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ABSTRACT: We have demonstrated an effective way of covalently functionalizing graphene with a chitosan polymer via nitrene chemistry. The biofunctionalized graphene was prepared by the chemical reduction of graphene oxide using a nitrene chemistry, and then covalently grafting chitosan to the graphene surface. The effectiveness of the biofunctionalized graphene as a reinforcing filler (4 wt %) in a chitosan polymer matrix was verified by the dramatic enhancement of the mechanical properties (breaking stress = 330%, Young’s modulus = 243%) and the electrical conductivity (0.3 S/m) without much loss in the elongation-at-break. The reinforcing effect can be explained by both the homogeneous dispersion of graphene within the matrix and the strong bond arising from the intrinsically intimate contact between the graphene and the matrix. The high antimicrobial activity of the biofunctionalized graphene compared with graphene oxide and chemically reduced graphene may be because of the presence of chitosan polymer on the edges of the graphene. Our strong, antimicrobial graphene-filled composite film can be used for food packaging and for coating various biomedical devices, where bacterial surface colonization is undesirable.
Particle and Particle Systems Characterization 05/2013; · 0.49 Impact Factor
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ABSTRACT: Electrospun biopolymer-derived nanofiber webs are promising scaffolds for growing tissue and cells. However, the webs are mechanically weak and electrically insulating. We have synthesized a polyethylene oxide (PEO) nanofiber web that is pliable, tough and electrically conductive, by incorporating optically active, DNA-wrapped, double-walled carbon nanotubes. The nanotubes were individually trapped along the length of the PEO nanofiber and acted as mechanically reinforcing filler and an electrical conductor.
ACS Applied Materials & Interfaces 04/2013; · 4.53 Impact Factor
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ABSTRACT: Electrospun polyvinylidene fluoride (PVDF) nanofiber membranes have 3-dementional (3-D) open pore channel and hence have excellent application potential in Western blot. In this study we have modified electrospun PVDF nanofiber membrane by argon (Ar) plasma treatment to improve the surface hydrophilic and detection sensitivity. The results showed that the detection sensitivity of the Ar plasma-treated PVDF nanofiber membrane increased with increasing plasma treatment time without the need for a methanol pre-wet step. This suggests that the Ar plasma treated PVDF nanofiber membrane can be useful in Western blot with high sensitivity and without methanol pre-wet step.
Journal of Nanoscience and Nanotechnology 01/2013; 13(1):674-7. · 1.56 Impact Factor
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ABSTRACT: We report a mechanically strong, electrically and thermally conductive, and optically transparent shape-memory polyurethane composite which was fabricated by introducing a small amount (0.1 wt%) of high-quality graphene as a filler. Geometrically large (≈4.6 μm(2)), but highly crystallized few-layer graphenes, verified by Raman spectroscopy and transmission electron microscopy, were prepared by the sonication of expandable graphite in an organic solvent. Oxygen- containing functional groups at the edge plane of graphene were crucial for an effective stress transfer from the graphene to polyurethane. Homogeneously dispersed few-layered graphene enabled polyurethane to have a high shape recovery force of 1.8 MPa cm(-3). Graphene, which is intrinsically stretchable up to 10%, will enable high-performance composites to be fabricated at relatively low cost and we thus envisage that such composites may replace carbon nanotubes for various applications in the near future.
Macromolecular Rapid Communications 02/2012; 33(8):628-34. · 4.60 Impact Factor
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Jin Hee Kim,
Masakazu Kataoka,
Kazunori Fujisawa,
Tomohiro Tojo,
Hiroyuki Muramatsu,
Sofía M Vega-Díaz,
F Tristán-López,
Takuya Hayashi,
Yoong Ahm Kim,
Morinobu Endo,
Mauricio Terrones,
Mildred S Dresselhaus
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ABSTRACT: The dispersibility in a DNA solution of bundled multiwalled carbon nanotubes (MWCNTs), having different chemical functional groups on the CNT sidewall, was investigated by optical spectroscopy. We observed that the dispersibility of nitrogen (N)-doped MWCNTs was significantly higher than that of pure MWCNTs and MWCNTs synthesized in the presence of ethanol. This result is supported by the larger amount of adsorbed DNA on N-doped MWCNTs, as well as by the higher binding energy established between nucleobases and the N-doped CNTs. Pure MWCNTs are dispersed in DNA solution via van der Waals and hydrophobic interactions; in contrast, the nitrogenated sites within N-doped MWCNTs provided additional sites for interactions that are important to disperse nanotubes in DNA solutions.
