Surface modification of detonation nanodiamonds by the perfluorobutyl radical

The method was developed for surface defunctionalization of detonation nanodiamonds by substitution of a perfluorinated organic radical for hydroxyl and carboxyl groups. Size-mass distributions of modified particles of detonation nanodiamonds in water and toluene were studied     

Structure of oriented fibers based on poly(vinyl alcohol) modified by detonation nanodiamonds

A comparative study of the structure and mechanical and thermal characteristics of nanocomposite oriented fibers based on poly(vinyl alcohol) impregnated with the nanodiamonds prepared by detonation synthesis and fibers based on the initial unmodified polymer has been performed. The conditions and regimes of gel spinning of the nanocomposite fibers containing highly dispersed nanosized filler without its aggregation are defined. The introduction of nanosized filler particles up to 7 vol % is found to entail no marked changes in the temperature intervals of glass transition and melting in the corresponding DSC thermograms. In this case, the amorphous-crystalline structure of the matrix polymer likewise remains practically unchanged. Under the selected conditions of gel spinning, the resultant nanocomposite fibers with comparable draw ratios are characterized by a higher longitudinal elastic modulus, close values of breaking strength, and lower values of elongation at break as compared with those observed for the fibers based on the initial unmodified polymer. The nanomodified fibers show promise as reinforcing elements in construction materials for various purposes.     

Peculiarities of atomic hydrogen interactions with detonation nanodiamonds

Hydrogen treatment is a popular way of surface modification of nanodiamonds. Here, we used atomic hydrogen treatment of the functionalized surface to increase its hydrophobicity gently and maintain its overall composition. Corresponding mechanism was revealed via combination of theoretical and experimental methods.     

The role of mineral surface chemistry in modified dextrin adsorption

The adsorption of two modified dextrins (phenyl succinate dextrin--PS Dextrin; styrene oxide dextrin--SO Dextrin) on four different mineral surfaces has been studied using X-ray photoelectron spectroscopy (XPS), in situ atomic force microscopy (AFM) imaging, and captive bubble contact angle measurements. The four surfaces include highly orientated pyrolytic graphite (HOPG), freshly cleaved synthetic sphalerite (ZnS), and two surfaces produced through surface reactions of sphalerite: one oxidized in alkaline solution (pH 9, 1 h immersion); and one subjected to metal ion exchange between copper and zinc (i.e. copper activation: exposed to 1×10(-3) M CuSO(4) solution for 1 h). XPS measurements indicate that the different sphalerite surfaces contain varying amounts of sulfur, zinc, oxygen, and copper, producing substrates for polymer adsorption with a range of possible binding sites. AFM imaging has shown that the two polymers adsorb to a similar extent on HOPG, and that the two polymers display very different propensities for adsorption on the three sphalerite surface types, with freshly cleaved sphalerite encouraging the least adsorption, and copper activated and oxidized sphalerite encouraging significantly more adsorption. Contact angle measurements of the four surfaces indicate that synthetic sphalerite has a low contact angle upon fracture, and that oxidation on the timescale of one hour substantially alters the hydrophobicity. HOPG and copper-activated sphalerite were the most hydrophobic, as expected due to the carbon and di/poly-sulfide rich surfaces of the two samples, respectively. SO Dextrin is seen to have a significant impact on the wettability of HOPG and the surface reacted sphalerite samples, highlighting the difficulty in selectively separating sphalerite from carbonaceous unwanted minerals in flotation. PS Dextrin has the least effect on the hydrophobicity of the reacted sphalerite surfaces, whilst still significantly increasing the wettability of graphite, and thus has more potential for use as a polymer depressant in this separation.     

An approach to unification of the physicochemical properties of commercial detonation nanodiamonds

Russian Journal of General Chemistry - In recent years, detonation nanodiamond is regarded as a promising material for biomedical applications. However, a significant problem that stops of...     

