scholarly journals Effect of the Organic Functional Group on the Grafting Ability of Trialkoxysilanes onto Graphene Oxide: A Combined NMR, XRD, and ESR Study

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3828 ◽  
Author(s):  
Calovi ◽  
Callone ◽  
Ceccato ◽  
Deflorian ◽  
Rossi ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Condensation Reaction ◽  
Direct Interaction ◽  
Model Systems ◽  
X Ray Diffraction ◽  
Spin Resonance ◽  
Lower Extent ◽  
Reactive Groups ◽  
Acrylic Coatings ◽  
Chain Group

The functional properties displayed by graphene oxide (GO)-polymer nanocomposites are strongly affected by the dispersion ability of GO sheets in the polymeric matrix, which can be largely improved by functionalization with organosilanes. The grafting to GO of organosilanes with the general formula RSi(OCH3)3 is generally explained by the condensation reactions of silanols with GO reactive groups. In this study, the influence of the organic group on the RSi(OCH3)3 grafting ability was analyzed in depth, taking into account the interactions of the R end chain group with GO oxidized groups. Model systems composed of commercial graphene oxide reacted with 3-aminopropyltrimethoxysilane (APTMS), 3-mercaptopropyltrimethoxysilane (MPTMS), and 3-methacryloxypropyltrimethoxysilane, (MaPTMS), respectively, were characterized by natural abundance 13C, 15N and 29Si solid state nuclear magnetic resonance (NMR), x-ray diffraction (XRD), and electron spin resonance (ESR). The silane organic tail significantly impacts the grafting, both in terms of the degree of functionalization and direct interaction with GO reactive sites. Both the NMR and XRD proved that this is particularly relevant for APTMS and to a lower extent for MPTMS. Moreover, the epoxy functional groups on the GO sheets appeared to be the preferential anchoring sites for the silane condensation reaction. The characterization approach was applied to the GO samples prepared by the nitric acid etching of graphene and functionalized with the same organosilanes, which were used as a filler in acrylic coatings obtained by cataphoresis, making it possible to correlate the structural properties and the corrosion protection ability of the layers.

scholarly journals SiO2-GO nanofillers enhance the corrosion resistance of waterborne polyurethane acrylic coatings

2020 ◽  
Vol 29 ◽  
pp. 2633366X2094152
Author(s):  
Liqi Liu ◽  
Xiaofeng Guo ◽  
Lei Shi ◽  
Liquan Chen ◽  
Fangzhou Zhang ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Electron Microscope ◽  
Electrochemical Impedance ◽  
Sol Gel ◽  
Waterborne Polyurethane ◽  
Metal Corrosion ◽  
X Ray Diffraction ◽  
Functionalized Graphene Oxide ◽  
Transmission Electron ◽  
Acrylic Coatings

Corrosion to metal is a great challenge to major industries. Anticorrosive coatings can effectively prevent metal corrosion. In this study, we propose a novel method to prepare silica nanoparticles-covered graphene oxide (SiO2-GO) nanohybrids and anticorrosion SiO2-GO/waterborne polyurethane acrylic (WPUA) coatings. Firstly, we obtained silane-functionalized graphene oxide (A-GO) via a simple covalent functionalization of graphene oxide (GO) with 3-aminopropyltriethoxysilane. Secondly, SiO2-GO was synthesized by a simple sol–gel method with tetraethoxysilane in water–alcohol solution. Finally, the obtained SiO2-GO nanofillers were added into WPUA to prepare SiO2-GO/WPUA coatings. GO, A-GO, and SiO2-GO nanohybrids could be confirmed by X-ray diffraction, Fourier transform infrared spectroscopy, Raman spectra, and transmission electron microscope. SiO2-GO nanohybrids showed small size compared with the unfunctionalized GO. Meanwhile, GO, A-GO, and SiO2-GO nanofillers were added into WPUA. The electrochemical impedance spectroscopy and field emission scanning electron microscope indicate that SiO2-GO nanohybrids can be homogeneously dispersed in the WPUA coatings at 0.4% loading level and the SiO2-GO/WPUA film exhibits excellent anticorrosion performance. SiO2-GO nanoparticles can effectively utilize in the area of anticorrosive nanofiller industry. This study provides a convenient method of anticorrosive coating production.

scholarly journals Magnetization of Ultraviolet-Reduced Graphene Oxide Flakes in Composites Based on Polystyrene

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2519
Author(s):  
Alexander N. Ionov ◽  
Mikhail P. Volkov ◽  
Marianna N. Nikolaeva ◽  
Ruslan Y. Smyslov ◽  
Alexander N. Bugrov
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Reduction Process ◽  
X Ray Diffraction ◽  
Mesoscopic Structure ◽  
Reduced Graphene ◽  
Study Results ◽  
Edge Defects ◽  
Mesoscopic Level ◽  
Ferromagnetic Hysteresis

