Amino-functionalized Graphene Oxide Research Articles

Amino-Modified Graphene Oxide from Kish Graphite for Enhancing Corrosion Resistance of Waterborne Epoxy Coatings.

Waterborne epoxy (WEP) coatings with enhanced corrosion resistance were prepared using graphene oxide (GO) that was obtained from kish graphite, and amino-functionalized graphene oxide (AGO) was modified by 2-aminomalonamide. The structural characteristics of the GO and AGO were analyzed using X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). And the anti-corrosive performance of waterborne epoxy-cased composite coatings with different addition amounts of AGO was investigated using electrochemical measurements, pull-off adhesion tests, and salt spray tests. The results indicate that AGO15/WEP with 0.15 wt.% of AGO has the best anti-corrosive performance, and the lowest frequency impedance modulus increased from 1.03 × 108 to 1.63 × 1010 ohm·cm-2 compared to that of WEP. Furthermore, AGO15/WEP also demonstrates the minimal corrosion products or bubbles in the salt spray test for 200 h, affirming its exceptional long-term corrosion protection capability.

Rheology of amino-functionalized graphene oxide suspensions in hydrogels

Rheology of amino-functionalized graphene oxide suspensions in hydrogels

Improved corrosion protection performance of electrophoretic epoxy coatings with the incorporation of amino-functionalized graphene oxide

Improved corrosion protection performance of electrophoretic epoxy coatings with the incorporation of amino-functionalized graphene oxide

A long-term anti-corrosion and cathodic delamination resistant epoxy coating based on COF grafted GO nanofillers

Here, a long-term anti-corrosive epoxy (EP) coating based on nano-hybrid filler was developed. The surface of graphene oxide (GO) was aminated with (3-aminopropyl) triethoxysilane (APTES), and then the porous covalent organic framework (COF) was in-situ grown on amino functionalized graphene oxide (FGO) nanosheets by Schiff-based reaction to prepare FGO-COF nanofillers. Different characterization methods proved the successful modification of GO nanosheets with COF particles. The excellent water resistance of composite coatings was characterized through contact angle, adhesion, and water uptake tests. Transmission electron microscope (TEM) and molecular dynamics (MD) methods showed that the grafting of COF enhanced the dispersion and compatibility of GO in the coating. EIS measurements, salt spray analysis and cathodic delamination test indicated the significant improvements in the protective properties of the composite coatings compared with pure EP coating. The low-frequency impedance modulus of 1% FGO-COF composite coating reached higher than 6.8 × 109 Ω·cm2 after immersed in sea water for 60 days. In addition, the 1% FGO-COF composite coating performed only 34% delamination ratio after 120 h cathodic delamination test.

High proton conductivity of the phosphate-linked graphene oxide monolith over a wide range from subzero to moderate temperature

Achieving proton-conducting solids with high proton conductivity at subzero temperatures remains a serious challenge. Thus, it is indispensable to develop the composites with high conductivity ranging from subzero to medium temperatures (243–343 ​K). Graphene oxide (GO) as an alternative matrix can provide the rich oxygen-containing groups. Thus, we prepared a series of proton conductors by covalently linking phosphate units onto the amino-functionalized GO monoliths (denoted NGOM-P), the structures of which are determined by FT-IR, XPS, XRD and Raman characterization techniques. Further, the fast proton transfer in effective acid-base networks in NGOM-P make the monolith achieve high proton conductivity from 2.61 ​× ​10−2 ​S ​cm−1 (243 ​K) to 0.68 ​S ​cm−1 (343 ​K) under 98% relative humidity (RH).

