Surface Modification Of Graphene Oxide Research Articles

Surface Modification of Graphene Oxide and Its Strengthening and Toughening Mechanism for Alumina-Based Ceramic Materials

Surface Modification of Graphene Oxide and Its Strengthening and Toughening Mechanism for Alumina-Based Ceramic Materials

Surface Modification of Graphene Oxide for Fast Removal of Per- and Polyfluoroalkyl Substances (PFAS) Mixtures from River Water.

Per- and polyfluoroalkyl substances (PFAS) make up a diverse group of industrially derived organic chemicals that are of significant concern due to their detrimental effects on human health and ecosystems. Although other technologies are available for removing PFAS, adsorption remains a viable and effective method. Accordingly, the current study reported a novel type of graphene oxide (GO)-based adsorbent and tested their removal performance toward removing PFAS from water. Among the eight adsorbents tested, GO modified by a cationic surfactant, cetyltrimethylammonium chloride (CTAC), GO-CTAC was found to be the best, showing an almost 100% removal for all 11 PFAS tested. The adsorption kinetics were best described by the pseudo-second-order model, indicating rapid adsorption. The isotherm data were well supported by the Toth model, suggesting that PFAS adsorption onto GO-CTAC involved complex interactions. Detailed characterization using scanning electron microscopy-energy dispersive X-ray spectroscopy, Fourier transform infrared, thermogravimetric analysis, X-ray diffraction, and X-ray photoelectron spectroscopy confirmed the proposed adsorption mechanisms, including electrostatic and hydrophobic interactions. Interestingly, the performance of GO-CTAC was not influenced by the solution pH, ionic strength, or natural organic matter. Furthermore, the removal efficiency of PFAS at almost 100% in river water demonstrated that GO-CTAC could be a suitable adsorbent for capturing PFAS in real surface water.

Effect of surface modification of graphene oxide with a reactive silane coupling agent on the mechanical properties and biocompatibility of acrylic bone cements

Carbon allotrope materials (i.e. carbon nanotubes (CNTs), graphene, graphene oxide (GO)), have been used to reinforce acrylic bone cement. Nevertheless, the intrinsic incompatibility among the above materials produces a deficient interphase. Thus, in this work, the effect of the content of functionalized graphene oxide with a reactive silane on the mechanical properties and cell adhesion of acrylic bone cement was studied. GO was obtained by an oxidative process on natural graphite; subsequently, GO was functionalized with 3-methacryloxypropyltrimethoxysilane (MPS) to enhance the interphase between the graphenic material and acrylic polymeric matrix. Pristine GO and functionalized graphene oxide (GO-MPS) were characterized physicochemically (XPS, XRD, FTIR, and Raman) and morphologically (SEM and TEM). Silanized GO was added into the acrylic bone cement at different concentrations; the resulting materials were characterized mechanically, and their biocompatibility was also evaluated. The physicochemical characterization results showed that graphite was successfully oxidized, and the obtained GO was successfully functionalized with the silane coupling agent (MPS). SEM and TEM images showed that the GO is composed of few stacked layers. Compression testing results indicated a tendency of increasing stiffness and toughness of the acrylic bone cements at low concentration of functionalized GO. Additionally, the bending testing results showed a slightly increase in bone cement strain with the incorporation of GO-MPS. Finally, all samples exhibited cell viability higher than 70%, which means that materials are considered non-cytotoxic, according to the ISO 10993-5 standard.

Computational identification of long non-coding RNAs associated with graphene therapy in glioblastoma multiforme.

