Enhancement of Hydrophobility and Thermal Property of Graphene Oxide by Paratoluidine Chemical Functionalization

2014 ◽  
Vol 809-810 ◽  
pp. 243-247
Author(s):  
Zhi Jia Luo ◽  
Hong Zhang Geng ◽  
Song Ting Zhang ◽  
Bao Tan Du ◽  
Xing Zhang ◽  
...  
Keyword(s):  
Drug Delivery ◽  
Graphene Oxide ◽  
Thermal Property ◽  
Functional Groups ◽  
Drug Delivery Systems ◽  
Graphite Powder ◽  
Hydroxyl Groups ◽  
Chemical Functionalization ◽  
Hummers Method ◽  
Modified Hummers Method

Graphene oxide (GO) is typically synthesized by graphite powder under strong oxidizing reaction, possessing with the same set of functional groups: epoxy and hydroxyl in basal plane and carboxyl and hydroxyl groups existence on the flake edges which endow GO with amphipathy. GO and its functionalized derivatives have been successfully tested in many domains, such as polymer composites, biosensors, drug delivery systems, etc. In this paper, GO was prepared by a modified Hummers method employing improved process (preparation and separation), aiming at industrialization with the lowest cost. Moreover, some novel functional groups with different properties were controlled chemically grafted onto GO to modify the wettability and reaction activity with other materials. The hydrophobicity and the thermal property of graphene oxide were enhanced by chemical functionalization.

Synthesis of Graphene Oxide Nanosheets via Modified Hummers’ Method and Its Physicochemical Properties

2015 ◽  
Vol 74 (1) ◽  
Author(s):  
Mohamad Fahrul Radzi Hanifah ◽  
Juhana Jaafar ◽  
Madzlan Aziz ◽  
Ahmad Fauzi Ismail ◽  
Mukhlis A. Rahman ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Physicochemical Properties ◽  
Functional Groups ◽  
Interlayer Spacing ◽  
Graphene Oxide Nanosheets ◽  
Hummers Method ◽  
Exfoliated Graphene ◽  
Transmission Electron ◽  
Direct Methanol ◽  
Modified Hummers Method

The efficient synthesis of exfoliated graphene oxide nanosheets (GO) via modified Hummers’ method was successfully carried out. The physicochemical properties of GO were determined by Fourier transform infrared spectroscopy (FTIR), UV-visible spectrophotometry (UV-vis), x-ray diffraction analysis (XRD), Raman spectroscopy, and transmission electron microscopy (TEM). The graphite was fully oxidized by strong oxidizing agent caused the oxygen-containing functional groups such as C-O-C, C=O, and COOH were introduced into the graphite layers as analyzed by Raman and FTIR.  XRD pattern of GO showed 2θ of 12.0o with interlayer spacing ~ 7.37A which describe non uniform crystal structure with the addition of oxygen containing functional groups. UV-vis spectrum of GO exhibit maximum absorption peak at ~ 234 nm corresponding to the aromatic C=C bond with π-π* transition. The morphology of GO was observed to have flake-like shape and less transparent layers by TEM. The properties of synthesized GO suggest high potential in producing the high quality of graphene which is can be applied as the electrocatalyst support for direct methanol fuel cell application.              

Anodic Aqueous Electrophoretic Deposition of Graphene Oxide on Copper Using Different Cathode Materials

2020 ◽  
Vol 1008 ◽  
pp. 21-27
Author(s):  
Essam Hares ◽  
Ahmed Hassan El-Shazly ◽  
Marwa Farouk El-Kady ◽  
Kholoud Madih ◽  
Hamdiya Orleans-Boham ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Electrophoretic Deposition ◽  
Graphite Oxide ◽  
Cathode Materials ◽  
Aqueous Suspension ◽  
Graphite Powder ◽  
Liquid Exfoliation ◽  
Hummers Method ◽  
Oxide Deposition ◽  
Modified Hummers Method