This work presents our study results of the magnetization of multilayer UV-reduced graphene oxide (UV-rGO), polymer matrix (polystyrene), and a conjugated composite based on them. The mesoscopic structure of the composites synthesized in this work was studied by such methods as X-ray diffraction, SEM, as well as NMR-, IR- and Raman spectroscopy. The magnetization of the composites under investigation and their components was measured using a vibrating-sample magnetometer. It has been shown that the UV-reduction process leads to the formation of many submicron holes distributed inside rGO flakes, which can create edge defects, causing possibly magnetic order in the graphite samples under investigation on the mesoscopic level. This article provides an alternative explanation for the ferromagnetic hysteresis loop in UV-rGO on the base of superconductivity type-II.

Photocatalytic Activity of Fe-Doped ZnO/Montmorillonite Nanocomposite for Degradation of Malachite Green

2015 ◽  
Vol 827 ◽  
pp. 19-24 ◽  
Author(s):  
Nur Afifah ◽  
Nadia Febiana Djaja ◽  
Rosari Saleh
Keyword(s):  
Photocatalytic Activity ◽  
Malachite Green ◽  
Organic Dyes ◽  
Uv Light ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Spin Resonance ◽  
Doped Zno ◽  
Co Precipitation

In this study, the photocatalytic activity of pure Fe- doped ZnO and Fe- doped ZnO/Montmorillonite nanocomposite has been investigated for the degradation of malachite green under UV light irradiation. Both photocatalysts were synthesized using co-precipitation method and characterized by X-ray diffraction, energy dispersive X-ray spectroscopy, Fourier-transform infrared absorption, and electron spin resonance. The results showed that the photocatalytic efficiency is better in the presence of montmorillonite compared to pure Fe- doped ZnO. To detect the possible reactive species involved in degradation of organic dyes control experiments with introducing scavengers into the solution of organic dyes were carried out. It is found that electron plays an important role in the degradation of malachite green.

scholarly journals Attached β-cyclodextrin/γ-(2,3-epoxypropoxy) propyl trimethoxysilane to graphene oxide and its application in copper removal

2017 ◽  
Vol 75 (10) ◽  
pp. 2403-2411 ◽  
Author(s):  
Zongxue Yu ◽  
Qi Chen ◽  
Liang Lv ◽  
Yang Pan ◽  
Guangyong Zeng ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
High Surface ◽  
High Surface Area ◽  
Esterification Reaction ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cavity Structure ◽  
Optimum Ph ◽  
Exchange Adsorption ◽  
Langmuir Isotherm Model

The environmental applications of graphene oxide and β-cyclodextrin (β-CD) have attracted great attention since their first discovery. Novel nanocomposites were successfully prepared by using an esterification reaction between β-cyclodextrin/γ-(2,3-epoxypropoxy) propyl trimethoxysilane grafted graphene oxide (β-CD/GPTMS/GO). The β-CD/GPTMS/GO nanocomposites were used to remove the Cu2+ from aqueous solutions. The characteristics of β-CD/GPTMS/GO were detected by scanning electron microscopy (SEM), Fourier transform infrared, X-ray diffraction (XRD), thermogravimetric analysis (TG) and energy dispersive X-ray (EDX). The dispersibility of graphene oxide was excellent due to the addition of β-CD. The adsorption isotherms data obtained at the optimum pH 7 were fitted by Langmuir isotherm model. The excellent adsorption properties of β-CD/GPTMS/GO for Cu2+ ions could be attributed to the apolar cavity structure of β-CD, the high surface area and abundant functional groups on the surface of GO. The adsorption patterns of β-CD/GPTMS/GO were electrostatic attraction, formation of host-guest inclusion complexes and the ion exchange adsorption. The efficient adsorption of β-CD/GPTMS/GO for Cu2+ ions suggested that these novel nanocomposites may be ideal candidates for removing other cation pollutants from waste water.

scholarly journals Combined XRD-paramagnetic 13C NMR spectroscopy of 1,2,3-triazoles for revealing copper traces in a Huisgen click-chemistry cycloaddition. A model case

2019 ◽  
Vol 25 (1) ◽  
pp. 98-106
Author(s):  
Daniel Canseco-González ◽  
José Luis Rodríguez de la O ◽  
José Enrique Herbert-Pucheta
Keyword(s):  
Click Chemistry ◽  
13C Nmr Spectroscopy ◽  
Model Systems ◽  
Paramagnetic Nmr ◽  
Resonance Spectroscopy ◽  
X Ray Diffraction ◽  
Model Case ◽  
Purification Methods ◽  
Paramagnetic Metal ◽  
Torsional Angles