Glioblastoma multiforme represents the most prevalent primary malignant brain tumour, while long non-coding RNA assumes a pivotal role in the pathogenesis and progression of glioblastoma multiforme. Nonetheless, the successful delivery of long non-coding RNA-based therapeutics to the tumour site has encountered significant obstacles attributable to inadequate biocompatibility and inefficient drug delivery systems. In this context, the use of a biofunctional surface modification of graphene oxide has emerged as a promising strategy to surmount these challenges. By changing the surface of graphene oxide, enhanced biocompatibility can be achieved, facilitating efficient transport of long non-coding RNA-based therapeutics specifically to the tumour site. This innovative approach presents the opportunity to exploit the therapeutic potential inherent in long non-coding RNA biology for treating glioblastoma multiforme patients. This study aimed to extract relevant genes from The Cancer Genome Atlas database and associate them with long non-coding RNAs to identify graphene therapy-related long non-coding RNA. We conducted a series of analyses to achieve this goal, including univariate Cox regression, least absolute shrinkage and selection operator regression and multivariate Cox regression. The resulting graphene therapy-related long non-coding RNAs were utilized to develop a risk score model. Subsequently, we conducted Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway analyses on the identified graphene therapy-related long non-coding RNAs. Additionally, we employed the risk model to construct the tumour microenvironment model and analyse drug sensitivity. To validate our findings, we referenced the IMvigor210 immunotherapy model. Finally, we investigated differences in the tumour stemness index. Through our investigation, we identified four promising graphene therapy-related long non-coding RNAs (AC011405.1, HOXC13-AS, LINC01127 and LINC01574) that could be utilized for treating glioblastoma multiforme patients. Furthermore, we identified 16 compounds that could be utilized in graphene therapy. Our study offers novel insights into the treatment of glioblastoma multiforme, and the identified graphene therapy-related long non-coding RNAs and compounds hold promise for further research in this field. Furthermore, additional biological experiments will be essential to validate the clinical significance of our model. These experiments can help confirm the potential therapeutic value and efficacy of the identified graphene therapy-related long non-coding RNAs and compounds in treating glioblastoma multiforme.

Surface modification of graphene oxide by functionalized dendritic polyesters based on phthalic acid and pentaerythritol as a novel nanoplatform for sustained drug delivery: Statistical optimization using response surface methodology and release kinetics modelling

In this work, the third generation of polyester dendrimers was synthesized by conjugating phthalic acid and pentaerythritol on the graphene oxide surface. After the esterification reaction, 3, 5-dinitrobenzoyl chloride was grafted to the polyester dendrimer and used as a nanocarrier for the antibiotic-sustained delivery of the metronidazole. The success of the synthesis was confirmed by using various techniques. The batch sorption test was conducted according to the variables set by the central composite design under response surface methodology. The statistically optimized sorption efficiency (95.11%) was attained at pH= 5, 15 µg mL−1 concentration, and a contact time of 15 min. This data indicated that the pseudo-second-order kinetic and Langmuir isotherm models had greater correlation coefficients (R2) of 0.9980 and 0.9995, respectively than the other non-linear models. Based on the thermodynamic study such as ΔH°, ΔG°, and ΔS°, the adsorption efficiency of drug by nanoadsorbent was an endothermic (ΔH°= 16121.68 J mol−1), spontaneous process (ΔG° = −7.83 to 9.84 kJ mol−1), and entropy driven (ΔS° = 80.35 J mol−1K−1). Nearly 98.92% of the drug was released in simulated intestinal fluid, pH= 7.4, in 6 h and 34.96% in simulated gastric fluid, pH= 1.2, in 1 h. The nanocarrier had an encapsulation efficiency of 86.90% and a drug loading of 38.12%. The Korsmeyer-Peppas mathematical model adjusted well to the experimental drug release kinetic profile with non-Fickian diffusion (0.5 <n < 0.9 for all pH). The findings display that the synthesized nanocarrier could be a promising choice for the sustained delivery of metronidazole.

Progress in the Graphene Oxide-Based Composite Coatings for Anticorrosion of Metal Materials

Graphene oxide (GO), derived from the two-dimensional nanosheet graphene, has received unprecedented attention in the field of metal corrosion protection owing to its excellent barrier performance and various active functional groups. In this review, the protection mechanism “labyrinth effect” of composite coatings against metal corrosion was demonstrated systematically. The origination, structure and properties of GO were also analyzed. Their poor dispersion in polymer and tendency to aggregate as nanofillers in composite coatings are the main limitations during application of the coating fillers. In addition, a comprehensive overview on the perspectives of the surface modification of GO and the multi-functionalization of the composite coatings based on GO were given in particular. Green modification methods, reasonable arrangement of GO sheets in composites and development of multi-functional coatings remain challenges in current studies and should be a focus in the future development of GO-based anticorrosive coatings. This review is of value to researchers interested in the design and application of GO in corrosion protection coatings.