The effect of four different cathode materials on the anodic deposition of graphene oxide (GO) nanosheets was studied experimentally. First, synthesis of graphite oxide from graphite powder was done by modified Hummers' method. Ultrasonic technique was adopted for the preparation of the stable aqueous suspension of GO by using liquid exfoliation of graphite oxide. Deposition of GO coating on copper sheets (the anode) was done via electrophoretic deposition (EPD) at the same operating condition (5V, 2 min, concentration of 0.5 mg/ml of GO per deionized water) with different cathode materials (copper, stainless steel, aluminum and graphite). The coatings’ morphological and microstructure were investigated using scanning electron microscope (SEM) and the effect of the current density in the EPD process was obtained. The change in the deposition weight was also measured. It was ascertained that the cathode’s material is a major factor can affect the GO’s EPD process and the characteristics of the final coating.

scholarly journals Effect of long-term ageing on graphene oxide: structure and thermal decomposition

2021 ◽  
Vol 8 (12) ◽  
Author(s):  
Chen Li ◽  
Yanling Lu ◽  
Jun Yan ◽  
Weibo Yu ◽  
Ran Zhao ◽  
...  
Keyword(s):  
Activation Energy ◽  
Thermal Decomposition ◽  
Graphene Oxide ◽  
Apparent Activation Energy ◽  
Functional Groups ◽  
Defect Density ◽  
Oxide Structure ◽  
Hummers Method ◽  
Modified Hummers Method

After long-term ageing, the structure of graphene oxide prepared by the modified Hummers method changed. Because of the desorption of oxygen-containing functional groups, the C/O ratio of graphene oxide increased from 1.96 to 2.76. However, the average interlayer distance decreased from 0.660 to 0.567 nm. The content of -CH- and -CH 2 - decreased; however, the type of oxygen-containing functional groups did not change. Moreover, I D / I G increased from 0.87 to 0.92, indicating that the defect density decreased because of desorbing oxygen functional groups after ageing. When the temperature exceeded 60°C, CO 2 produced by decomposing graphene oxide was detected. The thermal decomposition changed after ageing. The decomposition peak temperature decreased from 216°C to 195°C. The CO 2 amount produced remained almost unchanged; however, the amount of CO, SO 2 and H 2 O decreased. After ageing, the apparent activation energy of graphene oxide decreased from 150 to 134 kJ mol −1 .

scholarly journals Obtaining of Reduced Graphene Oxide from Graphite by using Hummer’s and Chemical Reduction Method

2019 ◽  
Vol 2 (3) ◽  
pp. 601-605
Author(s):  
Kübra Yıldız ◽  
Muhammet Uzun
Keyword(s):  
Graphene Oxide ◽  
Reduced Graphene Oxide ◽  
Reduction Method ◽  
Chemical Reduction ◽  
Graphite Powder ◽  
Chemical Reduction Method ◽  
Graphene Oxides ◽  
Hummers Method ◽  
Reduced Graphene ◽  
Modified Hummers Method

In this study, graphene oxide (GO) was synthesized from graphite using modified Hummers method. According to other methods known in the literature, modified Hummers method; it is simpler and less costly in terms of process steps. In addition, it is safer and environmentally friendly than the Hummers method. Reduced Graphene Oxide (RGO) was obtained by reduction of graphene oxides (GO) synthesized by modified Hummers method. It is understood from the obtained results that GO is synthesized successfully from graphite powder by modified Hummers method and RGO is obtained successfully by reduction of graphene oxides (GO).

scholarly journals Mechanical Properties of Graphene Oxide Coupled by Multi-Physical Field: Grain Boundaries and Functional Groups

Crystals ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 62
Author(s):  
Xu Xu ◽  
Zeping Zhang ◽  
Wenjuan Yao
Keyword(s):  
Mechanical Properties ◽  
Graphene Oxide ◽  
Grain Boundaries ◽  
Functional Groups ◽  
Oxygen Content ◽  
Tensile Fracture ◽  
Hydroxyl Groups ◽  
Molecular Configuration ◽  
Spatial Design ◽  
Out Of Plane

