, 11142;
  7. Xu, D.; Cheng, B.; Wang, W.; Jiang, C.; Yu, J. Ag2CrO4/g-C3N4/graphene oxide ternary nanocomposite Z-scheme photocatalyst with enhanced CO2 reduction activity. Appl. Catal. B Environ. 2018, 231, 368;
  8. Jiˇríˇcková, A.; Jankovský, O.; Sofer, Z.; Sedmidubský, D. Synthesis and Applications of Graphene Oxide. Materials 2022, 15, 920;
  9. M. Quintana, E. Vazquez & M. Prato, “Organic Functionalization of Graphene in Dispersions”, Acc. Chem. Res., vol. 46, n.o 1, pp. 138-148, 2013. DOI: 10.1021/ar300138e;
  10. Roberto Urcuyo1,2,3, Diego González-Flores1,3, Karla Cordero-Solano, Rev. Colomb. Quim., vol. 50, no. 1, pp. 51-85, 2021;
  11. B. Xue, M. Qin, J. Wu et al., “Electroresponsive Supramolecular Graphene Oxide Hydrogels for Active Bacteria Adsorption and Removal”, ACS Appl. Mater. Interfaces, 8, 24, 15120;
  12. C. Wang, C. Feng, Y. Gao, X. Ma, Q. Wu & Z. Wang, “Preparation of a graphene-based magnetic nanocomposite for the removal of an organic dye from aqueous solution”, Chem. Eng. J.,173, 1, 92.

Graphene as the Driver of the Energy Revolution

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Graphene as the Driver of the Energy Revolution:

Advances in Efficiency and Renewable Energy Storage

In today’s context, environmental concerns and climate change have shifted from being a trend to a top priority. This has led to the formation of multidisciplinary teams globally, focused on finding more sustainable technological solutions for energy challenges, such as energy generation and storage, with the additional aim of minimizing emissions.

In this context, thermal energy management through passive technologies, like solar energy, has gained significant importance. Its utilization as an eco-friendly and energetically efficient alternative has seen substantial growth, from its application in domestic settings to electricity generation systems.

However, the natural intermittence of solar energy due to diurnal and nocturnal cycles poses long-term challenges. Hence, it’s imperative to consider complementary technologies like Phase Change Materials (PCMs). These materials can absorb thermal energy from the surroundings to change their state, releasing stored energy for heating or cooling applications in various sectors, including construction, electronics, and aerospace.

Among the well-known PCMs is paraffin, which undergoes a solid-liquid phase change to store latent heat by absorbing thermal energy until reaching its melting point. While paraffins offer advantages such as being safe, reliable, economical, and having acceptable stability for long crystallization-fusion cycles, they also face challenges such as low thermal conductivity and leakage in the liquid state.

Fortunately, PCMs, including paraffin, benefit from advances in nanotechnology, especially when modified with nanoparticles like Graphene. Incorporating Graphene into PCMs like paraffin significantly enhances thermal conductivity and energy efficiency, facilitating solar-to-thermal energy conversion and storage.

What makes Graphene so special?

Graphene, with its exceptional physicochemical properties, is one of the most promising nanomaterials as a co-adjuvant in addressing energy-related challenges. Unlike other carbon nanostructures like diamond, graphite, activated carbon, fullerenes, or nanotubes, Graphene exhibits superior electrical and mechanical properties, with the added advantage of easy combination with other compounds like PCMs to share characteristics and enhance performance. For example, compared to nanotubes, one of the most well-known and studied carbon nanostructures, Graphene boasts higher charge mobility (200,000 cm2 V 1 s 1 Vs. 150,000 cm2 V 1 s 1), greater electrical conductivity (6.6 MS m -1 Vs. 0.35 MS m -1), and higher transmittance (97.0% Vs. 95.7%), making it highly attractive for energy-related applications.

How does Graphene relate to PCMs for solar energy utilization?