AbstractCopper-catalyzed Alkyne-Azide Cycloaddition (CuAAC) click chemistry robustness has been demonstrated over recent years to produce 1,2,3-triazoles with excellent yields at mild conditions with simple purification methods. However, the consequences of having copper paramagnetic traces in final products, which complicate spectroscopic assignments and can produce inaccurate conclusions, has been scarcely discussed. Herein we present a strategy that combines X-Ray Diffraction (XRD) with 13C- paramagnetic Nuclear Magnetic Resonance spectroscopy, in order to demonstrate the presence of paramagnetic metal traces at standard Huisgen synthesis and purification conditions. We also demonstrate that the derivatization of 1,4-disubstituted-1,2,3-triazoles to produce 1,3,4,-trisubstituted-1,2,3.triazolium salts, promotes an efficient removal of Cu(II/I) moieties. Evidence of paramagnetic metal moieties is given using XRD structural analysis of abnormalities in torsional angles between substituents and the 1,2,3-triazole center, in parallel to 13C- paramagnetic NMR chemical shift and line width analysis. As model systems to demonstrate the importance of characterizing paramagnetic traces, we present the synthesis of novel 1-((3s,5s,7s)-adamantan-1-yl)-4-cyclopropyl-1H-1,2,3-triazole and its derivatized 1-((3s,5s,7s)-adamantan-1-yl)-4-cyclopropyl-3-methyl-1H-[1,2,3]-triazol-3-ium triflate salt.

Characterization of X-ray irradiated graphene oxide coatings using X-ray diffraction, X-ray photoelectron spectroscopy, and atomic force microscopy

2013 ◽  
Vol 28 (2) ◽  
pp. 68-71 ◽  
Author(s):  
Thomas N. Blanton ◽  
Debasis Majumdar
Keyword(s):  
Atomic Force Microscopy ◽  
Graphene Oxide ◽  
Photoelectron Spectroscopy ◽  
High Energy ◽  
X Ray Diffraction ◽  
Carbon Phase ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Before And After

In an effort to study an alternative approach to make graphene from graphene oxide (GO), exposure of GO to high-energy X-ray radiation has been performed. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM) have been used to characterize GO before and after irradiation. Results indicate that GO exposed to high-energy radiation is converted to an amorphous carbon phase that is conductive.

scholarly journals Poly(3,4-ethylenedioxythiophene)-reduced graphene oxide/copper-based metal-organic frameworks as a high-performance symmetrical supercapacitor device

2021 ◽  
Author(s):  
Dharshini Mohanadas ◽  
Muhammad Amirul Aizat Mohd Abdah ◽  
Nur Hawa Nabilah Azman ◽  
Thahira B.S.A. Ravoof ◽  
Yusran Sulaiman
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
High Performance ◽  
Metal Organic Framework ◽  
Specific Power ◽  
X Ray Diffraction ◽  
Reduced Graphene ◽  
Metal Organic ◽  
Energy Storage Material ◽  
Organic Framework

Abstract A novel poly(3,4-ethylenedioxythiophene)-reduced graphene oxide/copper-based metal-organic framework (PrGO/HKUST-1) has been successfully fabricated by incorporating electrochemically synthesized poly(3,4-ethylenedioxythiophene)-reduced graphene oxide (PrGO) and hydrothermally synthesized copper-based metal-organic framework (HKUST-1). The field emission scanning microscopy (FESEM) and elemental mapping analysis revealed an even distribution of poly(3,4-ethylenedioxythiophene) (PEDOT), reduced graphene oxide (rGO) and HKUST-1. The crystalline structure and vibration modes of PrGO/HKUST-1 was validated utilizing X-ray diffraction (XRD) as well as Raman spectroscopy, respectively. A remarkable specific capacitance (360.5 F/g) was obtained for PrGO/HKUST-1 compared to HKUST-1 (103.1 F/g), PrGO (98.5 F/g) and PEDOT (50.8 F/g) using KCl/PVA as a gel electrolyte. Moreover, PrGO/HKUST-1 composite with the longest charge/discharge time displayed excellent specific energy (21.0 Wh/kg), specific power (479.7 W/kg) and outstanding cycle life (95.5%) over 4000 cycles. Thus, the PrGO/HKUST-1 can be recognized as a promising energy storage material.

scholarly journals Synthesis of Polyaniline coated Graphene Oxide @ SrTiO3 Nanocube Nanocomposites for Enhanced Removal of Carcinogenic Dyes from Aqueous Solution