Thiol-End-Group Dendrons Decorated with Gold Nanoparticles Immobilized on Amino-Functionalized Graphene Oxide for SERS Detection

Surface-enhanced Raman scattering (SERS) has abundant chemical fingerprint information to analyze complex analytes under aqueous conditions. However, SERS requires uniform metal particles to generate a hotspot effect and improve sensitivity and enhancement by localized surface plasmon resonance. Therefore, in this study, SERS detection chips have been developed using uniform gold nanoparticle (AuNP) arrays embedded on thiol-end-group dendritic polymers immobilized on amino-functionalized graphene oxide (AGO) thin films of transmission electron microscopy (TEM) grids. The graphene oxide (GO) thin film was fabricated by low-damage plasma with mixed gas (O2/H2) and then further functionalized by diethylenetriamine to form AGO substrates. Based on the efficient building block of dual-functional 4-isocyanato-4′-(3,3-dimethyl-2,4-dioxo-azetidino)-diphenylmethane (IDD), the 0.5 and 1.5 generations of thiol-end-functionalized poly(urea/malonamide) dendrons (DG0.5-SH and DG1.5-SH) were precisely synthesized and grafted onto AGO substrates. The interparticle gap of AuNPs could be well controlled and decorated on these thiol-end-group dendrons to achieve the optimal SERS enhancement effect by manipulating the sizes of AuNPs and generating dendrons. The results indicate that 31 nm AuNPs immobilized on the DG0.5-SH@AGO substrate exhibited reproducible and strong SERS enhancement compared with free AuNPs. Graphene-based SERS substrates provide rapid and stable SERS detection in solutions, which offers great potential for practical applications in detecting biomolecules and environmental pollutants.

Preparation and Anticorrosive Performance of Waterborne Epoxy Resin Composite Coating with Amino-Modified Graphene Oxide

A waterborne epoxy coating with superior corrosion resistance was developed by using a novel amino-functionalized graphene oxide (GO) that was modified by 2,5-diaminobenzenesulfonic acid. A battery of characterization methods, such as Fourier transform infrared spectroscopy (FT-IR), Raman spectra, X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM), was used to prove that DGO was successfully prepared by grafting the amino of 2,5-diaminobenzenesulfonic on GO. The results indicated that the surface of DGO became rougher than GO, but a complete sheet structure was still maintained after modification; the optimal modified GO could be achieved when the mass ratio of 2,5-diaminobenzenesulfonic acid and GO was 5:1. The electrochemical impedance spectroscopy (EIS) tests indicated that the impedance at 0.01 Hz of a coating with 0.2 wt.% DGO still remained at a relatively high value after immersion for 48 h in 3.5 wt.% NaCl, which was about one order higher than a pure waterborne epoxy resin coating, and the corrosion current density decreased from 3.76 × 10-11 A/cm2 to 3.62 × 10-12 A/cm2. The dry adhesion and wet adhesion increased to 1.90 and 1.22 MPa, respectively, and the adhesion loss decreased from 53% to 36%. These interesting features could make waterborne epoxy coatings a promising anticorrosion coating for metal in long-term protection.

Amino-functionalized graphene oxide membranes for efficient separation of Sr2+ ions

Graphene oxide (GO) membranes were integrated with diverse nitrogen functional groups by subjecting to ammonia (NH3) vapours and evaluated for resultant changes in their chemical functioning and strontium (Sr) adsorption performance. Exposure to NH3 vapours amends the functional groups of GO, introduces amine, amide, ammonium functionalities and generates abundant sites prone to react with Sr2+ ions. The extent of GO restructuring and repercussions on Sr adsorption behaviour were examined using different GO precursors, NH3 treatment methods, membranes with varying GO mass and other nitrogen reagents namely, tri-isooctyl amine, pyridine, N,N-dimethyl acetamide. Nitrogen group functionalization enhances the Sr adsorption capacity of GO membranes nearly by two times, irrespective of the NH3 exposure duration and nature of precursor GO membranes. These NH3 subjected GO membranes displayed optimum Sr adsorption performance of ~475 mg/g, reusable at least for nine filtration cycles and importantly, capable of discharging 35–60 % of adsorbed Sr. The N-group supported Sr separation demonstrated in the present work is an energy efficient solid state membrane based procedure, which also lays a road map for development of amine, amide, ammonium functionalized GO layers and provides flexible platform for separation of all those toxic elements displaying affinity to complex with N-groups.