Historically, from a sustainable perspective and as a real-world application, architecture is a clear example of solar energy utilization. Starting from ancient times with the construction of adobe walls to trap daytime heat and release it at night, to modern infrastructure using heaters or solar panels, to Trombe walls as a passive heating tool. For instance, Trombe walls comprise materials like glass, wood, steel, aluminum, concrete, and PCMs like paraffin, arranged in special configurations that collectively absorb heat to slowly conduct it into the dwelling.

Through the identification of Graphene’s multifunctional properties and the exploration of its benefits in various sectors, it was found that its integration into paraffin used for passive heating systems can significantly improve thermal conductivity or driving force by up to 164%, showcasing clear superiority over highly efficient hybrid nanoparticles like Cu-TiO2 or Al2O3-MWCNT, whose normal benefits range between 50 and 70%. This means that integrating these technologies into passive heating systems, besides improving thermal comfort throughout the year, would also yield significant energy savings and reduce CO2 emissions.

Solar cells

Another well-known potential application of nanotechnology in the energy sector is the design of the fourth generation of solar panels, which includes the use of two-dimensional nanomaterials like molybdenum disulfide (MoS2), tungsten diselenide (WSe2), and again, Graphene.

Among the most representative advantages that Graphene has demonstrated over other materials are, in addition to its mechanical strength, its high charge mobility, great transmittance, lightness, flexibility, and stability, which have led to significant advances in its performance for solar panel design, increasing its efficiency from 1.5% to 15% in less than 10 years, almost comparable to the efficiency of current cells ranging from 20 to 22%. However, in pursuit of further improving these percentages, experts in the field continue to explore methodologies based on Graphene doping with other structures like silicon, molybdenum hexafluoride, molybdenum oxide, thionyl chloride, trioxionitric acid, gold chloride, boron, oxygen, nitrogen, phosphorus, or sulfur, to reduce its resistance and better harness solar energy.

At Energeia-Graphenemex, the leading company in Latin America in the design and development of graphene-based applications, we are aware of the challenges that Graphene, like any emerging technology, faces, and we are pleased to be part of the select group of researchers and industrialists globally seeking to benefit society, the economy, and the environment with the advantages these wonderful materials can offer.

Thanks to our multidisciplinary team, we have quickly overcome the obstacles that have hindered the arrival of this material to the market in real applications, starting with its large-scale production, with controlled quality and at an affordable cost, as well as with the development of new products with graphene nanoengineering, where controlling its stability and compatibility with compounds and processes used in each application or industry has been fundamental.

Graphene as an ally of renewable energies is still in its early stages, not necessarily due to its manipulation but because of the complexity this sector represents. However, the significant advances made over the past decade should not be underestimated, as they lay the groundwork for the next generations of equipment and technologies.

Redaction: EF/DHS

References

  1. Jafaryar M, Sheikholeslami M. Simulation of melting paraffin with graphene nanoparticles within a solar thermal energy storage system. Sci Rep. 2023, 26;13(1):8604;
  2. R. Bharathiraja, T. Ramkumar, M. Selvakumar. Studies on the thermal characteristics of nano-enhanced paraffin wax phase change material (PCM) for thermal storage applications. J. Energy Storage, 73, Part C, 2023, 109216;
  3. Li-Wu Fan, Xin Fang, Xiao Wang, Yi Zeng, Yu-Qi Xiao, Zi-Tao Yu, Xu Xu, Ya-Cai Hu, Ke-Fa Cen, Effects of various carbon nanofillers on the thermal conductivity and energy storage properties of paraffin-based nanocomposite phase change materials, Applied Energy, 110, 2013, 163;
  4. Top Khac Le., et al., Advances in solar energy harvesting integrated by van der Waals graphene heterojunctions. RSC Adv., 2023, 13, 31273

Advancing Asphalt Durability

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Advancing Asphalt Durability:

Harnessing Graphene’s Potential for Sustainable Roads

Most of the the world’s road infrastructure is composed of pavement made from a complex system of asphalt, aggregates, and binders that interact at an interface to maintain its strength and structural stability. According to the Asphalt Institute, 87 million tons of asphalt are produced worldwide annually, with around 85% used in the paving industry, which, while offering great load capacity and durability, inevitably suffers damage from constant exposure to radiation, temperature, humidity, and traffic.

