Nanopiastrine in grafene funzionalizzato al plasma

Authors
Ana C. Estrada^a, Ernest Mendoza^b and Tito Trindade^a
a Aveiro Institute of Nanotechnology, University of Aveiro,
^b Centre de Recerca en Nanoenginyeria, Universitat Politècnica de Catalunya

Journal
Eur. J. Inorg. Chem., 2014 3184–3190
DOI: 10.1002/ejic.201402056

Abstract
Carbon nanostructures have emerged in recent decades as uniquely convenient materials for a number of technologies. Some of their envisaged applications require hybrid nanostructures that result from the coupling of semiconducting phases to the carbon materials. Here, we describe a new sonochemical method to decorate carbon-based materials (multiwalled carbon nanotubes, graphene oxide, and graphite flakes) with metal sulfide nanophases. In this research, we have used a Cd^II alkyldithiocarbamate complex as a single source to produce CdS nanophases that nucleate and grow over the carbon substrates. However, other metal sulfides can be produced by a similar methodology, which paves the way to a scalable method for the preparation of hybrid metal sulfide/carbon nanomaterials.

http://dx.doi.org/10.1002/ejic.201402056

Authors
Anna Kazmierczak-Balata ^a, Jacek Mazur ^b, Jerzy Bodzenta ^a, Dominika Trefon-Radziejewska ^a, Lukasz Drewniak ^a
a Institute of Physics-CND, Silesian University of Technology, Gliwice, Poland
^b Institute of Non Ferrous Metals, Gliwice, Poland

Journal
Int J Thermophys 2014?
DOI: 10.1007/s10765-014-1574-8

Abstract
This work presents an analysis of the influence of graphene reinforcement on properties of silicon carbide composites. Samples were prepared by a spark plasma sintering method. The density and hardness were obtained in the preliminary experiments. The thermal diffusivity was determined by the continuous wave photothermal technique with detection based on infrared radiometry. The thermal diffusivity is in the range of (0.48 to 0.57) cm²⋅s⁻¹ for samples prepared from granulated SiC and in the range of (0.56 to 0.71) cm²⋅s⁻¹ for samples prepared from SiC powder. Thermal properties are correlated with the density of SiC ceramics. The thermal diffusivity of samples with a higher density is lower in comparison to samples with a lower density.

http://dx.doi.org/10.1007/s10765-014-1574-8

Authors
John Williams ^a, Neil Graddage ^b, Sameer Rahatekar ^a
a ACCIS, Dept. Aerospace Engineering, University of Bristol
^b Welsh Centre for Printing and Coating, Swansea University

Journal
Composites: Part A, 2013, 54, 173–181
DOI: 10.1016/j.compositesa.2013.07.018

Abstract
Fibre reinforced pre-preg systems have very good in plane properties, however they are weak in their through thickness (z) direction. This research aims to address this issue by adding plasma treated carbon nanotubes (CNTs) between the prepreg plies using a simple drawdown coating procedure. The significant test result shows by coating carbon nanotubes with a relatively low areal density (1.2 g/m²) the propagation mode I toughness can be improved by up to 46%. Crack deviation leading to increased glass fibre bridging was observed for lower CNT coating concentrations explaining the improved performance. However at the highest areal coating density (2.0 g/m²) fibre bridging disappeared and a stick–slip crack response was observed resulting in lower delamination resistance. This research demonstrates a simple method to incorporate a nanointerlayer that can manipulate crack propagation, leading to increased delamination resistance.

http://dx.doi.org/10.1016/j.compositesa.2013.07.018

Authors
J. Williams ^a, W. Broughton ^b, T. Koukoulas ^b, S. S. Rahatekar ^a
a ACCIS, Department of Aerospace Engineering, University of Bristol,
^b Materials Division, National Physical Laboratory

Journal
Journal of Materials Science, 48, (3), 1005-1013
DOI: 10.1007/s10853-012-6830-3

Abstract
This study reports on the results of plasma-treated carbon nanotubes (CNTs) in the presence of oxygen and ammonia which can be scaled up for relatively large quantities of nanomaterials. The plasma treatment has been shown to change the surface chemistry and energy as well as the morphology of the carbon nanotubes. X-ray photoelectron spectroscopy analysis shows increases in oxygen and nitrogen groups on the oxygen- and ammonia-treated CNTs, respectively. Titration of the enhanced oxygen plasma-treated CNTs reveals an increased presence of carboxylic acid groups at 2.97 wt% whilst bulk density decreases from 151 kg/m³ for untreated carbon nanotubes to 76 kg/m³ after the enhanced oxygen treatment. The free surface energy has also been shown to increase from 33.70 up to 53.72 mJ/m² determined using a capillary rise technique. The plasma-treated carbon nanotubes have been mixed in epoxy and have shown an improvement in dispersion, which was quantitatively evaluated using an optical coherence tomography (OCT) technique shown to be suitable for nanocomposite characterisation. This research has demonstrated that it is possible to surface functionalise large quantities of carbon nanotubes in a single process, and that this process improves the dispersion of the carbon nanotubes in epoxy.