Modulation of Crystal Growth of an Energetic Metal–Organic Framework on the Surfaces of Graphene Derivatives for Improved Detonation Performance

Energetic materials are a special class of energy materials composed of C, H, O, and N. Their safety always deteriorates with increasing energy. Regulating the properties of energetic materials to meet application requirements is one of the focuses of research in this field. Energetic metal-organic frameworks (EMOFs) are good candidates as primary explosives to replace lead azide (LA) and other explosives containing toxic metal elements. However, safety remains the biggest concern in applications. In this paper, crystal morphology modulation of EMOF was carried out by stepwise coordination of metal ions and energetic ligands on surfaces of graphene oxide (GO) and amino-functionalized graphene oxide (AGO). Two energetic composite materials, Cu-AFTO@GO and Cu-AFTO@AGO, were successfully synthesized and also the EMOF (Cu-AFTO). The structures and morphologies of these materials were fully characterized. The thermal decomposition behaviors, mechanical sensitivity, and electrostatic discharge sensitivity were investigated in detail. The electric ignition ability of EMOF and two composite materials was tested. This study shows that it is possible to reduce the diameter of EMOF crystals from hundreds of microns to tens of nanometers by a stepwise coordination method. The high electrical conductivity and sensitivity-reducing effect of GO and/or AGO allow the nanosized EMOF crystals to have a lower ignition threshold and lower sensitivity.

Amino-functionalized graphene oxide supported in charcoal from the gasification of furniture scraps: From one-pot synthesis to wastewater remediation

Wood from furniture scraps were fed into a gasifier to produce clean energy, and its residual charcoal (FSC) was used as support for the development of an amino-functionalized multilayer graphene oxide (AmGO) composite. The AmGO supported on FSC (AmGO@FSC) and its pristine materials were characterized and then investigated as potential adsorbent of water pollutants. The supporting of AmGO on FSC consists in a two-way solution for environmental remediation, since a waste has been benefited to remove water pollutants. Moreover, supporting process eases the separation of the highly hydrophilic graphene oxide from the liquid medium, which is one of the main challenges in applying these nanomaterials. From equilibrium and kinetic studies, the maximum adsorption capacity at monolayer was 54.35 mg g−1, and equilibrium constant was 0.76 L mg−1, and Langmuir-Freundlich isotherm showed the best fit. Based on these studies, the predicted mechanisms of adsorption are governed by resistance to mass transfer in the bulk and liquid–solid film. Moreover, the molecules of Methylene Blue engaged the active sites of AmGO@FSC through π−π stacking and other weak interactions. Thermodynamic assays evidenced the spontaneity and the physical behavior of the adsorption, whilst the AmGO@FSC could be regenerated after six cycles. Finally, AmGO@FSC showed adsorptive capacity 2 times greater than its precursor material FSC. The great adsorptive capacity, high recoverability and easy separation bestow AmGO@FSC as one profitable adsorbent of textile dyes.

Role of low-dimensional carbon nanostructures in hybrid material as anticorrosive coating

In this work, different low-dimensional carbon nanostructures (graphite oxide, graphene oxide and amino-functionalized graphene oxide and graphite oxide) integrated into a hybrid, organic-inorganic matrix, were developed, obtaining different nanocomposite coatings. The hybrid matrix was obtained from an inorganic component, tetraethyl orthosilicate, and an organic composition resin, diglycidyl ether bisphenol-A. Each of the different coatings were separately applied on AISI 1018 carbon steel surfaces. The corrosion test was carried out by Electrochemical Impedance Spectroscopy on the coated metal in two different media, saline and acidic. The resistance to charge transfer was higher for coating containing graphene oxide in both electrolytes. A comparison between the coating's performance containing graphite oxide and graphene oxide showed that the exfoliation of graphite oxide is important to have a greater distribution and intercalation of the low dimensionality sheets inside the hybrid matrix up to form a uniform protective barrier. Wear test were carried out and structural stability of the coatings after 100 cycles was demonstrated, showing the persistent SiOSi groups produce a protection against corrosion to AISI 1018 carbon steel.