Poly(acrylamide-co-acrylic acid) grafted graphene oxide for improving the filtration performance of drilling fluids

An adequate drilling fluid filtration reduction additive should not only be able to minimize liquid leaking into the formation, but also be able to improve the applicability of drilling fluids in complex drilling conditions. In this study, polymer-grafted graphene oxide (GO) nanoadditives which could significantly improve the performance of drilling fluids are developed by surface modification of GO with charged polymer chains. The microstructures and compositions of the polymer-grafted GO nanoadditives are investigated with FT-IR, TEM with elemental mapping, ζ potential measurements, and TGA. Their performance as filtration reduction additives for drilling fluids is evaluated according to the American Petroleum Institute (API) standard. The results demonstrate that negatively charged poly (acrylamide-co-acrylic acid)-grafted GO nanoadditives are beneficial for water loss reduction in drilling fluids. The more negative charges on the surface, the higer the water loss reduction. This might be because the electrostatic repulsion between poly (acrylamide-co-acrylic acid)-grafted GO nanoadditives and bentonite particles slows down the formation of filter cake and make it denser, which slows down the penetration of water phase. Moreover, the results of filtration experiments under high salinity and high temperature conditions indicate that the addition of poly (acrylamide-co-acrylic acid)-grafted GO nanoadditives maintains the water loss reduction effect even at 180 °C or in fluids with 8 wt% NaCl. The presence of poly (acrylamide-co-acrylic acid)-grafted GO in the slurries could also improve their lubrication performance.

Simultaneously Improved Thermal Conductivity and Dielectric Properties of NBR Composites by Constructing 3D Hybrid Filler Networks

AbstractThis work aims to address the heat accumulation issue in electronic components during high‐frequency operation through the preparation of novel thermally conductive composites. First, polydopamine (PDA) and in‐situ growth of silver (Ag) nanoparticles are applied for the surface modification of graphene oxide (GO) and carbon nanotube (CNT) to prepare pGO@Ag and pCNT@Ag hybrid filler, respectively. Then, nitrile butadiene rubber (NBR) is chosen as the polymeric matrix and simultaneously incorporated with both pGO@Ag and pCNT@Ag to prepare polymeric composites with excellent thermal conductivity (TC) and dielectric constant (ɛr). Due to the construction of 3D heat conduction networks by utilizing 2D pGO@Ag and 1D pCNT@Ag, the fabricated NBR composites achieved the maximum TC of 1.0112 W/(mK), which is 636% higher than that of neat NBR (0.1373 W (mK)−1). At the filler loading of 9 vol%, the TC of pGO@Ag/pCNT@Ag/NBR composite is 152% that of GO/CNT/NBR composite (0.6660 W (mK)−1). Moreover, due to electron polarization effect of GO and CNT and micro‐capacitor effect of Ag nanoparticles, a large ɛr of 147.12 is attained at 10 Hz for NBR composites. Overall, the development of dielectric polymer materials with high TC is beneficial for enhancing the service life and safety stability of the electronic components.

Green modification of graphene oxide nanosheets under specific pH conditions

Green surface modification of graphene oxide (GO) using lysine (Lys) under different pH conditions was studied, aiming to activate the specific functional group of the amino acid structure: carboxylic acid (pH 2), the primary amine of α-carbon (pH 9.8) and, the primary amine of the lateral chain and α-carbon (pH 12), promoting three interaction mechanisms between Lys and the oxygenated groups of GO nanosheets. Chemical analyses suggest that at pH 2, ester bonds are formed on the GO’s surface from its interaction with Lys, while at pH 9.8, the formation of C-N bonds takes place. However, at pH 14, chemical reduction of GO nanosheets is induced. Density functional calculations predicted possible binding modes and reaction pathways for forming ester (at pH 2) and C−N bonds (at pH 9.8) on basal planes of GO nanosheets and gave deep insights into the electronic structure of reduced GO materials. The chemical changes generated at the surface of GO modified the crystalline structure and the thermal properties of GO nanosheets. Our results suggest that controlled chemical functionalization/reduction of GO nanosheets under environmental conditions can be performed under specific pH. However, the promotion of those functional groups benefits the potential used in biological applications.