Development of a rational technology for synthesis of high-quality detonation nanodiamonds

Concepts concerning the structure of detonation nanodiamonds were generalized on the basis of data reported in previous publications. The pH value of the nanodiamonds in an aqueous suspension was determined. The mechanism of the longest stage, washing of nanodiamonds with water to remove excess acidity, was considered. A novel method for substantially improving the quality of nanodiamonds and the stability of aqueous suspensions of nanodiamonds was suggested.     

Modified method for synthesis of detonation nanodiamonds and their real elemental composition

Modified technique for synthesis of detonation nanodiamonds by exploding a charge of high explosives in a water shell is described. Reducing agents are introduced into water. Their use enables solution of a number of problems: the carbon content of nanodiamonds is raised from 90 to 96 wt %, the content of incombustible admixtures is dramatically diminished from 3 to 0.1 wt %, and the yield of detonation nanodiamonds becomes two times higher. A new method for determining the elemental composition is described and the oxidation of nanodiamonds under heating in the presence of atmospheric oxygen is analyzed.     

Environmental issues related to preparation of detonation nanodiamonds. Surface and functionalization

Specific features of the preparation of detonation nanodiamond (DND) surface were considered from the viewpoint of their subsequent use in biology and medicine. Particular attention was given to quantitative determination of groups containing a labile proton on the DND particle surface. It was proposed to use only physical drying techniques to improve environmental parameters of DND surface functionalization techniques. The proposed procedure ensured for the first time additional purification of DND from latent carbon, which considerably improved their environmental properties.     

Effect of alkylpyridinium chlorides on aggregation stability of aqueous dispersions of detonation nanodiamonds

Adsorption of decyl-, dodecyl-, and hexadecylpyridinium chlorides (DePC, DoPC, and CPC, respectively) from aqueous solutions on the surface of detonation nanodiamonds (NDs) and its effect on the aggregation stability of ND hydrosols are studied. Hydrophobic interactions, which are enhanced with the length of hydrocarbon chains in surfactant molecules, are found to play the main role in surfactant adsorption on the ND surface. DePC is almost not adsorbed on NDs, and its addition has no effect on both the size and ζ potential of nanoparticles. Adsorption of DoPC decreases the ζ potential of ND particles, thus causing their coagulation. Superequivalent adsorption of CPC results in sign reversal of the ζ potential of ND particles, thereby leading to alternation of the zones of aggregation stability and coagulation of the hydrosols with a rise in the concentration of this surfactant.     

On the applicability of nanodiamonds produced by detonation synthesis for phenol testing in aqueous media

It was found that the catalytic effect of modified nanodiamonds (MND) in the H₂O₂–4-aminoantipyrine–phenol oxidative azo coupling reaction is due to microimpurities of iron and copper ions on the surface of nanoparticles. The efficiency of MND as a catalyst is determined by the amount of surface impurities of these ions and can be doubled by their additional adsorption on nanoparticles. Using MND for phenol indication ensures a linear yield of the colored product of the azo coupling reaction over an analyte concentration range of 0.05–10 μg/mL. The possibility of reusing MND for phenol testing in aqueous samples was demonstrated.     

Voltammetry of pharmaceuticals using different types of modified electrodes

Summary Cyclic voltammetry was used to study the electrochemical behaviour of several chemically interesting drugs on different types of carbon based electrodes. The behaviours of the carbon paste and glassy carbon electrodes were investigated and compared with the results obtained with home-made new types of modified electrodes based on colloidal graphite or carbon black dispersed in a suitable polymer. The behaviour of the couple hexacyanoferrate-(II/ III) has been reported as a typical model of depolarizer. It has been shown that electrode responses were markedly influenced by the nature of the substrate. Performances of each electrode have been evaluated with regard to the shape of the voltammetric curves obtained during the investigation of these drugs.