High-efficiency removal of cationic dye and heavy metal ions from aqueous solution using amino-functionalized graphene oxide, adsorption isotherms, kinetics studies, and mechanism.

GO-NH2 (amino functionalized graphene oxide) was synthesized by grafting (3-aminopropyl) triethoxysilane onto the surface GO (graphene oxide). The GO-NH2 with a higher surface area and many active sites was characterized and its effectiveness in removing Rhod B dye and Ni(II) ions from wastewater by adsorption was observed. The effects of pH, time, and strange ions on the adsorption efficiency were investigated. The equilibrium isotherm data confirmed that it fits the Langmuir and Freundlich isotherm models. GO and GO-NH2 exhibited high adsorption capacity (QM); 2500 (mg L-1) and 3333 (mg L-1) for Rhod B dye, and 312.5 (mg L-1), and 714.28 (mg L-1) for Ni(II) ions, respectively. The kinetics of adsorption was studied using pseudo-first-order, pseudo-second-order, intraparticle diffusion, and the Boyd model. It was found that the adsorption followed pseudo-second-order and film diffusion model are effective in this adsorption process. Adsorption mechanisms have been attributed to possible electrostatic attractions, hydrogen bonding, and interactions. In summary, the experimental results showed the synthesized GO and GO-NH2 would be promising adsorbents to remove aqueous solutions contaminated with Rhod B dye and Ni(II) ions.

Graphene oxide activates B cells with upregulation of granzyme B expression: evidence at the single-cell level for its immune-modulatory properties and anticancer activity.

We recently found by single-cell mass cytometry that ex vivo human B cells internalize graphene oxide (GO). The functional impact of such uptake on B cells remains unexplored. Here, we disclosed the effects of GO and amino-functionalized GO (GONH2) interacting with human B cells in vitro and ex vivo at the protein and gene expression levels. Moreover, our study considered three different subpopulations of B cells and their functionality in terms of: (i) cytokine production, (ii) activation markers, (iii) killing activity towards cancer cells. Single-cell mass cytometry screening revealed the higher impact of GO on cell viability towards naïve, memory, and plasma B cell subsets. Different cytokines such as granzyme B (GrB) and activation markers, like CD69, CD80, CD138, and CD38, were differently regulated by GONH2 compared to GO, supporting possible diverse B cell activation paths. Moreover, co-culture experiments also suggest the functional ability of both GOs to activate B cells and therefore enhance the toxicity towards HeLa cancer cell line. Complete transcriptomic analysis on a B cell line highlighted the distinctive GO and GONH2 elicited responses, inducing pathways such as B cell receptor and CD40 signaling pathways, key players for GrB secretion. B cells were regularly left behind the scenes in graphene biological studies; our results may open new horizons in the development of GO-based immune-modulatory strategies having B cell as main actors.

Preparation and properties of a self-crosslinking styrene acrylic emulsion using amino-functional graphene oxide as a crosslinking agent and anti-corrosion filler

In this paper, we prepared a self-crosslinking amino-functional graphene oxide/styrene acrylic hybrid emulsion (AGO/SA). The styrene acrylic emulsion (SA) was synthesized with acetoacetoxyethyl methacrylate (AAEM) by semicontinuous seeded emulsion polymerization. Then, amino-functionalized graphene oxide (AGO) was prepared via the modification of graphene oxide (GO) with 3-aminopropyltriethoxysilane (APTES) and reacted with the SA emulsion as a crosslinking agent by in situ polymerization. Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermal gravity analysis (TGA), and transmission electron microscopy (TEM) were applied to explore the chemical structures and morphologies of the samples. The anti-corrosion performance of the AGO/SA coatings was evaluated by Tafel polarization and electrochemical impedance spectroscopy (EIS). Along with the crosslink between AGO and SA, the micropores in the matrix were reduced, the coating expressed improved corrosion resistance due to the graphene barrier, and the hybrid emulsion with 0.7 wt.% AGO exhibited the best anti-corrosion properties. These results indicate that AGO can act as both a crosslinking agent and an anti-corrosion agent in self-crosslinking hybrid emulsions, which have great potential in the field of environmentally friendly emulsions.

