Non-covalent Functionalization of Graphene to Tune Its Band Gap and Stabilize Metal Nanoparticles on Its Surface.

Controlling graphene conductivity is crucial for its potential applications. With this focus, this paper shows the effect of the non-covalent bonding of a pyrimidine derivative (HIS) on the electronic properties of graphene (G). Several G-HIS hybrids are prepared through mild treatments keeping unaltered the structures of both G and HIS.

Multifunctional behavior of molecules comprising stacked cytosine-Ag-cytosine base pairs; towards conducting and photoluminescence silver-DNA nanowires.

DNA molecules containing a 1D silver array may be applied for nanotechnology applications, but first their conducting and photoluminescence behavior must be enhanced. Here we have synthesized and characterized three new helical compounds based on stacked silver-mediated cytosine base pairs [Ag(mC)]X (mC = N1-methylcytosine; X = NO (), BF () and ClO ()), that contain uninterrupted polymeric Ag chains that run through the center of the helixes, comparable to related silver-DNA structures. The exposure of nanostructures of [Ag(mC)]BF () to cold hydrogen plasma stimulates the reduction of the prearranged Ag polymeric chains to metallic silver along the material.

Grafting the surface of carbon nanotubes and carbon black with the chemical properties of hyperbranched polyamines.

Controlling the chemistry on the surface of new carbon materials is a key factor to widen the range of their applicability. In this paper we show a grafting methodology of polyalkylamines to the surface of carbon nanomaterials, in particular, carbon nanotubes and a carbon black. The aim of this work is to reach large degrees of covalent functionalization with hyperbranched polyethyleneimines (HBPEIs) and to efficiently preserve the strong chelating properties of the HBPEIs when they are fixed to the surface of these carbon materials.

A flexible pro-porous coordination polymer: non-conventional synthesis and separation properties towards CO(2)/CH(4) mixtures.

The novel coordination polymers [Cu(Hoxonic)(H(2)O)](n) (1) and [Cu(Hoxonic)(bpy)(0.5)](n)1.5 n H(2)O (2 subsetH(2)O) (H(3)oxonic: 4,6-dihydroxy-1,3,5-triazine-2-carboxylic acid; bpy: 4,4'-bipyridine) have been isolated and structurally characterised by ab initio X-ray powder diffraction.

Evaluation of the dispersive component of the surface energy of active carbons as determined by inverse gas chromatography at zero surface coverage.

The methods to obtain the dispersive component of the surface energy (gamma(s)(d)) of active carbons (AC) from inverse gas chromatography (IGC) measurements usually render values much higher than those obtained by other techniques. In this paper this is ascribed to two factors: (i) the high temperatures at that IGC measurements are carried out and (ii) the microporosity of the AC. It is shown that the temperature dependence of the area of the methylene group is an important factor in the high gamma(s)(d) values.

Use of specific surface areas in inverse gas chromatography studies at zero surface coverage.

Inverse gas chromatography (IGC) is frequently used to study adsorption processes at zero surface coverage on microporous activated carbons. This allows to determine the thermodynamic adsorption parameters as equilibrium constants, V(S), standard enthalpies of adsorption, Delta HA degrees, standard free energy of adsorption, Delta GA degrees, and so on. Nevertheless, the surface areas of the adsorbents (microporous carbons in this case) are needed for this purpose.

Surface characteristics of activated carbons obtained by pyrolysis of plasma pretreated PET.

Activated carbon materials have been prepared by pyrolysis of plasma pretreated recycled PET. The obtained carbon materials have been texturally characterized by N2 (77 K) and CO2 (273 K) adsorption. Atomic force microscopy (AFM) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) have been used to analyze the surface of the treated precursors.

On the characterization of chemical surface groups of carbon materials.

This paper deals with the use of several methods to characterize the chemical surface groups of carbon materials. Several samples embracing a wide range of acidic and basic characteristics have been used for this purpose. The quantitative determinations have been carried out by selective titrations in aqueous solutions, thermal programmed desorption connected to mass spectrometry (TPD-MS), and ammonia adsorption-desorption, measured by thermogravimetry (TG).

Surface characterisation of plasma-modified poly(ethylene terephthalate).

This paper reports the modifications produced by nitrogen and helium cold plasmas on the surface of PET. The changes have been studied by diffuse reflectance Fourier transform spectroscopy (DRIFTS), atomic force microscopy (AFM) and inverse gas-solid chromatography (IGSC). Nitrogen and oxygen atoms seem to appear on the surface of PET as a consequence of the exposure to the atmosphere after the treatments with plasmas.

Effects of oxygen and carbon dioxide plasmas on the surface of poly(ethylene terephthalate).

Poly(ethylene terephthalate) was exposed to oxygen and carbon dioxide plasmas for different periods of time. The surface-modified samples were characterized by infrared spectroscopy, atomic force microscopy, and inverse gas-solid chromatography. The main difference between both types of plasma was connected to the time scale of degradation, which was much faster when using oxygen plasma.

Effect of Some Oxidation Treatments on the Textural Characteristics and Surface Chemical Nature of an Activated Carbon.

The changes produced in an activated carbon by treatment in aqueous solutions of (NH(4))(2)S(2)O(8) and H(2)O(2) are compared with the modifications produced by oxygen plasma. These changes are monitored by measuring the textural characteristics (surface areas, porosity, pore size distributions) and surface chemical groups. The former are studied by N(2) and CO(2) adsorption, mercury porosimetry and hydrocarbon adsorption at zero surface coverage.