http://dx.doi.org/10.1007/s10853-012-6830-3

Authors
J. Baker ^a, D. Deganello ^a, D. T. Gethin ^a, T. M. Watson ^a
a Welsh Centre for Printing and Coating, Swansea University, Swansea, UK
^b SPECIFIC, Swansea University, Baglan Bay Innovation Centre, Baglan, UK

Journal
Energy Materials, 2014, 9, (1), 86-90
DOI: 10.1179/1433075X14Y.0000000203

Abstract
A semitransparent catalytically active graphene nanoplatelet (GNP) ink was developed suitable for roll to roll printing onto a flexible indium tin oxide substrate at a speed of 0?4 m s21. Dye sensitised solar cells using this ink as a catalyst demonstrated efficiencies of 2.0%, compared with 2.6% for sputtered platinum. Given further optimisation, GNP inks have the potential to replace chemically reduced or sputtered platinum. This would have the benefit of replacing the chemical reduction or sputtering operations as well as providing potential material cost benefits.

http://dx.doi.org/10.1179/1433075X14Y.0000000203

Authors
Mahesh Kumar Mani ^a, Giuseppe Viola ^{b c}, Mike J. Reece ^{b c}, Jeremy P. Hal ^a, Sam L. Evans ^d
a Wolfson Centre for Magnetics, Cardiff School of Engineering, Cardiff University, UK
^b School of Engineering and Materials Science, Queen Mary University of London, UK
^c Nanoforce Technology Limited, London, UK
^d Institute of Mechanical and Manufacturing Engineering, Cardiff University, UK

Journal
Materials Science and Engineering: B 2014, 188, 94–101
DOI: 10.1016/j.mseb.2014.06.009

Abstract
Fe–50Co matrix composites containing 1.5 and 3 vol% of electroless Ni–P plated carbon nanotubes (CNTs) were densified using spark plasma sintering. The powder mixtures for the composites were prepared by two different routes: (a) ultrasonication only; and (b) ultrasonication followed by dry ball milling. Drying of the Ni–P plated CNTs under atmospheric conditions in the presence of ethanol promoted the nucleation and growth of graphene oxide on the coating. The ball milling route was found to be the most efficient method to disperse the coated nanotubes uniformly in the matrix. The addition of coated CNTs, which formed Taenite phase with the matrix alloy, made the composites to exhibit: (a) higher ductility, higher flexural strength, lower coercivity (H_c) and lower saturation induction (B_sat) compared to the monolithic material; and (b) higher ductility, higher flexural strength, higher H_c and lower B_sat in relation to the material with similar amount of bare CNTs.

http://dx.doi.org/10.1016/j.mseb.2014.06.009

Authors
Rafael J. Zaldivar ^a, Paul M. Adams, Hyun I. Kim, James P. Nokes and Dhruv N. Patel
^a Materials Science Department, The Aerospace Corporation, El Segundo, California

Journal
Journal of Applied Polymer Science, 2014, 131, (18)
DOI: 10.1002/app.40802

Abstract
Nanographitic materials are gaining enormous interest as a new class of reinforcement for nanocomposites, promising revolutionary electrical, thermal, and mechanical properties. However, the progress has been quite limited especially in terms of mechanical properties. Here we report a significant leap, >2× increases in tensile strength and modulus of an epoxy composite using surface treated graphite nanoplatelets (GnPs). This corroborated by increases in T_gs as well as the presence of oxygen-functionalized groups verified by XPS, suggest improved distribution and chemical interaction at the filler-to-matrix interface. Toughness values also showed increases with concentration, without compromising the strength or failure strain. However, if solvent levels during degassing were not reduced sufficiently, negligible contributions to strength and stiffness were observed with GnP loading. Subsequent elevated temperature treatments increased the strength of the composite due to cure enhancement of the matrix material, yet did not provide mechanical enhancements due to the incorporation of the filler.

http://dx.doi.org/10.1002/app.40802

Authors
Titash Mondal ^a, Anil K. Bhowmick ^a and Ramanan Krishnamoorti ^b
a Department of Chemistry, Indian Institute of Technology, Patna, India
^b Department of Chemical and Biomolecular Engineering, University of Houston, USA

Journal
Journal of Materials Chemistry A, 2013, 1, (28), 8144-8153
DOI: 10.1039/C3TA11212H

