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1.
本文将聚乙二醇单甲醚(PEO)氨基化处理得到氨基化PEO(PEO-NH2),然后利用PEO-NH2与氧化石墨烯(GO)表面的环氧基团反应,将PEO-NH2接枝到石墨烯表面上。对产物进行红外及热重分析表征结果表明,PEO-NH2成功地接枝到了GO、还原氧化石墨烯(rGO)表面,接枝PEO-NH2的含量分别约为34.4wt%、20.5wt%。此外,经水合肼还原后的PEO-rGO在水溶液和N,N-二甲基甲酰胺(DMF)中仍具有较好的分散性。 相似文献
2.
Ungsoo Kim Yongjoon Cho Dasom Jeon Yongchul Kim Sanghyeon Park Jihyung Seo Junghyun Lee Nam Khen Oh Geunsik Lee Jungki Ryu Changduk Yang Hyesung Park 《Small (Weinheim an der Bergstrasse, Germany)》2020,16(11)
The functionalization of graphene has been extensively used as an effective route for modulating the surface property of graphene, and enhancing the dispersion stability of graphene in aqueous solutions via functionalization has been widely investigated to expand its use for various applications across a range of fields. Herein, an effective approach is described for enhancing the dispersibility of graphene in aqueous solutions at different pH levels via non‐covalent zwitterion functionalization. The results show that a surfactant with electron‐deficient carbon atoms in its backbone structure and large π–π interactive area enables strong interactions with graphene, and the zwitterionic side terminal groups of the molecule support the dispersibility of graphene in various pH conditions. Experimental and computational studies confirm that perylene diimide amino N‐oxide (PDI–NO) allows efficient functionalization and pH‐independent dispersion of graphene enabled by hydration repulsion effects induced by PDI–NO. The PDI–NO functionalized graphene is successfully used in the oxygen evolution reaction as an electron mediator for boosting the electrocatalytic activity of a Ru‐based polyoxometalate catalyst in an acidic medium. The proposed strategy is expected to bring significant advances in producing highly dispersible graphene in aqueous medium with pH‐independent stability, thus broadening the application range of graphene. 相似文献
3.
Youwei Zhang Hui-Ling Ma Jing Peng Maolin Zhai Zhong-Zhen Yu 《Journal of Materials Science》2013,48(5):1883-1889
Chemically reduced and functionalized graphene oxide (GO) was prepared by refluxing of GO with ethylenediamine (ED) using dimethyl formamide (DMF) as solvent. It was confirmed that both ED and DMF contributed to the reduction and functionalization of GO. The resulting adsorbent (ED–DMF–RGO) with amine groups was highly efficient in removing Cr(VI) from its aqueous solution and could be easily separated by filtration. The optimum pH for total Cr removal was observed at pH 2.0 and the Cr(VI) removal capacity of ED–DMF–RGO at this pH was 92.15 mg g?1, which was about 27 times higher than that of activated carbon, even nearly 4–8 times higher than that of various modified activated carbons. The presence of other ions such as Na+, K+, Ca2+, Cl?, and Br? had little effect on the removal of Cr(VI). Interestingly, Cr(VI) was reduced to low-toxic Cr(III) during the adsorption process, which followed an indirect reduction mechanism. Both the Cr(VI) adsorption and subsequent reduction of adsorbed Cr(VI) to Cr(III) contributed to the Cr(VI) removal. The obtained ED–DMF–RGO may be applicable in Cr(VI) removal if they are produced on a large scale and at low price in near future. 相似文献
4.
Kang Zhang Xiaohua Zhang Hengxiang Li Xiaohan Xing Li’e Jin Qing Cao Ping Li 《Journal of Materials Science》2018,53(4):2484-2496
Large-scale production of high-quality graphene is very critical for practical applications of graphene materials and devices. Exfoliation of graphite in an aqueous solution of surfactants is one of the most promising approaches to produce graphene. In this study, a novel anionic surfactant [sulfonated used engine oil (SUEO)], which was prepared from used engine oil, was employed to exfoliate the graphite nanoplatelets into graphene sheets in an aqueous solution under sonication to form a stable dispersion. The efficiency of SUEO for exfoliating and dispersing graphene was investigated and compared with that of traditional surfactants, such as sodium dodecyl sulfate, sodium dodecyl benzene sulfate, cetyl trimethyl ammonium bromide, and polyvinylpyrrolidone. Result showed that the graphene dispersion with excellent stability had a higher concentration (0.477 mg/mL) than others at 0.5 g/L optimal SUEO dosage in 4 h sonication time. The superior performance of SUEO can be attributed to its special molecular structures, whose hydrophobic moieties contain cycloalkanes/aromatics with different molecular weights and/or side chain –R with different lengths. Structural diversities are very helpful to the “jigsaw-puzzle” process on the graphene surface, where the total interfacial energy of the mixture system was minimized. Microscopic (SEM, TEM, and AFM) and spectroscopic (XRD, XPS, and Raman) measurements revealed that the dispersion consisted of few-layer graphene sheets with lower levels of defects or oxidation. This study presents a new class of dispersing agents for graphene that assists in the exfoliation process in water with high concentration and the stabilization of the graphene sheets against reaggregation. 相似文献
5.