PH-Induced Electrostatic Interaction between Polyacrylates and Amino-Functionalized Graphene Oxide on Stability and Coating Performances.

Electrostatic interaction between polymers and nanofillers is of great importance for the properties and design of their composites. Polyacrylates with carboxyl, hydroxyl and acylamino groups were synthesized via emulsion polymerization and marked as P(MMA-BA-AA), P(MMA-BA-HEA) and P(MMA-BA-AM), respectively. Amino-functionalized graphene oxide (NGO) was prepared by Hoffman rearrangement using GO as the raw material. The polyacrylate composites were prepared by mixing NGO with each of the three kinds of polyacrylate. Effects of pH and NGO amounts on the properties of polyacrylate composites were studied. It was found that the surface charge of polyacrylate and NGO had the greatest effect on the composite properties. P(MMA-BA-AM)/NGO was not stable at any pH (2–8). With the same NGO amount of 0.1 wt%, the toughening effect of NGO on P(MMA-BA-AA) was larger than that on P(MMA-BA-HEA). The break strength of P(MMA-BA-AA)/NGO and P(MMA-BA-HEA)/NGO increased to 5.22 MPa by 47% and 3.08 MPa by 31%, respectively. NGO could increase the thermal stability of P(MMA-BA-AA) and P(MMA-BA-HEA) to different degrees. The polyacrylate film-forming processes were tested, and it showed that NGO influenced polyacrylate through the whole film-forming process. The results provide potential methods for the design of polymer-based nanocomposites.

Water absorption and hydrothermal ageing of epoxy adhesives reinforced with amino-functionalized graphene oxide nanoparticles

The study is focused on quantitative characterization of water absorption and hydrothermal ageing effects in a room-temperature amine cured epoxy adhesive widely used in automotive, aerospace, construction, and marine industries. Amino-functionalized graphene oxide (mGO) nanoparticles were incorporated into the epoxy (up to 1.72 wt.%) enabled cross-linking reactions and providing high interfacial adhesion, superior reinforcement efficiency and enhanced resistance to hydrothermal ageing of nanocomposites. Anomalous water absorption accompanied by progressive weight loss of samples (down to 7%) is fitted by two-stage models considering additive and coupled contribution from water diffusion and leaching of low molecular weight epoxy species. Nanocomposites are characterized by lower water diffusivity (40%) and decreased leaching effects (70%). High reinforcing efficiency of epoxy/mGO appeared in the increased glassy and rubbery storage moduli (60%), glass transition temperature (10 °C) and activation energy of glass transition (70%) compared to the neat epoxy. Hydrothermal ageing resulted in noticeable properties degradation of samples, although to a much lower extent in the case of nanocomposites. The results will contribute to the enhancement of global durability of common epoxy-based adhesives and extension of their lifetime.

Fabrication and evaluation of nanofiltration membrane coated with amino-functionalized graphene oxide for highly efficient heavy metal removal

Fabrication and evaluation of nanofiltration membrane coated with amino-functionalized graphene oxide for highly efficient heavy metal removal

Partially Reduced Graphene Oxide Modified with Polyacrylonitrile for the Removal of Sm3+ from Water

