Amino-modified Graphene Oxide Research Articles

Multifunctional composite paper fabricated by graphene oxide/tannin decorated carbon fiber with excellent electromagnetic interference shielding, antibacterial and sound absorption properties

Considering the distinctive oxidative coupling characteristic of tannin acid, it was used as an interfacial interlayer to build a nano-coating structure on the surface of carbon fiber (CF)using amino-modified graphene oxide (GON) via Schiff base reaction. Furthermore, a kind of multifunctional composite paper (PTCF/GON) with excellent electromagnetic interference shielding, antibacterial and sound absorption properties was fabricated using surface modified CF (TCF/GON) and plant fibers. The increased active groups on the surface of TCF/GON improved its hydrophilicity and enhanced its dispersibility in water, which facilitated to form an effective interconnected conductive network of composite paper via traditional wet forming process. Composite paper fabricated by 30 wt% surface decorated CF (PTCF1.5/GON1.2) achieved an electromagnetic interference shielding effectiveness as high as 43.4 dB in X-band, shielding 99.9 % of incident electromagnetic energy. Meanwhile, PTCF1.5/GON1.2 exhibits good sound absorption performance in specific frequency bands, with a sound absorption coefficient of 0.98 around 1180 Hz. Besides, PTCF1.5/GON1.2 also exhibited excellent antibacterial properties. This strategy provides an economical and practical method for manufacturing multifunctional electromagnetic shielding materials with superior performance.

Selective adsorption of Cu(II) on amino-modified alginate-based aerogel: As a catalyst for the degradation of organic contaminant

In this study, amino-modified graphene oxide(NGO) was prepared by introducing amino functional groups. Based on the cross-linking between Ca(II) and sodium alginate (SA), associated with dense slit-like pore resulted from the nano-sheet accumulation of NGO and montmorillonite (MMT), composite aerogels (NGM) with stable pore structure were constructed, thus it realized the selective recovery of hydrated copper ions in complex wastewater systems. Raman analysis and density functional theory calculation confirmed the construction of amino-modified defect GO and significantly improved its chemical reactivity, which laid the foundation for the construction of slit pore structure of NGM (SEM can confirm). At the same time, it proposed that the good selective adsorption of Cu(II) on NGM was related to the synergism of strong electrostatic force, ion exchange and complexation based on the characterizations of FT-IR and XPS. In order to realize the value-added utilization of NGM aerogel (NGMC) after adsorbing Cu(II), NGMC was used as a catalyst to degrade organic pollutants in wastewater. Systematic experiments shown that NGMC can degrade organic pollutants with a degradation efficiency >80 %. In summary, NGM had a broad application prospect for selective recovery of Cu(II) from complex wastewater systems without second pollution.

Development of an epoxy resin-based anticorrosive coating enhanced by monolayer amino-modified graphene oxide

Epoxy resin (EP) serves as a prevalent material for anti-corrosion coatings, yet its corrosion resistance demands further refinement. In this work, monolayer amino-modified graphene oxide with an average height of 0.930 nm and 1.023 nm was synthesized using urea and melamine, named NGO and MGO, respectively. When incorporated into EP coatings, the NGO and MGO exhibit outstanding protective properties. The impact of different concentrations of NGO and MGO on the corrosion resistance of EP coated Q235 samples were meticulously examined. Through electrochemical measurements and salt spray tests, it was determined that the coatings containing 0.1 wt% NGO or 0.3 wt% MGO exhibited remarkable corrosion resistance. Furthermore, we conducted a comparative analysis of the corrosion resistance between the NGO and MGO composite EP coatings. Following immersion in a 3.5 wt% NaCl solution for 240 h, the impedance modulus at low frequencies (|Z|0.01 Hz) of the MGO composite coating was approximately two orders of magnitude greater than that of the NGO composite coating. Even following an extended immersion period of 480 h, the |Z|0.01 Hz for MGO-EP continued to maintain an advantage of one order of magnitude.

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.