A stable aqueous dispersion (5 mg ml?1) of graphene was synthesized by a simple protocol based on three-step reduction of graphene oxide (GO) dispersion synthesized using the modified version of Hummers and Offeman method. Reduction of GO was carried out using sodium borohydride, hydrazine hydrate and dimethyl hydrazine as reducing agents. The chemically synthesized graphene was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV–visible absorption spectroscopy, Fourier transform infrared (FTIR) and Raman spectroscopy, thermogravimetric analysis (TGA), optical microscopy. The stability of aqueous dispersions of graphene was confirmed through zeta potential measurements and the negative zeta potentials of 55–60 mV were obtained indicating the high stability of aqueous graphene dispersions. 相似文献
6.
Preparation of covalently functionalized graphene using residual oxygen-containing functional groups 总被引:1,自引:0,他引:1
Hsiao MC Liao SH Yen MY Liu PI Pu NW Wang CA Ma CC 《ACS applied materials & interfaces》2010,2(11):3092-3099
When fabricated by thermal exfoliation, graphene can be covalently functionalized more easily by applying a direct ring-opening reaction between the residual epoxide functional groups on the graphene and the amine-bearing molecules. Investigation by X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and transmission electron microscopy (TEM) all confirm that these molecules were covalently grafted to the surface of graphene. The resulting dispersion in an organic solvent demonstrated a long-term homogeneous stability of the products. Furthermore, comparison with traditional free radical functionalization shows the extent of the defects characterized by TEM and Raman spectroscopy and reveals that direct functionalization enables graphene to be covalently functionalized on the surface without causing any further damage to the surface structure. Thermogravmetric analysis (TGA) shows that the nondestroyed graphene structure provides greater thermal stability not only for the grafted molecules but also, more importantly, for the graphene itself, compared to the free-radical grafting method. 相似文献
7.
Xianhong Chen Feng Tao Jianfeng Wang Huajun Yang Jiagui Zou Xiaohua Chen Xue Feng 《Materials Science and Engineering: A》2009,499(1-2):469-475
Effective functionalization of multi-walled carbon nanotubes (MWCNTs) with styryl group was carried out via the esterification reaction of the carboxylate salt of carbon nanotubes and 4-vinylbenzyl chlorides in toluene. The functionalized MWCNTs were characterized through FTIR and Raman spectra to confirm the styryl groups covalently connected to the surface of MWCNTs. The weight loss of functionalized moieties determined by thermogravimetry-differential scanning calorimertry analysis is around 36%. Nanotube-reinforced polystyrene were fabricated by mixing functionalized MWCNTs and polystyrene. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images showed that the functionalized nanotubes had a better dispersion than the unfunctionalized MWCNTs in the matrix. Moreover, styryl-modified MWCNTs/PS nanocompsite presented obvious improvements in mechanical properties and thermal stability. 相似文献
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9.
Al(OH)3 functionalized graphene composites (Al–GO) were prepared using a simple sol–gel method. In this protocol, graphene oxide
(GO) was prepared according to the Hummers method and functionalized to enhance its reactivity with aluminum isopropoxide
by a LiAlH4 treatment. The functionalized graphene sheets were characterized by X-ray photoelectron spectroscopy, field emission scanning
electron microscopy, and transmission electron microscopy. These analyses confirmed that GO had been fabricated and the Al(OH)3 layer could have a homogeneous distribution with large and dense coverage onto GO sheets. In addition, the thermal and electrical
conductivity of the epoxy composites with GO and Al–GO fillers were measured. The thermal conductivities of the composites
with graphene-based fillers were enhanced by the addition of fillers. In particular, the thermal conductivity of GO/epoxy
composite containing 3 wt% was approximately two times higher than that of pure epoxy resin. In addition, the electrical conductivity
of Al–GO embedded composites degenerated compared to GO composites. 相似文献
10.
