Small Amount Of Graphene Oxide Research Articles

Systemic modulation of the stability of pluronic hydrogel by a small amount of graphene oxide

Thermo-sensitive and injectable hydrogels have been widely investigated for drug delivery, tissue engineering, and other biomedical applications. Pluronic copolymers can form thermo-sensitive physical gel state, thus applicable for injectable hydrogels. However, they are not stable in vivo, showing a very fast dissolution, which limits their applications. We propose a novel Pluronic-based physical hydrogel with enhanced stability by simply adding a small quantity of graphene oxide (GO) which has a large surface area and can make strong interactions with Pluronic. Further carboxylated GO could act as a more efficient additive. The addition of GO increased the moduli of hydrogels, but more importantly, it enhanced the stability of Pluronic gel dramatically. The in vitro dissolution rate of Pluronic hydrogel could be systematically modulated by increasing GO content. Upon subcutaneous injection at a sol state, GO-containing hydrogel induced a stable gel state, and was maintained over several weeks whereas very fast degradation was observed without the addition of GO. Furthermore, histological analyses demonstrated that the GO-containing Pluronic hydrogel was biocompatible and showed no severe inflammatory response. Similarly, GO-containing hydrogel resulting from the packing of Pluronic-based nanogel also showed the more enhanced stability by the addition of GO both in vitro and in vivo. In both systems, hydrogels with remarkably enhanced stability by the addition of GO were also effective for the sustained release of loaded protein, and the release rates were mainly determined by the degradation rates of hydrogels. Thus, these GO-containing Pluronic systems can be used as a thermo-sensitive injectable system with a sufficient stability in vivo.

Synthesis and adsorption performance of Mg(OH)2 hexagonal nanosheet–graphene oxide composites

A series of Mg(OH)2 hexagonal nanosheet–graphene oxide (GO) composites were synthesized through a simple hydrothermal method using magnesium nitrate and GO as precursors, sodium nitrate and sodium oxalate as additives, and sodium hydroxide and ammonia as precipitants. The as-prepared samples were characterized by X-ray diffraction, nitrogen adsorption–desorption isotherms, Raman spectroscopy, zeta potential analysis, and scanning electron microscopy (SEM). The adsorption affinity of the as-prepared samples toward congo red (CR) in water was analyzed and investigated. Results indicated that GO addition influenced the thickness, morphology, and adsorption performance of Mg(OH)2 hexagonal nanosheets. As GO concentration increased, the thickness decreased. Especially at high GO concentration (1wt%), Mg(OH)2 hexagonal nanosheets changed into aggregated flower-like spheres. Addition of small amounts of GO also increased the adsorption capacity of Mg(OH)2. The equilibrium adsorption data of CR on the composite were further investigated by Langmuir and Freundlich models, indicating that the Langmuir model was much more suitable for the experimental data. The sample prepared with 0.5wt% GO showed the highest adsorption capacity with 118mgg−1. The experimental data were then fitted using pseudo-second order kinetics, suggesting that pseudo-second order kinetics could well describe the adsorption of CR on composites. Adsorption thermodynamics analysis showed that the adsorption activation energy was 29.2kJmol−1, suggesting that the adsorption of CR onto the samples was physical adsorption. Adsorption between the samples and CR was mainly due to the strong electrostatic attraction between them because they had opposite charges. These findings indicated that Mg(OH)2–GO composite was an effective adsorbent for the removal of CR in water.

Tuning Rheological Performance of Silica Concentrated Shear Thickening Fluid by Using Graphene Oxide

The addition of a small amount of graphene oxide into a traditional colloidal silica-based shear thickening fluid (STF) can lead to a significant change in viscosity, critical shear rate, storage modulus, and loss modulus of STF. This finding provides an effective way to prepare stronger and light-weight STFs.

One-pot microfluidic fabrication of graphene oxide-patched hollow hydrogel microcapsules with remarkable shell impermeability.

Uniform hollow hydrogel microcapsules, composed of a graphene oxide platelet-patched shell, are fabricated in one step in a capillary-based microfluidic device. We demonstrate that patching a small amount of graphene oxide at the interfaces remarkably prevents the leakage of small molecules through the shell.

Porous chitosan doped with graphene oxide as highly effective adsorbent for methyl orange and amido black 10B

In the current study, porous chitosan aerogels doped with small amount of graphene oxide (CSGO aerogels) with high porosity (97.96–98.78%), extraordinarily high water absorption (5848–8917%) and low density (0.021–0.035gcm−3) were prepared and used as adsorbents for two azo dyes methyl orange (MO) and amido black 10B (AB10B). The adsorption behavior of these CSGO aerogels and some influence factors such as pH value, graphene oxide (GO) loading, concentration of pollutants, as well as adsorption kinetics were studied. Specifically, the adsorption capacity for MO is 686.89mgg−1, the highest comparing with other publication results, and it is 573.47mgg−1 for AB10B. Since they are biodegradable, non-toxic, efficient, low-cost and easy to prepare, we believe that these porous CSGO aerogels will be a promising candidate for dye removal.

