The evolution of the particle size distribution and the surface composition of silicon carbide and titanium carbide nanoparticle (NP) dispersions were studied. The pre-dispersions were prepared using two commonly used protocols for dispersion: stirring and sonication. Two dispersants were investigated (water and Pluronic F108 1 %) at two stages: predispersion and during in vitro assays. Our data show that for each tested condition, different time-dependent results for the surface chemical composition as well as size and percentage of the agglomerates and the primary particles are observed. De-agglomeration and successive or simultaneous cleaning-wrapping cycles of the nanomaterial are observed and are related to the dispersion method and the medium as well as to the chemical stability of the NP surface. Biological response during in vitro assessment was also performed for one given pre-dispersion time condition and demonstrates that the preparation method significantly alters the results.@en

he optimization of the photocatalytic activity and hydrophilic conversion of TiO(2) is an active research area in the field of self-cleaning materials and energy storage/conversion. One major focus is the crystalline phase of TiO(2), known to be the most efficient of the anatase structures. Another issue is the decoration of TiO2 with noble metals, which act as charge carrier traps for electrons. The latter hinders or reduces the electron-hole recombination rate and often leads to a more efficient photocatalytic activity. In this paper, we describe how an interlayer consisting of 3-4 nm silver nanoparticles (Ag-NPs) promotes TiO(2) anatase crystallisation and has a positive effect on the photoinduced catalytic and hydrophylic properties of TiO2 thin films. Ag-NPs and TiO(2) were deposited by magnetron sputtering in the same reactor in a two-step process: a) condensation of Ag-NPs produced in the gas phase thanks to a high-pressure discharge, and b) conventional TiO(2) magnetron deposition in oxide mode. Four temperatures from RT to 288 degrees C were investigated and film thickness was 80 nm. Particle size and film structure were determined by TEM, HRTEM and XRD. Photocatalytic activities of the samples were tracked by the evaluation of the surface hydrophilicity after UV illumination and 24 hours post-illumination, and by UV-induced palmitic acid degradation@en

Since the discovery of carbon nanotubes (CNTs), there has been great interest in finding ways to functionalize them effectively. Cold plasma treatment of a material can graft - in a short time and with high yield - a wide range of chemical functions to the CNT surface, greatly modifying its reactivity. In this work, we present the results of the first trials performed with a special plasma reactor that can be used to functionalize larger amounts of CNTs. The reactor is a homemade, rotating, cylindrical, hollow cathode involving a fixed magnetron setup. The magnetron configuration ensures a very high plasma density. Two different gas discharges were used: nitrogen and allylamin. The plasma treatment effects were investigated by Scanning and (High Resolution) Transmission Electron Microscopy. The treated surfaces were also analysed by x-ray photoelectron spectroscopy and nuclear reaction analysis to evaluate the influence of the plasma treatment time and quantity of CNTs loaded in the hollow cathode on the nitrogen concentration. Nitrogen incorporation of up to 12% and CNTs wrapping of 20 nm thick Plasma Polymer Allylamin was achieved in 90 s.@en

Multi-walled carbon nanotubes (MWCNTs) were dispersed in water and in a Pluronic F108 solution by four different dispersion methods (stirring, bath sonication, stirring followed by bath sonication, and sonication probe). The effect of the dispersion methods were evaluated in terms of the particle size distribution, the agglomerates size, and the exfoliated fraction produced, as well as in terms of the surface and bulk chemical composition. Energy dispersive X-ray, X-ray photoelectron spectroscopy, and centrifugal liquid sedimentation techniques were used to characterize pristine MWCNTs and their dispersion. It is shown that, irrespective of the dispersion methods used, the MWCNTs are strongly wrapped with the biocompatible surfactant Pluronic F108, thereby modifying the external surface of the MWCNTs. Some shortening of MWCNTs and more wrapping are also observed when sonication methods are used. These observations raise questions as to the validity of results obtained in toxicology tests, in vitro and in vivo, were such methods of dispersion procedures are used.@en