The effects of amino-modified graphene oxide on the water molecules diffusion and seawater barrier properties of DGEBA/3,3′-DDS epoxy resin: a molecular dynamics simulation

The effects of amino-modified graphene oxide on the water molecules diffusion and seawater barrier properties of DGEBA/3,3′-DDS epoxy resin: a molecular dynamics simulation

Schiff base crosslinked graphene/oxidized nanofibrillated cellulose/chitosan foam: An efficient strategy for selective removal of anionic dyes

A versatile foam based on Schiff base crosslinking of oxidized nanofibrillated cellulose (ONFC) with amino modified graphene oxide (NGO) and chitosan (CS) was prepared for the efficacious selective removal of anionic dyes. (3-aminopropyl) triethoxysilane (APTES) was employed as a surface modifier to yield an amino modified graphene oxide (NGO). Meanwhile, ONFC was obtained via a periodate oxidation process to produce dialdehyde groups. Thus, the Schiff base crosslinking of ONFC with NGO and CS enabled to be readily accomplished, producing a versatile NGO/ONFC/CS foam. Systematical characterizations confirmed the successful covalent crosslinking and formation of NGO/ONFC/CS foams. Selective adsorption of Allura Red (AR) and orange G (OG) over cationic dye methylene blue (MB) by NGO/ONFC/CS was confirmed. It was found the maximum adsorption capacities of AR and OG at 303 K were 416.7 and 300.5 mg g−1, while it was 14.60 mg g−1 for MB. Thus, the new Schiff base crosslinked NGO/ONFC/CS paves the way for developing versatile graphene based foams in the applications of water treatment.

Intratumor delivery of amino-modified graphene oxide as a multifunctional photothermal agent for efficient antitumor phototherapy

Due to the high selectivity and non-invasive property, phototherapy has attracted increasing attention in the treatment of cancer. Targeted delivery and retention of photoactive agents in tumor tissue is of great significance and importance for safe and efficient phototherapy. Herein, we report a multifunctional nanomaterial photothermal agent, namely amino-modified graphene oxide (AGO) for anti-oral cancer photothermal therapy (PTT). Compared to the parental graphene oxide (GO) which has a negative charge and weak photothermal effect, AGO possesses a positive charge (∼+50 mV) and the significantly enhanced photothermal effect. Positive charge allows AGO to efficiently interact with tumor cells and retain in tumor tissue after intratumor injection. The enhanced photothermal effect allows AGO to achieve the tunable and efficient PTT. In vitro results show that AGO (15 μg/mL) reduces the viability of HSC-3 cells (oral squamous cell carcinoma cell line) to 5% under near infrared (NIR) irradiation (temperature increased to 58.4 °C). In vivo antitumor study shows that intratumor delivery of AGO (200 μg/mouse) has no inhibition effects on tumor growth (454% of initial tumor size) without NIR. With a single dose of NIR irradiation, however, AGO significantly reduces the tumor size to 25% of initial size in 1 of 4 mice, and even induces the complete tumor ablation in 3 of 4 mice. Furthermore, the injected AGO falls off along with the scab after PTT. Our findings indicate that AGO is a potential nano-photothermal agent for tunable, convenient and efficient anticancer PTT.

Cellulose-Graphene Bifunctional Paper Conservation Materials: For Reinforcement and UV Aging Protection

Paper artifacts have unique cultural and historical values. However, over time, many paper artifacts appear with disease characteristics such as embrittlement and photoaging, losing the most fundamental function of the literature archive. The reinforcement handling of degraded paper artifacts is, therefore, a necessary measure to extend their service life, the key to which lies in the reinforcement and prevention of photoaging. This paper intended to use graphene oxide (GO) as a UV protective agent, carboxymethyl cellulose (CMC) as a reinforcement, and polyethyleneimine (PEI) as a modifier. In this work, the amino-modified graphene oxide carboxymethyl cellulose composite (CMC-aGO) was prepared by chemical modification, which was used as bifunctional paper protection material with anti-ultraviolet and reinforcement. It showed excellent performance in both tensile strength testing and UV resistance testing. The CMC-aGO raw material is low cost, colorless, transparent, simple to synthesize, convenient to operate, and is an excellent conservation material with dual functions of UV aging protection and paper reinforcement.

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.

Study of the water-oil interfacial activity of amino-modified graphene oxide

The interfacial properties of Graphene oxide (GO) based materials have been widely studied in emulsification processes. The 2D chemical structure and high reactivity of Graphene Oxide (GO) allows the properties modification as wettability and dispersibility. Furthermore, the functionalized GO has been tested as a surfactant agent; however, little or nothing is known about its mechanism of action. Here, we investigated the interfacial activity of amine-modified GO in a water-toluene system. To consider the effect of the aliphatic chain length, GO was functionalized by amidation reaction and nucleophilic substitutions with n-propylamine (GO@3 C) and n-dodecylamine (GO@12 C). The covalent functionalization of GO was confirmed by FTIR spectroscopy, Raman spectroscopy, XPS spectroscopy, XRD and their morphology were observed by Scanning Electron microscopy. Results showed that the chemical modification of GO with n-alkylamines can decrease the Interfacial Tension (IFT) of the water-toluene system as the nanomaterial concentration increase, like a molecular surfactant that obey the Traube´s rule. Wettability of the materials it was also determined by the sessile drop method, revealing that the GO hydrophobicity increases as the length of the aliphatic chain becomes longer. Characteristics of the emulsion droplets were determined by micrograph analysis, and it was revealed that the diameter size, stability, and kind of emulsion can be changed depending on the type of GO functionalization.