GO/ionic surfactant inspired photophysical modulation of rhodamine B in Reline with or without additives

Photophysical behaviour of rhodamine B (RB) in deep eutectic solvents (DES, formed by quaternary ammonium salt and hydrogen bond donor (HBD) in a specific eutectic ratio) with or without graphene oxide (GO) or ionic surfactants, is less known. The nature of Reline (choline chloride (ChCl): urea (HBD), 1:2), a well-known DES, has been designed by adding glycerol or water as the second HBD for sustained movement of RB. Effects of GO, surfactant, or GO + surfactant, in controlling RB movement, at various sites (GO surface, surfactant micelle, DES surface, or background solvent), have been fluorometrically reported. The basic nature of Reline (pH = 10.38) causes modification of GO surface (deprotonated site) and nature of RB (cationic → zwitter ionic). Above Reline-inspired changes have been found to modify interactions of RB with GO and/or sodium dodecyl sulphate (SDS, an anionic surfactant) or cetyl trimethyl ammonium bromide (CTAB, a cationic surfactant). SDS (10 mMdm−3, < critical micelle concentration (CMC) in Reline) shows ∼ 2.6, 1.6, and 1.4 fold fluorescence intensity enhancement of RB (in water, pure Reline, and methanol, respectively). However, GO and/or CTAB shows quenching behaviour. Further, the fluorescence of RB shows weak dependence on changing the second HBD (water or glycerol). DES-controlled cationic vs zwitterionic form of RB is responsible for the interaction and sustained movement towards GO surface, micellar surface, or negatively charged ion-pair formation (with SDS monomers). Findings of the work have implications in searching potential fluorescent levels/sensors for photophysics, photobiology, or wider vehicle means for sustained drug delivery.

Primary amine–thiourea grafted graphene–based heterogeneous chiral catalysts for highly enantioselective Michael additions

Heterogeneous asymmetric catalysis based on earth-abundant carbon materials put together the advantages for the ease of separation, simple regeneration, and high stability of solid catalysts as well as acts as low-cost, environmentally friendly metal-free alternative to the metal-based catalysts. Two new bifunctional carbocatalysts [(S,S) and (R,R) GO-PATU] were prepared by anchoring enantiomerically pure organosilanes bearing primary amine and thiourea groups to the graphene oxide (GO) skeleton covalently via silane coupling reaction. The surface modification of GO was analyzed by a combination of Fourier-transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and transmission electron spectroscopy (TEM) techniques. The catalytic performances of graphene-based materials were investigated in the asymmetric Michael addition reactions of α,α-disubstituted-aldehydes to nitrostyrenes and N-substituted-maleimides. The effects of solvents and Brønsted basic or acidic additives were evaluated using both catalysts and good yields (up to 85%) and stereoselectivities (up to 95% ee) were obtained in dichloromethane at room temperature in the presence of l- and d-camphorsulfonic acid. Besides, recycling and reusing studies of the catalysts were successfully performed.

Surface modification of graphene oxide for preparing self‐healing nanocomposite hydrogels

AbstractIn this work, graphene oxide (GO) and vinyl modified GO (V‐GO)‐based nanocomposite hydrogels with improved mechanical property and self‐healing ability have been synthesized and characterized. GO first was synthesized by modified Hummer's method using graphite powder and then functionalized with vinyl groups by using (3‐mercaptopropyl) trimethoxysilane (MPTS) via silanization method. The GO and V‐GO nanoparticles were characterized by FT‐IR, UV–vis spectroscopy, SEM, and dynamic light scattering technique (DLS). Hydrogels were obtained by in‐situ free‐radical polymerizations of acrylamide (AAm) and [3‐(methacryloylamino)propyl] trimethylammonium chloride (MAPTAC) monomers in the presence of GO and V‐GO nanoparticles. The effects of the amount of GO and V‐GO on the gelation profile and viscoelastic characteristics of the hydrogels were studied. The pH‐responsive action, swelling behavior, and swelling kinetics of the hydrogels with various GO and V‐GO contents were also evaluated. The mechanical performance of nanocomposite cationic hydrogels prepared with GO and V‐GO nanosheets was compared to the neat AAm‐MAPTAC hydrogels. The self‐healing ability of the hydrogels were elucidated as a function of the amount of GO and V‐GO nanosheets bound to the polymer network by physical interactions and chemical cross‐links, respectively.