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Voltammetrie von Pharmazeutica mit Hilfe verschiedener Typen von modifizierten Elektroden

Zusammenfassung Das elektrochemische Verhalten mehrerer chemisch interessanter Pharmazeutica an verschiedenen Kohlenstoff-Elektroden wurde mit Hilfe der cyclischen Voltammetrie untersucht. Die Eigenschaften der Kohlenstoffpaste-Elektrode und der Glaskohlenstoff-Elektrode wurden geprüft und verglichen mit denjenigen von selbst hergestellten modifizierten Elektroden auf der Basis von kolloidalem Graphit und in einem geeigneten Polymer dispergiertem Ruß. Das Verhalten des Hexacyanoferrat(II/III)-Paares wurden als typisch für einen Depolarisator angesehen. Es konnte gezeigt werden, daß das Ansprechen der Elektrode von der Art des Substrats deutlich beeinflußt wird. Die Leistungsfähigkeit jeder Elektrode wurde an Hand der voltammetrischen Kurven der verschiedenen Pharmaca ausgewertet.

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Thanks are expressed to the Fonds National de la Recherche Scientifique (F.N.R.S. Belgium) to one of us (G.J.P.) for partial support of this work.     

Structure and mechanical properties of thermoplastics modified with nanodiamonds

The structure and properties of composite materials based on amorphous thermoplastics and detonation nanodiamonds are studied. The conception of the “rheological method” is advanced for compatibilization of a polymer and a filler under the regime of elastic turbulence (spurt) for preparation of composites with a high level of dispersion and a homogeneous distribution of nanodiamond particles. As a rule, the dependences of strength and physicomechanical characteristics of the nanocomposites on the content of the dispersed phase are described by curves with an extremum or saturation. The concentration of the filler corresponding to the extremum or the approach to the plateau value for a specific parameter depends on the nature of the polymer matrix and is attained at filler contents below 2.5 wt %. The elastic modulus monotonically increases as the content of nanodiamonds is increased to 5 wt %.     

Regularities of retention of benzoic acids on microdispersed detonation nanodiamonds in water-methanol mobile phases

The dependences of the retention of benzoic acids on microdispersed sintered detonation nanodiamond (MSDN) on the concentration of the organic solvent in the eluent and the temperature of the chromatographic column under conditions of high-performance liquid chromatography (HPLC) are investigated. It is found that in the investigated range of methanol concentrations, the acids are retained by different mechanisms: at methanol contents of the eluent lower than 85%, retention decreases with increasing methanol concentration and increases at higher concentrations of the organic solvent. It is shown that retention of benzoic acids on MSDN under these conditions depends on the dissociation constant of the investigated substances. A comparison is made between the properties of MSDN and analogous properties of porous graphitic carbon.     

Irradiation of detonation nanodiamonds with γ-rays does not produce long living spin radicals

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Effect of detonation nanodiamonds on the electrocatalytic activity of asymmetric cobalt phthalocyanine: Covalent versus non-covalent linking

We report on the effect of detonation nanodiamonds (DNDs) on electrocatalytic properties of an asymmetrically substituted cobalt phthalocyanine (CoPc). The incorporation of DNDs onto cobalt phthalocyanine enhances its electrochemical behaviour. An asymmetrical CoPc alone, when π-π stacked (CoPc-DNDs(ππ)) or covalently linked (CoPc@DNDs) to DNDs is used to modify a glassy carbon electrode (GCE) for the electrocatalytic detection of hydrazine. In addition, the GCE was modified by sequentially adding CoPc and DNDs onto its surface, represented as GCE/CoPc-DNDs(seq) when CoPc is placed before DNDs on the electrode and GCE/DNDs-CoPc(seq) when DNDs are placed before CoPc, where seq represents sequential. The obtained catalytic rate for the detection of hydrazine on GCE/CoPc@DNDs was 9.3×10⁴ M⁻¹.s⁻¹ with a limit of detection as 0.33 μM. GCE/CoPc@DNDs gave better electrocatalytic activities when compared to its counterparts.     

Evidence for different types of sites on alumina surface

PASCA has been used to search for evidence on different types of sites existing on alumina surfaces. The results indicate that PtCl ₆ ^2– interacts with different surface sites, forming MSI complexes PtO_xCl_y–S_k, PtO_xCl_y–S_s and PtO_xCl_y–St. Surface sites in different aluminas may be different in chemical and electronic properties.

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. PtCl₆ ^2– , PtO_xCl_y–S_k, PtO_xCl_y–S_S PtO_xCl_y–S_t. .