The deterioration of asphalt not only impacts a basic transportation infrastructure crucial for socio-economic development but also involves environmental impacts in terms of resource depletion and high CO2 emissions caused by roadworks. These factors add to the reasons for the constant search for modification technologies that increase durability and improve mechanical properties of pavements using fibers, rubber; additives such as thermoplastic elastomers, plastic and synthetic resins, iron powder, hydrated lime, or glass waste. However, in some cases, the application of these products can present practical problems such as special preparation conditions, low storage stability, difficulty in mixing during construction, and complexity in compatibilizing these components with the asphalt system.

Fortunately, carbon nanostructures such as graphene and graphene oxide (GO) reappear on the scene as proposed solutions to these issues with interesting contributions to asphalt regarding stiffness, anti-aging, deformation, and penetration resistance; reduction in rutting, improved consistency, heat transfer capacity; skid resistance, and even a reduction in the effort required for compaction during preparation.

Additionally, among the advantages of graphene is its ability to be mixed with other asphalt modifying technologies such as low-density polyethylene (LDPE), high-density polyethylene (HDPE), polyethylene terephthalate (PET), polystyrene (PS), granulated rubber, blast furnace slag, epoxy resins, and especially with styrene-butadiene-styrene (SBS), which is one of the most accepted polymers in the asphalt industry, and with which graphene oxide (GO), thanks to its oxygen content, promotes the absorption of aromatics and saturates from SBS with a significant improvement in temperature response, adhesion, and binder stiffness.

Some identified methods that promise to simplify the incorporation of graphene into asphalt mixes are:

  1. Direct addition method: graphene is added to the previously melted asphalt binder.
  2. Indirect addition method: graphene and asphalt binder are simultaneously dissolved in a medium solution to later form a uniform solution.
  3. Auxiliary addition method: graphene is chemically modified with functional groups or added together with other modifying agents to later melt into the asphalt binder.

Although there are few companies that have explored graphene as an asphalt improving additive so far, the extensive research conducted over the past decade is helping to lay the groundwork for understanding and projecting the potential of this technology for the benefit of the paving industry. Even in February 2024, the Infrastructure journal published the results of the ECOPAVE project funded by the European Union, which consisted of a 5-year field test conducted over 1 km of heavy traffic in southern Rome, Italy. For the study, four sections of asphalt pavement with and without additions of graphene-modified polymers were installed. After the 5-year evaluation period, researchers reaffirmed the potential of asphalt modified with graphene polymer as an innovative and feasible technology for high-traffic road paving, as it demonstrated higher stiffness values at different temperatures, better fatigue behavior, and greater deformation resistance, promising an extended lifespan with a significant reduction in maintenance costs.

At Energeia-Graphenemex®, as leaders in graphene application development, we firmly believe that, although there is still work to be done, we are very close to enjoying the economic and environmental benefits that this wonderful technology can bring not only to our streets and roads but also to society.

Draft: EF/DHS

References

  1. Mechanism and Performance of Graphene Modified Asphalt: An Experimental Approach Combined with Molecular Dynamic Simulations. Case Studies in Construction Materials. 2023, 18, e01749;
  2. Properties and Characterization Techniques of Graphene Modified Asphalt Binders. Nanomaterials 2023, 13, 955;
  3. Analysis on the road performance of graphene composite rubber asphalt and its mixture. Case Studies in Construction Materials. 2022, 17, e01664;
  4. A complete study on an asphalt concrete modified with Graphene and recycled hard-plastics: A case study. Case Studies in Construction Materials. 2022, 17, e01437;
  5. Effect of Graphene Oxide on Aging Properties of polyurethane-SBS Modified Asphalt and Asphalt Mixture. Polymers 2022, 14, 3496;
  6. Mechanical Characteristics of Graphene Nanoplatelets-Modified Asphalt Mixes: A Comparison with Polymer- and Not-Modified Asphalt Mixes. Materials 2021, 14, 2434;
  7. Impact of Graphene Oxide on Zero Shear Viscosity, Fatigue Life and Low-Temperature Properties of Asphalt Binder. Materials 2021, 14, 3073;
  8. Experimental Investigation into the Structural and Functional Performance of Graphene Nano-Platelet (GNP)-Doped Asphalt. Appl. Sci. 2019, 9, 686;
  9. Modified Asphalt with Graphene-Enhanced Polymeric Compound: A Case Study. Infrastructures 2024, 9, 39.