Highly Sensitive Determination of Tenofovir in Pharmaceutical Formulations and Patients Urine-Comparative Electroanalytical Studies Using Different Sensing Methods.

This paper discusses the electrochemical behavior of antiviral drug Tenofovir (TFV) and its possible applicability towards electroanalytical determination with diverse detection strategies using square-wave voltammetry. Namely, oxidation processes were investigated using glassy carbon electrode with graphene oxide surface modification (GO/GCE), while the reduction processes, related to the studied analyte, were analyzed at a renewable silver amalgam electrode (Hg(Ag)FE). Scanning electron microscopy imaging confirmed the successful deposition of GO at the electrode surface. Catalytic properties of graphene oxide were exposed while being compared with those of bare GCE. The resultant modification of GCE with GO enhanced the electroactive surface area by 50% in comparison to the bare one. At both electrodes, i.e., GO/GCE and Hg(Ag)FE, the TFV response was used to examine and optimize the influence of square-wave excitation parameters, i.e., square wave frequency, step potential and amplitude, and supporting electrolyte composition and its pH. Broad selectivity studies were performed with miscellaneous interfering agents influence, including ascorbic acid, selected saccharides and aminoacids, metal ions, non-opioid analgesic metamizole, non-steroidal anti-inflammatory drug omeprazole, and several drugs used along with TFV treatment. The linear concentration range for TFV determination at GO/GCE and Hg(Ag)FE was found to be 0.3–30.0 µmol L–1 and 0.5–7.0 µmol L–1, respectively. The lowest LOD was calculated for GO/GCE and was equal to 48.6 nmol L–1. The developed procedure was used to detect TFV in pharmaceutical formulations and patient urine samples and has referenced utilization in HPLC studies.

The Effect of Pristine and Pegylated Graphene Oxide Nanosheets on the Functions of Human Neutrophils

Graphene oxide (GO) is very useful for biomedicine, due to its physicochemical properties; therefore, its interaction with cells of the immune system has beenextensively studied. Many studies have aimed toreduce the undesirable effects of GO through chemical modification, including through polyethylene glycol (PEG) coating. Neutrophils are the first to respond to foreign object invasion in the body. Their main functions are the uptake and destruction of foreign particles, including with the help of reactive oxygen species (ROS).Our study aimed to investigate theengulfment of unmodified graphene oxide (GO) and graphene oxide coated with polyethylene glycol (GO-PEG) by human neutrophils and the effect of nanosheets on the production of ROS.We used sheets of GO (Ossila, Great Britain, average plate size 1-5 μm) and GO-PEG (569 ± 14 nm, PEG coating≈ 20%) at concentrations of 12.5μg/mL, 25μg/mL, and 50 μg/mL. The uptake of nanosheets was assessed by flow cytometry, taking into account the level of background adhesion of nanoparticles. ROS production was evaluated by luminol-dependent chemiluminescence (LCL).It was found that GO (12.5μg/mL, 25μg/mL, and 50 μg/mL) was actively internalized by neutrophils, while the uptake of GO-PEG was not detected. GO and GO-PEG particles (25 μg/mLand 50 μg/mL) reduced the total production of ROS by human leukocytes.Thus, the modifying of GOnanosheets with PEG resulted in the abolishment of their active uptake by neutrophils but did not affect the GO inhibitory effect on their oxidative activity.&#x0D; Keywords: graphene oxide surface modification, pegylated graphene oxide nanosheets, nanoparticle uptake, human neutrophils, of reactive oxygen species

Improvement in bioavailability of curcumin within the castor‐oil based polyurethane nanocomposite through its conjugation on the surface of graphene oxide nanosheets