Preparation of graphene oxide/epoxy nanocomposites with significantly improved mechanical properties

The effect of graphene oxide (GO) on the mechanical properties and the curing reaction of Diglycidyl Ether of Bisphenol A/F and Triethylenetetramine epoxy system was investigated. GO was prepared by oxidation of graphite flakes and characterized by spectroscopic and microscopic techniques. Epoxy nanocomposites were fabricated with different GO loading by solution mixing technique. It was found that incorporation of small amount of GO into the epoxy matrix significantly enhanced the mechanical properties of the epoxy. In particular, model I fracture toughness was increased by nearly 50% with the addition of 0.1 wt. % GO to epoxy. The toughening mechanism was understood by fractography analysis of the tested samples. The more irregular, coarse, and multi-plane fracture surfaces of the epoxy/GO nanocomposites were observed. This implies that the two-dimensional GO sheets effectively disturbed and deflected the crack propagation. At 0.5 wt. % GO, elastic modulus was ∼35% greater than neat epoxy. Differential scanning calorimetry (DSC) results showed that GO addition moderately affect the glass transition temperature (Tg) of epoxy. The maximum decrease of Tg by ∼7 °C was shown for the nanocomposite with 0.5 wt. % GO. DSC results further revealed that GO significantly hindered the cure reaction in the epoxy system.

Filtration and transport of heavy metals in graphene oxide enabled sand columns

Abstract A fixed-bed sand column with graphene oxide (GO) layer was used to remove heavy metals (Cu(II) and Pb(II)) from an aqueous solution injected under steady flow. Due to the time constrained kinetic process of heavy metal sorption to GO, removal efficiency was affected by the injection flow rate. When injection flow rate changed from 1 to 5 mL min−1, the removal efficiency of the two metals decreased from 15.3% to 10.3% and from 26.7% to 19.0% for Cu(II) and Pb(II), respectively. Provided a fixed concentration of heavy metals in the injected flow, an increase in GO in column from 10 to 30 mg resulted in an sharp increase in the removal efficiency of Pb(II) from 26.7% to 40.5%. When Cu(II) and Pb(II) were applied simultaneously, the removal efficiency of the two metals was lower than when applied by individually. GO-sand column performance was much better for the removal of Pb(II) than for Cu(II) in each corresponding treatment. When breakthrough curve (BTC) data were simulated by the convection-dispersion-reaction (CDER) model, the fittings for Cu in every treatment were better than that of Pb in corresponding treatment. Considering the small amount of GO used to enable the sand columns that resulted in a great increase in k value, compared to the GO-free sand columns, the authors propose GO as an effective adsorption media in filters and reactive barriers to remove Pb(II) from flowing water.

Graphene Oxide Assisted Hydrothermal Carbonization of Carbon Hydrates

Hydrothermal carbonization (HTC) of biomass such as glucose and cellulose typically produces micrometer-sized carbon spheres that are insulating. Adding a very small amount of Graphene oxide (GO) to glucose (e.g., 1:800 weight ratio) can significantly alter the morphology of its HTC product, resulting in more conductive carbon materials with higher degree of carbonization. At low mass loading level of GO, HTC treatment results in dispersed carbon platelets of tens of nanometers in thickness, while at high mass loading levels, free-standing carbon monoliths are obtained. Control experiments with other carbon materials such as graphite, carbon nanotubes, carbon black, and reduced GO show that only GO has significant effect in promoting HTC conversion, likely due to its good water processability, amphiphilicity, and two-dimensional structure that may help to template the initially carbonized materials. GO offers an additional advantage in that its graphene product can act as an in situ heating element to enable further carbonization of the HTC products very rapidly upon microwave irradiation. Similar effect of GO is also observed for the HTC treatment of cellulose.