An in situ emulsion polymerization method was used for the synthesis of polyacrylonitrile nanoparticles amino-functionalized partially reduced graphene oxide (PAN-PRGO). After that, hydrolyzed polyacrylonitrile nanoparticles amino-functionalized partially reduced graphene oxide (HPAN-PRGO) nanocomposite was achieved by the modification of nitrile groups of the composite polymer chains to carboxylic groups, aminoethylene diamine, and amidoxime functional groups through partial hydrolysis using a basic solution of sodium hydroxide for 20 min. Different synthesized materials were characterized and compared using well-known techniques including transmission electron microscope (TEM), scanning electron microscope (SEM), Fourier-transform infrared spectroscopy (FT-IR), Raman spectra, and X-ray diffraction (XRD). The nanocomposite was structured through the interaction between acrylonitrile’s (AN) nitrile groups and amino-functionalized graphene oxide nanosheets’ amino groups to successfully graft polyacrylonitrile over the surface of functionalized nanosheets as approved by characterization techniques. The synthesized composite was examined for the removal of samarium ions (Sm3+) from water. Different experimental conditions including pH, contact time, initial concentration, and adsorbent dose were investigated to determine the optimum conditions for the metal capture from water. The optimum conditions were found to be a contact time of 15 min, pH 6, and 0.01 g of adsorbent dosage. The experimental results found, in a good agreement with the Langmuir isotherm model, the maximum adsorption capacity of Sm3+ uptake was equal to 357 mg/g. A regeneration and reusability study of synthesized composite up to six cycles indicated the ability to use HPAN-PRGO nanocomposite several times for Sm3+ uptake. The obtained results prove that this polymer-based composite is a promising adsorbent for water treatment that must be studied for additional pollutants removal in the future.

Removal of perfluorooctanoic acid (PFOA) from aqueous solution by amino-functionalized graphene oxide (AGO) aerogels: Influencing factors, kinetics, isotherms, and thermodynamic studies

Perfluorooctanoic acid (PFOA) is an emerging organic pollutant that has become ubiquitous in waterways and is difficult to be removed from wastewater using traditional treatment methods. In this study, amino-functionalized graphene oxide (AGO) aerogels were prepared as a potential remediation tool for water contaminated by PFOA. The structure of the prepared absorbent material was characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscope, and X-ray diffraction. The use of various adsorption times, temperatures, solution pH, and absorbent amount were investigated to determine optimum conditions for PFOA adsorption. Adsorption kinetics and thermodynamics of the absorbent were analyzed as well. AGO aerogels exhibited a high adsorption capacity of PFOA (1575 mg∙g−1) and high removal efficiency (99.95%) in a solution containing 10 mg PFOA L−1, likely due to the interconnected porous microstructures and amino groups of the AGO aerogels. The adsorption kinetics and isotherm of PFOA were well-fitted using pseudo-second-order and the Freundlich modelling. The adsorption mechanism of PFOA onto AGO aerogels followed spontaneous, exothermic, and physical processes. This study shows the potential of this material to remove PFOA from PFOA-contaminated waters effectively by providing insight into the understanding of the adsorption mechanisms of PFOA onto AGO aerogels.

An acid induction strategy to construct an ultralight and durable amino-functionalized graphene oxide aerogel for enhanced quinoline pollutants extraction from coking wastewater

The direct emission of quinoline in coking wastewater has great harm to human health and environmental quality. Therefore, it is urgent to develop advanced materials for efficient adsorption of quinoline in wastewater. In this study, a novel three-dimensional amino-functionalized graphene oxide aerogel (MGOA) was prepared by an acid induction strategy, which triggers the esterification and amidation of graphene oxide (GO) nanosheets and ammonium citrate. This strategy not only improves the chemical stability and mechanical strength of as-prepared MGOA, but also provides a large number of effective adsorption sites to achieve the efficient adsorption towards quinoline. MGOA has the advantages of three-dimensional interconnected hierarchical pore structure, large specific surface area, and low density. When the initial quinoline concentration is 50 mg L−1, the adsorption capacity (qe) of MGOA towards quinoline is as high as 103 mg g−1 at 298 K. More importantly, in the column adsorption system, the distribution coefficient (PC) at 10% breakthrough is 14.16 mg g−1 μM−1, which is the highest level yet reported. MGOA exhibits good reusability and outstanding solid-liquid separation advantage during eight adsorption-desorption cycles. Density functional theory and van der Waals surface electrostatic potential were used to investigated the adsorption behavior of quinoline on aerogel. The binding force between MGOA and quinoline molecule is strong, with an adsorption energy up to −78.68 kJ mol−1. Thus, MGOA is considered as a promising candidate for removing quinoline contaminants from aqueous solutions.