AbstractRecently biocompatible polyurethane (PU) films, made from renewable bioactive compounds have been introduced as a feasible option to accelerate wound healing process. In this work, graphene oxide (GO) nanostructures were applied as a practical nanocarrier system to enhance the bioavailability of curcumin within castor‐oil based PU elastomer nanocomposites. Successfully modification of GO nanosheets with curcumin (C‐GO) were confirmed by FT‐IR, XRD, TGA, Raman spectroscopy, and FE‐SEM microscopy techniques. FE‐SEM images demonstrated a good dispersion quality of C‐GO nanosheets in the PU matrix, demonstrating the enhanced bioavailability of curcumin. Based on XRD diffractograms, PU/C‐GO nanocomposite showed a lower crystallinity and microphase‐separation degree compared to blank PU sample. This finding is probably originated from the amphiphilic properties of C‐GO which provides possibility of good interactions with hard and soft domains in PU backbone. Moreover, compared to PU/GO nanocomposite, the surface modification of GO with curcumin increased the tensile strength and Young's modulus of PU/C‐GO nanocomposite to 4.92 and 44.49 MPa, respectively. The in vitro MTT assay revealed a significant viability for L929 fibroblast cells in exposure with PU/C‐GO film. Besides, the results of in vivo wound healing evaluation on the mouse model indicated that the PU/C‐GO sample could accelerate the healing rate by promoting the proliferation and re‐epithelialization of fibroblast cells in the wound site. Thus, it is suggested that the PU/C‐GO nanocomposite film may has a potential and promising application as a wound dressing.

Radio-frequency plasma assisted reduction and nitrogen doping of graphene oxide

The plasma treatment of graphene oxide (GO) is a promising method for safely carrying out the surface modification of GO because the treatment can be performed at room temperature without the use of toxic processing gases. In this study, plasma reduction and nitrogen doping were carried out on GO, and the chemical property of the treated GO were investigated in detail, thereby demonstrating the superior properties of plasma treatment. Unlike thermal reduction, in which epoxide and hydroxyl groups were preferentially removed, plasma reduction removes all types of functional groups, thus realizing a novel form of modified GO surface. Since the functional groups might behave as an active site for doping, its relative abundance during the nitrogen plasma treatment of GO at room temperature resulted in a large amount of the nitrogen content (up to 19.1 at%). These characteristics of plasma-assisted GO treatment are expected to improve the device performance and can open up new possibilities for GO applications.

GRAPHENE OXIDE NANOPARTICLES IN THE REGULATION OF THE OXIDATIVE ACTIVITY OF HUMAN MONOCYTES

Graphene-based materials have an opportunity for use in biomedicine, thanks to their properties. Nevertheless, due to its cytotoxic effects, the use of graphene-based drugs is problematic. However, the surface modification of graphene oxide (GO) nanoparticles with a polyethyleneglycol (PEG) is one way to reduce the harmful effects of graphene on cells. Applying nanoparticles implies their interaction with the immune system, which protects the body. Monocytes are innate immunity cells and the first line of defenсe of the human organism from microorganisms and other alien objects. One of the monocytes’ reactions to a stimulus of any nature is to produce reactive oxygen species (ROS). Published data shows an incomplete picture of modified graphene oxide nanoparticles’ effects on ROS formation by human monocytes. Thus, it was essential to evaluate the pegylated graphene oxide (GO-PEG and GO-8armedPEG) effect on ROS production by human monocytes, assessed by the luminol-dependent chemiluminescence (LCL). The objects of the study were CD14+-cells isolated from mononuclear cells of healthy donors. ROS production was stimulated by opsonized zymosan (OZ), spontaneous LCL was used as a control. PEG-modified (GO-PEG and GO-8armedPEG) GO nanoparticles with sizes of 100-200 nm (“small”) and 1-5 μm (“big”) with PEG covering ~ 20% were used at concentrations of 5 and 25 μg/ml. The study showed that small size nanoparticles at a low concentration of 5 μg/ml and big nanoparticles coated with 8-armed PEG at both concentrations have a significant suppressive effect on spontaneous ROS production. In the stimulated LCL reaction variant, it was found that small nanoparticles (25 μg/ml) also have a suppressive effect on ROS production, such as big-sized particles coated with linear PEG at the same concentration. Thus, we have established for the first time that graphene oxide nanoparticles functionalized with PEG are capable of inhibiting the ROS production by human monocytes, and therefore, we can speak of the antioxidant activity of GO-PEG.

Exploring Impacts of Hyper-Branched Polyester Surface Modification of Graphene Oxide on the Mechanical Performances of Acrylonitrile-Butadiene-Styrene.