Microporous spongy chitosan monoliths doped with graphene oxide as highly effective adsorbent for methyl orange and copper nitrate (Cu(NO3)2) ions

In the current study, microporous spongy chitosan monoliths doped with small amount of graphene oxide (CSGO monoliths) with high porosity (96–98%), extraordinary high water absorption (more than 2000%) and low density (0.0436–0.0607gcm−3) were prepared by the freeze-drying method and used as adsorbents for anionic dyes methyl orange (MO) and Cu2+ ions. The adsorption behavior of the CSGO monoliths and influencing factors such as pH value, graphene oxide (GO) content, concentration of pollutants as well as adsorption kinetics were studied. Specifically, the saturated adsorption capacity for MO is 567.07mgg−1, the highest comparing with other publication results, and it is 53.69mgg−1 for Cu2+ ions. Since they are biodegradable, non-toxic, efficient, low-cost and easy to prepare, we believe that these microporous spongy CSGO monoliths will be the promising candidates for water purification.

Improved Graphitic Structure of Continuous Carbon Nanofibers via Graphene Oxide Templating

AbstractContinuous carbon nanofibers (CNF) present an attractive building block for a variety of multifunctional materials and devices. However, the carbonization of poly(acrylonitrile) (PAN) precursors usually results in CNFs with poor graphitic structure and, consequently, modest/non‐optimized properties. This paper reports that the graphitic structure of CNFs can be improved with an addition of a small amount of graphene oxide into PAN prior to processing. Continuous CNFs with 1.4 wt% of graphene oxide nanoparticles are prepared from PAN solutions by electrospinning, stabilized, and carbonized at 800 °C, 1200 °C, and 1850 °C. While the as‐prepared graphene oxide‐filled PAN nanofibers exhibit a considerable reduction in polymer crystallinity, Raman analysis of the carbonized nanofibers shows that both templating with graphene oxide and increasing the carbonization temperature significantly improve the graphitic order in CNFs. The effect of graphene oxide is more significant at higher carbonization temperatures. Selected area electron diffraction analysis of individual nanofibers reveals increased graphitic order and preferred orientation both in the vicinity of visible graphene oxide nanoparticles and in the regions where nanoparticles were not visible. These results indicate a possibility of global templating in CNFs, where the addition of a small amount of graphene oxide nanoparticles can template the formation of good, preferentially oriented graphitic crystallites in CNFs, leading to improved structure and mechanical and transport properties.

Ag/AgBr/rGO nanocomposite: Synthesis and its application in photocatalysis

Ag/AgBr is a highly efficient visible-light plasmonic photocatalyst but suffers from severe aggregation of the particles. To settle this problem, we simply added a small amounts of graphene oxide (GO) to the Ag/AgBr reaction system. Expectedly, well monodispersed Ag/AgBr particles bonded on the rGO sheets (Ag/AgBr/rGO) was obtained, as observed by SEM. The adsorptive and photocatalytic activities of the as-prepared samples were investigated by degradation of RhB under visible light irradiation. Compared with pure Ag/AgBr, Ag/AgBr/rGO nanocomposite shows enhanced performance in both the adsorptive and photocatalytic activities.

A High‐Performance Graphene Oxide‐Doped Ion Gel as Gel Polymer Electrolyte for All‐Solid‐State Supercapacitor Applications

AbstractA high‐performance graphene oxide (GO)‐doped ion gel (P(VDF‐HFP)‐EMIMBF4‐GO gel) is prepared by exploiting copolymer (poly(vinylidene fluoride‐hexafluoro propylene), P(VDF‐HFP)) as the polymer matrix, ionic liquid (1‐ethyl‐3‐methylimidazolium tetrafluoroborate, EMIMBF4) as the supporting electrolyte, and GO as the ionic conducting promoter. This GO‐doped ion gel demonstrates significantly improved ionic conductivity compared with that of pure ion gel without the addition of GO, due to the homogeneously distributed GO as a 3D network throughout the GO‐doped ion gel by acting like a ion “highway” to facilitate the ion transport. With the incorporation of only a small amount of GO (1 wt%) in ion gel, there has been a dramatic improvement in ionic conductivity of about 260% compared with that of pure ion gel. In addition, the all‐solid‐state supercapacitor is fabricated and measured at room temperature using the GO‐doped ion gel as gel polymer electrolyte, which demonstrates more superior electrochemical performance than the all‐solid‐state supercapacitor with pure ion gel and the conventional supercapacitor with neat EMIMBF4, in the aspect of smaller internal resistance, higher capacitance performance, and better cycle stability. These excellent performances are due to the high ionic conductivity, excellent compatibility with carbon electrodes, and long‐term stability of the GO‐doped ion gel.