Tertiary amino-modified GO/Nafion composite membrane with enhanced ion selectivity for vanadium redox flow batteries

Tertiary amino-modified graphene oxide (GO) nanosheet (named as TAGO) was successfully synthesized by gamma-ray radiation-induced grafting of dimethylaminoethyl methacrylate onto the surface of GO. Then, a novel Nafion-TAGO composite membrane was prepared by solution casting method and TAGO could be dispersed uniformly in the Nafion due to a good compatibility with the Nafion matrix. In the composite membrane, acid-base pairs were formed through hydrogen-bond network among the tertiary amino groups, the carboxylic acid groups and hydroxyl groups in TAGO and/or sulfonic acid groups in Nafion, respectively. Owing to the acid-base pair interactions (such as –SO3H … -N(CH3)2), the ionic channels for proton transport could be provided in the composite membrane. As a result, the Nafion-TAGO composite membrane exhibited excellent thermal stability, high proton conductivity, low VO2+ permeability and high ion selectivity. Therefore, the TAGO is a good candidate for the performance improvement of Nafion used in vanadium redox flow battery.

The synthesis of an amended membrane coated with graphene oxide and dopamine and guanidyl-based modifier and its antifouling properties.

The membrane fouling issue has aroused great concern. To improve their antifouling properties, surface grafting with oxidative deposition were employed to amend a polyvinylidene fluoride (PVDF) membrane. The modifiers were amino-modified graphene oxide (AMGO), dopamine (DPA) and 1,3-diaminoguanidine hydrochloride (DAGH). To take bovine serum albumin (BSA, 1 g/l) as an example of organic materials, BSA interception rate and pure water flux recovery rate increased to 93.65% and 66.74%, respectively, while the corresponding values for the original membrane were much lower (72.82% and 31.72%). The optimum synthesis conditions were found to be 1.5 mg/ml of DPA, 1 wt% of DAGH, 2 mg/ml of AMGO, 4 h of DPA oxidation deposition time and 1 h of AMGO grafting time. Many functional groups like C = N, -NH2, C = O and -OH improved the membrane surface hydrophilicity leading to a higher resistance to organic pollution. Dopamine and guanidyl facilitated the antimicrobial performance of the modified membrane, whose antimicrobial rate was up to 96%, while the raw membrane had no antimicrobial activity. The amended membrane possessed 40% higher mechanical strength than the initial one. It could withstand a high pumping suction force. The noteworthy property was that the irreversible fouling rate decreased by 55%. Therefore, the amended membrane could restore its flux much more easily.

Highly efficient and ultrafast removal of Cr(VI) in aqueous solution to ppb level by poly(allylamine hydrochloride) covalently cross-linked amino-modified graphene oxide

We herein report a facile strategy to prepare poly(allylamine hydrochloride) cross-linked amino-modified graphene oxide (PAH−ASGO) by Schiff-base reactions. The resulting PAH-ASGO exhibited a maximum adsorption capacity of 373.1 mg/g for Cr(VI), which was nearly 9 times higher than that of pure graphene oxide, exceeding that of most GO-based materials previously reported. More significantly, PAH-ASGO can effectively diminish the Cr(VI) concentration from 9.9 mg/L to the extremely low level of 0.004 mg/L within 10 s, far below the maximum allowable level of Cr(VI) (0.05 mg/L) in drinking water. In addition, the adsorbents still displayed excellent removal efficiency of 91.8% after 10 cycles. Considering the broad diversity, we developed also a magnetic PAH−ASGO/Fe3O4 adsorbent by a simple cross-linking reaction to achieve rapid separation of PAH−ASGO from their aqueous solution. Finally, the PAH−ASGO was successfully utilized to treat the actual industrial effluent.