Herein, we report on a self-photocatalytic reduction (SPCR) strategy toward the production of reduced graphene oxide (GO), carried out by UV irradiation of GO dispersion in the presence of N,N-dimethylformamide (DMF) serving as an electron donor (ED). It is found that a stable dispersion of rGO is produced by UV irradiation of GO solution in the presence of DMF. The use of natural sunlight as driving force for such SPCR reaction is also demonstrated. 相似文献
11.
The dispersion characteristics of commercial Si3N4 powder in aqueous media (deionized water) was studied as a function of pH in the range 2–11. The slip was characterized for
its dispersion quality by various experimental techniques like particle size analysis, sedimentation phenomena, viscosity
and flow behaviour and zeta potential analysis. The optimum dispersion was found to be in the pH region 9–11 wherein the slurry
displayed minimum sedimentation height, minimum viscosity, near Newtonian flow behaviour and maximum zeta potential. The slip
is highly agglomerated in the pH range 2–8 as manifested by higher sedimentation height, higher viscosity, lower zeta potential
and thixotropic non-Newtonian flow behaviour. The 72 wt% (44 vol.%) Si3N4 slips made at pH = 10 resulted in green bodies having 53–59% of theoretical density after casting into plaster molds. 相似文献
12.
Kaminska I Das MR Coffinier Y Niedziolka-Jonsson J Sobczak J Woisel P Lyskawa J Opallo M Boukherroub R Szunerits S 《ACS applied materials & interfaces》2012,4(2):1016-1020
An easy and environmentally friendly chemical method for the simultaneous reduction and noncovalent functionalization of graphene oxide (GO) using dopamine derivatives is described. The reaction takes place at room temperature under ultrasonication of an aqueous suspension of GO and a dopamine derivative. X-ray photoelectron spectroscopy, FT-IR spectroscopy, and cyclic voltammetry characterizations revealed that the resulting material consists of graphene functionalized with the dopamine derivative. This one-step protocol is applied for simultaneous reduction and functionalization of graphene oxide with a dopamine derivative bearing an azide function. The chemical reactivity of the azide function was demonstrated by a postfunctionalization with ethynylferrocene using the Cu(I) catalyzed 1,3-dipolar cyloaddition. 相似文献
13.
The present work was devoted to synthesis of a novel UV-stabilizer based on graphene oxide for polypropylene. Hence, we grafted a hindered amine compound on graphene oxide through an amidation reaction. Fourier transform infrared (FTIR) spectroscopy and thermo-gravimetric analysis confirmed the grafting reaction. Also, X-ray diffraction together with scanning electron microscopy showed that the grafting reaction transforms the compact layered structure of graphene oxide into finer aggregation of loosely connected particles. Polypropylene film samples containing either of graphene oxide and the functionalized graphene oxide were prepared by solution mixing/anti-solvent precipitation followed by compression molding. Transmission electron microscopy showed significantly better dispersion of the modified graphene oxide in the polymer matrix compared to the pristine graphene oxide. Afterwards, the film samples were exposed to an artificial sunlight at 25?°C. It was proved by FTIR spectroscopy and tensile test that the modified graphene oxide at a concentration of 0.5?wt. % can efficiently retard the rate of the photo-oxidation of PP. 相似文献
14.
Juan Guo Lulu Ren Ruiyu Wang Chao Zhang Yang Yang Tianxi Liu 《Composites Part B》2011,42(8):2130-2135
Graphene sheets functionalized noncovalently with aromatic amino acid, tryptophan (Tryp), were prepared by reducing graphene oxide through hydrazine hydrate. Tryp-functionalized graphene is water dispersible and can be stabilized for several months. Atomic force microscopy (AFM), X-ray diffraction (XRD), UV–vis absorption and Raman spectroscopy were used to investigate the nanostructures and the properties of graphene. Application of the graphene dispersion to poly(vinyl alcohol) (PVA) with the help of tryptophan to prepare nanocomposite was also carried out. And the PVA/graphene nanocomposite was characterized by thermogravimetric analysis (TGA) and tensile testing. A 23% improvement in tensile strength and moderate increases in Young’s modulus and thermal stability for PVA were achieved by adding only 0.2 wt% graphene sheets. 相似文献
15.