Abstract
Two effects of an organolithium reagent (n-butyl lithium) on graphene and expanded graphite are reported. Its ability to simultaneously scavenge protons and act as a nucleophile leads to a bi-functionalized graphitic system. Subsequent treatment with carbon dioxide gas generates carboxylic functionality at the proton abstraction sites. This technique promises a greenermethod for single pot carboxylation for graphitic materials. The nucleophilicity of n-butyl lithiumleads to efficient grafting of butyl groups. Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and thermogravimetric analysis are used to prove the success of the reaction. Raman spectroscopy reveals more defect sites for expanded graphite compared to graphene, which leads to a higher degree of functionalization. Atomic force microscopyshows that the functional groups generated are nano-spike-shaped pendant structures attached to the graphene. These functionalized materials are used as adsorbers for efficient and fast removal of water-soluble dyes by non-covalent interaction between the dye and the carboxylic groups of the graphitic system. Spectrometric as well as kinetic studies are reported for crystal violet lactone dye adsorption. Both the modified materials show twice the adsorption capacity of the pristine materials. Superior dye adsorption properties were observed for the modified materials compared to graphene oxide.

http://dx.doi.org/10.1039/C3TA11212H

Authors
Ricardo M. F. Fernandes ^{a b}, Matat Buzaglo ^c, Michael Shtein ^c, Ilan Pri Bar ^c, Oren Regev ^c, Eduardo F. Marques ^a, and István Furó ^b
a Centro de Investigação em Química, University of Porto, Portugal
^b Division of Applied Physical Chemistry, KTH Royal Institute of Technology, Sweden
^c Ben-Gurion University of the Negev, Israel

Journal
J. Phys. Chem. C, 2014, 118, (1), 582–589
DOI: 10.1021/jp4114046

Abstract
Noncovalent dispersion of carbon nanotubes is essential to most applications but still poorly understood at the molecular level. The interaction of the dispersing molecule with the nanotube, wrapping or nonwrapping, still awaits consensus. Herein, we have studied by ¹H NMR diffusometry some features of molecular dynamics in the system of carbon nanotubes dispersed by triblock copolymer Pluronics F127 in water. The diffusional decays obtained at different diffusion times, Δ, are not single-exponential and have a complex Δ-dependent profile, ultimately implying that the polymer is observed in two states: free (in unimeric form) and nanotube-bound. Fitting a two-site exchange model to the data indicates that at any instant, only a small fraction of polymers are adsorbed on the nanotubes, with polydisperse residence times in the range of 100–400 ms. Most significantly, we further provide an estimate of D = (3–8) × 10^–12 m² s^–1 for the coefficient of lateral diffusion of the polymer along the nanotube surface, which is an order of magnitude slower than the corresponding self-diffusion coefficient in water. The emerging picture is that of a nonwrapping mode for the polymer–nanotube interaction.

http://dx.doi.org/10.1021/jp4114046

Authors
Titash Mondal ^a, Anil K. Bhowmick ^a and Ramanan Krishnamoorti ^b
a Department of Chemistry, Indian Institute of Technology Patna, India
^b Department of Chemical and Biomolecular Engineering, University of Houston, USA

Journal
J. Mater. Chem., 2012, 22, 22481-22487
DOI: 10.1039/C2JM33398H

Abstract
Facile synthesis of a chlorophenyl decorated graphene (CBG) sheet synthesized by a solventfree green diazotization technique is reported here. The functionalization of the material was supported by various characterization techniques including Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), infrared spectroscopy (IR) and thermal analysis. About 15 percent grafting, as determined by XPS and IR spectroscopy, could be achieved under the conditions employed. The CBG sheet was applied for the first time as a potential antibacterial agent on Gram negative bacteria Escherichia coli and Gram positive bacteria Staphylococcus aureus. The antibacterial character was quantified using the MacFarland number technique whereby the volumetric number density of colony forming units was determined. It was also quantified by a Kirby–Bauer test, where the zone formed due to mortality of bacteria caused by chlorine groups attached to the graphene was estimated by a mathematical model. Based on the zone of inhibition created, CBG was found to be more than twice as effective as unmodifiedgraphene and graphene oxide. The synthesis promises to open up a new avenue for the development of chemically converted graphene based antimicrobial agents.

http://dx.doi.org/10.1039/C2JM33398H

Authors
M.J. Eaton, W. Ayre, M. Williams, R. Pullin and S.L. Evans

Journal
16th International Conference on Experimental Mechanics

Abstract
The research leading to these results has received funding from the European Community's Seventh Framework Programme (FP7/2007-2013) for the Clean Sky Joint Technology Initiative under grant agreement n^° JTI-CS-2011-2-GRA-01-038. The project aims to develop nano-particle reinforced carbon fibre epoxy composites, manufactured by resin infusion (RI), for improved compression after impact (CAI) performance; thus facilitating lighter weight structures with lower manufacturing costs.

http://www.icem16.org/resumes/r_3YI8K54D.pdf