Amino-modified graphene oxide nanoplatelets for photo-thermal and anti-bacterial capability

In this study, graphene oxide (GO) nanoplatelets have been successfully amino-functionalized by electrostatic absorbed process of poly(diallyldimethylammoniumchloride) (GO-PDDA) and hydrothermal of ammonia solution (AMGO). The characterizations of GO derivative nanoplatelets (GO, GO-PDDA and AMGO nanoplatelets) were evaluated by Raman, X-ray diffraction, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy and zeta potential. The results show that the zeta potential change is from −51.7 mV (GO) to 29.7 mV (GO-PDDA) and 33.2 mV (AMGO), indicated that the huge charge changing by the amino group modification. A model bacterium, Escherichia coli (E. coli), was used to evaluate the anti-bacterial activity of GO, GO-PDDA and AMGO nanoplatelets. The anti-bacterial activity of AMGO and GO-PDDA nanoplatelets is superior to pristine GO nanoplatelets, owing to the positive charge of amino-modification to capture the negative charge of bacteria cell walls. Especially in AMGO nanoplatelets, it displays the most powerful anti-bacterial capability, due to the higher grafting density of amino functional group (higher zeta potential of AMGO). Furthermore, the photo-thermal test exhibits the temperature of GO derivative nanoplatelets could increase 38-50 °C while exposed in the near-IR laser (808 nm) for 5 min. Combination of physical capturing/splintering and photo-thermal effects for the bacteria, we suggest that amino-functionalized GO nanoplatelets would be anticipated to apply in the anti-bacterial coating and photo-thermal therapy.

Graphene oxide based ratiometric fluorescent paper sensor for hypochlorous acid visual detection

In this paper, a simple and effective ratiometric fluorescent nanoprobe for visual detection of hypochlorous acid (HOCl) has been developed by loading silicon coated rhodamine B (RBDS) nanospheres on the surface of amino-modified graphene oxide (GO-NH2) nanosheets. The fabricated nanoprobe exhibits dual-emissions peaked at 427 and 585 nm, under a single excitation wavelength of 365 nm. The blue fluorescence of GO-NH2 can be selectively quenched by oxidation of HOCl, while the red fluorescence of RBDS remain unchanged, resulting in a distinguishable fluorescent color change from blue to pink under a UV lamp. Nanoprobes present high selective and sensitive for HOCl determination with a limit of detection (LOD) of 2.92 μM. Moreover, potable paper sensor has been prepared by coating the ratiometric fluorescent probe on filter paper, which provides a convenient and simple approach for HOCl visual detection.

Enhancement of mechanical, thermal and tribological properties of AAPS-modified graphene oxide/ polyamide 6 nanocomposites

Abstract Polymer composites exploiting the outstanding properties of graphene have already attracted considerable attention. Amino-modified graphene oxide (AMG) was designed via N-(2-aminoethyl)-3-aminopropyltrimethoxysilane (AAPS) anchoring on the sheets' surfaces, as confirmed by X-ray photoelectron and fourier transform infrared spectroscopy data. It was found that the AMG had good dispersity and higher thermal stability. AMG/PA6 composites with various weight percentages of graphene platelets (0, 0.25, 0.5, 0.75, 1%) were prepared by solution blending and melting mixture. AMG markedly reduced the friction coefficient and increased the wear resistance of the polymer composites. It was shown that the friction coefficient of the AMG/PA6 composite reached 0.237, i.e., 44.6% lower than that of neat PA6, and the wear rate was decreased by 33.2%. The relations of the mechanical, thermal, tribological properties and the microstructure of the AMG/PA6 composites were also discussed. Such enhancement of tribological performance was primarily attributed to the synergistic influence of the mechanical and thermal properties of the composites and the high self-lubricity of AMG.

Oxovanadium(iv) and iron(iii) salen complexes immobilized on amino-functionalized graphene oxide for the aerobic epoxidation of styrene

Oxovanadium(IV) and iron(III) salen complexes grafted onto amino-modified graphene oxide (NH2–GO) have been synthesized via a stepwise procedure and the prepared materials were used as heterogeneous catalysts in the aerobic oxidation of styrene. The structures of these materials have been thoroughly investigated using different characterization techniques such as XRD, N2 adsorption–desorption, TEM, FT-IR, diffuse reflectance UV-visible spectroscopy, ICP-AES, TEM, TG, Raman, and XPS. The results of XRD, N2 adsorption–desorption and TEM revealed that the structures of the prepared catalysts were well preserved. In addition, the results of FT-IR, diffuse reflectance UV-visible spectroscopy, ICP-AES, TG, Raman and XPS suggested that the oxovanadium(IV) and iron(III) complexes had been incorporated onto amino-modified graphene oxide (GO). It was found that the heterogeneous oxovanadium(IV) catalyst was more active than its homogeneous analogue in the epoxidation of styrene, using acetonitrile as solvent and air as the oxidant in combination with the sacrificial co-reductant isobutyraldehyde, due to site-isolation. Furthermore, the tethered vanadium catalyst was quite stable and could be recycled many times.