《材料与设计》2015
Graphene oxide (GO) was chemically functionalized to prepare polyurethane (PU) composites with improved mechanical and thermal properties. In order to achieve a well exfoliated and stable GO suspension in an organic solvent (dimethylformamide, DMF), 4, 4′-methylenebis(phenyl isocyanate) and polycaprolactone diol, which were the two monomers for synthesizing PU, were selectively used to functionalize GO. The obtained functionalized GO (FGO) could form homogeneous dispersions in DMF solvent and the PU matrix, as well as provide a good compatibility with the PU matrix. The most efficient improvement of mechanical properties was achieved when 0.4 wt.% FGO was added into the PU matrix, showing increases in the tensile stress, elongation at break and toughness by 34.2%, 27.6%, and 64.5%, respectively, compared with those of PU. Regarding the thermal stability, PU filled with 1 wt.% FGO showed the largest extent of improvement with T2% and T50% (the temperatures at which 2% and 50% weight-loss happened) 16 °C and 21 °C higher than those of PU, respectively. The significant improvement in both mechanical properties and thermal stability of FGO/PU composites should be attributed to the homogeneous dispersion of FGO in the PU matrix and strong interfacial interaction between them. 相似文献
16.
We demonstrate a simple method to prepare alkylated graphene/polyaniline composites (a-GR/PANI) using solution mixing of exfoliated alkyl Iodododecane treated graphene oxide sheets with polyaniline nanofiber; polyaniline nanofibers (PANI) prepared by using rapid mixing polymerization significantly improve the processibility of polyaniline and its performance in many conventional applications. Also, polyaniline nanofibers exhibit excellent water dispersibility due to their uniform nanofiber morphology. Morphological study using SEM and TEM analysis showed that the fibrous PANI in the composites a-GR/PANI mainly adsorbed onto the surface or intercalated between the graphene sheets, due especially to the good interfacial interaction between the alkylated gaphene and the polyaniline nanofibers. The existence of polyaniline nanofibers on the surface of the garphene and the alkylated graphene sheets was confirmed by using FT-IR, FT-Raman and X-ray diffraction analysis. Due to the good interfacial interaction between the alkylated graphene and the polyanilines nanofibers, the composite (a-GR/PANI) exhibited excellent dispersion stability in DMF compared to the same composite (GR/PANI) without alkylation. The electrical conductivity of the (GR/PANI) composite was 9% higher than that of pure PANI and the same weight percent for the composite after alkylation was 13% higher than that of pure PANI nanofibers. 相似文献
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18.
Functionalized graphene sheets for polymer nanocomposites 总被引:7,自引:0,他引:7
Ramanathan T Abdala AA Stankovich S Dikin DA Herrera-Alonso M Piner RD Adamson DH Schniepp HC Chen X Ruoff RS Nguyen ST Aksay IA Prud'Homme RK Brinson LC 《Nature nanotechnology》2008,3(6):327-331
Polymer-based composites were heralded in the 1960s as a new paradigm for materials. By dispersing strong, highly stiff fibres in a polymer matrix, high-performance lightweight composites could be developed and tailored to individual applications. Today we stand at a similar threshold in the realm of polymer nanocomposites with the promise of strong, durable, multifunctional materials with low nanofiller content. However, the cost of nanoparticles, their availability and the challenges that remain to achieve good dispersion pose significant obstacles to these goals. Here, we report the creation of polymer nanocomposites with functionalized graphene sheets, which overcome these obstacles and provide superb polymer-particle interactions. An unprecedented shift in glass transition temperature of over 40 degrees C is obtained for poly(acrylonitrile) at 1 wt% functionalized graphene sheet, and with only 0.05 wt% functionalized graphene sheet in poly(methyl methacrylate) there is an improvement of nearly 30 degrees C. Modulus, ultimate strength and thermal stability follow a similar trend, with values for functionalized graphene sheet- poly(methyl methacrylate) rivaling those for single-walled carbon nanotube-poly(methyl methacrylate) composites. 相似文献
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20.
We demonstrate a new approach to tune the electrical properties of graphene and functionalized graphene. Graphene was synthesized using thermal chemical vapour deposition(TCVD) method on copper foil using precursor gas acetylene and co-catalyst H2 gas. TCVD assisted graphene was successfully transferred onto a silicon wafer. Transferred graphene sheet was then functionalized to prepare graphene oxide(GO) and reduced graphene oxide(rGO). Different surface charge carbon nanoparticles, e.g. carbon nanoparticle with net positive charge and carbon nanoparticle with net negative charge were then immobilized on transferred graphene and functionalized graphene sheets. The functionalized graphene and charge mobilized functionalized graphene were characterized by Uv–vis spectroscopy,Fourier transformed infrared spectroscopy, scanning electron microscopy, and Raman spectroscopy. After immobilization of carbon nanomaterials, the ac electrical conductivity was found to increase due to enhancement of the surface charge, electron density, and mobility. It was observed that negative surface charge immobilized graphene and functionalized graphene show higher conductivity. Thus, the electrical property of graphene and functionalized graphene can be tuned by surface modification with different surface charge carbon nanomaterials. 相似文献