The Journal of Physical Chemistry B 12/2011; 115(48):14295-300. · 3.70 Impact Factor
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ABSTRACT: A method of dispersing strongly bundled double-walled carbon nanotubes (DWNTs) via a homogeneous coating of mussel protein in an aqueous solution is presented. Optical activity, mechanical strength, as well as electrical conductivity coming from the nanotubes and the versatile biological activity from the mussel protein make mussel-coated DWNTs promising as a multifunctional scaffold and for anti-fouling materials.
Small 12/2011; 7(23):3292-7. · 8.35 Impact Factor
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Kazunori Fujisawa,
Tomohiro Tojo,
Hiroyuki Muramatsu,
Ana L Elías,
Sofía M Vega-Díaz,
Ferdinando Tristán-López, Jin Hee Kim,
Takuya Hayashi,
Yoong Ahm Kim,
Morinobu Endo,
Mauricio Terrones
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ABSTRACT: The thermal stability of nitrogen (N) functionalities on the sidewalls of N-doped multi-walled carbon nanotubes was investigated at temperatures ranging between 1000 °C and 2000 °C. The structural stability of the doped tubes was then correlated with the electrical conductivity both at the bulk and at the individual tube levels. When as-grown tubes were thermally treated at 1000 °C, we observed a very significant decrease in the electrical resistance of the individual nanotubes, from 54 kΩ to 0.5 kΩ, which is attributed to a low N doping level (e.g. 0.78 at% N). We noted that pyridine-type N was first decomposed whereas the substitutional N was stable up to 1500 °C. For nanotubes heat treated to 1800 °C and 2000 °C, the tubes exhibited an improved degree of crystallinity which was confirmed by both the low R value (I(D)/I(G)) in the Raman spectra and the presence of straight graphitic planes observed in TEM images. However, N atoms were not detected in these tubes and caused an increase in their electrical resistivity and resistance. These partially annealed doped tubes with enhanced electrical conductivities could be used in the fabrication of robust and electrically conducting composites, and these results could be extrapolated to N-doped graphene and other nanocarbons.
Nanoscale 09/2011; 3(10):4359-64. · 5.91 Impact Factor
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ChemSusChem 07/2011; 4(11):1595-7. · 6.83 Impact Factor
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Berichte der deutschen chemischen Gesellschaft 07/2010; 2010(27):4305 - 4308. · 2.94 Impact Factor
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ABSTRACT: We have fabricated electrically conductive, optically transparent, and mechanically strong shape-memory polyurethane film by incorporating photochemically surface-modified multiwalled carbon nanotubes (MWNTs). The oxygen functional groups on the sidewall of the MWNTs, created by vacuum ultraviolet light, provide reactive sites to bind strongly with polyurethane. The homogeneous dispersion of MWNTs is confirmed by the optical signals coming from the innermost tube (ca. 0.9 nm) of the MWNTs, not from isolated single walled carbon nanotubes. The optimally introduced functional groups as well as the judicious selection of organic solvent, both for dispersing MWNTs homogeneously and dissolving the polymer completely, are critical to fabricate high functional polyurethane film.
06/2010;
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Yoong Ahm Kim,
Hiroshi Kakegawa,
Kazunori Fujisawa,
Daisuke Shimamoto,
Hiroyuki Muramatsu, Jin Hee Kim,
Yong Chae Jung,
Takuya Hayashi,
Morinobu Endo,
Mauricio Terrones,
Mildred S Dresselhaus
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ABSTRACT: We have studied the structural parameters of catalytically grown highly disordered multi-walled carbon nanotubes that were heat treated at temperatures between 1200 degrees C and 2600 degrees C in an argon atmosphere. Rather than the interlayer spacing or the R value (the intensity of the D band divided by the intensity of the G band), we found that the half width at half maximum intensity of the G band was the most sensitive parameter that is correlated with the altered electrical conductivity of an individual carbon nanotube that had been heat treated at high temperatures. This is because one-dimensional nanocarbons exhibit a preference for two-dimensional structural development along the length of the tube due to the limited mobility of carbon atoms along the circumferential direction. Tubes heat treated at 2200 degrees C exhibited both a high electrical conductivity and an absence of lithium-ion intercalation, and thus are the best conductive filler for the active materials of lithium-ion batteries for long-term stability.