Glass and Carbon Fiber Composites Enhancement

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Glass and Carbon Fiber Composites Enhancement:

Improving Properties with Graphene Nanoparticles

Glass and carbon fibers, thanks to their excellent properties, are widely used in industries such as aerospace, maritime, automotive, sports, construction, and even in the manufacturing of fundamental components for renewable energies such as wind power. However, despite their excellent performance, they often exhibit a phenomenon known as “interlaminar delamination” due to weak fiber/resin interfacial interaction, which can compromise the product’s lifespan and safety due to their significant role in stress transfer between both elements. As this interaction is key to the long-term success of composite structures, various improvement alternatives have been explored, such as Z-pinning, stitching, and braiding; increasing the surface area and reactivity of fibers through surface modifications such as plasma treatment, thermal modification, or chemical functionalization, which are complex, costly processes that are not always efficient and tend to reduce the laminate’s in-plane performance.

“As an additional strategy of relatively recent emergence, the incorporation of nanoparticles into fiber composite materials was proposed to favor interaction with the embedding matrix.”

Graphene, the nanomaterial known as the cornerstone of the carbon family and which since its isolation has been described as “the material of the future” or “the miracle material,” is an attractive candidate as a nanoreinforcement for countless polymeric compounds due to its unique graphitized flat structure, which leads to better mechanical, thermal, and other properties that, unlike other nanoparticles such as carbon nanotubes (CNTs), do not significantly increase resin viscosity and therefore allow higher concentrations to be incorporated, favoring the aforementioned fiber/matrix interaction.

Research on the effects of graphene for the design of hybrid materials based on fibers (glass/carbon) embedded in a commonly epoxy-based polymeric matrix has highlighted greater compound stiffness, improvements in fracture resistance, better lubrication, and even improved electrical conductivity. This is because its large surface area allows effective load transmission from the soft polymer matrix to the relatively stiffer graphene sheets, which is an essential requirement for improving mechanical performance, confirmed by increased interlaminar shear strength of the material, greater tensile and impact strength. Additionally, during the manipulation and cutting of hybrid fiber structures, the presence of graphene contributes to generating less heat during milling, leading to lower cutting temperatures and smoother surface roughness; likewise, another benefit is that graphene produces a greater hardening effect and better bending resistance of the material exposed to different temperatures ranging from 40 °C to 200 °C.

At Energeia-Graphenemex, the leading company in Latin America in the production of graphene materials and in the development of applications, we are convinced that graphene’s extraordinary capabilities as a nanoreinforcement for countless three-dimensional matrices will continue to encourage researchers and industrial colleagues to explore its benefits for the manufacture of stronger and lighter structural components for aircraft such as fuselage and wings; automotive parts and aerodynamic bodywork; wind turbines, sports equipment, construction materials, among others.

Draft: EF/DH

References:

  1. Effect of dispersion of alumina nanoparticles and graphene nanoplatelets on microstructural and mechanical characteristics of hybrid carbon/glass fibers reinforced polymer composite. Journal of material research and technology. 2021, 14, 2624;
  2. Experimental investigation on the properties of glass fiber-reinforced polymer composites containing Graphene. AIP Conf. Proc. 2022, 2405, 050009;
  3. Reinforcement effect of graphene oxide in glass fibre/epoxy composites at in-situ elevated temperature environments: An emphasis on graphene oxide content. Composites part A: Applied science and manufacturing. 2017, 95, 40;
  4. Preparation and Mechanical Properties of Graphene/Carbon Fiber-Reinforced Hierarchical Polymer Composites. J. compos sci. 2019, 3, 30;
  5. Improving fiber/matrix interfacial strength through graphene and graphene-oxide nano platelets. IOP Conf. Ser.: Mater. Sci. Eng. 2016, 139, 012004;
  6. Effect of Graphene on Machinability of Glass Fiber Reinforced Polymer (GFRP). J. Manuf. Mater. Process. 2019, 3, 78;
  7. Size effect of graphene nanoplatelets on the morphology and mechanical behavior of glass fiber/epoxy composites. J Mater Sci. 2016, 51, 3337.