In this manuscript, the graphene oxide (GO) was modified by hyper-branched polyester (HBP). The effects of GO or modified GO (HBP-m-GO) on the mechanical performance and wearing properties were investigated. The results of X-ray photoelectron spectra (XPS), Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM) revealed the successful grafting of HBP onto GO. The thermogravimetric analysis (TGA) indicated that the graft amount of HBP is calculated to be 9.6 wt%. The GO or HBP-m-GO was added into acrylonitrile-butadiene-styrene copolymer (ABS) to prepare the ABS/GO composites. The mechanical properties and wear performance of the composites were studied to comparatively study the impact of GO modification on the properties of the composites. The results revealed that the addition of GO has a significant effect on the mechanical properties of ABS, and when HBP-m-GO was added, the elastic modulus and tensile strength of ABS/HBP-m-GO increased evidently compared with ABS/GO. The tensile strength increased from 42.1 ± 0.6 MPa of pure ABS to 55.9 ± 0.9 MPa, up to 30%. Meanwhile, the elongation at break was significantly higher than ABS/GO to 20.1 ± 1.3%, slightly lower than that of pure ABS. For wear performance, the addition of raw GO decreased the friction coefficient, and when the HBP-m-GO was added, the friction coefficient of the ABS/HBP-m-GO dropped more evidently. Meanwhile, the weight loss during the wear test decreased evidently. The related mechanism was discussed.

Impacts of Modified Graphite Oxide on Crystallization, Thermal and Mechanical Properties of Polybutylene Terephthalate.

In this study, the surface modification on graphene oxide (GO) was performed using octadecylamine (ODA). Furthermore, polybutylene terephthalate/GO (PBT/GO) composites were prepared to elucidate the role of GO surface modification on the mechanical performance, thermal stability and crystallization behavior. Results of Fourier transform infrared spectra (FT-IR), Raman spectrum, thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and transmission electron microscope (TEM) revealed that ODA was successfully grafted on GO. Differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), tensile test, Izod impact strength test and TGA were carried out on the PBT/GO composites. Results indicated that the addition of raw GO can enhance the crystallization temperature and degree of crystallinity and can slightly improve the thermal stability and tensile strength of the composites. However, the impact strength and elongation at break were seriously decreased owing to the poor compatibility between the GO and PBT matrix. Once the modified GO was added, the crystallization temperature and degree of crystallinity were greatly increased. The tensile strength increased greatly while the elongation at break and Izod impact strength were efficiently maintained; these were evidently higher than those of PBT/raw GO. Moreover, thermal stability was greatly enhanced. SEM (scanning electron microscope) observation results on the impact-fractured surface clearly confirmed the improved compatibility between the modified GO and PBT matrix. A related mechanism had been discussed.

Hybrid graphene oxide-immobilized silver nanocomposite with optimal fabrication route and multifunctional application

Herein, the surface modification of graphene oxide with silver nanoparticles was examined with the type of reducing agents, the reducing agent:AgNO3 mass ratio, reduction temperature, reduction time, and AgNO3:GO mass ratio. The optimal fabrication condition was determined based on the AgNPs density on GO, AgNPs size, and the antibacterial activity of the Ag/GO by plate colony–counting and optical density methods. The as-prepared materials were analyzed by Fourier transform infrared spectroscopy, X-ray diffraction, Raman spectroscopy, transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, and UV–vis spectroscopy. Results revealed that the appropriate reducing agent is ascorbic acid (AA) with the conditions: the ratio AA:AgNO3 = 1:1; reaction at 40 °C in 10 min with AgNO3:GO ratio of 1.25:1. More than 99.99 % of bacteria was inhibited, with a minimum bactericidal concentration of 50 and 100 µg/mL for P. aeruginosa, and S. aureus, respectively. Furthermore, the materials were surveyed in terms of their interface sorption and sensing applications. The maximum adsorption capacity of the nanocomposite reached 98.04 mg/L at 40–100 mg/L methylene blue, while the limit of detection for detecting Hg(II) in water was indicated to be 223 nM. Therefore, Ag/GO has shown sustainably promising usage for multiple purposes.