2016 ◽  
Author(s):  
Syed Shahabuddin ◽  
Norazilawati Muhamad Sarih ◽  
Muhammad Afzal Kamboh ◽  
Hamid Rashidi Nodeh ◽  
Sharifah Mohamad
Keyword(s):  
Electron Microscopy ◽  
Aqueous Solution ◽  
Methylene Blue ◽  
Graphene Oxide ◽  
Methyl Orange ◽  
Oxidative Polymerization ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Polymerization Method

The present investigation highlights the synthesis of polyaniline (PANI) coated graphene oxide doped with SrTiO3 nanocube nanocomposites through facile in-situ oxidative polymerization method for the efficient removal of carcinogenic dyes, namely, the cationic dye methylene blue (MB) and the anionic dye methyl orange (MO). The synthesised nanocomposites were characterised by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The adsorption efficiencies of graphene oxide (GO), PANI homopolymer and SrTiO3 nanocubes-doped nanocomposites were assessed by monitoring the adsorption of methylene blue and methyl orange dyes from aqueous solution. The adsorption efficiency of nanocomposites doped with SrTiO3 nanocubes were found to be of higher magnitude as compared with undoped nanocomposite. Moreover, the nanocomposite with 2 wt% SrTiO3 with respect to graphene oxide demonstrated excellent adsorption behaviour with 99% and 91% removal of MB and MO respectively, in a very short duration of time.

Effects of Electron Beam on Structure and Physical Properties of Natural Colorless Topaz

2015 ◽  
Vol 1125 ◽  
pp. 60-63
Author(s):  
Chutharat Paikaew ◽  
Juthamas Inthanont ◽  
Adisak Punyanut ◽  
Ekachai Hoonnivathana ◽  
Pichet Limsuwan ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Electron Beam ◽  
Physical Properties ◽  
Orthorhombic Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Spin Resonance ◽  
Function Group ◽  
And Function ◽  
Beam Dose

The purpose of this research was to investigate physical properties, configuration and color of topaz. Topazes were irradiated with electron beam linear accelerator at different dose from 40 to 180 MGy. The color of topaz was analyzed by UV-vis and it was shown that the color of topaz was becoming strong color with increased electron beam dose. Crystal structure and function group of topaz were characterized by X- ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. The results showed that the topaz has orthorhombic structure and no other crystalline. After irradiated, topaz released OH indicating higher crystallinity of topaz and this was confirmed with the results of electron spin resonance (ESR). Electron beam dose response of topaz was investigated. ESR results showed that the Al3+ ion was substituted in Si4+ site and Ti3+ impurity in Al4+ site and this result corresponds to the results of FTIR. The experiment result indicated that electron beam could be making defect on crystal structure and color enhancement of topaz.

scholarly journals Diffusion in the aqueous compartment.

1984 ◽  
Vol 99 (1) ◽  
pp. 180s-187s ◽  
Author(s):  
A M Mastro ◽  
A D Keith
Keyword(s):  
Rotational Motion ◽  
Spin Label ◽  
Mammalian Cells ◽  
Translational Motion ◽  
Diffusion Constant ◽  
Rotational Correlation Time ◽  
Model Systems ◽  
Quiescent Cells ◽  
Spin Resonance ◽  
In Cells

Measurements of diffusion of molecules in cells can provide information about cytoplasmic viscosity and structure. In a series of studies electron-spin resonance was used to measure the diffusion of a small spin label in the aqueous cytoplasm of mammalian cells. Translational and rotational motion were determined from the same spectra. Based on measurements made in model systems, it was hypothesized that calculations of the apparent viscosity of the cytoplasm from both rotational and translational motion would distinguish between the effects of viscosity and structure on diffusion. The diffusion constant measured in several cell lines averaged 3.3 X 10(-6) cm2/s. It was greater in growing cells and in cells treated with cytochalasin B than in quiescent cells. The viscosity of the cytoplasm calculated from the translational diffusion constant or the rotational correlation time was 2.0-3.0 centipoise, about two to three times that of the spin label in water. Therefore, over the dimensions measured by the technique, 50-100 A, solvent viscosity appears to be the major determinant of particle movement in cells under physiologic conditions. However, when cells were subjected to hypertonic conditions, the translational motion of the spin label decreased threefold, whereas the rotational motion changed by less than 20%. These data suggest that the decrease in cell volume under hypertonic conditions is accompanied by an increase in cytoplasmic barriers and a decrease in the space between existing cytoplasmic components without a significant increase in viscosity in the aqueous phase. In addition, a comparison of reported diffusion values of a variety of molecules in water and in cells indicates that cytoplasmic structure plays an important role in the diffusion of proteins such as bovine serum albumin.

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