Tapping into Graphene’s Potential:

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Tapping into Graphene’s Potential:

Enhancing Coatings with Nanotechnology for Weather Resistance

Coatings are designed for decorative purposes and to protect surfaces, especially against corrosion and moisture. In a coating system (multilayer), the top or finishing layer plays a crucial role as it must provide a good appearance and protect the inner layers and the substrate against environmental factors such as sunlight, humidity, corrosion, chemical resistance, soiling, etc., throughout its lifespan.

Today, Polyurethane (PU) is considered one of the coatings with the best physical-chemical characteristics for finishing coating applications and for its weather resistance. However, its weather resistance decreases with exposure to ultraviolet light over long periods.

Sunlight is one of the main causes of damage to coatings. Damage ranges from loss of physical properties, powdering (chalking), cracking, peeling, discoloration, and color change, because of chemical photodegradation, migration, evaporation, and interaction of other components with the coating.

In recent years, various nanostructured materials such as titanium, zinc oxide, cerium, and iron oxide have been implemented to improve the weather resistance of polymeric coatings. The mechanism is based on their projection effect (both absorption and dispersion) of incident rays in the UV region. These materials can stabilize coatings against exterior exposure, possess photocatalytic activity that can destroy the organic binder material present in coatings, leading to modifying the surface of these nanostructured materials to eliminate or inhibit their photocatalytic activity, requiring more processes, time, and money.

Recently, graphene has attracted much attention as a new additive and material for producing coatings to enhance anticorrosive, antimicrobial, and weather-resistant properties, due to its special electronic structure that provides unique electrical, mechanical, and chemical properties. Graphene is a nanomaterial formed by one or more layers of carbon (formed by carbon atoms bonded hexagonally with a thickness of one carbon atom). This structure enables graphene-based materials to absorb photons in the UV region. This UV absorption capacity, as well as the absence of photocatalytic activity of graphene materials, allows introducing these materials as new additives for the photo-stabilization of polymeric coatings, i.e., with greater resistance to UV radiation

Currently, Energeia – Graphenemex®, is in constant development of nanotechnological coatings with better properties. Studies have been conducted on the influence of graphene oxide on the weathering behavior of PU coatings. To evaluate the performance of graphene oxide, a PU coating with graphene oxide (PU/GO) was compared with a PU coating containing a commercial organic UV absorber (PU/control).

Color change in a coating during exposure to weathering (sunlight) is the most important and rapid parameter to visually evaluate coating degradation. To evaluate, color change, samples coated with Polyurethane with and without graphene material were introduced into an accelerated weathering chamber (based on ASTM G154). According to the standard, a QUV weathering chamber model QUV/se was used to accelerate weathering conditions. Coated samples were cyclically exposed to UVA radiation (energy 0.89 W/m2) for 8 hours, followed by moisture condensation for 4 hours at 50 °C. The color of the coatings was evaluated before exposure to compare their initial color, and subsequently evaluated at different exposure times, this evaluation was performed until reaching an exposure time of 1200 hours.

The main component of color typically considered in weathering behavior is the total color change or Delta E (ΔE). Fig. 1 shows the ΔE, as the most comprehensive criterion of color changes, which is the sum of changes in all color components.

As can be seen, most of the color variations throughout the exposure time belong to the PU/control coating. The sample containing graphene oxide (PU/GO) at 251 hours of exposure time shows a lower color change compared to PU/control. With the increase in exposure time in the weathering chamber, color variations can be observed, but the sample with graphene oxide continues to show lower color changes, indicating that the incorporation of GO in Polyurethane provides more resistance and maintains its stability for longer exposure times to weathering.