Journal of Nanoscience and Nanotechnology 06/2010; 10(6):3940-4. · 1.56 Impact Factor
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Jin Hee Kim,
Masakazu Kataoka,
Daisuke Shimamoto,
Hiroyuki Muramatsu,
Yong Chae Jung,
Takuya Hayashi,
Yoong Ahm Kim,
Morinobu Endo,
Jin Sung Park,
Riichiro Saito,
Mauricio Terrones,
Mildred S Dresselhaus
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ABSTRACT: We performed resonant Raman/fluorescence spectroscopic studies on double-walled carbon nanotubes (DWNTs) that were dispersed in an aqueous single stranded DNA solution. The luminescence signals from the inner tubes of DWNTs are intensified in the isolated state of each individual DWNT. The completely depressed radial breathing modes (RBMs) associated with the outer tubes (whether semiconducting or metallic) via the mechanical wrapping and the strong charge transfer between DNA and the outer tubes support our interpretation that the bright luminescence and sharp absorption spectra come from only the inner tubes, and not from isolated SWNTs. The circumferentially wrapped DNA on the outer tubes of individually isolated DWNTs in an aqueous solution gives rise to strong charge transfer to the semiconducting and metallic outer tubes as well as to generating physical strain in the outer tubes.
ACS Nano 02/2010; 4(2):1060-6. · 10.77 Impact Factor
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ABSTRACT: It is demonstrated that an optically transparent and electrically conductive polyethylene oxide (PEO) film is fabricated by the introduction of individualized single-walled carbon nanotubes (SWNTs). The incorporated SWNTs in the PEO film sustain their intrinsic electronic and optical properties and, in addition, the intrinsic properties of the polymer matrix are retained. The individualized SWNTs with smaller diameter provide high transmittance as well as good electrical conductivity in PEO films.
Macromolecular Rapid Communications 10/2009; 30(24):2084 - 2088. · 4.60 Impact Factor
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Jin Hee Kim,
Masakazu Kataoka,
Daisuke Shimamoto,
Hiroyuki Muramatsu,
Yong Chae Jung,
Tomohiro Tojo,
Takuya Hayashi,
Yoong Ahm Kim,
Morinobu Endo,
Mauricio Terrones,
Mildred S Dresselhaus
ChemPhysChem 08/2009; 10(14):2414-7. · 3.41 Impact Factor
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ABSTRACT: Carbon nanofibers containing palladium nanoparticles were prepared simply by electrospinning a polymer solution containing palladium chloride and the subsequent thermal treatment in argon. It is demonstrated that palladium oxide formed in air stabilization transforms into nanoparticles through an interaction with carbon materials. Since the palladium nanoparticles covering the outer surface of nanofibers homogeneously are small enough to have high catalytic activity, this material could find applications as efficient catalysts and hydrogen sensors.
Nanotechnology 04/2008; 19(14):145602. · 3.98 Impact Factor
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Leora Cooper,
Hiroki Amano,
Masayuki Hiraide,
Satoshi Houkyou,
In Young Jang,
Yong Jung Kim,
Hiroyuki Muramatsu, Jin Hee Kim,
Takuya Hayashi,
Morinobu Endo,
Mildred S Dresselhaus
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ABSTRACT: Freestanding, thin, and bendable electrodes for supercapacitors are fabricated by filtering DNA-dispersed double walled carbon nanotubes (DWNTs) into a thin film and thermally treating the film in argon. We found that DNA has the ability to disperse the strongly bundled DWNTs and is converted to phosphorus-enriched carbons, which give rise to strong redox peaks at around 0.4 V. The combination of the large capacitance from the DNA-derived carbons and the high electrical conductivity of carbon nanotubes allow DWNT/DNA films to be used as a potential electrode material for supercapacitors.