Photocatalytic TiO2–RGO/nylon-6 spider-wave-like nano-nets via electrospinning and hydrothermal treatment

A new route for the formation of reusable photocatalytic TiO2 (P25)-reduced graphene oxide/nylon-6 (P25-RGO/nylon-6) composite filter membrane using electrospinning and hydrothermal techniques is being reported. Addition of small amount of graphene oxide (GO) into nylon-6 solution prior to electrospinning was able to cause the formation of a large-scale uniform bimodal fibers with distributed thick (≈200nm) and thin (≈13nm) fiber diameters in spider-wave-like nano-nets by electrospinning, and facilitated the deposition of P25 NPs during its reduction at the time of hydrothermal treatment. Different analyses confirmed that GO was successfully incorporated into the electrospun nylon-6 fibers and simultaneous reduction of GO as well as deposition of P25 NPs on the surface of fibers was possible during hydrothermal treatment. The photoactive property of the as-prepared nanocomposites was tested against methylene blue. The results showed that P25-RGO/nylon-6 nanocomposite mat is more effective than the TiO2/nylon-6 electrospun composite mat. The water flux at a given pressure of different mats was measured to find out the filter efficiency of the membranes. The as-prepared composite mat has great potentiality as an economically–friendly water filter media and reusable photocatalyst.

Syntheses, Characterizations and Adsorption Properties of MIL‐101/Graphene Oxide Composites

AbstractComposites of the Cr3+‐based metal‐organic framework (MIL‐101) and graphene oxide (GO) have been synthesized with different ratios of MIL‐101 and GO. The composites and the parent material MIL‐101 were characterized by X‐ray diffraction, scanning electron microscopy and nitrogen adsorption. The results indicated that the incorporation of large amounts of GO (10 and 20 wt%) almost did not prevent the formation of MIL‐101 units, but had an obvious impact on the size of MIL‐101 crystals. On the contrary, small amounts of GO added (2 and 5 wt%) prevented significantly the proper assembly of MIL‐101 units, thus resulting in a pronounced decrease in the porosities of composites.

In situ preparation of transparent polyimide nanocomposite with a small load of graphene oxide

AbstractPolyimide (PI) nanocomposites with 4,4′‐bisphenol A dianhydride, 4,4′‐oxydiphthalic anhydride, and diaminodiphenyl methane (MDA) as comonomers and functionalized with graphene oxide (GO), were prepared by in situ polymerization. Only a small amount of GO (0.03–0.12 wt %) is added to improve the mechanical properties of PI and to avoid a substantial decrease of PI transparence. The nanocomposites are characterized by FTIR, X‐ray diffraction, thermogravimetric analysis, transmission electron microscope, tensile test, and UV‐vis spectroscopy. It is demonstrated that the PI/GO composite films possess transmittance of above 80% at wavelengths of 500–800 nm when the GO content is under 0.12 wt %, while the stress intensity and Young's modulus are improved by 29 and 25%, respectively. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Synthesis and anticoagulation activities of polymer/functional graphene oxide nanocomposites via Reverse Atom Transfer Radical Polymerization (RATRP)

The anticoagulation properties of biomaterials are crucial for biomedical applications, especially for blood-contacting materials. In this work, a range of functional graphene oxide based on the biomimetic monomer 2-(methacryloyloxy) ethyl phosphorylcholine (GO-g-pMPC) were synthesized by RATRP in alcoholic media using peroxide groups as initiator, and then filled into the polyurethane matrix to obtain the polyurethane (PU)/functional graphene oxide nanocomposite films (PU/GO-g-pMPC). The tensile strength and elongation and morphology of the PU/GO-g-pMPC were characterized by mechanical properties test, Transmission electron microscope (TEM), respectively. The results showed that a small amount of graphene oxide can improve the mechanical properties of PU. The blood compatibility of the PU substrates was evaluated by protein adsorption tests and platelet adhesion tests in vitro. It was found that all the PU/GO-g-pMPC showed improved resistance to nonspecific protein adsorption and platelet adhesion.

Graphene Oxide-terminated Partially Fluorinated Poly(arylene ether sulfone)

Abstract Graphene oxide-terminated partially fluorinated poly(arylene ether sulfone) (GO-PAES) was synthesized via step growth polymerization with graphene oxide. A small amount of graphene oxide was incorporated into the polymer matrix to enhance the properties of the polymer/GO composites. The chemical structures of the synthesized copolymers containing graphene oxide were confirmed by 1H NMR and FT-IR spectra. The thermal properties of GO-PAES analyzed by TGA and DSC were significantly improved due to the thermal stability of graphene oxide.

A promising alternative to conventional polyethylene with poly(propylene carbonate) reinforced by graphene oxide nanosheets

We show an order of magnitude increase in yield strength and Young's modulus of poly(propylene carbonate) (PPC) by adding a small amount of graphene oxide (GO) nanosheets, accompanied by a dramatic increase of glass transition temperature (Tg). The reinforced tensile properties are comparable to those of conventional polyethylene. This work opens the door to replace conventional polyethylene by PPC.