Fig 1. Total color change (ΔE) versus exposure time for Polyurethane coatings with graphene oxide (PU/GO) and without graphene oxide (PU/control) during accelerated weathering test.

From a physical point of view, graphene oxide (GO) has higher transmittance in the visible region compared to graphene, which is more favorable for its use as a UV protector in finishing coatings. On the other hand, thanks to the high surface area of graphene materials, they can also provide excellent barrier effect properties and thus develop anticorrosive coatings with greater weather resistance.

Energeia – Graphenemex®, through its Graphenergy line, offers a wide range of nanotechnological coatings with graphene. These coatings offer high anticorrosive and antimicrobial protection. In addition to providing high wear resistance, UV resistance, impermeability, and extraordinary adhesion, with the aim of improving the life of any surface or installation and reducing maintenance costs.

References

  1. G. Wang, X. Shen, B. Wang, J. Yao, J. Park, Synthesis and characterisation of hydrophilic and organophilic graphene nanosheets, Carbon N. Y. 47 (no. 5) (2009) 1359–1364.
  2. B. Ramezanzadeh, M. Mohseni, H. Yari, S. Sabbaghian, A study of thermal-mechanical properties of an automotive coating exposed to natural and simulated bird droppings, J. Therm. Anal. Calorim. 102 (no. 1) (2010).
  3. N. Rajagopalan, A.S. Khanna, Effect of Methyltrimethoxy Silane Modification on Yellowing of Epoxy Coating on UV (B) Exposure vol. 2014, (2014).
  4. M. Hasani, M. Mahdavian, H. Yari⁎, B. Ramezanzadeh. Versatile protection of exterior coatings by the aid of graphene oxide nanosheets; comparison with conventional UV absorbers. 2017.
  5. S.M. Mirabedini, M. Sabzi, J. Zohuriaan-Mehr, M. Atai, M. Behzadnasab,
  6. Weathering performance of the polyurethane nanocomposite coatings containing silane treated TiO2 nanoparticles, Appl. Surf. Sci. 257 (no. 9) (2011) 4196–4203.
  7. N.S. Allen, M. Edge, A. Ortega, C.M. Liauw, J. Stratton, R.B. McIntyre, Behaviour of nanoparticle (ultrafine) titanium dioxide pigments and stabilisers on the photooxidative stability of water based acrylic and isocyanate based acrylic coatings, Polym. Degrad. Stab. 78 (no. 3) (2002) 467–478.
  8. Effect of Silane Modified Nano ZnO on UV Degradation of Polyurethane Coatings. vol. 79, (2015), pp. 68–74.
  9. M. Rashvand, Z. Ranjbar, S. Rastegar, Nano zinc oxide as a UV-stabilizer for aromatic polyurethane coatings, Prog. Org. Coatings 71 (4) (Aug. 2011) 362–368.

Graphenemex: Driving Global Innovation in Graphene

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The invitation to participate in the convention came to Graphenemex thanks to the American University of Sharjah and its commercial partner, World Direct Tech, sponsor of the event. The convention focused on exchanging the latest advances in materials science and engineering, promoting regional and international collaborations between academics, government and industry.

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Graphenemex and World Direct Tech shine at materials science conference

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The alliance between Graphenemex, represented by its CEO Eduardo Priego Mondragón, and World Direct Tech, headed by CEO Paulo Armas, was the center of attention at the International Congress on Frontiers in Materials Science and Engineering (FMSE), organized by the American University of Sharjah (AUS) in the United Arab Emirates on February 14 and 15, 2024. Graphenemex was the only Latin American company invited to this event, being a leader in the field of Nanotechnology.

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Atlanta-based WDT hosts Graphenemex at FMSE International Congress in Dubai

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American University of Sharjah (AUS), United Arab Emirates, is preparing to host the International Frontier Congress in Materials Science and Engineering (FMSE) from February 13 to 15, 2024.

The collaboration between the American University of Sharjah, World Direct Tech and Energeia-Graphenemex aims to show the advances in Latin America in the development of nanotechnological products for the construction industry.

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