Graphene and graphene oxide (GO) usually have grain boundaries (GBs) in the process of synthesis and preparation. Here, we “attach” GBs into GO, a new molecular configuration i.e., polycrystalline graphene oxide (PGO) is proposed. This paper aims to provide an insight into the stability and mechanical properties of PGO by using the molecular dynamics method. For this purpose, the “bottom-up” multi-structure-spatial design performance of PGO and the physical mechanism associated with the spatial structure in mixed dimensions (combination of sp2 and sp3) were studied. Also, the effect of defect coupling (GBs and functional groups) on the mechanical properties was revealed. Our results demonstrate that the existence of the GBs reduces the mechanical properties of PGO and show an “induction” role during the tensile fracture process. The presence of functional groups converts in-plane sp2 carbon atoms into out-of-plane sp3 hybrid carbons, causing uneven stress distribution. Moreover, the mechanical characteristics of PGO are very sensitive to the oxygen content of functional groups, which decrease with the increase of oxygen content. The weakening degree of epoxy groups is slightly greater than that of hydroxyl groups. Finally, we find that the mechanical properties of PGO will fall to the lowest values due to the defect coupling amplification mechanism when the functional groups are distributed at GBs.

Graphene Oxide as a Substrate for Biosensors: Synthesis and Characterization

2021 ◽  
Vol 324 ◽  
pp. 87-93
Author(s):  
Mohamed Adel ◽  
Abdel Hady A. Abdel-Wahab ◽  
Ahmed Abdel-Mawgood ◽  
Ahmed Osman Egiza
Keyword(s):  
Raman Spectroscopy ◽  
Graphene Oxide ◽  
Acidic Solution ◽  
Cost Effective ◽  
Sem Analysis ◽  
Visible Spectroscopy ◽  
Sem Images ◽  
Hummers Method ◽  
Uv Visible ◽  
Modified Hummers Method

Graphene oxide (GO) is an oxidized nanosheets of graphite with a 2D planar structure. GO could be readily complexed with bio-entities as it possesses many oxygen-containing functionalities on its surface. The preparation process is fast, easy, and cost-effective. It was prepared using modified Hummers’ method in acidic solution as a primary solvent and potassium permanganate as an oxidizing agent. Afterwards, it was successfully characterized by FTIR, UV-visible spectroscopy, as well as XRD and Raman spectroscopy, and finally, SEM analysis. It was observed that the formed GO is mainly composed of carbon and oxygen elements rich in oxygen functional groups. Furthermore, the existence of (001) plane in XRD interprets the complete oxidation of graphite with d-spacing 9 Å. Moreover, Raman spectroscopy displayed the sp3 carbon hybridization, besides, the ID/IG ratio is found to be 0.84, which confirms the disorder between graphene oxide layers. The SEM images also pointed out that graphene oxide sheets were regularly stacked together as flake-like structures. Accordingly, the richness of oxygen-containing functionalities was confirmed. Hence, it is appropriate to be used as a base transducer for biosensing applications.

scholarly journals Inulin and Its Application in Drug Delivery

2021 ◽  
Vol 14 (9) ◽  
pp. 855
Author(s):  
Franklin Afinjuomo ◽  
Sadikalmahdi Abdella ◽  
Souha H. Youssef ◽  
Yunmei Song ◽  
Sanjay Garg
Keyword(s):  
Drug Delivery ◽  
Drug Delivery Systems ◽  
Delivery Systems ◽  
Flexible Structure ◽  
Hydroxyl Groups ◽  
Protective Effects ◽  
Drug Delivery Carrier ◽  
Targeting Ability ◽  
Organ Targeting ◽  
Structure Stabilization

Inulin’s unique and flexible structure, stabilization/protective effects, and organ targeting ability make it an excellent drug delivery carrier compared to other biodegradable polysaccharides. The three hydroxyl groups attached to each fructose unit serve as an anchor for chemical modification. This, in turn, helps in increasing bioavailability, improving cellular uptake, and achieving targeted, sustained, and controlled release of drugs and biomolecules. This review focuses on the various types of inulin drug delivery systems such as hydrogel, conjugates, nanoparticles, microparticles, micelles, liposomes, complexes, prodrugs, and solid dispersion. The preparation and applications of the different inulin drug delivery systems are further discussed. This work highlights the fact that modification of inulin allows the use of this polymer as multifunctional scaffolds for different drug delivery systems.

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